CLDSRV-320 [8.1] bump version to 8.1.93

2023-04-04 11:27:03 -07:00
131 changed files with 11556 additions and 15398 deletions
--- a/.eslintrc
+++ b/.eslintrc
@ -1,6 +1 @@
-{
+{ "extends": "scality" }
    "extends": "scality",
    "parserOptions": {
        "ecmaVersion": 2020
    }
 }
--- a/.github/workflows/codeql.yaml
+++ b/.github/workflows/codeql.yaml
@ -1,25 +0,0 @@
 ---
 name: codeQL
 on:
  push:
    branches: [development/*, stabilization/*, hotfix/*]
  pull_request:
    branches: [development/*, stabilization/*, hotfix/*]
  workflow_dispatch:
 jobs:
  analyze:
    name: Static analysis with CodeQL
    runs-on: ubuntu-latest
    steps:
      - name: Checkout code
        uses: actions/checkout@v4
      - name: Initialize CodeQL
        uses: github/codeql-action/init@v3
        with:
          languages: javascript, typescript
      - name: Build and analyze
        uses: github/codeql-action/analyze@v3
--- a/.github/workflows/dependency-review.yaml
+++ b/.github/workflows/dependency-review.yaml
@ -1,16 +0,0 @@
 ---
 name: dependency review
 on:
  pull_request:
    branches: [development/*, stabilization/*, hotfix/*]
 jobs:
  dependency-review:
    runs-on: ubuntu-latest
    steps:
      - name: 'Checkout Repository'
        uses: actions/checkout@v4
      - name: 'Dependency Review'
        uses: actions/dependency-review-action@v4
--- a/.github/workflows/tests.yaml
+++ b/.github/workflows/tests.yaml
@ -25,8 +25,8 @@ jobs:
          - 6379:6379
    steps:
    - name: Checkout
-      uses: actions/checkout@v4
+      uses: actions/checkout@v2
-    - uses: actions/setup-node@v4
+    - uses: actions/setup-node@v2
      with:
        node-version: '16'
        cache: 'yarn'
@ -46,9 +46,7 @@ jobs:
      run: yarn --silent coverage
    - name: run functional tests
      run: yarn ft_test
-    - uses: codecov/codecov-action@v4
+    - uses: codecov/codecov-action@v2
      with:
        token: ${{ secrets.CODECOV_TOKEN }}
    - name: run executables tests
      run: yarn install && yarn test
      working-directory: 'lib/executables/pensieveCreds/'
@ -59,9 +57,9 @@ jobs:
    runs-on: ubuntu-latest
    steps:
    - name: Checkout
-      uses: actions/checkout@v4
+      uses: actions/checkout@v2
    - name: Install NodeJS
-      uses: actions/setup-node@v4
+      uses: actions/setup-node@v2
      with:
        node-version: '16'
        cache: yarn
@ -72,7 +70,7 @@ jobs:
      run: yarn build
      continue-on-error: true # TODO ARSN-97 Remove it when no errors in TS
    - name: Upload artifacts
-      uses: scality/action-artifacts@v4
+      uses: scality/action-artifacts@v2
      with:
        url: https://artifacts.scality.net
        user: ${{ secrets.ARTIFACTS_USER }}
--- a/.swcrc
+++ b/.swcrc
@ -1,12 +0,0 @@
 {
  "$schema": "https://swc.rs/schema.json",
  "jsc": {
    "parser": {
      "syntax": "typescript"
    },
    "target": "es2017"
  },
  "module": {
    "type": "commonjs"
  }
 }
--- a/documentation/BucketInfoModelVersion.md
+++ b/documentation/BucketInfoModelVersion.md
@ -246,15 +246,3 @@ For capacity-enabled buckets, contains the following data:
 ### Usage
 Used to store bucket tagging
 ## Model version 17
 ### Properties Added
 ```javascript
 this._quotaMax = quotaMax || 0;
 ```
 ### Usage
 Used to store bucket quota
--- a/documentation/listingAlgos/delimiter.md
+++ b/documentation/listingAlgos/delimiter.md
@ -1,27 +0,0 @@
 # Delimiter
 The Delimiter class handles raw listings from the database with an
 optional delimiter, and fills in a curated listing with "Contents" and
 "CommonPrefixes" as a result.
 ## Expected Behavior
 - only lists keys belonging to the given **prefix** (if provided)
 - groups listed keys that have a common prefix ending with a delimiter
  inside CommonPrefixes
 - can take a **marker** or **continuationToken** to list from a specific key
 - can take a **maxKeys** parameter to limit how many keys can be returned
 ## State Chart
 - States with grey background are *Idle* states, which are waiting for
  a new listing key
 - States with blue background are *Processing* states, which are
  actively processing a new listing key passed by the filter()
  function
 ![Delimiter State Chart](./pics/delimiterStateChart.svg)
--- a/documentation/listingAlgos/delimiterMaster.md
+++ b/documentation/listingAlgos/delimiterMaster.md
@ -1,45 +0,0 @@
 # DelimiterMaster
 The DelimiterMaster class handles raw listings from the database of a
 versioned or non-versioned bucket with an optional delimiter, and
 fills in a curated listing with "Contents" and "CommonPrefixes" as a
 result.
 ## Expected Behavior
 - only lists latest versions of versioned buckets
 - only lists keys belonging to the given **prefix** (if provided)
 - does not list latest versions that are delete markers
 - groups listed keys that have a common prefix ending with a delimiter
  inside CommonPrefixes
 - can take a **marker** or **continuationToken** to list from a specific key
 - can take a **maxKeys** parameter to limit how many keys can be returned
 - reconciles internal PHD keys with the next version (those are
  created when a specific version that is the latest version is
  deleted)
 - skips internal keys like replay keys
 ## State Chart
 - States with grey background are *Idle* states, which are waiting for
  a new listing key
 - States with blue background are *Processing* states, which are
  actively processing a new listing key passed by the filter()
  function
 ### Bucket Vformat=v0
 ![DelimiterMaster State Chart for v0 format](./pics/delimiterMasterV0StateChart.svg)
 ### Bucket Vformat=v1
 For buckets in versioning key format **v1**, the algorithm used is the
 one from [Delimiter](delimiter.md).
--- a/documentation/listingAlgos/pics/delimiterMasterV0StateChart.dot
+++ b/documentation/listingAlgos/pics/delimiterMasterV0StateChart.dot
@ -1,45 +0,0 @@
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  "NotSkippingPrefixNorVersions.Idle" [label="NotSkippingPrefixNorVersions",group="NotSkippingPrefixNorVersions",width=4];
  "SkippingPrefix.Idle" [label="SkippingPrefix",group="SkippingPrefix"];
  "SkippingVersions.Idle" [label="SkippingVersions",group="SkippingVersions"];
  "WaitVersionAfterPHD.Idle" [label="WaitVersionAfterPHD",group="WaitVersionAfterPHD"];
  node [fillcolor="lightblue"];
  "NotSkippingPrefixNorVersions.Processing" [label="NotSkippingPrefixNorVersions",group="NotSkippingPrefixNorVersions",width=4];
  "SkippingPrefix.Processing" [label="SkippingPrefix",group="SkippingPrefix"];
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  "SkippingPrefix.Idle" -> "SkippingPrefix.Processing" [label="filter(key, value)"]
  "SkippingVersions.Idle" -> "SkippingVersions.Processing" [label="filter(key, value)"]
  "WaitVersionAfterPHD.Idle" -> "WaitVersionAfterPHD.Processing" [label="filter(key, value)"]
  "NotSkippingPrefixNorVersions.Processing" -> "SkippingVersions.Idle" [label="[Version.isDeleteMarker(value)]\n-> FILTER_ACCEPT"]
  "NotSkippingPrefixNorVersions.Processing" -> "WaitVersionAfterPHD.Idle" [label="[Version.isPHD(value)]\n-> FILTER_ACCEPT"]
  "NotSkippingPrefixNorVersions.Processing" -> "SkippingPrefix.Idle" [label="[key.startsWith(<ReplayPrefix>)]\n/ prefix <- <ReplayPrefix>\n-> FILTER_SKIP"]
  "NotSkippingPrefixNorVersions.Processing" -> END [label="[isListableKey(key, value) and\nKeys == maxKeys]\n-> FILTER_END"]
  "NotSkippingPrefixNorVersions.Processing" -> "SkippingPrefix.Idle" [label="[isListableKey(key, value) and\nnKeys < maxKeys and\nhasDelimiter(key)]\n/ prefix <- prefixOf(key)\n/ CommonPrefixes.append(prefixOf(key))\n-> FILTER_ACCEPT"]
  "NotSkippingPrefixNorVersions.Processing" -> "SkippingVersions.Idle" [label="[isListableKey(key, value) and\nnKeys < maxKeys and\nnot hasDelimiter(key)]\n/ Contents.append(key, value)\n-> FILTER_ACCEPT"]
  "SkippingPrefix.Processing" -> "SkippingPrefix.Idle" [label="[key.startsWith(prefix)]\n-> FILTER_SKIP"]
  "SkippingPrefix.Processing" -> "NotSkippingPrefixNorVersions.Processing" [label="[not key.startsWith(prefix)]"]
  "SkippingVersions.Processing" -> "SkippingVersions.Idle" [label="[isVersionKey(key)]\n-> FILTER_SKIP"]
  "SkippingVersions.Processing" -> "NotSkippingPrefixNorVersions.Processing" [label="[not isVersionKey(key)]"]
  "WaitVersionAfterPHD.Processing" -> "NotSkippingPrefixNorVersions.Processing" [label="[isVersionKey(key) and master(key) == PHDkey]\n/ key <- master(key)"]
  "WaitVersionAfterPHD.Processing" -> "NotSkippingPrefixNorVersions.Processing" [label="[not isVersionKey(key) or master(key) != PHDkey]"]
 }
--- a/documentation/listingAlgos/pics/delimiterMasterV0StateChart.svg
+++ b/documentation/listingAlgos/pics/delimiterMasterV0StateChart.svg
@ -1,216 +0,0 @@
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 <text text-anchor="middle" x="609.5" y="-204.8" font-family="Times,serif" font-size="14.00">[nKeys &lt; maxKeys and hasDelimiter(key)]</text>
 <text text-anchor="middle" x="609.5" y="-189.8" font-family="Times,serif" font-size="14.00">/ prefix &lt;&#45; prefixOf(key)</text>
 <text text-anchor="middle" x="609.5" y="-174.8" font-family="Times,serif" font-size="14.00">/ CommonPrefixes.append(prefixOf(key))</text>
 <text text-anchor="middle" x="609.5" y="-159.8" font-family="Times,serif" font-size="14.00">&#45;&gt; FILTER_ACCEPT</text>
 </g>
 <!-- SkippingPrefix.Processing&#45;&gt;SkippingPrefix.Idle -->
 <g id="edge12" class="edge">
 <title>SkippingPrefix.Processing&#45;&gt;SkippingPrefix.Idle</title>
 <path fill="none" stroke="black" d="M593.49,-36.23C591.32,-50.84 586,-71.39 573,-84 567.75,-89.09 561.77,-93.45 555.38,-97.17"/>
 <polygon fill="black" stroke="black" points="553.66,-94.12 546.43,-101.87 556.91,-100.32 553.66,-94.12"/>
 <text text-anchor="middle" x="672" y="-72.8" font-family="Times,serif" font-size="14.00">[key.startsWith(prefix)]</text>
 <text text-anchor="middle" x="672" y="-57.8" font-family="Times,serif" font-size="14.00">&#45;&gt; FILTER_SKIP</text>
 </g>
 <!-- SkippingPrefix.Processing&#45;&gt;NotSkippingPrefix.Processing -->
 <g id="edge13" class="edge">
 <title>SkippingPrefix.Processing&#45;&gt;NotSkippingPrefix.Processing</title>
 <path fill="none" stroke="black" d="M703.16,-31.64C728.6,-36.87 750.75,-44.11 759,-54 778.46,-77.34 776.26,-200.01 762,-216 749.37,-230.17 656.13,-239.42 576.2,-244.84"/>
 <polygon fill="black" stroke="black" points="575.77,-241.36 566.03,-245.51 576.24,-248.34 575.77,-241.36"/>
 <text text-anchor="middle" x="870" y="-116.3" font-family="Times,serif" font-size="14.00">[not key.startsWith(prefix)]</text>
 </g>
 </g>
 </svg>
--- a/index.ts
+++ b/index.ts
@ -1,9 +1,6 @@
 import * as evaluators from './lib/policyEvaluator/evaluator';
 import evaluatePrincipal from './lib/policyEvaluator/principal';
-import RequestContext, {
+import RequestContext from './lib/policyEvaluator/RequestContext';
    actionNeedQuotaCheck,
    actionNeedQuotaCheckCopy,
    actionWithDataDeletion } from './lib/policyEvaluator/RequestContext';
 import * as requestUtils from './lib/policyEvaluator/requestUtils';
 import * as actionMaps from './lib/policyEvaluator/utils/actionMaps';
 import { validateUserPolicy } from './lib/policy/policyValidator'
@ -28,7 +25,6 @@ import * as objectRestore from './lib/s3middleware/objectRestore';
 import * as lifecycleHelpers from './lib/s3middleware/lifecycleHelpers';
 export { default as errors } from './lib/errors';
 export { default as Clustering } from './lib/Clustering';
 export * as ClusterRPC from './lib/clustering/ClusterRPC';
 export * as ipCheck from './lib/ipCheck';
 export * as auth from './lib/auth/auth';
 export * as constants from './lib/constants';
@ -52,8 +48,6 @@ export const algorithms = {
        Skip: require('./lib/algos/list/skip'),
    },
    cache: {
        GapSet: require('./lib/algos/cache/GapSet'),
        GapCache: require('./lib/algos/cache/GapCache'),
        LRUCache: require('./lib/algos/cache/LRUCache'),
    },
    stream: {
@ -70,9 +64,6 @@ export const policies = {
    RequestContext,
    requestUtils,
    actionMaps,
    actionNeedQuotaCheck,
    actionWithDataDeletion,
    actionNeedQuotaCheckCopy,
 };
 export const testing = {
--- a/lib/algos/cache/GapCache.ts
+++ b/lib/algos/cache/GapCache.ts
@ -1,363 +0,0 @@
 import { OrderedSet } from '@js-sdsl/ordered-set';
 import {
    default as GapSet,
    GapSetEntry,
 } from './GapSet';
 // the API is similar but is not strictly a superset of GapSetInterface
 // so we don't extend from it
 export interface GapCacheInterface {
    exposureDelayMs: number;
    maxGapWeight: number;
    size: number;
    setGap: (firstKey: string, lastKey: string, weight: number) => void;
    removeOverlappingGaps: (overlappingKeys: string[]) => number;
    lookupGap: (minKey: string, maxKey?: string) => Promise<GapSetEntry | null>;
    [Symbol.iterator]: () => Iterator<GapSetEntry>;
    toArray: () => GapSetEntry[];
 };
 class GapCacheUpdateSet {
    newGaps: GapSet;
    updatedKeys: OrderedSet<string>;
    constructor(maxGapWeight: number) {
        this.newGaps = new GapSet(maxGapWeight);
        this.updatedKeys = new OrderedSet();
    }
    addUpdateBatch(updatedKeys: OrderedSet<string>): void {
        this.updatedKeys.union(updatedKeys);
    }
 };
 /**
 * Cache of listing "gaps" i.e. ranges of keys that can be skipped
 * over during listing (because they only contain delete markers as
 * latest versions).
 *
 * Typically, a single GapCache instance would be attached to a raft session.
 *
 * The API usage is as follows:
 *
 * - Initialize a GapCache instance by calling start() (this starts an internal timer)
 *
 * - Insert a gap or update an existing one via setGap()
 *
 * - Lookup existing gaps via lookupGap()
 *
 * - Invalidate gaps that overlap a specific set of keys via removeOverlappingGaps()
 *
 * - Shut down a GapCache instance by calling stop() (this stops the internal timer)
 *
 * Gaps inserted via setGap() are not exposed immediately to lookupGap(), but only:
 *
 * - after a certain delay always larger than 'exposureDelayMs' and usually shorter
 *   than twice this value (but might be slightly longer in rare cases)
 *
 * - and only if they haven't been invalidated by a recent call to removeOverlappingGaps()
 *
 * This ensures atomicity between gap creation and invalidation from updates under
 * the condition that a gap is created from first key to last key within the time defined
 * by 'exposureDelayMs'.
 *
 * The implementation is based on two extra temporary "update sets" on top of the main
 * exposed gap set, one called "staging" and the other "frozen", each containing a
 * temporary updated gap set and a list of updated keys to invalidate gaps with (coming
 * from calls to removeOverlappingGaps()). Every "exposureDelayMs" milliseconds, the frozen
 * gaps are invalidated by all key updates coming from either of the "staging" or "frozen"
 * update set, then merged into the exposed gaps set, after which the staging updates become
 * the frozen updates and won't receive any new gap until the next cycle.
 */
 export default class GapCache implements GapCacheInterface {
    _exposureDelayMs: number;
    maxGaps: number;
    _stagingUpdates: GapCacheUpdateSet;
    _frozenUpdates: GapCacheUpdateSet;
    _exposedGaps: GapSet;
    _exposeFrozenInterval: NodeJS.Timeout | null;
    /**
     * @constructor
     *
     * @param {number} exposureDelayMs - minimum delay between
     * insertion of a gap via setGap() and its exposure via
     * lookupGap()
     * @param {number} maxGaps - maximum number of cached gaps, after
     * which no new gap can be added by setGap(). (Note: a future
     * improvement could replace this by an eviction strategy)
     * @param {number} maxGapWeight - maximum "weight" of individual
     * cached gaps, which is also the granularity for
     * invalidation. Individual gaps can be chained together,
     * which lookupGap() transparently consolidates in the response
     * into a single large gap.
     */
    constructor(exposureDelayMs: number, maxGaps: number, maxGapWeight: number) {
        this._exposureDelayMs = exposureDelayMs;
        this.maxGaps = maxGaps;
        this._stagingUpdates = new GapCacheUpdateSet(maxGapWeight);
        this._frozenUpdates = new GapCacheUpdateSet(maxGapWeight);
        this._exposedGaps = new GapSet(maxGapWeight);
        this._exposeFrozenInterval = null;
    }
    /**
     * Create a GapCache from an array of exposed gap entries (used in tests)
     *
     * @return {GapCache} - a new GapCache instance
     */
    static createFromArray(
        gaps: GapSetEntry[],
        exposureDelayMs: number,
        maxGaps: number,
        maxGapWeight: number
    ): GapCache {
        const gapCache = new GapCache(exposureDelayMs, maxGaps, maxGapWeight);
        gapCache._exposedGaps = GapSet.createFromArray(gaps, maxGapWeight)
        return gapCache;
    }
    /**
     * Internal helper to remove gaps in the staging and frozen sets
     * overlapping with previously updated keys, right before the
     * frozen gaps get exposed.
     *
     * @return {undefined}
     */
    _removeOverlappingGapsBeforeExpose(): void {
        for (const { updatedKeys } of [this._stagingUpdates, this._frozenUpdates]) {
            if (updatedKeys.size() === 0) {
                continue;
            }
            for (const { newGaps } of [this._stagingUpdates, this._frozenUpdates]) {
                if (newGaps.size === 0) {
                    continue;
                }
                newGaps.removeOverlappingGaps(updatedKeys);
            }
        }
    }
    /**
     * This function is the core mechanism that updates the exposed gaps in the
     * cache. It is called on a regular interval defined by 'exposureDelayMs'.
     *
     * It does the following in order:
     *
     * - remove gaps from the frozen set that overlap with any key present in a
     *   batch passed to removeOverlappingGaps() since the last two triggers of
     *   _exposeFrozen()
     *
     * - merge the remaining gaps from the frozen set to the exposed set, which
     *   makes them visible from calls to lookupGap()
     *
     * - rotate by freezing the currently staging updates and initiating a new
     *   staging updates set
     *
     * @return {undefined}
     */
    _exposeFrozen(): void {
        this._removeOverlappingGapsBeforeExpose();
        for (const gap of this._frozenUpdates.newGaps) {
            // Use a trivial strategy to keep the cache size within
            // limits: refuse to add new gaps when the size is above
            // the 'maxGaps' threshold. We solely rely on
            // removeOverlappingGaps() to make space for new gaps.
            if (this._exposedGaps.size < this.maxGaps) {
                this._exposedGaps.setGap(gap.firstKey, gap.lastKey, gap.weight);
            }
        }
        this._frozenUpdates = this._stagingUpdates;
        this._stagingUpdates = new GapCacheUpdateSet(this.maxGapWeight);
    }
    /**
     * Start the internal GapCache timer
     *
     * @return {undefined}
     */
    start(): void {
        if (this._exposeFrozenInterval) {
            return;
        }
        this._exposeFrozenInterval = setInterval(
            () => this._exposeFrozen(),
            this._exposureDelayMs);
    }
    /**
     * Stop the internal GapCache timer
     *
     * @return {undefined}
     */
    stop(): void {
        if (this._exposeFrozenInterval) {
            clearInterval(this._exposeFrozenInterval);
            this._exposeFrozenInterval = null;
        }
    }
    /**
     * Record a gap between two keys, associated with a weight to
     * limit individual gap's spanning ranges in the cache, for a more
     * granular invalidation.
     *
     * The function handles splitting and merging existing gaps to
     * maintain an optimal weight of cache entries.
     *
     * NOTE 1: the caller must ensure that the full length of the gap
     * between 'firstKey' and 'lastKey' has been built from a listing
     * snapshot that is more recent than 'exposureDelayMs' milliseconds,
     * in order to guarantee that the exposed gap will be fully
     * covered (and potentially invalidated) from recent calls to
     * removeOverlappingGaps().
     *
     * NOTE 2: a usual pattern when building a large gap from multiple
     * calls to setGap() is to start the next gap from 'lastKey',
     * which will be passed as 'firstKey' in the next call, so that
     * gaps can be chained together and consolidated by lookupGap().
     *
     * @param {string} firstKey - first key of the gap
     * @param {string} lastKey - last key of the gap, must be greater
     * or equal than 'firstKey'
     * @param {number} weight - total weight between 'firstKey' and 'lastKey'
     * @return {undefined}
     */
    setGap(firstKey: string, lastKey: string, weight: number): void {
        this._stagingUpdates.newGaps.setGap(firstKey, lastKey, weight);
    }
    /**
     * Remove gaps that overlap with a given set of keys. Used to
     * invalidate gaps when keys are inserted or deleted.
     *
     * @param {OrderedSet<string> | string[]} overlappingKeys - remove gaps that
     * overlap with any of this set of keys
     * @return {number} - how many gaps were removed from the exposed
     * gaps only (overlapping gaps not yet exposed are also invalidated
     * but are not accounted for in the returned value)
     */
    removeOverlappingGaps(overlappingKeys: OrderedSet<string> | string[]): number {
        let overlappingKeysSet;
        if (Array.isArray(overlappingKeys)) {
            overlappingKeysSet = new OrderedSet(overlappingKeys);
        } else {
            overlappingKeysSet = overlappingKeys;
        }
        this._stagingUpdates.addUpdateBatch(overlappingKeysSet);
        return this._exposedGaps.removeOverlappingGaps(overlappingKeysSet);
    }
    /**
     * Lookup the next exposed gap that overlaps with [minKey, maxKey]. Internally
     * chained gaps are coalesced in the response into a single contiguous large gap.
     *
     * @param {string} minKey - minimum key overlapping with the returned gap
     * @param {string} [maxKey] - maximum key overlapping with the returned gap
     * @return {Promise<GapSetEntry | null>} - result of the lookup if a gap
     *   was found, null otherwise, as a Promise
     */
    lookupGap(minKey: string, maxKey?: string): Promise<GapSetEntry | null> {
        return this._exposedGaps.lookupGap(minKey, maxKey);
    }
    /**
     * Get the maximum weight setting for individual gaps.
     *
     * @return {number} - maximum weight of individual gaps
     */
    get maxGapWeight(): number {
        return this._exposedGaps.maxWeight;
    }
    /**
     * Set the maximum weight setting for individual gaps.
     *
     * @param {number} gapWeight - maximum weight of individual gaps
     */
    set maxGapWeight(gapWeight: number) {
        this._exposedGaps.maxWeight = gapWeight;
        // also update transient gap sets
        this._stagingUpdates.newGaps.maxWeight = gapWeight;
        this._frozenUpdates.newGaps.maxWeight = gapWeight;
    }
    /**
     * Get the exposure delay in milliseconds, which is the minimum
     * time after which newly cached gaps will be exposed by
     * lookupGap().
     *
     * @return {number} - exposure delay in milliseconds
     */
    get exposureDelayMs(): number {
        return this._exposureDelayMs;
    }
    /**
     * Set the exposure delay in milliseconds, which is the minimum
     * time after which newly cached gaps will be exposed by
     * lookupGap(). Setting this attribute automatically updates the
     * internal state to honor the new value.
     *
     * @param {number} - exposure delay in milliseconds
     */
    set exposureDelayMs(exposureDelayMs: number) {
        if (exposureDelayMs !== this._exposureDelayMs) {
            this._exposureDelayMs = exposureDelayMs;
            if (this._exposeFrozenInterval) {
                // invalidate all pending gap updates, as the new interval may not be
                // safe for them
                this._stagingUpdates = new GapCacheUpdateSet(this.maxGapWeight);
                this._frozenUpdates = new GapCacheUpdateSet(this.maxGapWeight);
                // reinitialize the _exposeFrozenInterval timer with the updated delay
                this.stop();
                this.start();
            }
        }
    }
    /**
     * Get the number of exposed gaps
     *
     * @return {number} number of exposed gaps
     */
    get size(): number {
        return this._exposedGaps.size;
    }
    /**
     * Iterate over exposed gaps
     *
     * @return {Iterator<GapSetEntry>} an iterator over exposed gaps
     */
    [Symbol.iterator](): Iterator<GapSetEntry> {
        return this._exposedGaps[Symbol.iterator]();
    }
    /**
     * Get an array of all exposed gaps
     *
     * @return {GapSetEntry[]} array of exposed gaps
     */
    toArray(): GapSetEntry[] {
        return this._exposedGaps.toArray();
    }
    /**
     * Clear all exposed and staging gaps from the cache.
     *
     * Note: retains invalidating updates from removeOverlappingGaps()
     * for correctness of gaps inserted afterwards.
     *
     * @return {undefined}
     */
    clear(): void {
        this._stagingUpdates.newGaps = new GapSet(this.maxGapWeight);
        this._frozenUpdates.newGaps = new GapSet(this.maxGapWeight);
        this._exposedGaps = new GapSet(this.maxGapWeight);
    }
 }
--- a/lib/algos/cache/GapSet.ts
+++ b/lib/algos/cache/GapSet.ts
@ -1,366 +0,0 @@
 import assert from 'assert';
 import { OrderedSet } from '@js-sdsl/ordered-set';
 import errors from '../../errors';
 export type GapSetEntry = {
    firstKey: string,
    lastKey: string,
    weight: number,
 };
 export interface GapSetInterface {
    maxWeight: number;
    size: number;
    setGap: (firstKey: string, lastKey: string, weight: number) => GapSetEntry;
    removeOverlappingGaps: (overlappingKeys: string[]) => number;
    lookupGap: (minKey: string, maxKey?: string) => Promise<GapSetEntry | null>;
    [Symbol.iterator]: () => Iterator<GapSetEntry>;
    toArray: () => GapSetEntry[];
 };
 /**
 * Specialized data structure to support caching of listing "gaps",
 * i.e. ranges of keys that can be skipped over during listing
 * (because they only contain delete markers as latest versions)
 */
 export default class GapSet implements GapSetInterface, Iterable<GapSetEntry> {
    _gaps: OrderedSet<GapSetEntry>;
    _maxWeight: number;
    /**
     * @constructor
     * @param {number} maxWeight - weight threshold for each cached
     * gap (unitless). Triggers splitting gaps when reached
     */
    constructor(maxWeight: number) {
        this._gaps = new OrderedSet(
            [],
            (left: GapSetEntry, right: GapSetEntry) => (
                left.firstKey < right.firstKey ? -1 :
                left.firstKey > right.firstKey ? 1 : 0
            )
        );
        this._maxWeight = maxWeight;
    }
    /**
     * Create a GapSet from an array of gap entries (used in tests)
     */
    static createFromArray(gaps: GapSetEntry[], maxWeight: number): GapSet {
        const gapSet = new GapSet(maxWeight);
        for (const gap of gaps) {
            gapSet._gaps.insert(gap);
        }
        return gapSet;
    }
    /**
     * Record a gap between two keys, associated with a weight to limit
     * individual gap sizes in the cache.
     *
     * The function handles splitting and merging existing gaps to
     * maintain an optimal weight of cache entries.
     *
     * @param {string} firstKey - first key of the gap
     * @param {string} lastKey - last key of the gap, must be greater
     * or equal than 'firstKey'
     * @param {number} weight - total weight between 'firstKey' and 'lastKey'
     * @return {GapSetEntry} - existing or new gap entry
     */
    setGap(firstKey: string, lastKey: string, weight: number): GapSetEntry {
        assert(lastKey >= firstKey);
        // Step 1/4: Find the closest left-overlapping gap, and either re-use it
        // or chain it with a new gap depending on the weights if it exists (otherwise
        // just creates a new gap).
        const curGapIt = this._gaps.reverseLowerBound(<GapSetEntry>{ firstKey });
        let curGap;
        if (curGapIt.isAccessible()) {
            curGap = curGapIt.pointer;
            if (curGap.lastKey >= lastKey) {
                // return fully overlapping gap already cached
                return curGap;
            }
        }
        let remainingWeight = weight;
        if (!curGap                         // no previous gap
            || curGap.lastKey < firstKey    // previous gap not overlapping
            || (curGap.lastKey === firstKey // previous gap overlapping by one key...
                && curGap.weight + weight > this._maxWeight) // ...but we can't extend it
           ) {
            // create a new gap indexed by 'firstKey'
            curGap = { firstKey, lastKey: firstKey, weight: 0 };
            this._gaps.insert(curGap);
        } else if (curGap.lastKey > firstKey && weight > this._maxWeight) {
            // previous gap is either fully or partially contained in the new gap
            // and cannot be extended: substract its weight from the total (heuristic
            // in case the previous gap doesn't start at 'firstKey', which is the
            // uncommon case)
            remainingWeight -= curGap.weight;
            // there may be an existing chained gap starting with the previous gap's
            // 'lastKey': use it if it exists
            const chainedGapIt = this._gaps.find(<GapSetEntry>{ firstKey: curGap.lastKey });
            if (chainedGapIt.isAccessible()) {
                curGap = chainedGapIt.pointer;
            } else {
                // no existing chained gap: chain a new gap to the previous gap
                curGap = {
                    firstKey: curGap.lastKey,
                    lastKey: curGap.lastKey,
                    weight: 0,
                };
                this._gaps.insert(curGap);
            }
        }
        // Step 2/4: Cleanup existing gaps fully included in firstKey -> lastKey, and
        // aggregate their weights in curGap to define the minimum weight up to the
        // last merged gap.
        let nextGap;
        while (true) {
            const nextGapIt = this._gaps.upperBound(<GapSetEntry>{ firstKey: curGap.firstKey });
            nextGap = nextGapIt.isAccessible() && nextGapIt.pointer;
            // stop the cleanup when no more gap or if the next gap is not fully
            // included in curGap
            if (!nextGap || nextGap.lastKey > lastKey) {
                break;
            }
            this._gaps.eraseElementByIterator(nextGapIt);
            curGap.lastKey = nextGap.lastKey;
            curGap.weight += nextGap.weight;
        }
        // Step 3/4: Extend curGap to lastKey, adjusting the weight.
        // At this point, curGap weight is the minimum weight of the finished gap, save it
        // for step 4.
        let minMergedWeight = curGap.weight;
        if (curGap.lastKey === firstKey && firstKey !== lastKey) {
            // extend the existing gap by the full amount 'firstKey -> lastKey'
            curGap.lastKey = lastKey;
            curGap.weight += remainingWeight;
        } else if (curGap.lastKey <= lastKey) {
            curGap.lastKey = lastKey;
            curGap.weight = remainingWeight;
        }
        // Step 4/4: Find the closest right-overlapping gap, and if it exists, either merge
        // it or chain it with curGap depending on the weights.
        if (nextGap && nextGap.firstKey <= lastKey) {
            // nextGap overlaps with the new gap: check if we can merge it
            minMergedWeight += nextGap.weight;
            let mergedWeight;
            if (lastKey === nextGap.firstKey) {
                // nextGap is chained with curGap: add the full weight of nextGap
                mergedWeight = curGap.weight + nextGap.weight;
            } else {
                // strict overlap: don't add nextGap's weight unless
                // it's larger than the sum of merged ranges (as it is
                // then included in `minMergedWeight`)
                mergedWeight = Math.max(curGap.weight, minMergedWeight);
            }
            if (mergedWeight <= this._maxWeight) {
                // merge nextGap into curGap
                curGap.lastKey = nextGap.lastKey;
                curGap.weight = mergedWeight;
                this._gaps.eraseElementByKey(nextGap);
            } else {
                // adjust the last key to chain with nextGap and substract the next
                // gap's weight from curGap (heuristic)
                curGap.lastKey = nextGap.firstKey;
                curGap.weight = Math.max(mergedWeight - nextGap.weight, 0);
                curGap = nextGap;
            }
        }
        // return a copy of curGap
        return Object.assign({}, curGap);
    }
    /**
     * Remove gaps that overlap with one or more keys in a given array or
     * OrderedSet. Used to invalidate gaps when keys are inserted or deleted.
     *
     * @param {OrderedSet<string> | string[]} overlappingKeys - remove gaps that overlap
     * with any of this set of keys
     * @return {number} - how many gaps were removed
     */
    removeOverlappingGaps(overlappingKeys: OrderedSet<string> | string[]): number {
        // To optimize processing with a large number of keys and/or gaps, this function:
        //
        // 1. converts the overlappingKeys array to a OrderedSet (if not already a OrderedSet)
        // 2. queries both the gaps set and the overlapping keys set in a loop, which allows:
        //    - skipping ranges of overlapping keys at once when there is no new overlapping gap
        //    - skipping ranges of gaps at once when there is no overlapping key
        //
        // This way, it is efficient when the number of non-overlapping gaps is large
        // (which is the most common case in practice).
        let overlappingKeysSet;
        if (Array.isArray(overlappingKeys)) {
            overlappingKeysSet = new OrderedSet(overlappingKeys);
        } else {
            overlappingKeysSet = overlappingKeys;
        }
        const firstKeyIt = overlappingKeysSet.begin();
        let currentKey = firstKeyIt.isAccessible() && firstKeyIt.pointer;
        let nRemoved = 0;
        while (currentKey) {
            const closestGapIt = this._gaps.reverseUpperBound(<GapSetEntry>{ firstKey: currentKey });
            if (closestGapIt.isAccessible()) {
                const closestGap = closestGapIt.pointer;
                if (currentKey <= closestGap.lastKey) {
                    // currentKey overlaps closestGap: remove the gap
                    this._gaps.eraseElementByIterator(closestGapIt);
                    nRemoved += 1;
                }
            }
            const nextGapIt = this._gaps.lowerBound(<GapSetEntry>{ firstKey: currentKey });
            if (!nextGapIt.isAccessible()) {
                // no more gap: we're done
                return nRemoved;
            }
            const nextGap = nextGapIt.pointer;
            // advance to the last key potentially overlapping with nextGap
            let currentKeyIt = overlappingKeysSet.reverseLowerBound(nextGap.lastKey);
            if (currentKeyIt.isAccessible()) {
                currentKey = currentKeyIt.pointer;
                if (currentKey >= nextGap.firstKey) {
                    // currentKey overlaps nextGap: remove the gap
                    this._gaps.eraseElementByIterator(nextGapIt);
                    nRemoved += 1;
                }
            }
            // advance to the first key potentially overlapping with another gap
            currentKeyIt = overlappingKeysSet.lowerBound(nextGap.lastKey);
            currentKey = currentKeyIt.isAccessible() && currentKeyIt.pointer;
        }
        return nRemoved;
    }
    /**
     * Internal helper to coalesce multiple chained gaps into a single gap.
     *
     * It is only used to construct lookupGap() return values and
     * doesn't modify the GapSet.
     *
     * NOTE: The function may take a noticeable amount of time and CPU
     * to execute if a large number of chained gaps have to be
     * coalesced, but it should never take more than a few seconds. In
     * most cases it should take less than a millisecond. It regularly
     * yields to the nodejs event loop to avoid blocking it during a
     * long execution.
     *
     * @param {GapSetEntry} firstGap - first gap of the chain to coalesce with
     * the next ones in the chain
     * @return {Promise<GapSetEntry>} - a new coalesced entry, as a Promise
     */
    _coalesceGapChain(firstGap: GapSetEntry): Promise<GapSetEntry> {
        return new Promise(resolve => {
            const coalescedGap: GapSetEntry = Object.assign({}, firstGap);
            const coalesceGapChainIteration = () => {
                // efficiency trade-off: 100 iterations of log(N) complexity lookups should
                // not block the event loop for too long
                for (let opCounter = 0; opCounter < 100; ++opCounter) {
                    const chainedGapIt = this._gaps.find(
                            <GapSetEntry>{ firstKey: coalescedGap.lastKey });
                    if (!chainedGapIt.isAccessible()) {
                        // chain is complete
                        return resolve(coalescedGap);
                    }
                    const chainedGap = chainedGapIt.pointer;
                    if (chainedGap.firstKey === chainedGap.lastKey) {
                        // found a single-key gap: chain is complete
                        return resolve(coalescedGap);
                    }
                    coalescedGap.lastKey = chainedGap.lastKey;
                    coalescedGap.weight += chainedGap.weight;
                }
                // yield to the event loop before continuing the process
                // of coalescing the gap chain
                return process.nextTick(coalesceGapChainIteration);
            };
            coalesceGapChainIteration();
        });
    }
    /**
     * Lookup the next gap that overlaps with [minKey, maxKey]. Internally chained
     * gaps are coalesced in the response into a single contiguous large gap.
     *
     * @param {string} minKey - minimum key overlapping with the returned gap
     * @param {string} [maxKey] - maximum key overlapping with the returned gap
     * @return {Promise<GapSetEntry | null>} - result of the lookup if a gap
     *   was found, null otherwise, as a Promise
     */
    async lookupGap(minKey: string, maxKey?: string): Promise<GapSetEntry | null> {
        let firstGap: GapSetEntry | null = null;
        const minGapIt = this._gaps.reverseLowerBound(<GapSetEntry>{ firstKey: minKey });
        const minGap = minGapIt.isAccessible() && minGapIt.pointer;
        if (minGap && minGap.lastKey >= minKey) {
            firstGap = minGap;
        } else {
            const maxGapIt = this._gaps.upperBound(<GapSetEntry>{ firstKey: minKey });
            const maxGap = maxGapIt.isAccessible() && maxGapIt.pointer;
            if (maxGap && (maxKey === undefined || maxGap.firstKey <= maxKey)) {
                firstGap = maxGap;
            }
        }
        if (!firstGap) {
            return null;
        }
        return this._coalesceGapChain(firstGap);
    }
    /**
     * Get the maximum weight setting for individual gaps.
     *
     * @return {number} - maximum weight of individual gaps
     */
    get maxWeight(): number {
        return this._maxWeight;
    }
    /**
     * Set the maximum weight setting for individual gaps.
     *
     * @param {number} gapWeight - maximum weight of individual gaps
     */
    set maxWeight(gapWeight: number) {
        this._maxWeight = gapWeight;
    }
    /**
     * Get the number of gaps stored in this set.
     *
     * @return {number} - number of gaps stored in this set
     */
    get size(): number {
        return this._gaps.size();
    }
    /**
     * Iterate over each gap of the set, ordered by first key
     *
     * @return {Iterator<GapSetEntry>} - an iterator over all gaps
     *   Example:
     *     for (const gap of myGapSet) { ... }
     */
    [Symbol.iterator](): Iterator<GapSetEntry> {
        return this._gaps[Symbol.iterator]();
    }
    /**
     * Return an array containing all gaps, ordered by first key
     *
     * NOTE: there is a toArray() method in the OrderedSet implementation
     * but it does not scale well and overflows the stack quickly. This is
     * why we provide an implementation based on an iterator.
     *
     * @return {GapSetEntry[]} - an array containing all gaps
     */
    toArray(): GapSetEntry[] {
        return [...this];
    }
 }
--- a/lib/algos/list/Extension.js
+++ b/lib/algos/list/Extension.js
@ -1,6 +1,6 @@
 'use strict'; // eslint-disable-line strict
-const { FILTER_ACCEPT, SKIP_NONE } = require('./tools');
+const { FILTER_SKIP, SKIP_NONE } = require('./tools');
 // Use a heuristic to amortize the cost of JSON
 // serialization/deserialization only on largest metadata where the
@ -92,26 +92,21 @@ class Extension {
     * @param {object} entry - a listing entry from metadata
     *                         expected format: { key, value }
     * @return {number} - result of filtering the entry:
-     *                    FILTER_ACCEPT: entry is accepted and may or not be included
+     *                    > 0: entry is accepted and included in the result
-     *                                   in the result
+     *                    = 0: entry is accepted but not included (skipping)
-     *                    FILTER_SKIP: listing may skip directly (with "gte" param) to
+     *                    < 0: entry is not accepted, listing should finish
     *                                 the key returned by the skipping() method
     *                    FILTER_END: the results are complete, listing can be stopped
     */
-    filter(/* entry: { key, value } */) {
+    filter(entry) {
-        return FILTER_ACCEPT;
+        return entry ? FILTER_SKIP : FILTER_SKIP;
    }
    /**
-     * Provides the next key at which the listing task is allowed to skip to.
+     * Provides the insight into why filter is skipping an entry. This could be
-     * This could allow to skip over:
+     * because it is skipping a range of delimited keys or a range of specific
-     * - a key prefix ending with the delimiter
+     * version when doing master version listing.
     * - all remaining versions of an object when doing a current
     *   versions listing in v0 format
     * - a cached "gap" of deleted objects when doing a current
     *   versions listing in v0 format
     *
-     * @return {string} - the next key at which the listing task is allowed to skip to
+     * @return {string} - the insight: a common prefix or a master key,
     *                                 or SKIP_NONE if there is no insight
     */
    skipping() {
        return SKIP_NONE;
--- a/lib/algos/list/MPU.js
+++ b/lib/algos/list/MPU.js
@ -1,7 +1,7 @@
 'use strict'; // eslint-disable-line strict
 const { inc, checkLimit, listingParamsMasterKeysV0ToV1,
-    FILTER_END, FILTER_ACCEPT, SKIP_NONE } = require('./tools');
+    FILTER_END, FILTER_ACCEPT } = require('./tools');
 const DEFAULT_MAX_KEYS = 1000;
 const VSConst = require('../../versioning/constants').VersioningConstants;
 const { DbPrefixes, BucketVersioningKeyFormat } = VSConst;
@ -163,7 +163,7 @@ class MultipartUploads {
    }
    skipping() {
-        return SKIP_NONE;
+        return '';
    }
    /**
--- a/lib/algos/list/basic.js
+++ b/lib/algos/list/basic.js
@ -2,7 +2,7 @@
 const Extension = require('./Extension').default;
-const { checkLimit, FILTER_END, FILTER_ACCEPT } = require('./tools');
+const { checkLimit, FILTER_END, FILTER_ACCEPT, FILTER_SKIP } = require('./tools');
 const DEFAULT_MAX_KEYS = 10000;
 /**
@ -91,7 +91,7 @@ class List extends Extension {
     *                     < 0 : listing done
     */
    filter(elem) {
-        // Check if the result array is full
+        // Check first in case of maxkeys <= 0
        if (this.keys >= this.maxKeys) {
            return FILTER_END;
        }
@ -99,7 +99,7 @@ class List extends Extension {
             this.filterKeyStartsWith !== undefined) &&
            typeof elem === 'object' &&
            !this.customFilter(elem.value)) {
-            return FILTER_ACCEPT;
+            return FILTER_SKIP;
        }
        if (typeof elem === 'object') {
            this.res.push({
--- a/lib/algos/list/delimiter.js
+++ b/lib/algos/list/delimiter.js
@ -0,0 +1,274 @@
 'use strict'; // eslint-disable-line strict
 const Extension = require('./Extension').default;
 const { inc, listingParamsMasterKeysV0ToV1,
    FILTER_END, FILTER_ACCEPT, FILTER_SKIP } = require('./tools');
 const VSConst = require('../../versioning/constants').VersioningConstants;
 const { DbPrefixes, BucketVersioningKeyFormat } = VSConst;
 /**
 * Find the common prefix in the path
 *
 * @param {String} key            - path of the object
 * @param {String} delimiter      - separator
 * @param {Number} delimiterIndex - 'folder' index in the path
 * @return {String}               - CommonPrefix
 */
 function getCommonPrefix(key, delimiter, delimiterIndex) {
    return key.substring(0, delimiterIndex + delimiter.length);
 }
 /**
 * Handle object listing with parameters
 *
 * @prop {String[]} CommonPrefixes     - 'folders' defined by the delimiter
 * @prop {String[]} Contents           - 'files' to list
 * @prop {Boolean} IsTruncated         - truncated listing flag
 * @prop {String|undefined} NextMarker - marker per amazon format
 * @prop {Number} keys                 - count of listed keys
 * @prop {String|undefined} delimiter  - separator per amazon format
 * @prop {String|undefined} prefix     - prefix per amazon format
 * @prop {Number} maxKeys              - number of keys to list
 */
 class Delimiter extends Extension {
    /**
     * Create a new Delimiter instance
     * @constructor
     * @param {Object}  parameters                     - listing parameters
     * @param {String}  [parameters.delimiter]         - delimiter per amazon
     *                                                   format
     * @param {String}  [parameters.prefix]            - prefix per amazon
     *                                                   format
     * @param {String}  [parameters.marker]            - marker per amazon
     *                                                   format
     * @param {Number}  [parameters.maxKeys]           - number of keys to list
     * @param {Boolean} [parameters.v2]                - indicates whether v2
     *                                                   format
     * @param {String}  [parameters.startAfter]        - marker per amazon
     *                                                   format
     * @param {String}  [parameters.continuationToken] - obfuscated amazon
     *                                                   token
     * @param {Boolean} [parameters.alphabeticalOrder] - Either the result is
     *                                                   alphabetically ordered
     *                                                   or not
     * @param {RequestLogger} logger                   - The logger of the
     *                                                   request
     * @param {String} [vFormat]                       - versioning key format
     */
    constructor(parameters, logger, vFormat) {
        super(parameters, logger);
        // original listing parameters
        this.delimiter = parameters.delimiter;
        this.prefix = parameters.prefix;
        this.marker = parameters.marker;
        this.maxKeys = parameters.maxKeys || 1000;
        this.startAfter = parameters.startAfter;
        this.continuationToken = parameters.continuationToken;
        this.alphabeticalOrder =
          typeof parameters.alphabeticalOrder !== 'undefined' ?
              parameters.alphabeticalOrder : true;
        this.vFormat = vFormat || BucketVersioningKeyFormat.v0;
        // results
        this.CommonPrefixes = [];
        this.Contents = [];
        this.IsTruncated = false;
        this.NextMarker = parameters.marker;
        this.NextContinuationToken =
            parameters.continuationToken || parameters.startAfter;
        this.startMarker = parameters.v2 ? 'startAfter' : 'marker';
        this.continueMarker = parameters.v2 ? 'continuationToken' : 'marker';
        this.nextContinueMarker = parameters.v2 ?
            'NextContinuationToken' : 'NextMarker';
        if (this.delimiter !== undefined &&
            this[this.nextContinueMarker] !== undefined &&
            this[this.nextContinueMarker].startsWith(this.prefix || '')) {
            const nextDelimiterIndex =
                this[this.nextContinueMarker].indexOf(this.delimiter,
                    this.prefix ? this.prefix.length : 0);
            this[this.nextContinueMarker] =
                this[this.nextContinueMarker].slice(0, nextDelimiterIndex +
                                        this.delimiter.length);
        }
        Object.assign(this, {
            [BucketVersioningKeyFormat.v0]: {
                genMDParams: this.genMDParamsV0,
                getObjectKey: this.getObjectKeyV0,
                skipping: this.skippingV0,
            },
            [BucketVersioningKeyFormat.v1]: {
                genMDParams: this.genMDParamsV1,
                getObjectKey: this.getObjectKeyV1,
                skipping: this.skippingV1,
            },
        }[this.vFormat]);
    }
    genMDParamsV0() {
        const params = {};
        if (this.prefix) {
            params.gte = this.prefix;
            params.lt = inc(this.prefix);
        }
        const startVal = this[this.continueMarker] || this[this.startMarker];
        if (startVal) {
            if (params.gte && params.gte > startVal) {
                return params;
            }
            delete params.gte;
            params.gt = startVal;
        }
        return params;
    }
    genMDParamsV1() {
        const params = this.genMDParamsV0();
        return listingParamsMasterKeysV0ToV1(params);
    }
    /**
     * check if the max keys count has been reached and set the
     * final state of the result if it is the case
     * @return {Boolean} - indicates if the iteration has to stop
     */
    _reachedMaxKeys() {
        if (this.keys >= this.maxKeys) {
            // In cases of maxKeys <= 0 -> IsTruncated = false
            this.IsTruncated = this.maxKeys > 0;
            return true;
        }
        return false;
    }
    /**
     *  Add a (key, value) tuple to the listing
     *  Set the NextMarker to the current key
     *  Increment the keys counter
     *  @param {String} key   - The key to add
     *  @param {String} value - The value of the key
     *  @return {number}      - indicates if iteration should continue
     */
    addContents(key, value) {
        if (this._reachedMaxKeys()) {
            return FILTER_END;
        }
        this.Contents.push({ key, value: this.trimMetadata(value) });
        this[this.nextContinueMarker] = key;
        ++this.keys;
        return FILTER_ACCEPT;
    }
    getObjectKeyV0(obj) {
        return obj.key;
    }
    getObjectKeyV1(obj) {
        return obj.key.slice(DbPrefixes.Master.length);
    }
    /**
     *  Filter to apply on each iteration, based on:
     *  - prefix
     *  - delimiter
     *  - maxKeys
     *  The marker is being handled directly by levelDB
     *  @param {Object} obj       - The key and value of the element
     *  @param {String} obj.key   - The key of the element
     *  @param {String} obj.value - The value of the element
     *  @return {number}          - indicates if iteration should continue
     */
    filter(obj) {
        const key = this.getObjectKey(obj);
        const value = obj.value;
        if ((this.prefix && !key.startsWith(this.prefix))
            || (this.alphabeticalOrder
                && typeof this[this.nextContinueMarker] === 'string'
                && key <= this[this.nextContinueMarker])) {
            return FILTER_SKIP;
        }
        if (this.delimiter) {
            const baseIndex = this.prefix ? this.prefix.length : 0;
            const delimiterIndex = key.indexOf(this.delimiter, baseIndex);
            if (delimiterIndex === -1) {
                return this.addContents(key, value);
            }
            return this.addCommonPrefix(key, delimiterIndex);
        }
        return this.addContents(key, value);
    }
    /**
     * Add a Common Prefix in the list
     * @param {String} key   - object name
     * @param {Number} index - after prefix starting point
     * @return {Boolean}     - indicates if iteration should continue
     */
    addCommonPrefix(key, index) {
        const commonPrefix = getCommonPrefix(key, this.delimiter, index);
        if (this.CommonPrefixes.indexOf(commonPrefix) === -1
                && this[this.nextContinueMarker] !== commonPrefix) {
            if (this._reachedMaxKeys()) {
                return FILTER_END;
            }
            this.CommonPrefixes.push(commonPrefix);
            this[this.nextContinueMarker] = commonPrefix;
            ++this.keys;
            return FILTER_ACCEPT;
        }
        return FILTER_SKIP;
    }
    /**
     * If repd happens to want to skip listing on a bucket in v0
     * versioning key format, here is an idea.
     *
     * @return {string} - the present range (NextMarker) if repd believes
     *                    that it's enough and should move on
     */
    skippingV0() {
        return this[this.nextContinueMarker];
    }
    /**
     * If repd happens to want to skip listing on a bucket in v1
     * versioning key format, here is an idea.
     *
     * @return {string} - the present range (NextMarker) if repd believes
     *                    that it's enough and should move on
     */
    skippingV1() {
        return DbPrefixes.Master + this[this.nextContinueMarker];
    }
    /**
     *  Return an object containing all mandatory fields to use once the
     *  iteration is done, doesn't show a NextMarker field if the output
     *  isn't truncated
     *  @return {Object} - following amazon format
     */
    result() {
        /* NextMarker is only provided when delimiter is used.
         * specified in v1 listing documentation
         * http://docs.aws.amazon.com/AmazonS3/latest/API/RESTBucketGET.html
         */
        const result = {
            CommonPrefixes: this.CommonPrefixes,
            Contents: this.Contents,
            IsTruncated: this.IsTruncated,
            Delimiter: this.delimiter,
        };
        if (this.parameters.v2) {
            result.NextContinuationToken = this.IsTruncated
                ? this.NextContinuationToken : undefined;
        } else {
            result.NextMarker = (this.IsTruncated && this.delimiter)
                ? this.NextMarker : undefined;
        }
        return result;
    }
 }
 module.exports = { Delimiter };
--- a/lib/algos/list/delimiter.ts
+++ b/lib/algos/list/delimiter.ts
@ -1,356 +0,0 @@
 'use strict'; // eslint-disable-line strict
 const Extension = require('./Extension').default;
 const { inc, listingParamsMasterKeysV0ToV1,
    FILTER_END, FILTER_ACCEPT, FILTER_SKIP, SKIP_NONE } = require('./tools');
 const VSConst = require('../../versioning/constants').VersioningConstants;
 const { DbPrefixes, BucketVersioningKeyFormat } = VSConst;
 export interface FilterState {
    id: number,
 };
 export interface FilterReturnValue {
    FILTER_ACCEPT,
    FILTER_SKIP,
    FILTER_END,
 };
 export const enum DelimiterFilterStateId {
    NotSkipping = 1,
    SkippingPrefix = 2,
 };
 export interface DelimiterFilterState_NotSkipping extends FilterState {
    id: DelimiterFilterStateId.NotSkipping,
 };
 export interface DelimiterFilterState_SkippingPrefix extends FilterState {
    id: DelimiterFilterStateId.SkippingPrefix,
    prefix: string;
 };
 type KeyHandler = (key: string, value: string) => FilterReturnValue;
 export type ResultObject = {
    CommonPrefixes: string[];
    Contents: {
        key: string;
        value: string;
    }[];
    IsTruncated: boolean;
    Delimiter ?: string;
    NextMarker ?: string;
    NextContinuationToken ?: string;
 };
 /**
 * Handle object listing with parameters
 *
 * @prop {String[]} CommonPrefixes     - 'folders' defined by the delimiter
 * @prop {String[]} Contents           - 'files' to list
 * @prop {Boolean} IsTruncated         - truncated listing flag
 * @prop {String|undefined} NextMarker - marker per amazon format
 * @prop {Number} keys                 - count of listed keys
 * @prop {String|undefined} delimiter  - separator per amazon format
 * @prop {String|undefined} prefix     - prefix per amazon format
 * @prop {Number} maxKeys              - number of keys to list
 */
 export class Delimiter extends Extension {
    state: FilterState;
    keyHandlers: { [id: number]: KeyHandler };
    /**
     * Create a new Delimiter instance
     * @constructor
     * @param {Object}  parameters                     - listing parameters
     * @param {String}  [parameters.delimiter]         - delimiter per amazon
     *                                                   format
     * @param {String}  [parameters.prefix]            - prefix per amazon
     *                                                   format
     * @param {String}  [parameters.marker]            - marker per amazon
     *                                                   format
     * @param {Number}  [parameters.maxKeys]           - number of keys to list
     * @param {Boolean} [parameters.v2]                - indicates whether v2
     *                                                   format
     * @param {String}  [parameters.startAfter]        - marker per amazon
     *                                                   format
     * @param {String}  [parameters.continuationToken] - obfuscated amazon
     *                                                   token
     * @param {RequestLogger} logger                   - The logger of the
     *                                                   request
     * @param {String} [vFormat]                       - versioning key format
     */
    constructor(parameters, logger, vFormat) {
        super(parameters, logger);
        // original listing parameters
        this.delimiter = parameters.delimiter;
        this.prefix = parameters.prefix;
        this.maxKeys = parameters.maxKeys || 1000;
        if (parameters.v2) {
            this.marker = parameters.continuationToken || parameters.startAfter;
        } else {
            this.marker = parameters.marker;
        }
        this.nextMarker = this.marker;
        this.vFormat = vFormat || BucketVersioningKeyFormat.v0;
        // results
        this.CommonPrefixes = [];
        this.Contents = [];
        this.IsTruncated = false;
        this.keyHandlers = {};
        Object.assign(this, {
            [BucketVersioningKeyFormat.v0]: {
                genMDParams: this.genMDParamsV0,
                getObjectKey: this.getObjectKeyV0,
                skipping: this.skippingV0,
            },
            [BucketVersioningKeyFormat.v1]: {
                genMDParams: this.genMDParamsV1,
                getObjectKey: this.getObjectKeyV1,
                skipping: this.skippingV1,
            },
        }[this.vFormat]);
        // if there is a delimiter, we may skip ranges by prefix,
        // hence using the NotSkippingPrefix flavor that checks the
        // subprefix up to the delimiter for the NotSkipping state
        if (this.delimiter) {
            this.setKeyHandler(
                DelimiterFilterStateId.NotSkipping,
                this.keyHandler_NotSkippingPrefix.bind(this));
        } else {
            // listing without a delimiter never has to skip over any
            // prefix -> use NeverSkipping flavor for the NotSkipping
            // state
            this.setKeyHandler(
                DelimiterFilterStateId.NotSkipping,
                this.keyHandler_NeverSkipping.bind(this));
        }
        this.setKeyHandler(
            DelimiterFilterStateId.SkippingPrefix,
            this.keyHandler_SkippingPrefix.bind(this));
        this.state = <DelimiterFilterState_NotSkipping> {
            id: DelimiterFilterStateId.NotSkipping,
        };
    }
    genMDParamsV0() {
        const params: { gt ?: string, gte ?: string, lt ?: string } = {};
        if (this.prefix) {
            params.gte = this.prefix;
            params.lt = inc(this.prefix);
        }
        if (this.marker && this.delimiter) {
            const commonPrefix = this.getCommonPrefix(this.marker);
            if (commonPrefix) {
                const afterPrefix = inc(commonPrefix);
                if (!params.gte || afterPrefix > params.gte) {
                    params.gte = afterPrefix;
                }
            }
        }
        if (this.marker && (!params.gte || this.marker >= params.gte)) {
            delete params.gte;
            params.gt = this.marker;
        }
        return params;
    }
    genMDParamsV1() {
        const params = this.genMDParamsV0();
        return listingParamsMasterKeysV0ToV1(params);
    }
    /**
     * check if the max keys count has been reached and set the
     * final state of the result if it is the case
     * @return {Boolean} - indicates if the iteration has to stop
     */
    _reachedMaxKeys(): boolean {
        if (this.keys >= this.maxKeys) {
            // In cases of maxKeys <= 0 -> IsTruncated = false
            this.IsTruncated = this.maxKeys > 0;
            return true;
        }
        return false;
    }
    /**
     *  Add a (key, value) tuple to the listing
     *  Set the NextMarker to the current key
     *  Increment the keys counter
     *  @param {String} key   - The key to add
     *  @param {String} value - The value of the key
     *  @return {number}      - indicates if iteration should continue
     */
    addContents(key: string, value: string): void {
        this.Contents.push({ key, value: this.trimMetadata(value) });
        ++this.keys;
        this.nextMarker = key;
    }
    getCommonPrefix(key: string): string | undefined {
        if (!this.delimiter) {
            return undefined;
        }
        const baseIndex = this.prefix ? this.prefix.length : 0;
        const delimiterIndex = key.indexOf(this.delimiter, baseIndex);
        if (delimiterIndex === -1) {
            return undefined;
        }
        return key.substring(0, delimiterIndex + this.delimiter.length);
    }
    /**
     * Add a Common Prefix in the list
     * @param {String} commonPrefix   - common prefix to add
     * @param {String} key            - full key starting with commonPrefix
     * @return {Boolean}     - indicates if iteration should continue
     */
    addCommonPrefix(commonPrefix: string, key: string): void {
        // add the new prefix to the list
        this.CommonPrefixes.push(commonPrefix);
        ++this.keys;
        this.nextMarker = commonPrefix;
    }
    addCommonPrefixOrContents(key: string, value: string): string | undefined {
        // add the subprefix to the common prefixes if the key has the delimiter
        const commonPrefix = this.getCommonPrefix(key);
        if (commonPrefix) {
            this.addCommonPrefix(commonPrefix, key);
            return commonPrefix;
        }
        this.addContents(key, value);
        return undefined;
    }
    getObjectKeyV0(obj: { key: string }): string {
        return obj.key;
    }
    getObjectKeyV1(obj: { key: string }): string {
        return obj.key.slice(DbPrefixes.Master.length);
    }
    /**
     *  Filter to apply on each iteration, based on:
     *  - prefix
     *  - delimiter
     *  - maxKeys
     *  The marker is being handled directly by levelDB
     *  @param {Object} obj       - The key and value of the element
     *  @param {String} obj.key   - The key of the element
     *  @param {String} obj.value - The value of the element
     *  @return {number}          - indicates if iteration should continue
     */
    filter(obj: { key: string, value: string }): FilterReturnValue {
        const key = this.getObjectKey(obj);
        const value = obj.value;
        return this.handleKey(key, value);
    }
    setState(state: FilterState): void {
        this.state = state;
    }
    setKeyHandler(stateId: number, keyHandler: KeyHandler): void {
        this.keyHandlers[stateId] = keyHandler;
    }
    handleKey(key: string, value: string): FilterReturnValue {
        return this.keyHandlers[this.state.id](key, value);
    }
    keyHandler_NeverSkipping(key: string, value: string): FilterReturnValue {
        if (this._reachedMaxKeys()) {
            return FILTER_END;
        }
        this.addContents(key, value);
        return FILTER_ACCEPT;
    }
    keyHandler_NotSkippingPrefix(key: string, value: string): FilterReturnValue {
        if (this._reachedMaxKeys()) {
            return FILTER_END;
        }
        const commonPrefix = this.addCommonPrefixOrContents(key, value);
        if (commonPrefix) {
            // transition into SkippingPrefix state to skip all following keys
            // while they start with the same prefix
            this.setState(<DelimiterFilterState_SkippingPrefix> {
                id: DelimiterFilterStateId.SkippingPrefix,
                prefix: commonPrefix,
            });
        }
        return FILTER_ACCEPT;
    }
    keyHandler_SkippingPrefix(key: string, value: string): FilterReturnValue {
        const { prefix } = <DelimiterFilterState_SkippingPrefix> this.state;
        if (key.startsWith(prefix)) {
            return FILTER_SKIP;
        }
        this.setState(<DelimiterFilterState_NotSkipping> {
            id: DelimiterFilterStateId.NotSkipping,
        });
        return this.handleKey(key, value);
    }
    skippingBase(): string | undefined {
        switch (this.state.id) {
        case DelimiterFilterStateId.SkippingPrefix:
            const { prefix } = <DelimiterFilterState_SkippingPrefix> this.state;
            return inc(prefix);
        default:
            return SKIP_NONE;
        }
    }
    skippingV0() {
        return this.skippingBase();
    }
    skippingV1() {
        const skipTo = this.skippingBase();
        if (skipTo === SKIP_NONE) {
            return SKIP_NONE;
        }
        return DbPrefixes.Master + skipTo;
    }
    /**
     *  Return an object containing all mandatory fields to use once the
     *  iteration is done, doesn't show a NextMarker field if the output
     *  isn't truncated
     *  @return {Object} - following amazon format
     */
    result(): ResultObject {
        /* NextMarker is only provided when delimiter is used.
         * specified in v1 listing documentation
         * http://docs.aws.amazon.com/AmazonS3/latest/API/RESTBucketGET.html
         */
        const result: ResultObject = {
            CommonPrefixes: this.CommonPrefixes,
            Contents: this.Contents,
            IsTruncated: this.IsTruncated,
            Delimiter: this.delimiter,
        };
        if (this.parameters.v2) {
            result.NextContinuationToken = this.IsTruncated
                ? this.nextMarker : undefined;
        } else {
            result.NextMarker = (this.IsTruncated && this.delimiter)
                ? this.nextMarker : undefined;
        }
        return result;
    }
 }
--- a/lib/algos/list/delimiterCurrent.ts
+++ b/lib/algos/list/delimiterCurrent.ts
@ -1,5 +1,4 @@
-const { DelimiterMaster } = require('./delimiterMaster');
+const { Delimiter } = require('./delimiter');
 const { FILTER_ACCEPT, FILTER_END } = require('./tools');
 type ResultObject = {
    Contents: {
@ -11,16 +10,14 @@ type ResultObject = {
 };
 /**
- * Handle object listing with parameters. This extends the base class DelimiterMaster
+ * Handle object listing with parameters. This extends the base class Delimiter
 * to return the master/current versions.
 */
-class DelimiterCurrent extends DelimiterMaster {
+class DelimiterCurrent extends Delimiter {
    /**
     * Delimiter listing of current versions.
     * @param {Object}  parameters            - listing parameters
     * @param {String}  parameters.beforeDate - limit the response to keys older than beforeDate
     * @param {String}  parameters.excludedDataStoreName - excluded datatore name
     * @param {Number} parameters.maxScannedLifecycleListingEntries - max number of entries to be scanned
     * @param {RequestLogger} logger          - The logger of the request
     * @param {String} [vFormat]              - versioning key format
     */
@ -28,97 +25,27 @@ class DelimiterCurrent extends DelimiterMaster {
        super(parameters, logger, vFormat);
        this.beforeDate = parameters.beforeDate;
        this.excludedDataStoreName = parameters.excludedDataStoreName;
        this.maxScannedLifecycleListingEntries = parameters.maxScannedLifecycleListingEntries;
        this.scannedKeys = 0;
    }
-    genMDParamsV0() {
+    genMDParamsV1() {
-        const params = super.genMDParamsV0();
+        const params = super.genMDParamsV1();
-        // lastModified and dataStoreName parameters are used by metadata that enables built-in filtering, 
+ 
        // a feature currently exclusive to MongoDB
        if (this.beforeDate) {
            params.lastModified = {
                lt: this.beforeDate,
            };
        }
        if (this.excludedDataStoreName) {
            params.dataStoreName = {
                ne: this.excludedDataStoreName,
            }
        }
        return params;
    }
-    /**
+    result(): ResultObject {
     * Parses the stringified entry's value.
     * @param s - sringified value
     * @return - undefined if parsing fails, otherwise it contains the parsed value.
     */
    _parse(s) {
        let p;
        try {
            p = JSON.parse(s);
        } catch (e: any) {
            this.logger.warn(
                'Could not parse Object Metadata while listing',
                { err: e.toString() });
        }
        return p;
    }
    /**
     * check if the max keys count has been reached and set the
     * final state of the result if it is the case
     *
     * specialized implementation on DelimiterCurrent to also check
     * the number of scanned keys
     *
     * @return {Boolean} - indicates if the iteration has to stop
     */
    _reachedMaxKeys(): boolean {
        if (this.maxScannedLifecycleListingEntries && this.scannedKeys >= this.maxScannedLifecycleListingEntries) {
            this.IsTruncated = true;
            this.logger.info('listing stopped due to reaching the maximum scanned entries limit',
                {
                    maxScannedLifecycleListingEntries: this.maxScannedLifecycleListingEntries,
                    scannedKeys: this.scannedKeys,
                });
            return true;
        }
        return super._reachedMaxKeys();
    }
    addContents(key, value) {
        ++this.scannedKeys;
        const parsedValue = this._parse(value);
        // if parsing fails, skip the key.
        if (parsedValue) {
            const lastModified = parsedValue['last-modified'];
            const dataStoreName = parsedValue.dataStoreName;
            // We then check if the current version is older than the "beforeDate" and
            // "excludedDataStoreName" is not specified or if specified and the data store name is different.
            if ((!this.beforeDate || (lastModified && lastModified < this.beforeDate)) &&
                (!this.excludedDataStoreName || dataStoreName !== this.excludedDataStoreName)) {
                super.addContents(key, value);
            }
            // In the event of a timeout occurring before any content is added,
            // NextMarker is updated even if the object is not eligible.
            // It minimizes the amount of data that the client needs to re-process if the request times out.
            this.nextMarker = key;
        }
    }
    result(): object {
        const result: ResultObject = {
            Contents: this.Contents,
            IsTruncated: this.IsTruncated,
        };
        if (this.IsTruncated) {
-            result.NextMarker = this.nextMarker;
+            result.NextMarker = this.NextMarker;
        }
        return result;
--- a/lib/algos/list/delimiterMaster.js
+++ b/lib/algos/list/delimiterMaster.js
@ -0,0 +1,196 @@
 'use strict'; // eslint-disable-line strict
 const Delimiter = require('./delimiter').Delimiter;
 const Version = require('../../versioning/Version').Version;
 const VSConst = require('../../versioning/constants').VersioningConstants;
 const { BucketVersioningKeyFormat } = VSConst;
 const { FILTER_ACCEPT, FILTER_SKIP, SKIP_NONE } = require('./tools');
 const VID_SEP = VSConst.VersionId.Separator;
 const { DbPrefixes } = VSConst;
 /**
 * Handle object listing with parameters. This extends the base class Delimiter
 * to return the raw master versions of existing objects.
 */
 class DelimiterMaster extends Delimiter {
    /**
     * Delimiter listing of master versions.
     * @param {Object}  parameters            - listing parameters
     * @param {String}  parameters.delimiter  - delimiter per amazon format
     * @param {String}  parameters.prefix     - prefix per amazon format
     * @param {String}  parameters.marker     - marker per amazon format
     * @param {Number}  parameters.maxKeys    - number of keys to list
     * @param {Boolean} parameters.v2         - indicates whether v2 format
     * @param {String}  parameters.startAfter - marker per amazon v2 format
     * @param {String}  parameters.continuationToken - obfuscated amazon token
     * @param {RequestLogger} logger          - The logger of the request
     * @param {String} [vFormat]              - versioning key format
     */
    constructor(parameters, logger, vFormat) {
        super(parameters, logger, vFormat);
        // non-PHD master version or a version whose master is a PHD version
        this.prvKey = undefined;
        this.prvPHDKey = undefined;
        this.inReplayPrefix = false;
        Object.assign(this, {
            [BucketVersioningKeyFormat.v0]: {
                filter: this.filterV0,
                skipping: this.skippingV0,
            },
            [BucketVersioningKeyFormat.v1]: {
                filter: this.filterV1,
                skipping: this.skippingV1,
            },
        }[this.vFormat]);
    }
    /**
     *  Filter to apply on each iteration for buckets in v0 format,
     *  based on:
     *  - prefix
     *  - delimiter
     *  - maxKeys
     *  The marker is being handled directly by levelDB
     *  @param {Object} obj       - The key and value of the element
     *  @param {String} obj.key   - The key of the element
     *  @param {String} obj.value - The value of the element
     *  @return {number}          - indicates if iteration should continue
     */
    filterV0(obj) {
        let key = obj.key;
        const value = obj.value;
        if (key.startsWith(DbPrefixes.Replay)) {
            this.inReplayPrefix = true;
            return FILTER_SKIP;
        }
        this.inReplayPrefix = false;
        /* Skip keys not starting with the prefix or not alphabetically
         * ordered. */
        if ((this.prefix && !key.startsWith(this.prefix))
                || (typeof this[this.nextContinueMarker] === 'string' &&
                    key <= this[this.nextContinueMarker])) {
            return FILTER_SKIP;
        }
        /* Skip version keys (<key><versionIdSeparator><version>) if we already
         * have a master version. */
        const versionIdIndex = key.indexOf(VID_SEP);
        if (versionIdIndex >= 0) {
            key = key.slice(0, versionIdIndex);
            /* - key === this.prvKey is triggered when a master version has
             *   been accepted for this key,
             * - key === this.NextMarker or this.NextContinueToken is triggered
             *   when a listing page ends on an accepted obj and the next page
             *   starts with a version of this object.
             *   In that case prvKey is default set to undefined
             *   in the constructor and comparing to NextMarker is the only
             *   way to know  we should not accept this version. This test is
             *   not redundant with the one at the beginning of this function,
             *   we are comparing here the key without the version suffix,
             * - key startsWith the previous NextMarker happens because we set
             *   NextMarker to the common prefix instead of the whole key
             *   value. (TODO: remove this test once ZENKO-1048 is fixed)
             *   */
            if (key === this.prvKey || key === this[this.nextContinueMarker] ||
                (this.delimiter &&
                key.startsWith(this[this.nextContinueMarker]))) {
                /* master version already filtered */
                return FILTER_SKIP;
            }
        }
        if (Version.isPHD(value)) {
            /* master version is a PHD version, we want to wait for the next
             * one:
             * - Set the prvKey to undefined to not skip the next version,
             * - return accept to avoid users to skip the next values in range
             *   (skip scan mechanism in metadata backend like Metadata or
             *   MongoClient). */
            this.prvKey = undefined;
            this.prvPHDKey = key;
            return FILTER_ACCEPT;
        }
        if (Version.isDeleteMarker(value)) {
            /* This entry is a deleteMarker which has not been filtered by the
             * version test. Either :
             * - it is a deleteMarker on the master version, we want to SKIP
             *   all the following entries with this key (no master version),
             * - or a deleteMarker following a PHD (setting prvKey to undefined
             *   when an entry is a PHD avoids the skip on version for the
             *   next entry). In that case we expect the master version to
             *   follow. */
            if (key === this.prvPHDKey) {
                this.prvKey = undefined;
                return FILTER_ACCEPT;
            }
            this.prvKey = key;
            return FILTER_SKIP;
        }
        this.prvKey = key;
        if (this.delimiter) {
            // check if the key has the delimiter
            const baseIndex = this.prefix ? this.prefix.length : 0;
            const delimiterIndex = key.indexOf(this.delimiter, baseIndex);
            if (delimiterIndex >= 0) {
                // try to add the prefix to the list
                return this.addCommonPrefix(key, delimiterIndex);
            }
        }
        return this.addContents(key, value);
    }
    /**
     *  Filter to apply on each iteration for buckets in v1 format,
     *  based on:
     *  - prefix
     *  - delimiter
     *  - maxKeys
     *  The marker is being handled directly by levelDB
     *  @param {Object} obj       - The key and value of the element
     *  @param {String} obj.key   - The key of the element
     *  @param {String} obj.value - The value of the element
     *  @return {number}          - indicates if iteration should continue
     */
    filterV1(obj) {
        // Filtering master keys in v1 is simply listing the master
        // keys, as the state of version keys do not change the
        // result, so we can use Delimiter method directly.
        return super.filter(obj);
    }
    skippingBase() {
        if (this[this.nextContinueMarker]) {
            // next marker or next continuation token:
            // - foo/ : skipping foo/
            // - foo  : skipping foo.
            const index = this[this.nextContinueMarker].
                lastIndexOf(this.delimiter);
            if (index === this[this.nextContinueMarker].length - 1) {
                return this[this.nextContinueMarker];
            }
            return this[this.nextContinueMarker] + VID_SEP;
        }
        return SKIP_NONE;
    }
    skippingV0() {
        if (this.inReplayPrefix) {
            return DbPrefixes.Replay;
        }
        return this.skippingBase();
    }
    skippingV1() {
        const skipTo = this.skippingBase();
        if (skipTo === SKIP_NONE) {
            return SKIP_NONE;
        }
        return DbPrefixes.Master + skipTo;
    }
 }
 module.exports = { DelimiterMaster };
--- a/lib/algos/list/delimiterMaster.ts
+++ b/lib/algos/list/delimiterMaster.ts
@ -1,620 +0,0 @@
 import {
    Delimiter,
    FilterState,
    FilterReturnValue,
    DelimiterFilterStateId,
    DelimiterFilterState_NotSkipping,
    DelimiterFilterState_SkippingPrefix,
    ResultObject,
 } from './delimiter';
 const Version = require('../../versioning/Version').Version;
 const VSConst = require('../../versioning/constants').VersioningConstants;
 const { BucketVersioningKeyFormat } = VSConst;
 const { FILTER_ACCEPT, FILTER_SKIP, FILTER_END, SKIP_NONE, inc } = require('./tools');
 import { GapSetEntry } from '../cache/GapSet';
 import { GapCacheInterface } from '../cache/GapCache';
 const VID_SEP = VSConst.VersionId.Separator;
 const { DbPrefixes } = VSConst;
 export const enum DelimiterMasterFilterStateId {
    SkippingVersionsV0 = 101,
    WaitVersionAfterPHDV0 = 102,
    SkippingGapV0 = 103,
 };
 interface DelimiterMasterFilterState_SkippingVersionsV0 extends FilterState {
    id: DelimiterMasterFilterStateId.SkippingVersionsV0,
    masterKey: string,
 };
 interface DelimiterMasterFilterState_WaitVersionAfterPHDV0 extends FilterState {
    id: DelimiterMasterFilterStateId.WaitVersionAfterPHDV0,
    masterKey: string,
 };
 interface DelimiterMasterFilterState_SkippingGapV0 extends FilterState {
    id: DelimiterMasterFilterStateId.SkippingGapV0,
 };
 export const enum GapCachingState {
    NoGapCache = 0, // there is no gap cache
    UnknownGap = 1, // waiting for a cache lookup
    GapLookupInProgress = 2, // asynchronous gap lookup in progress
    GapCached = 3, // an upcoming or already skippable gap is cached
    NoMoreGap = 4, // the cache doesn't have any more gaps inside the listed range
 };
 type GapCachingInfo_NoGapCache = {
    state: GapCachingState.NoGapCache;
 };
 type GapCachingInfo_NoCachedGap = {
    state: GapCachingState.UnknownGap
        | GapCachingState.GapLookupInProgress
    gapCache: GapCacheInterface;
 };
 type GapCachingInfo_GapCached = {
    state: GapCachingState.GapCached;
    gapCache: GapCacheInterface;
    gapCached: GapSetEntry;
 };
 type GapCachingInfo_NoMoreGap = {
    state: GapCachingState.NoMoreGap;
 };
 type GapCachingInfo = GapCachingInfo_NoGapCache
    | GapCachingInfo_NoCachedGap
    | GapCachingInfo_GapCached
    | GapCachingInfo_NoMoreGap;
 export const enum GapBuildingState {
    Disabled = 0, // no gap cache or no gap building needed (e.g. in V1 versioning format)
    NotBuilding = 1, // not currently building a gap (i.e. not listing within a gap)
    Building = 2, // currently building a gap (i.e. listing within a gap)
    Expired = 3, // not allowed to build due to exposure delay timeout
 };
 type GapBuildingInfo_NothingToBuild = {
    state: GapBuildingState.Disabled | GapBuildingState.Expired;
 };
 type GapBuildingParams = {
    /**
     * minimum weight for a gap to be created in the cache
     */
    minGapWeight: number;
    /**
     * trigger a cache setGap() call every N skippable keys
     */
    triggerSaveGapWeight: number;
    /**
     * timestamp to assess whether we're still inside the validity period to
     * be allowed to build gaps
     */
    initTimestamp: number;
 };
 type GapBuildingInfo_NotBuilding = {
    state: GapBuildingState.NotBuilding;
    gapCache: GapCacheInterface;
    params: GapBuildingParams;
 };
 type GapBuildingInfo_Building = {
    state: GapBuildingState.Building;
    gapCache: GapCacheInterface;
    params: GapBuildingParams;
    /**
     * Gap currently being created
     */
    gap: GapSetEntry;
    /**
     * total current weight of the gap being created
     */
    gapWeight: number;
 };
 type GapBuildingInfo = GapBuildingInfo_NothingToBuild
    | GapBuildingInfo_NotBuilding
    | GapBuildingInfo_Building;
 /**
 * Handle object listing with parameters. This extends the base class Delimiter
 * to return the raw master versions of existing objects.
 */
 export class DelimiterMaster extends Delimiter {
    _gapCaching: GapCachingInfo;
    _gapBuilding: GapBuildingInfo;
    _refreshedBuildingParams: GapBuildingParams | null;
    /**
     * Delimiter listing of master versions.
     * @param {Object}  parameters            - listing parameters
     * @param {String}  [parameters.delimiter]  - delimiter per amazon format
     * @param {String}  [parameters.prefix]     - prefix per amazon format
     * @param {String}  [parameters.marker]     - marker per amazon format
     * @param {Number}  [parameters.maxKeys]    - number of keys to list
     * @param {Boolean} [parameters.v2]         - indicates whether v2 format
     * @param {String}  [parameters.startAfter] - marker per amazon v2 format
     * @param {String}  [parameters.continuationToken] - obfuscated amazon token
     * @param {RequestLogger} logger            - The logger of the request
     * @param {String}  [vFormat="v0"]          - versioning key format
     */
    constructor(parameters, logger, vFormat?: string) {
        super(parameters, logger, vFormat);
        if (this.vFormat === BucketVersioningKeyFormat.v0) {
            // override Delimiter's implementation of NotSkipping for
            // DelimiterMaster logic (skipping versions and special
            // handling of delete markers and PHDs)
            this.setKeyHandler(
                DelimiterFilterStateId.NotSkipping,
                this.keyHandler_NotSkippingPrefixNorVersionsV0.bind(this));
            // add extra state handlers specific to DelimiterMaster with v0 format
            this.setKeyHandler(
                DelimiterMasterFilterStateId.SkippingVersionsV0,
                this.keyHandler_SkippingVersionsV0.bind(this));
            this.setKeyHandler(
                DelimiterMasterFilterStateId.WaitVersionAfterPHDV0,
                this.keyHandler_WaitVersionAfterPHDV0.bind(this));
            this.setKeyHandler(
                DelimiterMasterFilterStateId.SkippingGapV0,
                this.keyHandler_SkippingGapV0.bind(this));
            if (this.marker) {
                // distinct initial state to include some special logic
                // before the first master key is found that does not have
                // to be checked afterwards
                this.state = <DelimiterMasterFilterState_SkippingVersionsV0> {
                    id: DelimiterMasterFilterStateId.SkippingVersionsV0,
                    masterKey: this.marker,
                };
            } else {
                this.state = <DelimiterFilterState_NotSkipping> {
                    id: DelimiterFilterStateId.NotSkipping,
                };
            }
        } else {
            // save base implementation of the `NotSkipping` state in
            // Delimiter before overriding it with ours, to be able to call it from there
            this.keyHandler_NotSkipping_Delimiter = this.keyHandlers[DelimiterFilterStateId.NotSkipping];
            this.setKeyHandler(
                DelimiterFilterStateId.NotSkipping,
                this.keyHandler_NotSkippingPrefixNorVersionsV1.bind(this));
        }
        // in v1, we can directly use Delimiter's implementation,
        // which is already set to the proper state
        // default initialization of the gap cache and building states, can be
        // set by refreshGapCache()
        this._gapCaching = {
            state: GapCachingState.NoGapCache,
        };
        this._gapBuilding = {
            state: GapBuildingState.Disabled,
        };
        this._refreshedBuildingParams = null;
    }
    /**
     * Get the validity period left before a refresh of the gap cache is needed
     * to continue building new gaps.
     *
     * @return {number|null} one of:
     * - the remaining time in milliseconds in which gaps can be added to the
     *   cache before a call to refreshGapCache() is required
     * - or 0 if there is no time left and a call to refreshGapCache() is required
     *   to resume caching gaps
     * - or null if refreshing the cache is never needed (because the gap cache
     *   is either not available or not used)
     */
    getGapBuildingValidityPeriodMs(): number | null {
        let gapBuilding;
        switch (this._gapBuilding.state) {
        case GapBuildingState.Disabled:
            return null;
        case GapBuildingState.Expired:
            return 0;
        case GapBuildingState.NotBuilding:
            gapBuilding = <GapBuildingInfo_NotBuilding> this._gapBuilding;
            break;
        case GapBuildingState.Building:
            gapBuilding = <GapBuildingInfo_Building> this._gapBuilding;
            break;
        }
        const { gapCache, params } = gapBuilding;
        const elapsedTime = Date.now() - params.initTimestamp;
        return Math.max(gapCache.exposureDelayMs - elapsedTime, 0);
    }
    /**
     * Refresh the gaps caching logic (gaps are series of current delete markers
     * in V0 bucket metadata format). It has two effects:
     *
     * - starts exposing existing and future gaps from the cache to efficiently
     *   skip over series of current delete markers that have been seen and cached
     *   earlier
     *
     * - enables building and caching new gaps (or extend existing ones), for a
     *   limited time period defined by the `gapCacheProxy.exposureDelayMs` value
     *   in milliseconds. To refresh the validity period and resume building and
     *   caching new gaps, one must restart a new listing from the database (starting
     *   at the current listing key, included), then call refreshGapCache() again.
     *
     * @param {GapCacheInterface} gapCacheProxy - API proxy to the gaps cache
     *   (the proxy should handle prefixing object keys with the bucket name)
     * @param {number} [minGapWeight=100] - minimum weight of a gap for it to be
     *   added in the cache
     * @param {number} [triggerSaveGapWeight] - cumulative weight to wait for
     *   before saving the current building gap. Cannot be greater than
     *   `gapCacheProxy.maxGapWeight` (the value is thresholded to `maxGapWeight`
     *   otherwise). Defaults to `gapCacheProxy.maxGapWeight / 2`.
     * @return {undefined}
     */
    refreshGapCache(
        gapCacheProxy: GapCacheInterface,
        minGapWeight?: number,
        triggerSaveGapWeight?: number
    ): void {
        if (this.vFormat !== BucketVersioningKeyFormat.v0) {
            return;
        }
        if (this._gapCaching.state === GapCachingState.NoGapCache) {
            this._gapCaching = {
                state: GapCachingState.UnknownGap,
                gapCache: gapCacheProxy,
            };
        }
        const refreshedBuildingParams: GapBuildingParams = {
            minGapWeight: minGapWeight || 100,
            triggerSaveGapWeight: triggerSaveGapWeight
                || Math.trunc(gapCacheProxy.maxGapWeight / 2),
            initTimestamp: Date.now(),
        };
        if (this._gapBuilding.state === GapBuildingState.Building) {
            // refreshed params will be applied as soon as the current building gap is saved
            this._refreshedBuildingParams = refreshedBuildingParams;
        } else {
            this._gapBuilding = {
                state: GapBuildingState.NotBuilding,
                gapCache: gapCacheProxy,
                params: refreshedBuildingParams,
            };
        }
    }
    /**
     * Trigger a lookup of the closest upcoming or already skippable gap.
     *
     * @param {string} fromKey - lookup a gap not before 'fromKey'
     * @return {undefined} - the lookup is asynchronous and its
     * response is handled inside this function
     */
    _triggerGapLookup(gapCaching: GapCachingInfo_NoCachedGap, fromKey: string): void {
        this._gapCaching = {
            state: GapCachingState.GapLookupInProgress,
            gapCache: gapCaching.gapCache,
        };
        const maxKey = this.prefix ? inc(this.prefix) : undefined;
        gapCaching.gapCache.lookupGap(fromKey, maxKey).then(_gap => {
            const gap = <GapSetEntry | null> _gap;
            if (gap) {
                this._gapCaching = {
                    state: GapCachingState.GapCached,
                    gapCache: gapCaching.gapCache,
                    gapCached: gap,
                };
            } else {
                this._gapCaching = {
                    state: GapCachingState.NoMoreGap,
                };
            }
        });
    }
    _checkGapOnMasterDeleteMarker(key: string): FilterReturnValue {
        switch (this._gapBuilding.state) {
        case GapBuildingState.Disabled:
        case GapBuildingState.Expired:
            break;
        case GapBuildingState.NotBuilding:
            this._createBuildingGap(key, 1);
            break;
        case GapBuildingState.Building:
            this._updateBuildingGap(key);
            break;
        }
        if (this._gapCaching.state === GapCachingState.GapCached) {
            const { gapCached } = this._gapCaching;
            if (key >= gapCached.firstKey) {
                if (key <= gapCached.lastKey) {
                    // we are inside the last looked up cached gap: transition to
                    // 'SkippingGapV0' state
                    this.setState(<DelimiterMasterFilterState_SkippingGapV0> {
                        id: DelimiterMasterFilterStateId.SkippingGapV0,
                    });
                    // cut the current gap before skipping, it will be merged or
                    // chained with the existing one (depending on its weight)
                    if (this._gapBuilding.state === GapBuildingState.Building) {
                        // substract 1 from the weight because we are going to chain this gap,
                        // which has an overlap of one key.
                        this._gapBuilding.gap.weight -= 1;
                        this._cutBuildingGap();
                    }
                    return FILTER_SKIP;
                }
                // as we are past the cached gap, we will need another lookup
                this._gapCaching = {
                    state: GapCachingState.UnknownGap,
                    gapCache: this._gapCaching.gapCache,
                };
            }
        }
        if (this._gapCaching.state === GapCachingState.UnknownGap) {
            this._triggerGapLookup(this._gapCaching, key);
        }
        return FILTER_ACCEPT;
    }
    filter_onNewMasterKeyV0(key: string, value: string): FilterReturnValue {
        // if this master key is a delete marker, accept it without
        // adding the version to the contents
        if (Version.isDeleteMarker(value)) {
            // update the state to start skipping versions of the new master key
            this.setState(<DelimiterMasterFilterState_SkippingVersionsV0> {
                id: DelimiterMasterFilterStateId.SkippingVersionsV0,
                masterKey: key,
            });
            return this._checkGapOnMasterDeleteMarker(key);
        }
        if (Version.isPHD(value)) {
            // master version is a PHD version: wait for the first
            // following version that will be considered as the actual
            // master key
            this.setState(<DelimiterMasterFilterState_WaitVersionAfterPHDV0> {
                id: DelimiterMasterFilterStateId.WaitVersionAfterPHDV0,
                masterKey: key,
            });
            return FILTER_ACCEPT;
        }
        // cut the current gap as soon as a non-deleted entry is seen
        this._cutBuildingGap();
        if (key.startsWith(DbPrefixes.Replay)) {
            // skip internal replay prefix entirely
            this.setState(<DelimiterFilterState_SkippingPrefix> {
                id: DelimiterFilterStateId.SkippingPrefix,
                prefix: DbPrefixes.Replay,
            });
            return FILTER_SKIP;
        }
        if (this._reachedMaxKeys()) {
            return FILTER_END;
        }
        const commonPrefix = this.addCommonPrefixOrContents(key, value);
        if (commonPrefix) {
            // transition into SkippingPrefix state to skip all following keys
            // while they start with the same prefix
            this.setState(<DelimiterFilterState_SkippingPrefix> {
                id: DelimiterFilterStateId.SkippingPrefix,
                prefix: commonPrefix,
            });
            return FILTER_ACCEPT;
        }
        // update the state to start skipping versions of the new master key
        this.setState(<DelimiterMasterFilterState_SkippingVersionsV0> {
            id: DelimiterMasterFilterStateId.SkippingVersionsV0,
            masterKey: key,
        });
        return FILTER_ACCEPT;
    }
    keyHandler_NotSkippingPrefixNorVersionsV0(key: string, value: string): FilterReturnValue {
        return this.filter_onNewMasterKeyV0(key, value);
    }
    filter_onNewMasterKeyV1(key: string, value: string): FilterReturnValue {
        // if this master key is a delete marker, accept it without
        // adding the version to the contents
        if (Version.isDeleteMarker(value)) {
            return FILTER_ACCEPT;
        }
        // use base Delimiter's implementation
        return this.keyHandler_NotSkipping_Delimiter(key, value);
    }
    keyHandler_NotSkippingPrefixNorVersionsV1(key: string, value: string): FilterReturnValue {
        return this.filter_onNewMasterKeyV1(key, value);
    }
    keyHandler_SkippingVersionsV0(key: string, value: string): FilterReturnValue {
        /* In the SkippingVersionsV0 state, skip all version keys
         * (<key><versionIdSeparator><version>) */
        const versionIdIndex = key.indexOf(VID_SEP);
        if (versionIdIndex !== -1) {
            // version keys count in the building gap weight because they must
            // also be listed until skipped
            if (this._gapBuilding.state === GapBuildingState.Building) {
                this._updateBuildingGap(key);
            }
            return FILTER_SKIP;
        }
        return this.filter_onNewMasterKeyV0(key, value);
    }
    keyHandler_WaitVersionAfterPHDV0(key: string, value: string): FilterReturnValue {
        // After a PHD key is encountered, the next version key of the
        // same object if it exists is the new master key, hence
        // consider it as such and call 'onNewMasterKeyV0' (the test
        // 'masterKey == phdKey' is probably redundant when we already
        // know we have a versioned key, since all objects in v0 have
        // a master key, but keeping it in doubt)
        const { masterKey: phdKey } = <DelimiterMasterFilterState_WaitVersionAfterPHDV0> this.state;
        const versionIdIndex = key.indexOf(VID_SEP);
        if (versionIdIndex !== -1) {
            const masterKey = key.slice(0, versionIdIndex);
            if (masterKey === phdKey) {
                return this.filter_onNewMasterKeyV0(masterKey, value);
            }
        }
        return this.filter_onNewMasterKeyV0(key, value);
    }
    keyHandler_SkippingGapV0(key: string, value: string): FilterReturnValue {
        const { gapCache, gapCached } = <GapCachingInfo_GapCached> this._gapCaching;
        if (key <= gapCached.lastKey) {
            return FILTER_SKIP;
        }
        this._gapCaching = {
            state: GapCachingState.UnknownGap,
            gapCache,
        };
        this.setState(<DelimiterMasterFilterState_SkippingVersionsV0> {
            id: DelimiterMasterFilterStateId.SkippingVersionsV0,
        });
        // Start a gap with weight=0 from the latest skippable key. This will
        // allow to extend the gap just skipped with a chained gap in case
        // other delete markers are seen after the existing gap is skipped.
        this._createBuildingGap(gapCached.lastKey, 0, gapCached.weight);
        return this.handleKey(key, value);
    }
    skippingBase(): string | undefined {
        switch (this.state.id) {
        case DelimiterMasterFilterStateId.SkippingVersionsV0:
            const { masterKey } = <DelimiterMasterFilterState_SkippingVersionsV0> this.state;
            return masterKey + inc(VID_SEP);
        case DelimiterMasterFilterStateId.SkippingGapV0:
            const { gapCached } = <GapCachingInfo_GapCached> this._gapCaching;
            return gapCached.lastKey;
        default:
            return super.skippingBase();
        }
    }
    result(): ResultObject {
        this._cutBuildingGap();
        return super.result();
    }
    _checkRefreshedBuildingParams(params: GapBuildingParams): GapBuildingParams {
        if (this._refreshedBuildingParams) {
            const newParams = this._refreshedBuildingParams;
            this._refreshedBuildingParams = null;
            return newParams;
        }
        return params;
    }
    /**
     * Save the gap being built if allowed (i.e. still within the
     * allocated exposure time window).
     *
     * @return {boolean} - true if the gap was saved, false if we are
     * outside the allocated exposure time window.
     */
    _saveBuildingGap(): boolean {
        const { gapCache, params, gap, gapWeight } =
              <GapBuildingInfo_Building> this._gapBuilding;
        const totalElapsed = Date.now() - params.initTimestamp;
        if (totalElapsed >= gapCache.exposureDelayMs) {
            this._gapBuilding = {
                state: GapBuildingState.Expired,
            };
            this._refreshedBuildingParams = null;
            return false;
        }
        const { firstKey, lastKey, weight } = gap;
        gapCache.setGap(firstKey, lastKey, weight);
        this._gapBuilding = {
            state: GapBuildingState.Building,
            gapCache,
            params: this._checkRefreshedBuildingParams(params),
            gap: {
                firstKey: gap.lastKey,
                lastKey: gap.lastKey,
                weight: 0,
            },
            gapWeight,
        };
        return true;
    }
    /**
     * Create a new gap to be extended afterwards
     *
     * @param {string} newKey - gap's first key
     * @param {number} startWeight - initial weight of the building gap (usually 0 or 1)
     * @param {number} [cachedWeight] - if continuing a cached gap, weight of the existing
     *   cached portion
     * @return {undefined}
     */
    _createBuildingGap(newKey: string, startWeight: number, cachedWeight?: number): void {
        if (this._gapBuilding.state === GapBuildingState.NotBuilding) {
            const { gapCache, params } = <GapBuildingInfo_NotBuilding> this._gapBuilding;
            this._gapBuilding = {
                state: GapBuildingState.Building,
                gapCache,
                params: this._checkRefreshedBuildingParams(params),
                gap: {
                    firstKey: newKey,
                    lastKey: newKey,
                    weight: startWeight,
                },
                gapWeight: (cachedWeight || 0) + startWeight,
            };
        }
    }
    _updateBuildingGap(newKey: string): void {
        const gapBuilding = <GapBuildingInfo_Building> this._gapBuilding;
        const { params, gap } = gapBuilding;
        gap.lastKey = newKey;
        gap.weight += 1;
        gapBuilding.gapWeight += 1;
        // the GapCache API requires updating a gap regularly because it can only split
        // it once per update, by the known last key. In practice the default behavior
        // is to trigger an update after a number of keys that is half the maximum weight.
        // It is also useful for other listings to benefit from the cache sooner.
        if (gapBuilding.gapWeight >= params.minGapWeight &&
            gap.weight >= params.triggerSaveGapWeight) {
            this._saveBuildingGap();
        }
    }
    _cutBuildingGap(): void {
        if (this._gapBuilding.state === GapBuildingState.Building) {
            let gapBuilding = <GapBuildingInfo_Building> this._gapBuilding;
            let { gapCache, params, gap, gapWeight } = gapBuilding;
            // only set gaps that are significant enough in weight and
            // with a non-empty extension
            if (gapWeight >= params.minGapWeight && gap.weight > 0) {
                // we're done if we were not allowed to save the gap
                if (!this._saveBuildingGap()) {
                    return;
                }
                // params may have been refreshed, reload them
                gapBuilding = <GapBuildingInfo_Building> this._gapBuilding;
                params = gapBuilding.params;
            }
            this._gapBuilding = {
                state: GapBuildingState.NotBuilding,
                gapCache,
                params,
            };
        }
    }
 }
--- a/lib/algos/list/delimiterNonCurrent.js
+++ b/lib/algos/list/delimiterNonCurrent.js
@ -1,37 +1,82 @@
-const { DelimiterVersions } = require('./delimiterVersions');
+'use strict'; // eslint-disable-line strict
-const { FILTER_END, FILTER_SKIP } = require('./tools');
+const Delimiter = require('./delimiter').Delimiter;
 const VSConst = require('../../versioning/constants').VersioningConstants;
 const { inc, FILTER_ACCEPT, FILTER_END, SKIP_NONE } = require('./tools');
 const VID_SEP = VSConst.VersionId.Separator;
 const { DbPrefixes } = VSConst;
 // TODO: find an acceptable timeout value.
 const DELIMITER_TIMEOUT_MS = 10 * 1000; // 10s
 const TRIM_METADATA_MIN_BLOB_SIZE = 10000;
 /**
- * Handle object listing with parameters. This extends the base class DelimiterVersions
+ * Handle object listing with parameters. This extends the base class Delimiter
 * to return the raw non-current versions objects.
 */
-class DelimiterNonCurrent extends DelimiterVersions {
+class DelimiterNonCurrent extends Delimiter {
    /**
     * Delimiter listing of non-current versions.
     * @param {Object}  parameters                  - listing parameters
     * @param {String}  parameters.keyMarker        - key marker
     * @param {String}  parameters.versionIdMarker  - version id marker
-     * @param {String}  parameters.beforeDate       - limit the response to keys with stale date older than beforeDate.
+     * @param {String}  parameters.beforeDate       - limit the response to keys with stale date older than beforeDate
     * “stale date” is the date on when a version becomes non-current.
-     * @param {Number} parameters.maxScannedLifecycleListingEntries - max number of entries to be scanned
+     * @param {String}  parameters.keyMarker        - key marker
     * @param {String} parameters.excludedDataStoreName - exclude dataStoreName matches from the versions
     * @param {RequestLogger} logger                - The logger of the request
     * @param {String} [vFormat]                    - versioning key format
     */
    constructor(parameters, logger, vFormat) {
        super(parameters, logger, vFormat);
        this.versionIdMarker = parameters.versionIdMarker;
        this.beforeDate = parameters.beforeDate;
-        this.excludedDataStoreName = parameters.excludedDataStoreName;
+        this.keyMarker = parameters.keyMarker;
-        this.maxScannedLifecycleListingEntries = parameters.maxScannedLifecycleListingEntries;
+        this.NextKeyMarker = null;
-        // internal state
+        this.skipping = this.skippingV1;
-        this.prevKey = null;
+        this.genMDParams = this.genMDParamsV1;
        this.keyName = null;
        this.staleDate = null;
-        this.scannedKeys = 0;
+        // used for monitoring
        this.evaluatedKeys = 0;
    }
    skippingV1() {
        return SKIP_NONE;
    }
    genMDParamsV1() {
        const params = {
            gte: DbPrefixes.Version,
            lt: inc(DbPrefixes.Version),
        };
        if (this.prefix) {
            params.gte = `${DbPrefixes.Version}${this.prefix}`;
            params.lt = `${DbPrefixes.Version}${inc(this.prefix)}`;
        }
        if (this.keyMarker && `${DbPrefixes.Version}${this.keyMarker}` >= params.gte) {
            if (this.versionIdMarker) {
                // versionIdMarker should always come with keyMarker but may not be the other way around.
                // NOTE: "gte" (instead of "gt") is used to include the last version of the "previous"
                // truncated listing when a versionId marker is specified.
                // This "previous"/"already evaluated" version will be used to retrieve the stale date and
                // skipped to not evaluate the same key twice in the addContents() method.
                params.gte = DbPrefixes.Version
                    + this.keyMarker
                    + VID_SEP
                    + this.versionIdMarker;
            } else {
                delete params.gte;
                params.gt = DbPrefixes.Version + inc(this.keyMarker + VID_SEP);
            }
        }
        this.start = Date.now();
        return params;
    }
    getLastModified(value) {
@ -49,151 +94,117 @@ class DelimiterNonCurrent extends DelimiterVersions {
        return lastModified;
    }
    // Overwrite keyHandler_SkippingVersions to include the last version from the previous listing.
    // The creation (last-modified) date of this version will be the stale date for the following version.
    // eslint-disable-next-line camelcase
    keyHandler_SkippingVersions(key, versionId, value) {
        if (key === this.keyMarker) {
            // since the nonversioned key equals the marker, there is
            // necessarily a versionId in this key
            const _versionId = versionId;
            if (_versionId < this.versionIdMarker) {
                // skip all versions until marker
                return FILTER_SKIP;
            }
        }
        this.setState({
            id: 1 /* NotSkipping */,
        });
        return this.handleKey(key, versionId, value);
    }
    filter(obj) {
        if (this.maxScannedLifecycleListingEntries && this.scannedKeys >= this.maxScannedLifecycleListingEntries) {
            this.IsTruncated = true;
            this.logger.info('listing stopped due to reaching the maximum scanned entries limit',
                {
                    maxScannedLifecycleListingEntries: this.maxScannedLifecycleListingEntries,
                    scannedKeys: this.scannedKeys,
                });
            return FILTER_END;
        }
        ++this.scannedKeys;
        return super.filter(obj);
    }
    /**
     * NOTE: Each version of a specific key is sorted from the latest to the oldest
     * thanks to the way version ids are generated.
-     * DESCRIPTION: Skip the version if it represents the master key, but keep its last-modified date in memory,
+     * DESCRIPTION: For a given key, the latest version is skipped since it represents the current version or
-     * which will be the stale date of the following version.
+     * the last version of the previous truncated listing.
-     * The following version is pushed only:
+     * The current last-modified date is kept in memory and used as a "stale date" for the following version.
-     * - if the "stale date" (picked up from the previous version) is available (JSON.parse has not failed),
+     * The following version is pushed only if the "stale date" (picked up from the previous version)
-     * - if "beforeDate" is not specified or if specified and the "stale date" is older.
+     * is available (JSON.parse has not failed), if the "beforeDate" argument is specified, and
-     * - if "excludedDataStoreName" is not specified or if specified and the data store name is different
+     * the "stale date" is older than the "beforeDate".
     * The in-memory "stale date" is then updated with the version's last-modified date to be used for
     * the following version.
     * The process stops and returns the available results if either:
     * - no more metadata key is left to be processed
     * - the listing reaches the maximum number of key to be returned
     * - the internal timeout is reached
-     *  @param {String} key   - The key to add
+     *  @param {String} keyVersionSuffix   - The key to add
     *  @param {String} versionId - The version id
     *  @param {String} value - The value of the key
-     *  @return {undefined}
+     *  @return {number}      - indicates if iteration should continue
     */
-    addVersion(key, versionId, value) {
+    addContents(keyVersionSuffix, value) {
-        this.nextKeyMarker = key;
+        if (this._reachedMaxKeys()) {
-        this.nextVersionIdMarker = versionId;
+            return FILTER_END;
        // Skip the version if it represents the non-current version, but keep its last-modified date,
        // which will be the stale date of the following version.
        const isCurrentVersion = key !== this.prevKey;
        if (isCurrentVersion) {
            this.staleDate = this.getLastModified(value);
            this.prevKey = key;
            return;
        }
-        // The following version is pushed only:
+        if (this.start && Date.now() - this.start > DELIMITER_TIMEOUT_MS) {
-        // - if the "stale date" (picked up from the previous version) is available (JSON.parse has not failed),
+            this.IsTruncated = true;
-        // - if "beforeDate" is not specified or if specified and the "stale date" is older.
+            this.logger.info('listing stopped after expected internal timeout',
-        // - if "excludedDataStoreName" is not specified or if specified and the data store name is different
+                {
                    timeoutMs: DELIMITER_TIMEOUT_MS,
                    evaluatedKeys: this.evaluatedKeys,
                });
            return FILTER_END;
        }
        ++this.evaluatedKeys;
        const versionIdIndex = keyVersionSuffix.indexOf(VID_SEP);
        const key = keyVersionSuffix.slice(0, versionIdIndex);
        const versionId = keyVersionSuffix.slice(versionIdIndex + 1);
        this.NextKeyMarker = key;
        this.NextVersionIdMarker = versionId;
        // For a given key, the latest version is skipped since it represents either:
        // - the current version or
        // - the last version of the previous truncated listing
        const isLatestVersion = key !== this.keyName;
        if (isLatestVersion) {
            this.keyName = key;
            // The current last-modified date is kept in memory and used as a "stale date" for the following version.
            this.staleDate = this.getLastModified(value);
            return FILTER_ACCEPT;
        }
        // The following version is pushed only if the "stale date" (picked up from the previous version)
        // is available (JSON.parse has not failed) and, if the "beforeDate" argument is specified,
        // the "stale date" is older than the "beforeDate".
        let lastModified;
        if (this.staleDate && (!this.beforeDate || this.staleDate < this.beforeDate)) {
-            const parsedValue = this._parse(value);
+            const v = this.trimMetadataAddStaleDate(value, this.staleDate);
-            // if parsing fails, skip the key.
+            lastModified = v.lastModified;
-            if (parsedValue) {
+            const { contentValue } = v;
-                const dataStoreName = parsedValue.dataStoreName;
+            // check that trimMetadataAddStaleDate succeeds to only push objects with a defined staleDate.
-                lastModified = parsedValue['last-modified'];
+            if (contentValue) {
-                if (!this.excludedDataStoreName || dataStoreName !== this.excludedDataStoreName) {
+                this.Contents.push({ key, value: contentValue });
                    const s = this._stringify(parsedValue, this.staleDate);
                    // check that _stringify succeeds to only push objects with a defined staleDate.
                    if (s) {
                        this.Versions.push({ key, value: s });
                ++this.keys;
            }
        }
            }
        }
        // The in-memory "stale date" is then updated with the version's last-modified date to be used for
        // the following version.
        this.staleDate = lastModified || this.getLastModified(value);
-        return;
+        return FILTER_ACCEPT;
    }
-    /**
+    trimMetadataAddStaleDate(value, staleDate) {
-     * Parses the stringified entry's value and remove the location property if too large.
+        let ret = undefined;
-     * @param {string} s - sringified value
+        let lastModified = undefined;
     * @return {object} p - undefined if parsing fails, otherwise it contains the parsed value.
     */
    _parse(s) {
        let p;
        try {
-            p = JSON.parse(s);
+            ret = JSON.parse(value);
-            if (s.length >= TRIM_METADATA_MIN_BLOB_SIZE) {
+            ret.staleDate = staleDate;
-                delete p.location;
+            lastModified = ret['last-modified'];
            if (value.length >= TRIM_METADATA_MIN_BLOB_SIZE) {
                delete ret.location;
            }
            ret = JSON.stringify(ret);
        } catch (e) {
-            this.logger.warn('Could not parse Object Metadata while listing', {
+            // Prefer returning an unfiltered data rather than
-                method: 'DelimiterNonCurrent._parse',
+            // stopping the service in case of parsing failure.
            // The risk of this approach is a potential
            // reproduction of MD-692, where too much memory is
            // used by repd.
            this.logger.warn('could not parse Object Metadata while listing',
                {
                    method: 'trimMetadataAddStaleDate',
                    err: e.toString(),
                });
        }
-        return p;
+        return { contentValue: ret, lastModified };
    }
    _stringify(parsedMD, staleDate) {
        const p = parsedMD;
        let s = undefined;
        p.staleDate = staleDate;
        try {
            s = JSON.stringify(p);
        } catch (e) {
            this.logger.warn('could not stringify Object Metadata while listing', {
                method: 'DelimiterNonCurrent._stringify',
                err: e.toString(),
            });
        }
        return s;
    }
    result() {
        const { Versions, IsTruncated, NextKeyMarker, NextVersionIdMarker } = super.result();
        const result = {
-            Contents: Versions,
+            Contents: this.Contents,
-            IsTruncated,
+            IsTruncated: this.IsTruncated,
        };
-        if (NextKeyMarker) {
+        if (this.IsTruncated) {
-            result.NextKeyMarker = NextKeyMarker;
+            result.NextKeyMarker = this.NextKeyMarker;
-        }
+            result.NextVersionIdMarker = this.NextVersionIdMarker;
        if (NextVersionIdMarker) {
            result.NextVersionIdMarker = NextVersionIdMarker;
        }
        return result;
--- a/lib/algos/list/delimiterOrphanDeleteMarker.js
+++ b/lib/algos/list/delimiterOrphanDeleteMarker.js
@ -1,50 +1,45 @@
-const DelimiterVersions = require('./delimiterVersions').DelimiterVersions;
+'use strict'; // eslint-disable-line strict
-const { FILTER_END } = require('./tools');
+const Delimiter = require('./delimiter').Delimiter;
 const VSConst = require('../../versioning/constants').VersioningConstants;
 const { inc, FILTER_ACCEPT, FILTER_END, SKIP_NONE } = require('./tools');
 const VID_SEP = VSConst.VersionId.Separator;
 const { DbPrefixes } = VSConst;
 const DELIMITER_TIMEOUT_MS = 10 * 1000; // 10s
 const TRIM_METADATA_MIN_BLOB_SIZE = 10000;
 /**
- * Handle object listing with parameters. This extends the base class DelimiterVersions
+ * Handle object listing with parameters. This extends the base class Delimiter
 * to return the orphan delete markers. Orphan delete markers are also
 * refered as expired object delete marker.
 * They are delete marker with zero noncurrent versions.
 */
-class DelimiterOrphanDeleteMarker extends DelimiterVersions {
+class DelimiterOrphanDeleteMarker extends Delimiter {
    /**
-     * Delimiter listing of orphan delete markers.
+     * Delimiter listing of non-current versions.
     * @param {Object}  parameters            - listing parameters
     * @param {String}  parameters.beforeDate - limit the response to keys older than beforeDate
     * @param {Number} parameters.maxScannedLifecycleListingEntries - max number of entries to be scanned
     * @param {RequestLogger} logger          - The logger of the request
     * @param {String} [vFormat]              - versioning key format
     */
    constructor(parameters, logger, vFormat) {
-        const {
+        super(parameters, logger, vFormat);
            marker,
            maxKeys,
            prefix,
            beforeDate,
            maxScannedLifecycleListingEntries,
        } = parameters;
-        const versionParams = {
+        this.beforeDate = parameters.beforeDate;
-            // The orphan delete marker logic uses the term 'marker' instead of 'keyMarker',
+
-            // as the latter could suggest the presence of a 'versionIdMarker'.
+        this.skipping = this.skippingV1;
-            keyMarker: marker,
+        this.genMDParams = this.genMDParamsV1;
            maxKeys,
            prefix,
        };
        super(versionParams, logger, vFormat);
        this.maxScannedLifecycleListingEntries = maxScannedLifecycleListingEntries;
        this.beforeDate = beforeDate;
        // this.prevKeyName is used as a marker for the next listing when the current one reaches its entry limit.
        // We cannot rely on this.keyName, as it contains the name of the current key.
        // In the event of a listing interruption due to reaching the maximum scanned entries,
        // relying on this.keyName would cause the next listing to skip the current key because S3 starts
        // listing after the marker.
        this.prevKeyName = null;
        this.keyName = null;
        this.staleDate = null;
        this.value = null;
-        this.scannedKeys = 0;
+
        // used for monitoring
        this.evaluatedKeys = 0;
    }
    skippingV1() {
        return SKIP_NONE;
    }
    _reachedMaxKeys() {
@ -54,6 +49,28 @@ class DelimiterOrphanDeleteMarker extends DelimiterVersions {
        return false;
    }
    genMDParamsV1() {
        const params = {
            gte: DbPrefixes.Version,
            lt: inc(DbPrefixes.Version),
        };
        if (this.prefix) {
            params.gte = `${DbPrefixes.Version}${this.prefix}`;
            params.lt = `${DbPrefixes.Version}${inc(this.prefix)}`;
        }
        if (this.marker && `${DbPrefixes.Version}${this.marker}` >= params.gte) {
            delete params.gte;
            params.gt = DbPrefixes.Version
                    + inc(this.marker + VID_SEP);
        }
        this.start = Date.now();
        return params;
    }
    _addOrphan() {
        const parsedValue = this._parse(this.value);
        // if parsing fails, skip the key.
@ -63,73 +80,43 @@ class DelimiterOrphanDeleteMarker extends DelimiterVersions {
            // We then check if the orphan version is a delete marker and if it is older than the "beforeDate"
            if ((!this.beforeDate || (lastModified && lastModified < this.beforeDate)) && isDeleteMarker) {
                // Prefer returning an untrimmed data rather than stopping the service in case of parsing failure.
-                const s = this._stringify(parsedValue) || this.value;
+                const s = this._trimAndStringify(parsedValue) || this.value;
-                this.Versions.push({ key: this.keyName, value: s });
+                this.Contents.push({ key: this.keyName, value: s });
-                this.nextKeyMarker = this.keyName;
+                this.NextMarker = this.keyName;
                ++this.keys;
            }
        }
    }
    /**
     * Parses the stringified entry's value and remove the location property if too large.
     * @param {string} s - sringified value
     * @return {object} p - undefined if parsing fails, otherwise it contains the parsed value.
     */
    _parse(s) {
        let p;
        try {
            p = JSON.parse(s);
            if (s.length >= TRIM_METADATA_MIN_BLOB_SIZE) {
                delete p.location;
            }
        } catch (e) {
-            this.logger.warn('Could not parse Object Metadata while listing', {
+            this.logger.warn(
-                method: 'DelimiterOrphanDeleteMarker._parse',
+                'Could not parse Object Metadata while listing',
-                err: e.toString(),
+                { err: e.toString() });
            });
        }
        return p;
    }
-    _stringify(value) {
+    _trimAndStringify(value) {
        const p = value;
        let s = undefined;
        try {
            if (p.length >= TRIM_METADATA_MIN_BLOB_SIZE) {
                delete p.location;
            }
            s = JSON.stringify(p);
        } catch (e) {
-            this.logger.warn('could not stringify Object Metadata while listing',
+            this.logger.warn('could not trim and stringify Object Metadata while listing',
                {
-                    method: 'DelimiterOrphanDeleteMarker._stringify',
+                    method: 'trimMetadataAddStaleDate',
                    err: e.toString(),
                });
        }
        return s;
    }
    /**
     * The purpose of _isMaxScannedEntriesReached is to restrict the number of scanned entries,
     * thus controlling resource overhead (CPU...).
     * @return {boolean} isMaxScannedEntriesReached - true if the maximum limit on the number
     * of entries scanned has been reached, false otherwise.
    */
    _isMaxScannedEntriesReached() {
        return this.maxScannedLifecycleListingEntries && this.scannedKeys >= this.maxScannedLifecycleListingEntries;
    }
    filter(obj) {
        if (this._isMaxScannedEntriesReached()) {
            this.nextKeyMarker = this.prevKeyName;
            this.IsTruncated = true;
            this.logger.info('listing stopped due to reaching the maximum scanned entries limit',
                {
                    maxScannedLifecycleListingEntries: this.maxScannedLifecycleListingEntries,
                    scannedKeys: this.scannedKeys,
                });
            return FILTER_END;
        }
        ++this.scannedKeys;
        return super.filter(obj);
    }
    /**
     * NOTE: Each version of a specific key is sorted from the latest to the oldest
@ -143,38 +130,51 @@ class DelimiterOrphanDeleteMarker extends DelimiterVersions {
     * - the internal timeout is reached
     * NOTE: we cannot leverage MongoDB to list keys older than "beforeDate"
     * because then we will not be able to assess its orphanage.
-     *  @param {String} key   - The object key.
+     *  @param {String} keyVersionSuffix   - The key with version id as a suffix.
     * @param {String} versionId   - The object version id.
     *  @param {String} value              - The value of the key
-     *  @return {undefined}
+     *  @return {number}                   - indicates if iteration should continue
     */
-    addVersion(key, versionId, value) {
+    addContents(keyVersionSuffix, value) {
        if (this._reachedMaxKeys()) {
            return FILTER_END;
        }
        if (this.start && Date.now() - this.start > DELIMITER_TIMEOUT_MS) {
            this.IsTruncated = true;
            this.NextMarker = this.keyName;
            this.logger.info('listing stopped after expected internal timeout',
                {
                    timeoutMs: DELIMITER_TIMEOUT_MS,
                    evaluatedKeys: this.evaluatedKeys,
                });
            return FILTER_END;
        }
        ++this.evaluatedKeys;
        const versionIdIndex = keyVersionSuffix.indexOf(VID_SEP);
        // key without version suffix
        const key = keyVersionSuffix.slice(0, versionIdIndex);
        // For a given key, the youngest version is kept in memory since it represents the current version.
        if (key !== this.keyName) {
            // If this.value is defined, it means that <this.keyName, this.value> pair is "allowed" to be an orphan.
            if (this.value) {
                this._addOrphan();
            }
            this.prevKeyName = this.keyName;
            this.keyName = key;
            this.value = value;
-            return;
+            return FILTER_ACCEPT;
        }
        // If the key is not the current version, we can skip it in the next listing
        // in the case where the current listing is interrupted due to reaching the maximum scanned entries.
        this.prevKeyName = key;
        this.keyName = key;
        this.value = null;
-        return;
+        return FILTER_ACCEPT;
    }
    result() {
        // Only check for remaining last orphan delete marker if the listing is not interrupted.
        // This will help avoid false positives.
        if (!this._isMaxScannedEntriesReached()) {
        // The following check makes sure the last orphan delete marker is not forgotten.
        if (this.keys < this.maxKeys) {
            if (this.value) {
@ -186,19 +186,17 @@ class DelimiterOrphanDeleteMarker extends DelimiterVersions {
        } else {
            this.IsTruncated = this.maxKeys > 0;
        }
        }
        const result = {
-            Contents: this.Versions,
+            Contents: this.Contents,
            IsTruncated: this.IsTruncated,
        };
        if (this.IsTruncated) {
-            result.NextMarker = this.nextKeyMarker;
+            result.NextMarker = this.NextMarker;
        }
        return result;
    }
 }
 module.exports = { DelimiterOrphanDeleteMarker };
--- a/lib/algos/list/delimiterVersions.ts
+++ b/lib/algos/list/delimiterVersions.ts
@ -1,12 +1,6 @@
 'use strict'; // eslint-disable-line strict
-const Extension = require('./Extension').default;
+const Delimiter = require('./delimiter').Delimiter;
 import {
    FilterState,
    FilterReturnValue,
 } from './delimiter';
 const Version = require('../../versioning/Version').Version;
 const VSConst = require('../../versioning/constants').VersioningConstants;
 const { inc, FILTER_END, FILTER_ACCEPT, FILTER_SKIP, SKIP_NONE } =
@ -15,10 +9,24 @@ const { inc, FILTER_END, FILTER_ACCEPT, FILTER_SKIP, SKIP_NONE } =
 const VID_SEP = VSConst.VersionId.Separator;
 const { DbPrefixes, BucketVersioningKeyFormat } = VSConst;
 // TODO: when S3C-4682 code is back, cleanup fields, methods and types
 // already present in Delimiter class
 export interface FilterState {
    id: number,
 };
 export interface FilterReturnValue {
    FILTER_ACCEPT,
    FILTER_SKIP,
    FILTER_END,
 };
 export const enum DelimiterVersionsFilterStateId {
    NotSkipping = 1,
    SkippingPrefix = 2,
-    SkippingVersions = 3,
+    WaitForNullKey = 3,
    SkippingVersions = 4,
 };
 export interface DelimiterVersionsFilterState_NotSkipping extends FilterState {
@ -30,12 +38,16 @@ export interface DelimiterVersionsFilterState_SkippingPrefix extends FilterState
    prefix: string;
 };
 export interface DelimiterVersionsFilterState_WaitForNullKey extends FilterState {
    id: DelimiterVersionsFilterStateId.WaitForNullKey,
 };
 export interface DelimiterVersionsFilterState_SkippingVersions extends FilterState {
    id: DelimiterVersionsFilterStateId.SkippingVersions,
    gt: string;
 };
-type KeyHandler = (key: string, versionId: string | undefined, value: string) => FilterReturnValue;
+type KeyHandler = (key: string, value: string) => FilterReturnValue;
 type ResultObject = {
    CommonPrefixes: string[],
@ -68,17 +80,13 @@ type GenMDParamsItem = {
 * @prop {String|undefined} prefix     - prefix per amazon format
 * @prop {Number} maxKeys              - number of keys to list
 */
-export class DelimiterVersions extends Extension {
+export class DelimiterVersions extends Delimiter {
    state: FilterState;
    keyHandlers: { [id: number]: KeyHandler };
    constructor(parameters, logger, vFormat) {
-        super(parameters, logger);
+        super(parameters, logger, vFormat);
        // original listing parameters
        this.delimiter = parameters.delimiter;
        this.prefix = parameters.prefix;
        this.maxKeys = parameters.maxKeys || 1000;
        // specific to version listing
        this.keyMarker = parameters.keyMarker;
        this.versionIdMarker = parameters.versionIdMarker;
@ -86,11 +94,7 @@ export class DelimiterVersions extends Extension {
        this.masterKey = undefined;
        this.masterVersionId = undefined;
        this.nullKey = null;
        this.vFormat = vFormat || BucketVersioningKeyFormat.v0;
        // listing results
        this.CommonPrefixes = [];
        this.Versions = [];
        this.IsTruncated = false;
        this.nextKeyMarker = parameters.keyMarker;
        this.nextVersionIdMarker = undefined;
@ -122,14 +126,17 @@ export class DelimiterVersions extends Extension {
            DelimiterVersionsFilterStateId.SkippingPrefix,
            this.keyHandler_SkippingPrefix.bind(this));
        this.setKeyHandler(
            DelimiterVersionsFilterStateId.WaitForNullKey,
            this.keyHandler_WaitForNullKey.bind(this));
        this.setKeyHandler(
            DelimiterVersionsFilterStateId.SkippingVersions,
            this.keyHandler_SkippingVersions.bind(this));
        if (this.versionIdMarker) {
-            this.state = <DelimiterVersionsFilterState_SkippingVersions> {
+            this.state = <DelimiterVersionsFilterState_WaitForNullKey> {
-                id: DelimiterVersionsFilterStateId.SkippingVersions,
+                id: DelimiterVersionsFilterStateId.WaitForNullKey,
                gt: `${this.keyMarker}${VID_SEP}${this.versionIdMarker}`,
            };
        } else {
            this.state = <DelimiterVersionsFilterState_NotSkipping> {
@ -194,20 +201,6 @@ export class DelimiterVersions extends Extension {
        return [mParams, vParams];
    }
    /**
     * check if the max keys count has been reached and set the
     * final state of the result if it is the case
     * @return {Boolean} - indicates if the iteration has to stop
     */
    _reachedMaxKeys(): boolean {
        if (this.keys >= this.maxKeys) {
            // In cases of maxKeys <= 0 -> IsTruncated = false
            this.IsTruncated = this.maxKeys > 0;
            return true;
        }
        return false;
    }
    /**
     * Used to synchronize listing of M and V prefixes by object key
     *
@ -243,30 +236,6 @@ export class DelimiterVersions extends Extension {
        return { key: nonversionedKey, versionId };
    }
    /**
     * Include a key in the listing output, in the Versions or CommonPrefix result
     *
     * @param {string} key - key (without version ID)
     * @param {string} versionId - version ID
     * @param {string} value - metadata value
     * @return {undefined}
     */
    addKey(key: string, versionId: string, value: string) {
        // add the subprefix to the common prefixes if the key has the delimiter
        const commonPrefix = this.getCommonPrefix(key);
        if (commonPrefix) {
            this.addCommonPrefix(commonPrefix);
            // transition into SkippingPrefix state to skip all following keys
            // while they start with the same prefix
            this.setState(<DelimiterVersionsFilterState_SkippingPrefix> {
                id: DelimiterVersionsFilterStateId.SkippingPrefix,
                prefix: commonPrefix,
            });
        } else {
            this.addVersion(key, versionId, value);
        }
    }
    /**
     *  Add a (key, versionId, value) tuple to the listing.
     *  Set the NextMarker to the current key
@ -276,8 +245,8 @@ export class DelimiterVersions extends Extension {
     *  @param {String} value       - The value of the key
     *  @return {undefined}
     */
-    addVersion(key: string, versionId: string, value: string) {
+    addContents(key: string, versionId: string, value: string) {
-        this.Versions.push({
+        this.Contents.push({
            key,
            versionId,
            value: this.trimMetadata(value),
@ -288,9 +257,6 @@ export class DelimiterVersions extends Extension {
    }
    getCommonPrefix(key: string): string | undefined {
        if (!this.delimiter) {
            return undefined;
        }
        const baseIndex = this.prefix ? this.prefix.length : 0;
        const delimiterIndex = key.indexOf(this.delimiter, baseIndex);
        if (delimiterIndex === -1) {
@ -309,7 +275,6 @@ export class DelimiterVersions extends Extension {
        this.CommonPrefixes.push(commonPrefix);
        ++this.keys;
        this.nextKeyMarker = commonPrefix;
        this.nextVersionIdMarker = undefined;
    }
    /**
@ -325,6 +290,21 @@ export class DelimiterVersions extends Extension {
        this.nullKey = { key, versionId, value };
    }
    /**
     * Add the cached null key to the results. This is called when
     * reaching the correct position for the null key in the output.
     *
     * @return {undefined}
     */
    addCurrentNullKey(): void {
        this.addContents(
            this.nullKey.key,
            this.nullKey.versionId,
            this.nullKey.value,
        );
        this.nullKey = null;
    }
    getObjectKeyV0(obj: { key: string }): string {
        return obj.key;
    }
@ -348,24 +328,7 @@ export class DelimiterVersions extends Extension {
        const key = this.getObjectKey(obj);
        const value = obj.value;
-        const { key: nonversionedKey, versionId: keyVersionId } = this.parseKey(key);
+        return this.handleKey(key, value);
        if (this.nullKey) {
            if (this.nullKey.key !== nonversionedKey
                || this.nullKey.versionId < <string> keyVersionId) {
                this.handleKey(
                    this.nullKey.key, this.nullKey.versionId, this.nullKey.value);
                this.nullKey = null;
            }
        }
        if (keyVersionId === '') {
            // null key
            this.cacheNullKey(nonversionedKey, Version.from(value).getVersionId(), value);
            if (this.state.id === DelimiterVersionsFilterStateId.SkippingVersions) {
                return FILTER_SKIP;
            }
            return FILTER_ACCEPT;
        }
        return this.handleKey(nonversionedKey, keyVersionId, value);
    }
    setState(state: FilterState): void {
@ -376,11 +339,11 @@ export class DelimiterVersions extends Extension {
        this.keyHandlers[stateId] = keyHandler;
    }
-    handleKey(key: string, versionId: string | undefined, value: string): FilterReturnValue {
+    handleKey(key: string, value: string): FilterReturnValue {
-        return this.keyHandlers[this.state.id](key, versionId, value);
+        return this.keyHandlers[this.state.id](key, value);
    }
-    keyHandler_NotSkippingV0(key: string, versionId: string | undefined, value: string): FilterReturnValue {
+    keyHandler_NotSkippingV0(key: string, value: string): FilterReturnValue {
        if (key.startsWith(DbPrefixes.Replay)) {
            // skip internal replay prefix entirely
            this.setState(<DelimiterVersionsFilterState_SkippingPrefix> {
@ -392,37 +355,68 @@ export class DelimiterVersions extends Extension {
        if (Version.isPHD(value)) {
            return FILTER_ACCEPT;
        }
-        return this.filter_onNewKey(key, versionId, value);
+        return this.filter_onNewKey(key, value);
    }
-    keyHandler_NotSkippingV1(key: string, versionId: string | undefined, value: string): FilterReturnValue {
+    keyHandler_NotSkippingV1(key: string, value: string): FilterReturnValue {
        // NOTE: this check on PHD is only useful for Artesca, S3C
        // does not use PHDs in V1 format
        if (Version.isPHD(value)) {
            return FILTER_ACCEPT;
        }
-        return this.filter_onNewKey(key, versionId, value);
+        return this.filter_onNewKey(key, value);
    }
-    filter_onNewKey(key: string, versionId: string | undefined, value: string): FilterReturnValue {
+    filter_onNewKey(key: string, value: string): FilterReturnValue {
        if (this._reachedMaxKeys()) {
            return FILTER_END;
        }
-        if (versionId === undefined) {
+        const { key: nonversionedKey, versionId: keyVersionId } = this.parseKey(key);
        if (this.nullKey &&
            (this.nullKey.key !== nonversionedKey
             || this.nullKey.versionId < <string> keyVersionId)) {
            this.addCurrentNullKey();
            if (this._reachedMaxKeys()) {
                // IsTruncated: true is set, which is wanted because
                // there is at least one more key to output: the one
                // being processed here
                return FILTER_END;
            }
        }
        let versionId: string;
        if (keyVersionId === undefined) {
            this.masterKey = key;
            this.masterVersionId = Version.from(value).getVersionId() || 'null';
-            this.addKey(this.masterKey, this.masterVersionId, value);
+            versionId = this.masterVersionId;
        } else {
-            if (this.masterKey === key && this.masterVersionId === versionId) {
+            if (keyVersionId === '') {
                // null key
                this.cacheNullKey(nonversionedKey, Version.from(value).getVersionId(), value);
                return FILTER_ACCEPT;
            }
            if (this.masterKey === nonversionedKey && this.masterVersionId === keyVersionId) {
                // do not add a version key if it is the master version
                return FILTER_ACCEPT;
            }
-            this.addKey(key, versionId, value);
+            versionId = keyVersionId;
        }
        // add the subprefix to the common prefixes if the key has the delimiter
        const commonPrefix = this.getCommonPrefix(nonversionedKey);
        if (commonPrefix) {
            this.addCommonPrefix(commonPrefix);
            // transition into SkippingPrefix state to skip all following keys
            // while they start with the same prefix
            this.setState(<DelimiterVersionsFilterState_SkippingPrefix> {
                id: DelimiterVersionsFilterStateId.SkippingPrefix,
                prefix: commonPrefix,
            });
            return FILTER_ACCEPT;
        }
        this.addContents(nonversionedKey, versionId, value);
        return FILTER_ACCEPT;
    }
-    keyHandler_SkippingPrefix(key: string, versionId: string | undefined, value: string): FilterReturnValue {
+    keyHandler_SkippingPrefix(key: string, value: string): FilterReturnValue {
        const { prefix } = <DelimiterVersionsFilterState_SkippingPrefix> this.state;
        if (key.startsWith(prefix)) {
            return FILTER_SKIP;
@ -430,11 +424,39 @@ export class DelimiterVersions extends Extension {
        this.setState(<DelimiterVersionsFilterState_NotSkipping> {
            id: DelimiterVersionsFilterStateId.NotSkipping,
        });
-        return this.handleKey(key, versionId, value);
+        return this.handleKey(key, value);
    }
-    keyHandler_SkippingVersions(key: string, versionId: string | undefined, value: string): FilterReturnValue {
+    keyHandler_WaitForNullKey(key: string, value: string): FilterReturnValue {
-        if (key === this.keyMarker) {
+        const { key: nonversionedKey, versionId } = this.parseKey(key);
        if (nonversionedKey !== this.keyMarker) {
            this.setState(<DelimiterVersionsFilterState_NotSkipping> {
                id: DelimiterVersionsFilterStateId.NotSkipping,
            });
            return this.handleKey(key, value);
        }
        // we may now skip versions until VersionIdMarker
        this.setState(<DelimiterVersionsFilterState_SkippingVersions> {
            id: DelimiterVersionsFilterStateId.SkippingVersions,
            gt: `${this.keyMarker}${VID_SEP}${this.versionIdMarker}`,
        });
        if (versionId === '') {
            // only cache the null key if its version is older than
            // the current version ID marker, otherwise it has already
            // been output in a previous listing output
            const nullVersionId = Version.from(value).getVersionId();
            if (nullVersionId > this.versionIdMarker) {
                this.cacheNullKey(nonversionedKey, nullVersionId, value);
            }
            return FILTER_SKIP;
        }
        return this.handleKey(key, value);
    }
    keyHandler_SkippingVersions(key: string, value: string): FilterReturnValue {
        const { key: nonversionedKey, versionId } = this.parseKey(key);
        if (nonversionedKey === this.keyMarker) {
            // since the nonversioned key equals the marker, there is
            // necessarily a versionId in this key
            const _versionId = <string> versionId;
@ -450,21 +472,18 @@ export class DelimiterVersions extends Extension {
        this.setState(<DelimiterVersionsFilterState_NotSkipping> {
            id: DelimiterVersionsFilterStateId.NotSkipping,
        });
-        return this.handleKey(key, versionId, value);
+        return this.handleKey(key, value);
    }
-    skippingBase(): string | undefined {
+    skippingBase() {
        switch (this.state.id) {
        case DelimiterVersionsFilterStateId.SkippingPrefix:
            const { prefix } = <DelimiterVersionsFilterState_SkippingPrefix> this.state;
-            return inc(prefix);
+            return prefix;
        case DelimiterVersionsFilterStateId.SkippingVersions:
            const { gt } = <DelimiterVersionsFilterState_SkippingVersions> this.state;
-            // the contract of skipping() is to return the first key
+            return gt;
            // that can be skipped to, so adding a null byte to skip
            // over the existing versioned key set in 'gt'
            return `${gt}\0`;
        default:
            return SKIP_NONE;
@ -511,12 +530,12 @@ export class DelimiterVersions extends Extension {
        //   does not fit, so we know the result is now truncated
        //   because there remains the null key to be output.
        //
-        if (this.nullKey) {
+        if (this.nullKey && !this._reachedMaxKeys()) {
-            this.handleKey(this.nullKey.key, this.nullKey.versionId, this.nullKey.value);
+            this.addCurrentNullKey();
        }
        const result: ResultObject = {
            CommonPrefixes: this.CommonPrefixes,
-            Versions: this.Versions,
+            Versions: this.Contents,
            IsTruncated: this.IsTruncated,
        };
        if (this.delimiter) {
--- a/lib/algos/list/skip.js
+++ b/lib/algos/list/skip.js
@ -52,21 +52,21 @@ class Skip {
        assert(this.skipRangeCb);
        const filteringResult = this.extension.filter(entry);
-        const skipTo = this.extension.skipping();
+        const skippingRange = this.extension.skipping();
        if (filteringResult === FILTER_END) {
            this.listingEndCb();
        } else if (filteringResult === FILTER_SKIP
-                   && skipTo !== SKIP_NONE) {
+                   && skippingRange !== SKIP_NONE) {
            if (++this.streakLength >= MAX_STREAK_LENGTH) {
                let newRange;
-                if (Array.isArray(skipTo)) {
+                if (Array.isArray(skippingRange)) {
                    newRange = [];
-                    for (let i = 0; i < skipTo.length; ++i) {
+                    for (let i = 0; i < skippingRange.length; ++i) {
-                        newRange.push(skipTo[i]);
+                        newRange.push(this._inc(skippingRange[i]));
                    }
                } else {
-                    newRange = skipTo;
+                    newRange = this._inc(skippingRange);
                }
                /* Avoid to loop on the same range again and again. */
                if (newRange === this.gteParams) {
@ -79,6 +79,16 @@ class Skip {
            this.streakLength = 0;
        }
    }
    _inc(str) {
        if (!str) {
            return str;
        }
        const lastCharValue = str.charCodeAt(str.length - 1);
        const lastCharNewValue = String.fromCharCode(lastCharValue + 1);
        return `${str.slice(0, str.length - 1)}${lastCharNewValue}`;
    }
 }
--- a/lib/auth/Vault.ts
+++ b/lib/auth/Vault.ts
@ -14,7 +14,7 @@ function vaultSignatureCb(
    err: Error | null,
    authInfo: { message: { body: any } },
    log: Logger,
-    callback: (err: Error | null, data?: any, results?: any, params?: any, infos?: any) => void,
+    callback: (err: Error | null, data?: any, results?: any, params?: any) => void,
    streamingV4Params?: any
 ) {
    // vaultclient API guarantees that it returns:
@ -38,9 +38,7 @@ function vaultSignatureCb(
    }
    // @ts-ignore
    log.addDefaultFields(auditLog);
-    return callback(null, userInfo, authorizationResults, streamingV4Params, {
+    return callback(null, userInfo, authorizationResults, streamingV4Params);
        accountQuota: info.accountQuota || {},
    });
 }
 export type AuthV4RequestParams = {
@ -386,19 +384,4 @@ export default class Vault {
            return callback(null, respBody);
        });
    }
    report(log: Logger, callback: (err: Error | null, data?: any) => void) {
        // call the report function of the client
        if (!this.client.report) {
            return callback(null, {});
        }
        // @ts-ignore
        return this.client.report(log.getSerializedUids(), (err: Error | null, obj?: any) => {
            if (err) {
                log.debug(`error from ${this.implName}`, { error: err });
                return callback(err);
            }
            return callback(null, obj);
        });
    }
 }
--- a/lib/auth/auth.ts
+++ b/lib/auth/auth.ts
@ -163,20 +163,6 @@ function doAuth(
    return cb(errors.InternalError);
 }
 /**
 * This function will generate a version 4 content-md5 header
 * It looks at the request path to determine what kind of header encoding is required
 *
 * @param path - the request path
 * @param payload - the request payload to hash
 */
 function generateContentMD5Header(
    path: string,
    payload: string,
 ) {
    const encoding = path && path.startsWith('/_/backbeat/') ? 'hex' : 'base64';
    return crypto.createHash('md5').update(payload, 'binary').digest(encoding);
 }
 /**
 * This function will generate a version 4 header
 *
@ -189,7 +175,6 @@ function generateContentMD5Header(
 * @param [proxyPath] - path that gets proxied by reverse proxy
 * @param [sessionToken] - security token if the access/secret keys
 *                                are temporary credentials from STS
 * @param [payload] - body of the request if any
 */
 function generateV4Headers(
    request: any,
@ -197,9 +182,8 @@ function generateV4Headers(
    accessKey: string,
    secretKeyValue: string,
    awsService: string,
-    proxyPath?: string,
+    proxyPath: string,
-    sessionToken?: string,
+    sessionToken: string
    payload?: string,
 ) {
    Object.assign(request, { headers: {} });
    const amzDate = convertUTCtoISO8601(Date.now());
@ -212,7 +196,7 @@ function generateV4Headers(
    const timestamp = amzDate;
    const algorithm = 'AWS4-HMAC-SHA256';
-    payload = payload || '';
+    let payload = '';
    if (request.method === 'POST') {
        payload = queryString.stringify(data, undefined, undefined, {
            encodeURIComponent,
@ -223,7 +207,6 @@ function generateV4Headers(
    request.setHeader('host', request._headers.host);
    request.setHeader('x-amz-date', amzDate);
    request.setHeader('x-amz-content-sha256', payloadChecksum);
    request.setHeader('content-md5', generateContentMD5Header(request.path, payload));
    if (sessionToken) {
        request.setHeader('x-amz-security-token', sessionToken);
@ -234,7 +217,6 @@ function generateV4Headers(
        .filter(headerName =>
            headerName.startsWith('x-amz-')
            || headerName.startsWith('x-scal-')
            || headerName === 'content-md5'
            || headerName === 'host',
        ).sort().join(';');
    const params = { request, signedHeaders, payloadChecksum,
--- a/lib/auth/backends/ChainBackend.ts
+++ b/lib/auth/backends/ChainBackend.ts
@ -134,7 +134,7 @@ export default class ChainBackend extends BaseBackend {
            }
            const check = (policy) => {
-                const key = (policy.arn || '') + (policy.versionId || '') + (policy.action || '');
+                const key = (policy.arn || '') + (policy.versionId || '');
                if (!policyMap[key] || !policyMap[key].isAllowed) {
                    policyMap[key] = policy;
                }
@ -158,12 +158,6 @@ export default class ChainBackend extends BaseBackend {
            if (policyMap[key].versionId) {
                policyRes.versionId = policyMap[key].versionId;
            }
            if (policyMap[key].isImplicit !== undefined) {
                policyRes.isImplicit = policyMap[key].isImplicit;
            }
            if (policyMap[key].action) {
                policyRes.action = policyMap[key].action;
            }
            return policyRes;
        });
    }
@ -212,22 +206,4 @@ export default class ChainBackend extends BaseBackend {
            return callback(null, res);
        });
    }
    report(reqUid: string, callback: any) {
        this._forEachClient((client, done) =>
            client.report(reqUid, done),
            (err, res) => {
                if (err) {
                    return callback(err);
                }
                const mergedRes = res.reduce((acc, val) => {
                    Object.keys(val).forEach(k => {
                        acc[k] = val[k];
                    });
                    return acc;
                }, {});
                return callback(null, mergedRes);
            });
    }
 }
--- a/lib/auth/backends/in_memory/Backend.ts
+++ b/lib/auth/backends/in_memory/Backend.ts
@ -161,10 +161,6 @@ class InMemoryBackend extends BaseBackend {
        };
        return cb(null, vaultReturnObject);
    }
    report(log: Logger, callback: any) {
        return callback(null, {});
    }
 }
--- a/lib/clustering/ClusterRPC.ts
+++ b/lib/clustering/ClusterRPC.ts
@ -1,569 +0,0 @@
 import cluster, { Worker } from 'cluster';
 import * as werelogs from 'werelogs';
 import { default as errors } from '../../lib/errors';
 const rpcLogger = new werelogs.Logger('ClusterRPC');
 /**
 * Remote procedure calls support between cluster workers.
 *
 * When using the cluster module, new processes are forked and are
 * dispatched workloads, usually HTTP requests. The ClusterRPC module
 * implements a RPC system to send commands to all cluster worker
 * processes at once from any particular worker, and retrieve their
 * individual command results, like a distributed map operation.
 *
 * The existing nodejs cluster IPC channel is setup from the primary
 * to each worker, but not between workers, so there has to be a hop
 * by the primary.
 *
 * How a command is treated:
 *
 * - a worker sends a command message to the primary
 *
 * - the primary then forwards that command to each existing worker
 *   (including the requestor)
 *
 * - each worker then executes the command and returns a result or an
 *   error
 *
 * - the primary gathers all workers results into an array
 *
 * - finally, the primary dispatches the results array to the original
 *   requesting worker
 *
 *
 * Limitations:
 *
 * - The command payload must be serializable, which means that:
 *   - it should not contain circular references
 *   - it should be of a reasonable size to be sent in a single RPC message
 *
 * - The "toWorkers" parameter of value "*" targets the set of workers
 *   that are available at the time the command is dispatched. Any new
 *   worker spawned after the command has been dispatched for
 *   processing, but before the command completes, don't execute
 *   the command and hence are not part of the results array.
 *
 *
 * To set it up:
 *
 * - On the primary:
 *     if (cluster.isPrimary) {
 *         setupRPCPrimary();
 *     }
 *
 * - On the workers:
 *     if (!cluster.isPrimary) {
 *         setupRPCWorker({
 *             handler1: (payload: object, uids: string, callback: HandlerCallback) => void,
 *             handler2: ...
 *         });
 *     }
 *     Handler functions will be passed the command payload, request
 *     serialized uids, and must call the callback when the worker is done
 *     processing the command:
 *         callback(error: Error | null | undefined, result?: any)
 *
 * When this setup is done, any worker can start sending commands by calling
 * the async function sendWorkerCommand().
 */
 // exported types
 export type ResultObject = {
    error: Error | null;
    result: any;
 };
 /**
 * saved Promise for sendWorkerCommand
 */
 export type CommandPromise = {
    resolve: (results?: ResultObject[]) => void;
    reject: (error: Error) => void;
    timeout: NodeJS.Timeout | null;
 };
 export type HandlerCallback = (error: (Error & { code?: number }) | null | undefined, result?: any) => void;
 export type HandlerFunction = (payload: object, uids: string, callback: HandlerCallback) => void;
 export type HandlersMap = {
    [index: string]: HandlerFunction;
 };
 export type PrimaryHandlerFunction = (worker: Worker, payload: object, uids: string, callback: HandlerCallback) => void;
 export type PrimaryHandlersMap = Record<string, PrimaryHandlerFunction>;
 // private types
 type RPCMessage<T extends string, P> = {
    type: T;
    uids: string;
    payload: P;
 };
 type RPCCommandMessage = RPCMessage<'cluster-rpc:command', any> & {
    toWorkers: string;
    toHandler: string;
 };
 type MarshalledResultObject = {
    error: string | null;
    errorCode?: number;
    result: any;
 };
 type RPCCommandResultMessage = RPCMessage<'cluster-rpc:commandResult', MarshalledResultObject>;
 type RPCCommandResultsMessage = RPCMessage<'cluster-rpc:commandResults', {
    results: MarshalledResultObject[];
 }>;
 type RPCCommandErrorMessage = RPCMessage<'cluster-rpc:commandError', {
    error: string;
 }>;
 interface RPCSetupOptions {
    /**
     * As werelogs is not a peerDependency, arsenal and a parent project
     * might have their own separate versions duplicated in dependencies.
     * The config are therefore not shared.
     * Use this to propagate werelogs config to arsenal's ClusterRPC.
     */
    werelogsConfig?: Parameters<typeof werelogs.configure>[0];
 };
 /**
 * In primary: store worker IDs that are waiting to be dispatched
 * their command's results, as a mapping.
 */
 const uidsToWorkerId: {
    [index: string]: number;
 } = {};
 /**
 * In primary: store worker responses for commands in progress as a
 * mapping.
 *
 * Result objects are 'null' while the worker is still processing the
 * command. When a worker finishes processing it stores the result as:
 *    {
 *        error: string | null,
 *        result: any
 *    }
 */
 const uidsToCommandResults: {
    [index: string]: {
        [index: number]: MarshalledResultObject | null;
    };
 } = {};
 /**
 * In workers: store promise callbacks for commands waiting to be
 * dispatched, as a mapping.
 */
 const uidsToCommandPromise: {
    [index: string]: CommandPromise;
 } = {};
 function _isRpcMessage(message) {
    return (message !== null &&
            typeof message === 'object' &&
            typeof message.type === 'string' &&
            message.type.startsWith('cluster-rpc:'));
 }
 /**
 * Setup cluster RPC system on the primary
 *
 * @param {object} [handlers] - mapping of handler names to handler functions
 *     handler function:
 *         `handler({Worker} worker, {object} payload, {string} uids, {function} callback)`
 *     handler callback must be called when worker is done with the command:
 *         `callback({Error|null} error, {any} [result])`
 * @return {undefined}
 */
 export function setupRPCPrimary(handlers?: PrimaryHandlersMap, options?: RPCSetupOptions) {
    if (options?.werelogsConfig) {
        werelogs.configure(options.werelogsConfig);
    }
    cluster.on('message', (worker, message) => {
        if (_isRpcMessage(message)) {
            _handlePrimaryMessage(worker, message, handlers);
        }
    });
 }
 /**
 * Setup RPCs on a cluster worker process
 *
 * @param {object} handlers - mapping of handler names to handler functions
 *     handler function:
 *         handler({object} payload, {string} uids, {function} callback)
 *     handler callback must be called when worker is done with the command:
 *         callback({Error|null} error, {any} [result])
 * @return {undefined}
 * }
 */
 export function setupRPCWorker(handlers: HandlersMap, options?: RPCSetupOptions) {
    if (!process.send) {
        throw new Error('fatal: cannot setup cluster RPC: "process.send" is not available');
    }
    if (options?.werelogsConfig) {
        werelogs.configure(options.werelogsConfig);
    }
    process.on('message', (message: RPCCommandMessage | RPCCommandResultsMessage) => {
        if (_isRpcMessage(message)) {
            _handleWorkerMessage(message, handlers);
        }
    });
 }
 /**
 * Send a command for workers to execute in parallel, and wait for results
 *
 * @param {string} toWorkers - which workers should execute the command
 *     Currently the supported values are:
 *         - "*", meaning all workers will execute the command
 *         - "PRIMARY", meaning primary process will execute the command
 * @param {string} toHandler - name of handler that will execute the
 * command in workers, as declared in setupRPCWorker() parameter object
 * @param {string} uids - unique identifier of the command, must be
 * unique across all commands in progress
 * @param {object} payload - message payload, sent as-is to the handler
 * @param {number} [timeoutMs=60000] - timeout the command with a
 * "RequestTimeout" error after this number of milliseconds - set to 0
 * to disable timeouts (the command may then hang forever)
 * @returns {Promise}
 */
 export async function sendWorkerCommand(
    toWorkers: string,
    toHandler: string,
    uids: string,
    payload: object,
    timeoutMs: number = 60000
 ) {
    if (typeof uids !== 'string') {
        rpcLogger.error('missing or invalid "uids" field', { uids });
        throw errors.MissingParameter;
    }
    if (uidsToCommandPromise[uids] !== undefined) {
        rpcLogger.error('a command is already in progress with same uids', { uids });
        throw errors.OperationAborted;
    }
    rpcLogger.info('sending command', { toWorkers, toHandler, uids, payload });
    return new Promise((resolve, reject) => {
        let timeout: NodeJS.Timeout | null = null;
        if (timeoutMs) {
            timeout = setTimeout(() => {
                delete uidsToCommandPromise[uids];
                reject(errors.RequestTimeout);
            }, timeoutMs);
        }
        uidsToCommandPromise[uids] = { resolve, reject, timeout };
        const message: RPCCommandMessage = {
            type: 'cluster-rpc:command',
            toWorkers,
            toHandler,
            uids,
            payload,
        };
        return process.send?.(message);
    });
 }
 /**
 * Get the number of commands in flight
 * @returns {number}
 */
 export function getPendingCommandsCount() {
    return Object.keys(uidsToCommandPromise).length;
 }
 function _dispatchCommandResultsToWorker(
    worker: Worker,
    uids: string,
    resultsArray: MarshalledResultObject[]
 ): void {
    const message: RPCCommandResultsMessage = {
        type: 'cluster-rpc:commandResults',
        uids,
        payload: {
            results: resultsArray,
        },
    };
    worker.send(message);
 }
 function _dispatchCommandErrorToWorker(
    worker: Worker,
    uids: string,
    error: Error,
 ): void {
    const message: RPCCommandErrorMessage = {
        type: 'cluster-rpc:commandError',
        uids,
        payload: {
            error: error.message,
        },
    };
    worker.send(message);
 }
 function _sendPrimaryCommandResult(
    worker: Worker,
    uids: string,
    error: (Error & { code?: number }) | null | undefined,
    result?: any
 ): void {
    const message: RPCCommandResultsMessage = {
        type: 'cluster-rpc:commandResults',
        uids,
        payload: {
            results: [{ error: error?.message || null, errorCode: error?.code, result }],
        },
    };
    worker.send?.(message);
 }
 function _handlePrimaryCommandMessage(
    fromWorker: Worker,
    logger: any,
    message: RPCCommandMessage,
    handlers?: PrimaryHandlersMap
 ): void {
    const { toWorkers, toHandler, uids, payload } = message;
    if (toWorkers === '*') {
        if (uidsToWorkerId[uids] !== undefined) {
            logger.warn('new command already has a waiting worker with same uids', {
                uids, workerId: uidsToWorkerId[uids],
            });
            return undefined;
        }
        const commandResults = {};
        for (const workerId of Object.keys(cluster.workers || {})) {
            commandResults[workerId] = null;
        }
        uidsToWorkerId[uids] = fromWorker?.id;
        uidsToCommandResults[uids] = commandResults;
        for (const [workerId, worker] of Object.entries(cluster.workers || {})) {
            logger.debug('sending command message to worker', {
                workerId, toHandler, payload,
            });
            if (worker) {
                worker.send(message);
            }
        }
    } else if (toWorkers === 'PRIMARY') {
        const { toHandler, uids, payload } = message;
        const cb: HandlerCallback = (err, result) => _sendPrimaryCommandResult(fromWorker, uids, err, result);
        if (toHandler in (handlers || {})) {
            return handlers![toHandler](fromWorker, payload, uids, cb);
        }
        logger.error('no such handler in "toHandler" field from worker command message', {
            toHandler,
        });
        return cb(errors.NotImplemented);
    } else {
        logger.error('unsupported "toWorkers" field from worker command message', {
            toWorkers,
        });
        if (fromWorker) {
            _dispatchCommandErrorToWorker(fromWorker, uids, errors.NotImplemented);
        }
    }
 }
 function _handlePrimaryCommandResultMessage(
    fromWorkerId: number,
    logger: any,
    message: RPCCommandResultMessage
 ): void {
    const { uids, payload } = message;
    const commandResults = uidsToCommandResults[uids];
    if (!commandResults) {
        logger.warn('received command response message from worker for command not in flight', {
            workerId: fromWorkerId,
            uids,
        });
        return undefined;
    }
    if (commandResults[fromWorkerId] === undefined) {
        logger.warn('received command response message with unexpected worker ID', {
            workerId: fromWorkerId,
            uids,
        });
        return undefined;
    }
    if (commandResults[fromWorkerId] !== null) {
        logger.warn('ignoring duplicate command response from worker', {
            workerId: fromWorkerId,
            uids,
        });
        return undefined;
    }
    commandResults[fromWorkerId] = payload;
    const commandResultsArray = Object.values(commandResults);
    if (commandResultsArray.every(response => response !== null)) {
        logger.debug('all workers responded to command', { uids });
        const completeCommandResultsArray = <MarshalledResultObject[]> commandResultsArray;
        const toWorkerId = uidsToWorkerId[uids];
        const toWorker = cluster.workers?.[toWorkerId];
        delete uidsToCommandResults[uids];
        delete uidsToWorkerId[uids];
        if (!toWorker) {
            logger.warn('worker shut down while its command was executing', {
                workerId: toWorkerId, uids,
            });
            return undefined;
        }
        // send back response to original worker
        _dispatchCommandResultsToWorker(toWorker, uids, completeCommandResultsArray);
    }
 }
 function _handlePrimaryMessage(
    fromWorker: Worker,
    message: RPCCommandMessage | RPCCommandResultMessage,
    handlers?: PrimaryHandlersMap
 ): void {
    const { type: messageType, uids } = message;
    const logger = rpcLogger.newRequestLoggerFromSerializedUids(uids);
    logger.debug('primary received message from worker', {
        workerId: fromWorker?.id, rpcMessage: message,
    });
    if (messageType === 'cluster-rpc:command') {
        return _handlePrimaryCommandMessage(fromWorker, logger, message, handlers);
    }
    if (messageType === 'cluster-rpc:commandResult') {
        return _handlePrimaryCommandResultMessage(fromWorker?.id, logger, message);
    }
    logger.error('unsupported message type', {
        workerId: fromWorker?.id, messageType, uids,
    });
    return undefined;
 }
 function _sendWorkerCommandResult(
    uids: string,
    error: Error | null | undefined,
    result?: any
 ): void {
    const message: RPCCommandResultMessage = {
        type: 'cluster-rpc:commandResult',
        uids,
        payload: {
            error: error ? error.message : null,
            result,
        },
    };
    process.send?.(message);
 }
 function _handleWorkerCommandMessage(
    logger: any,
    message: RPCCommandMessage,
    handlers: HandlersMap
 ): void {
    const { toHandler, uids, payload } = message;
    const cb: HandlerCallback = (err, result) => _sendWorkerCommandResult(uids, err, result);
    if (toHandler in handlers) {
        return handlers[toHandler](payload, uids, cb);
    }
    logger.error('no such handler in "toHandler" field from worker command message', {
        toHandler,
    });
    return cb(errors.NotImplemented);
 }
 function _handleWorkerCommandResultsMessage(
    logger: any,
    message: RPCCommandResultsMessage,
 ): void {
    const { uids, payload } = message;
    const { results } = payload;
    const commandPromise: CommandPromise = uidsToCommandPromise[uids];
    if (commandPromise === undefined) {
        logger.error('missing promise for command results', { uids, payload });
        return undefined;
    }
    if (commandPromise.timeout) {
        clearTimeout(commandPromise.timeout);
    }
    delete uidsToCommandPromise[uids];
    const unmarshalledResults = results.map(workerResult => {
        let workerError: Error | null = null;
        if (workerResult.error) {
            if (workerResult.error in errors) {
                workerError = errors[workerResult.error];
            } else {
                workerError = new Error(workerResult.error);
            }
        }
        if (workerError && workerResult.errorCode) {
            (workerError as Error & { code: number }).code = workerResult.errorCode;
        }
        const unmarshalledResult: ResultObject = {
            error: workerError,
            result: workerResult.result,
        };
        return unmarshalledResult;
    });
    return commandPromise.resolve(unmarshalledResults);
 }
 function _handleWorkerCommandErrorMessage(
    logger: any,
    message: RPCCommandErrorMessage,
 ): void {
    const { uids, payload } = message;
    const { error } = payload;
    const commandPromise: CommandPromise = uidsToCommandPromise[uids];
    if (commandPromise === undefined) {
        logger.error('missing promise for command results', { uids, payload });
        return undefined;
    }
    if (commandPromise.timeout) {
        clearTimeout(commandPromise.timeout);
    }
    delete uidsToCommandPromise[uids];
    let commandError: Error | null = null;
    if (error in errors) {
        commandError = errors[error];
    } else {
        commandError = new Error(error);
    }
    return commandPromise.reject(<Error> commandError);
 }
 function _handleWorkerMessage(
    message: RPCCommandMessage | RPCCommandResultsMessage | RPCCommandErrorMessage,
    handlers: HandlersMap
 ): void {
    const { type: messageType, uids } = message;
    const workerId = cluster.worker?.id;
    const logger = rpcLogger.newRequestLoggerFromSerializedUids(uids);
    logger.debug('worker received message from primary', {
        workerId, rpcMessage: message,
    });
    if (messageType === 'cluster-rpc:command') {
        return _handleWorkerCommandMessage(logger, message, handlers);
    }
    if (messageType === 'cluster-rpc:commandResults') {
        return _handleWorkerCommandResultsMessage(logger, message);
    }
    if (messageType === 'cluster-rpc:commandError') {
        return _handleWorkerCommandErrorMessage(logger, message);
    }
    logger.error('unsupported message type', {
        workerId, messageType,
    });
    return undefined;
 }
--- a/lib/constants.ts
+++ b/lib/constants.ts
@ -171,7 +171,3 @@ export const maxCachedBuckets = process.env.METADATA_MAX_CACHED_BUCKETS ?
    Number(process.env.METADATA_MAX_CACHED_BUCKETS) : 1000;
 export const validRestoreObjectTiers = new Set(['Expedited', 'Standard', 'Bulk']);
 export const maxBatchingConcurrentOperations = 5;
 /** For policy resource arn check we allow empty account ID to not break compatibility */
 export const policyArnAllowedEmptyAccountId = ['utapi', 'scuba'];
--- a/lib/db.ts
+++ b/lib/db.ts
@ -148,7 +148,7 @@ export class IndexTransaction {
                'missing condition for conditional put'
            );
        }
-        if (typeof condition.notExists !== 'string' && typeof condition.exists !== 'string') {
+        if (typeof condition.notExists !== 'string') {
            throw propError(
                'unsupportedConditionalOperation',
                'missing key or supported condition'
--- a/lib/errors/arsenalErrors.ts
+++ b/lib/errors/arsenalErrors.ts
@ -690,11 +690,6 @@ export const ReportNotPresent: ErrorFormat = {
        'The request was rejected because the credential report does not exist. To generate a credential report, use GenerateCredentialReport.',
 };
 export const Found: ErrorFormat = {
    code: 302,
    description: 'Resource Found'
 };
 // ------------- Special non-AWS S3 errors -------------
 export const MPUinProgress: ErrorFormat = {
@ -1042,15 +1037,3 @@ export const AuthMethodNotImplemented: ErrorFormat = {
    description: 'AuthMethodNotImplemented',
    code: 501,
 };
 // --------------------- quotaErros ---------------------
 export const NoSuchQuota: ErrorFormat = {
    code: 404,
    description: 'The specified resource does not have a quota.',
 };
 export const QuotaExceeded: ErrorFormat = {
    code: 429,
    description: 'The quota set for the resource is exceeded.',
 };
--- a/lib/models/BackendInfo.ts
+++ b/lib/models/BackendInfo.ts
@ -1,5 +1,3 @@
 import { RequestLogger } from 'werelogs';
 import { legacyLocations } from '../constants';
 import escapeForXml from '../s3middleware/escapeForXml';
--- a/lib/models/BucketInfo.ts
+++ b/lib/models/BucketInfo.ts
@ -101,7 +101,6 @@ export default class BucketInfo {
    _azureInfo: any | null;
    _ingestion: { status: 'enabled' | 'disabled' } | null;
    _capabilities?: Capabilities;
    _quotaMax: number | 0;
    /**
    * Represents all bucket information.
@ -158,7 +157,6 @@ export default class BucketInfo {
    * @param [notificationConfiguration] - bucket notification configuration
    * @param [tags] - bucket tag set
    * @param [capabilities] - capabilities for the bucket
    * @param quotaMax - bucket quota
    */
    constructor(
        name: string,
@ -187,7 +185,6 @@ export default class BucketInfo {
        notificationConfiguration?: any,
        tags?: Array<BucketTag> | [],
        capabilities?: Capabilities,
        quotaMax?: number | 0,
    ) {
        assert.strictEqual(typeof name, 'string');
        assert.strictEqual(typeof owner, 'string');
@ -288,10 +285,6 @@ export default class BucketInfo {
            tags = [] as BucketTag[];
        }
        assert.strictEqual(areTagsValid(tags), true);
        if (quotaMax) {
            assert.strictEqual(typeof quotaMax, 'number');
            assert(quotaMax >= 0, 'Quota cannot be negative');
        }
        // IF UPDATING PROPERTIES, INCREMENT MODELVERSION NUMBER ABOVE
        this._acl = aclInstance;
@ -320,7 +313,6 @@ export default class BucketInfo {
        this._notificationConfiguration = notificationConfiguration || null;
        this._tags = tags;
        this._capabilities = capabilities || undefined;
        this._quotaMax = quotaMax || 0;
        return this;
    }
@ -356,7 +348,6 @@ export default class BucketInfo {
            notificationConfiguration: this._notificationConfiguration,
            tags: this._tags,
            capabilities: this._capabilities,
            quotaMax: this._quotaMax,
        };
        const final = this._websiteConfiguration
            ? {
@ -383,7 +374,7 @@ export default class BucketInfo {
            obj.bucketPolicy, obj.uid, obj.readLocationConstraint, obj.isNFS,
            obj.ingestion, obj.azureInfo, obj.objectLockEnabled,
            obj.objectLockConfiguration, obj.notificationConfiguration, obj.tags,
-            obj.capabilities, obj.quotaMax);
+            obj.capabilities);
    }
    /**
@ -410,8 +401,7 @@ export default class BucketInfo {
            data._bucketPolicy, data._uid, data._readLocationConstraint,
            data._isNFS, data._ingestion, data._azureInfo,
            data._objectLockEnabled, data._objectLockConfiguration,
-            data._notificationConfiguration, data._tags, data._capabilities,
+            data._notificationConfiguration, data._tags, data._capabilities);
            data._quotaMax);
    }
    /**
@ -949,22 +939,4 @@ export default class BucketInfo {
        this._capabilities = capabilities;
        return this;
    }
    /**
     * Get the bucket quota information
     * @return quotaMax
     */
    getQuota() {
        return this._quotaMax;
    }
    /**
     * Set bucket quota
     * @param quota - quota to be set
     * @return - bucket quota info
     */
    setQuota(quota: number) {
        this._quotaMax = quota || 0;
        return this;
    }
 }
--- a/lib/models/LifecycleConfiguration.ts
+++ b/lib/models/LifecycleConfiguration.ts
@ -666,38 +666,13 @@ export default class LifecycleConfiguration {
     * @return Returns an error object or `null`
     */
    _checkDate(date: string) {
-        const isoRegex = new RegExp(
+        const isoRegex = new RegExp('^(-?(?:[1-9][0-9]*)?[0-9]{4})-' +
-            "^(-?(?:[1-9][0-9]*)?[0-9]{4})" + // Year
+            '(1[0-2]|0[1-9])-(3[01]|0[1-9]|[12][0-9])T(2[0-3]|[01][0-9])' +
-            "-(1[0-2]|0[1-9])" + // Month
+            ':([0-5][0-9]):([0-5][0-9])(.[0-9]+)?(Z)?$');
-            "-(3[01]|0[1-9]|[12][0-9])" + // Day
+        if (!isoRegex.test(date)) {
            "T(2[0-3]|[01][0-9])" + // Hour
            ":([0-5][0-9])" + // Minute
            ":([0-5][0-9])" + // Second
            "(\\.[0-9]+)?" + // Fractional second
            "(Z|[+-][01][0-9]:[0-5][0-9])?$", // Timezone
            "g"
        );
        const matches = [...date.matchAll(isoRegex)];
        if (matches.length !== 1) {
            const msg = 'Date must be in ISO 8601 format';
            return errors.InvalidArgument.customizeDescription(msg);
        }
        // Check for a timezone in the last match group. If none, add a Z to indicate UTC.
        if (!matches[0][matches[0].length-1]) {
            date += 'Z';
        }
        const dateObj = new Date(date);
        if (Number.isNaN(dateObj.getTime())) {
            const msg = 'Date is not a valid date';
            return errors.InvalidArgument.customizeDescription(msg);
        }
        if (dateObj.getUTCHours() !== 0
            || dateObj.getUTCMinutes() !== 0
            || dateObj.getUTCSeconds() !== 0
            || dateObj.getUTCMilliseconds() !== 0) {
            const msg = '\'Date\' must be at midnight GMT';
            return errors.InvalidArgument.customizeDescription(msg);
        }
        return null;
    }
--- a/lib/models/ObjectMD.ts
+++ b/lib/models/ObjectMD.ts
@ -58,7 +58,6 @@ export type ObjectMDData = {
    'x-amz-server-side-encryption-customer-algorithm': string;
    'x-amz-website-redirect-location': string;
    'x-amz-scal-transition-in-progress'?: boolean;
    'x-amz-scal-transition-time'?: string;
    azureInfo?: any;
    acl: ACL;
    key: string;
@ -650,24 +649,10 @@ export default class ObjectMD {
     * Set metadata transition in progress value
     *
     * @param inProgress - True if transition is in progress, false otherwise
     * @param transitionTime - Date when the transition started
     * @return itself
     */
-    setTransitionInProgress(inProgress: false): this
+    setTransitionInProgress(inProgress: boolean) {
    setTransitionInProgress(inProgress: true, transitionTime: Date|string|number): this
    setTransitionInProgress(inProgress: boolean, transitionTime?: Date|string|number) {
        this._data['x-amz-scal-transition-in-progress'] = inProgress;
        if (!inProgress || !transitionTime) {
            delete this._data['x-amz-scal-transition-time'];
        } else {
            if (typeof transitionTime === 'number') {
                transitionTime = new Date(transitionTime);
            }
            if (transitionTime instanceof Date) {
                transitionTime = transitionTime.toISOString();
            }
            this._data['x-amz-scal-transition-time'] = transitionTime;
        }
        return this;
    }
@ -680,14 +665,6 @@ export default class ObjectMD {
        return this._data['x-amz-scal-transition-in-progress'];
    }
    /**
     * Gets the transition time of the object.
     * @returns The transition time of the object.
     */
    getTransitionTime() {
        return this._data['x-amz-scal-transition-time'];
    }
    /**
     * Set access control list
     *
--- a/lib/models/ReplicationConfiguration.ts
+++ b/lib/models/ReplicationConfiguration.ts
@ -1,8 +1,6 @@
 import assert from 'assert';
 import UUID from 'uuid';
 import { RequestLogger } from 'werelogs';
 import escapeForXml from '../s3middleware/escapeForXml';
 import errors from '../errors';
 import { isValidBucketName } from '../s3routes/routesUtils';
--- a/lib/network/http/server.ts
+++ b/lib/network/http/server.ts
@ -435,6 +435,7 @@ export default class Server {
            this._server.on('connection', sock => {
                // Setting no delay of the socket to the value configured
                // TODO fix this
                // @ts-expect-errors
                sock.setNoDelay(this.isNoDelay());
                sock.on('error', err => this._logger.info(
                    'socket error - request rejected', { error: err }));
--- a/lib/network/probe/HealthProbeServer.ts
+++ b/lib/network/probe/HealthProbeServer.ts
@ -62,7 +62,7 @@ export default class HealthProbeServer extends httpServer {
    _onLiveness(
        _req: http.IncomingMessage,
        res: http.ServerResponse,
-        log: werelogs.RequestLogger,
+        log: RequestLogger,
    ) {
        if (this._livenessCheck(log)) {
            sendSuccess(res, log);
@ -74,7 +74,7 @@ export default class HealthProbeServer extends httpServer {
    _onReadiness(
        _req: http.IncomingMessage,
        res: http.ServerResponse,
-        log: werelogs.RequestLogger,
+        log: RequestLogger,
    ) {
        if (this._readinessCheck(log)) {
            sendSuccess(res, log);
--- a/lib/network/probe/ProbeServer.ts
+++ b/lib/network/probe/ProbeServer.ts
@ -16,7 +16,7 @@ export const DEFAULT_METRICS_ROUTE = '/metrics';
 * @param log - Werelogs instance for logging if you choose to
 */
-export type ProbeDelegate = (res: http.ServerResponse, log: werelogs.RequestLogger) => string | void
+export type ProbeDelegate = (res: http.ServerResponse, log: RequestLogger) => string | void
 export type ProbeServerParams = {
    port: number;
--- a/lib/network/probe/Utils.ts
+++ b/lib/network/probe/Utils.ts
@ -1,7 +1,4 @@
 import * as http from 'http';
 import { RequestLogger } from 'werelogs';
 import { ArsenalError } from '../../errors';
 /**
--- a/lib/network/rest/RESTClient.ts
+++ b/lib/network/rest/RESTClient.ts
@ -119,7 +119,7 @@ export default class RESTClient {
        method: string,
        headers: http.OutgoingHttpHeaders | null,
        key: string | null,
-        log: werelogs.RequestLogger,
+        log: RequestLogger,
        responseCb: (res: http.IncomingMessage) => void,
    ) {
        const reqHeaders = headers || {};
--- a/lib/network/rest/RESTServer.ts
+++ b/lib/network/rest/RESTServer.ts
@ -25,7 +25,7 @@ function setContentRange(
 function sendError(
    res: http.ServerResponse,
-    log: werelogs.RequestLogger,
+    log: RequestLogger,
    error: ArsenalError,
    optMessage?: string,
 ) {
@ -141,7 +141,7 @@ export default class RESTServer extends httpServer {
    _onPut(
        req: http.IncomingMessage,
        res: http.ServerResponse,
-        log: werelogs.RequestLogger,
+        log: RequestLogger,
    ) {
        let size: number;
        try {
@ -183,7 +183,7 @@ export default class RESTServer extends httpServer {
    _onGet(
        req: http.IncomingMessage,
        res: http.ServerResponse,
-        log: werelogs.RequestLogger,
+        log: RequestLogger,
    ) {
        let pathInfo: ReturnType<typeof parseURL>;
        let rangeSpec: ReturnType<typeof httpUtils.parseRangeSpec> | undefined =
@ -266,7 +266,7 @@ export default class RESTServer extends httpServer {
    _onDelete(
        req: http.IncomingMessage,
        res: http.ServerResponse,
-        log: werelogs.RequestLogger,
+        log: RequestLogger,
    ) {
        let pathInfo: ReturnType<typeof parseURL>;
        try {
--- a/lib/network/rpc/rpc.ts
+++ b/lib/network/rpc/rpc.ts
@ -1,6 +1,6 @@
 import ioClient from 'socket.io-client';
 import * as http from 'http';
-import { Server as IOServer } from 'socket.io';
+import io from 'socket.io';
 import * as sioStream from './sio-stream';
 import async from 'async';
 import assert from 'assert';
@ -497,7 +497,7 @@ export function RPCServer(params: {
    assert(params.logger);
    const httpServer = http.createServer();
-    const server = new IOServer(httpServer, { maxHttpBufferSize: 1e8 });
+    const server = io(httpServer);
    const log = params.logger;
    /**
@ -508,7 +508,7 @@ export function RPCServer(params: {
     *
     * @param {BaseService} serviceList - list of services to register
     */
-    (server as any).registerServices = function registerServices(...serviceList: any[]) {
+    server.registerServices = function registerServices(...serviceList: any[]) {
        serviceList.forEach(service => {
            const sock = this.of(service.namespace);
            sock.on('connection', conn => {
@ -536,7 +536,7 @@ export function RPCServer(params: {
        });
    };
-    (server as any).listen = function listen(port, bindAddress = undefined) {
+    server.listen = function listen(port, bindAddress = undefined) {
        httpServer.listen(port, bindAddress);
    };
--- a/lib/policy/resourcePolicySchema.json
+++ b/lib/policy/resourcePolicySchema.json
@ -38,7 +38,7 @@
        },
        "principalAWSUserArn": {
            "type": "string",
-            "pattern": "^arn:aws:iam::[0-9]{12}:user/(?!\\*)[\\w+=,.@ -/]{1,2017}$"
+            "pattern": "^arn:aws:iam::[0-9]{12}:user/(?!\\*)[\\w+=,.@ -/]{1,64}$"
        },
        "principalAWSRoleArn": {
            "type": "string",
@ -360,9 +360,6 @@
            "type": "string",
            "const": "2012-10-17"
        },
        "Id": {
            "type": "string"
        },
        "Statement": {
            "oneOf": [
                {
--- a/lib/policy/userPolicySchema.json
+++ b/lib/policy/userPolicySchema.json
@ -28,7 +28,7 @@
        },
        "principalAWSUserArn": {
            "type": "string",
-            "pattern": "^arn:aws:iam::[0-9]{12}:user/(?!\\*)[\\w+=,.@ -/]{1,2017}$"
+            "pattern": "^arn:aws:iam::[0-9]{12}:user/(?!\\*)[\\w+=,.@ -/]{1,64}$"
        },
        "principalAWSRoleArn": {
            "type": "string",
--- a/lib/policyEvaluator/RequestContext.ts
+++ b/lib/policyEvaluator/RequestContext.ts
@ -12,39 +12,13 @@ import {
    actionMapSSO,
    actionMapSTS,
    actionMapMetadata,
    actionMapScuba,
 } from './utils/actionMaps';
-export const actionNeedQuotaCheck = {
+const _actionNeedQuotaCheck = {
    objectPut: true,
    objectPutVersion: true,
    objectPutPart: true,
    objectRestore: true,
 };
 /**
 * This variable describes APIs that change the bytes
 * stored, requiring quota updates
 */
 export const actionWithDataDeletion = {
    objectDelete: true,
    objectDeleteVersion: true,
    multipartDelete: true,
    multiObjectDelete: true,
 };
 /**
 * The function returns true if the current API call is a copy object
 * and the action requires a quota evaluation logic, post retrieval
 * of the object metadata.
 * @param {string} action - the action being performed
 * @param {string} currentApi - the current API being called
 * @return {boolean} - whether the action requires a quota check
 */
 export function actionNeedQuotaCheckCopy(action: string, currentApi: string) {
    return action === 'objectGet' && (currentApi === 'objectCopy' || currentApi === 'objectPutCopyPart');
 }
 function _findAction(service: string, method: string) {
    switch (service) {
        case 's3':
@ -62,8 +36,6 @@ function _findAction(service: string, method: string) {
            return actionMapSTS[method];
        case 'metadata':
            return actionMapMetadata[method];
        case 'scuba':
            return actionMapScuba[method];
        default:
            return undefined;
    }
@ -133,10 +105,6 @@ function _buildArn(
            return `arn:scality:metadata::${requesterInfo!.accountid}:` +
            `${generalResource}/`;
        }
        case 'scuba': {
            return `arn:scality:scuba::${requesterInfo!.accountid}:` +
            `${generalResource}${specificResource ? '/' + specificResource : ''}`;
        }
        default:
            return undefined;
    }
@ -205,7 +173,6 @@ export default class RequestContext {
    _needTagEval: boolean;
    _foundAction?: string;
    _foundResource?: string;
    _objectLockRetentionDays?: number | null;
    constructor(
        headers: { [key: string]: string | string[] },
@ -227,7 +194,6 @@ export default class RequestContext {
        requestObjTags?: string,
        existingObjTag?: string,
        needTagEval?: false,
        objectLockRetentionDays?: number,
    ) {
        this._headers = headers;
        this._query = query;
@ -256,12 +222,10 @@ export default class RequestContext {
        this._securityToken = securityToken;
        this._policyArn = policyArn;
        this._action = action;
-        this._needQuota = actionNeedQuotaCheck[apiMethod] === true
+        this._needQuota = _actionNeedQuotaCheck[apiMethod] === true;
            || actionWithDataDeletion[apiMethod] === true;
        this._requestObjTags = requestObjTags || null;
        this._existingObjTag = existingObjTag || null;
        this._needTagEval = needTagEval || false;
        this._objectLockRetentionDays = objectLockRetentionDays || null;
        return this;
    }
@ -293,7 +257,6 @@ export default class RequestContext {
            requestObjTags: this._requestObjTags,
            existingObjTag: this._existingObjTag,
            needTagEval: this._needTagEval,
            objectLockRetentionDays: this._objectLockRetentionDays,
        };
        return JSON.stringify(requestInfo);
    }
@ -334,7 +297,6 @@ export default class RequestContext {
            obj.requestObjTags,
            obj.existingObjTag,
            obj.needTagEval,
            obj.objectLockRetentionDays,
        );
    }
@ -738,24 +700,4 @@ export default class RequestContext {
    getNeedTagEval() {
        return this._needTagEval;
    }
    /**
     * Get object lock retention days
     *
     * @returns objectLockRetentionDays - object lock retention days 
     */
    getObjectLockRetentionDays() {
        return this._objectLockRetentionDays;
    }
    /**
     * Set object lock retention days
     *
     * @param objectLockRetentionDays - object lock retention days
     * @returns itself
     */
    setObjectLockRetentionDays(objectLockRetentionDays: number) {
        this._objectLockRetentionDays = objectLockRetentionDays;
        return this;
    }
 }
--- a/lib/policyEvaluator/evaluator.ts
+++ b/lib/policyEvaluator/evaluator.ts
@ -310,7 +310,6 @@ export function evaluatePolicy(
 }
 /**
 * @deprecated Upgrade to standardEvaluateAllPolicies
 * Evaluate whether a request is permitted under a policy.
 * @param requestContext - Info necessary to
 * evaluate permission
@ -326,16 +325,6 @@ export function evaluateAllPolicies(
    allPolicies: any[],
    log: Logger,
 ): string {
    return standardEvaluateAllPolicies(requestContext, allPolicies, log).verdict;
 }
 export function standardEvaluateAllPolicies(
    requestContext: RequestContext,
    allPolicies: any[],
    log: Logger,
 ): {
    verdict: string;
    isImplicit: boolean;
 } {
    log.trace('evaluating all policies');
    let allow = false;
    let allowWithTagCondition = false;
@ -344,10 +333,7 @@ export function standardEvaluateAllPolicies(
        const singlePolicyVerdict = evaluatePolicy(requestContext, allPolicies[i], log);
        // If there is any Deny, just return Deny
        if (singlePolicyVerdict === 'Deny') {
-            return {
+            return 'Deny';
                verdict: 'Deny',
                isImplicit: false,
            };
        }
        if (singlePolicyVerdict === 'Allow') {
            allow = true;
@ -358,7 +344,6 @@ export function standardEvaluateAllPolicies(
        } // else 'Neutral'
    }
    let verdict;
    let isImplicit = false;
    if (allow) {
        if (denyWithTagCondition) {
            verdict = 'NeedTagConditionEval';
@ -370,9 +355,8 @@ export function standardEvaluateAllPolicies(
            verdict = 'NeedTagConditionEval';
        } else {
            verdict = 'Deny';
            isImplicit = true;
        }
    }
-    log.trace('result of evaluating all policies', { verdict, isImplicit });
+    log.trace('result of evaluating all policies', { verdict });
-    return { verdict, isImplicit };
+    return verdict;
 }
--- a/lib/policyEvaluator/utils/actionMaps.ts
+++ b/lib/policyEvaluator/utils/actionMaps.ts
@ -52,12 +52,6 @@ const sharedActionMap = {
    objectPutVersion: 's3:PutObjectVersion',
 };
 const actionMapBucketQuotas = {
    bucketGetQuota: 'scality:GetBucketQuota',
    bucketUpdateQuota: 'scality:UpdateBucketQuota',
    bucketDeleteQuota: 'scality:DeleteBucketQuota',
 };
 // action map used for request context
 const actionMapRQ = {
    bucketPut: 's3:CreateBucket',
@ -71,7 +65,6 @@ const actionMapRQ = {
    initiateMultipartUpload: 's3:PutObject',
    objectDeleteVersion: 's3:DeleteObjectVersion',
    objectDeleteTaggingVersion: 's3:DeleteObjectVersionTagging',
    objectGetArchiveInfo: 'scality:GetObjectArchiveInfo',
    objectGetVersion: 's3:GetObjectVersion',
    objectGetACLVersion: 's3:GetObjectVersionAcl',
    objectGetTaggingVersion: 's3:GetObjectVersionTagging',
@ -86,11 +79,10 @@ const actionMapRQ = {
    objectPutLegalHoldVersion: 's3:PutObjectLegalHold',
    listObjectVersions: 's3:ListBucketVersions',
    ...sharedActionMap,
    ...actionMapBucketQuotas,
 };
 // action map used for bucket policies
-const actionMapBP = actionMapRQ;
+const actionMapBP = { ...sharedActionMap };
 // action map for all relevant s3 actions
 const actionMapS3 = {
@ -159,15 +151,6 @@ const actionMonitoringMapS3 = {
    objectPutTagging: 'PutObjectTagging',
    objectRestore: 'RestoreObject',
    serviceGet: 'ListBuckets',
    bucketGetQuota: 'GetBucketQuota',
    bucketUpdateQuota: 'UpdateBucketQuota',
    bucketDeleteQuota: 'DeleteBucketQuota', 
 };
 const actionMapAccountQuotas = {
    UpdateAccountQuota : 'scality:UpdateAccountQuota',
    DeleteAccountQuota : 'scality:DeleteAccountQuota',
    GetAccountQuota : 'scality:GetAccountQuota',
 };
 const actionMapIAM = {
@ -211,7 +194,6 @@ const actionMapIAM = {
    tagUser: 'iam:TagUser',
    unTagUser: 'iam:UntagUser',
    listUserTags: 'iam:ListUserTags',
    ...actionMapAccountQuotas,
 };
 const actionMapSSO = {
@ -227,14 +209,6 @@ const actionMapMetadata = {
    default: 'metadata:bucketd',
 };
 const actionMapScuba = {
    GetMetrics: 'scuba:GetMetrics',
    AdminStartIngest: 'scuba:AdminStartIngest',
    AdminStopIngest: 'scuba:AdminStopIngest',
    AdminReadRaftCseq: 'scuba:AdminReadRaftCseq',
    AdminTriggerRepair: 'scuba:AdminTriggerRepair',
 };
 export {
    actionMapRQ,
    actionMapBP,
@ -244,5 +218,4 @@ export {
    actionMapSSO,
    actionMapSTS,
    actionMapMetadata,
    actionMapScuba,
 };
--- a/lib/policyEvaluator/utils/checkArnMatch.ts
+++ b/lib/policyEvaluator/utils/checkArnMatch.ts
@ -1,5 +1,5 @@
 import { handleWildcardInResource } from './wildcards';
-import { policyArnAllowedEmptyAccountId } from '../../constants';
+
 /**
 * Checks whether an ARN from a request matches an ARN in a policy
 * to compare against each portion of the ARN from the request
@ -38,10 +38,9 @@ export default function checkArnMatch(
        const requestSegment = caseSensitive ? requestArnArr[j] :
            requestArnArr[j].toLowerCase();
        const policyArnArr = policyArn.split(':');
-        // We want to allow an empty account ID for utapi and scuba service ARNs to not
+        // We want to allow an empty account ID for utapi service ARNs to not
        // break compatibility.
-        if (j === 4 && policyArnAllowedEmptyAccountId.includes(policyArnArr[2])
+        if (j === 4 && policyArnArr[2] === 'utapi' && policyArnArr[4] === '') {
            && policyArnArr[4] === '') {
            continue;
        } else if (!segmentRegEx.test(requestSegment)) {
            return false;
--- a/lib/policyEvaluator/utils/conditions.ts
+++ b/lib/policyEvaluator/utils/conditions.ts
@ -168,9 +168,6 @@ export function findConditionKey(
        return requestContext.getNeedTagEval() && requestContext.getRequestObjTags()
            ? getTagKeys(requestContext.getRequestObjTags()!)
            : undefined;
    // The maximum retention period is 100 years.
    case 's3:object-lock-remaining-retention-days':
        return requestContext.getObjectLockRetentionDays() || undefined;
    default:
        return undefined;
    }
--- a/lib/s3middleware/azureHelpers/mpuUtils.ts
+++ b/lib/s3middleware/azureHelpers/mpuUtils.ts
@ -2,9 +2,6 @@ import assert from 'assert';
 import * as crypto from 'crypto';
 import * as stream from 'stream';
 import azure from '@azure/storage-blob';
 import { RequestLogger } from 'werelogs';
 import ResultsCollector from './ResultsCollector';
 import SubStreamInterface from './SubStreamInterface';
 import * as objectUtils from '../objectUtils';
--- a/lib/s3middleware/lifecycleHelpers/LifecycleDateTime.ts
+++ b/lib/s3middleware/lifecycleHelpers/LifecycleDateTime.ts
@ -1,25 +1,19 @@
-import { scaleMsPerDay } from '../objectUtils';
+const oneDay = 24 * 60 * 60 * 1000; // Milliseconds in a day.
 const msInOneDay = 24 * 60 * 60 * 1000; // Milliseconds in a day.
 export default class LifecycleDateTime {
    _transitionOneDayEarlier?: boolean;
    _expireOneDayEarlier?: boolean;
    _timeProgressionFactor?: number;
    _scaledMsPerDay: number;
    constructor(params?: {
        transitionOneDayEarlier: boolean;
        expireOneDayEarlier: boolean;
        timeProgressionFactor: number;
    }) {
        this._transitionOneDayEarlier = params?.transitionOneDayEarlier;
        this._expireOneDayEarlier = params?.expireOneDayEarlier;
        this._timeProgressionFactor = params?.timeProgressionFactor || 1;
        this._scaledMsPerDay = scaleMsPerDay(this._timeProgressionFactor);
    }
    getCurrentDate() {
-        const timeTravel = this._expireOneDayEarlier ? msInOneDay : 0;
+        const timeTravel = this._expireOneDayEarlier ? oneDay : 0;
        return Date.now() + timeTravel;
    }
@ -31,7 +25,7 @@ export default class LifecycleDateTime {
    findDaysSince(date: Date) {
        const now = this.getCurrentDate();
        const diff = now - date.getTime();
-        return Math.floor(diff / this._scaledMsPerDay);
+        return Math.floor(diff / (1000 * 60 * 60 * 24));
    }
    /**
@ -58,8 +52,8 @@ export default class LifecycleDateTime {
        }
        if (transition.Days !== undefined) {
            const lastModifiedTime = this.getTimestamp(lastModified);
-            const timeTravel = this._transitionOneDayEarlier ? -msInOneDay : 0;
+            const timeTravel = this._transitionOneDayEarlier ? -oneDay : 0;
-            return lastModifiedTime + (transition.Days * this._scaledMsPerDay) + timeTravel;
+            return lastModifiedTime + (transition.Days * oneDay) + timeTravel;
        }
    }
@ -75,8 +69,8 @@ export default class LifecycleDateTime {
    ) {
        if (transition.NoncurrentDays !== undefined) {
            const lastModifiedTime = this.getTimestamp(lastModified);
-            const timeTravel = this._transitionOneDayEarlier ? -msInOneDay : 0;
+            const timeTravel = this._transitionOneDayEarlier ? -oneDay : 0;
-            return lastModifiedTime + (transition.NoncurrentDays * this._scaledMsPerDay) + timeTravel;
+            return lastModifiedTime + (transition.NoncurrentDays * oneDay) + timeTravel;
        }
    }
 }
--- a/lib/s3middleware/objectUtils.ts
+++ b/lib/s3middleware/objectUtils.ts
@ -1,5 +1,3 @@
 const msInOneDay = 24 * 60 * 60 * 1000; // Milliseconds in a day.
 export const getMD5Buffer = (base64MD5: WithImplicitCoercion<string> | Uint8Array) =>
    base64MD5 instanceof Uint8Array ? base64MD5 : Buffer.from(base64MD5, 'base64')
@ -8,14 +6,3 @@ export const getHexMD5 = (base64MD5: WithImplicitCoercion<string> | Uint8Array)
 export const getBase64MD5 = (hexMD5: WithImplicitCoercion<string>) =>
    Buffer.from(hexMD5, 'hex').toString('base64');
 /**
 * Calculates the number of scaled milliseconds per day based on the given time progression factor.
 * This function is intended for testing and simulation purposes only.
 * @param {number} timeProgressionFactor - The desired time progression factor for scaling.
 * @returns {number} The number of scaled milliseconds per day.
 * If the result is 0, the minimum value of 1 millisecond is returned.
 */
 export const scaleMsPerDay = (timeProgressionFactor: number): number =>
    Math.round(msInOneDay / (timeProgressionFactor || 1)) || 1;
--- a/lib/s3routes/routes.ts
+++ b/lib/s3routes/routes.ts
@ -1,7 +1,4 @@
 import assert from 'assert';
 import { RequestLogger } from 'werelogs';
 import errors from '../errors';
 import routeGET from './routes/routeGET';
 import routePUT from './routes/routePUT';
--- a/lib/s3routes/routes/routeDELETE.ts
+++ b/lib/s3routes/routes/routeDELETE.ts
@ -1,5 +1,3 @@
 import { RequestLogger } from 'werelogs';
 import * as routesUtils from '../routesUtils';
 import errors from '../../errors';
 import StatsClient from '../../metrics/StatsClient';
@ -43,8 +41,6 @@ export default function routeDELETE(
            return call('bucketDeleteEncryption');
        } else if (query?.tagging !== undefined) {
            return call('bucketDeleteTagging');
        } else if (query?.quota !== undefined) {
            return call('bucketDeleteQuota');
        }
        call('bucketDelete');
    } else {
--- a/lib/s3routes/routes/routeGET.ts
+++ b/lib/s3routes/routes/routeGET.ts
@ -1,5 +1,3 @@
 import { RequestLogger } from 'werelogs';
 import * as routesUtils from '../routesUtils';
 import errors from '../../errors';
 import * as http from 'http';
@ -60,8 +58,6 @@ export default function routerGET(
            call('bucketGetEncryption');
        } else if (query.search !== undefined) {
            call('metadataSearch')
        } else if (query.quota !== undefined) {
            call('bucketGetQuota');
        } else {
            // GET bucket
            call('bucketGet');
--- a/lib/s3routes/routes/routeHEAD.ts
+++ b/lib/s3routes/routes/routeHEAD.ts
@ -1,5 +1,3 @@
 import { RequestLogger } from 'werelogs';
 import * as routesUtils from '../routesUtils';
 import errors from '../../errors';
 import StatsClient from '../../metrics/StatsClient';
--- a/lib/s3routes/routes/routeOPTIONS.ts
+++ b/lib/s3routes/routes/routeOPTIONS.ts
@ -1,5 +1,3 @@
 import { RequestLogger } from 'werelogs';
 import * as routesUtils from '../routesUtils';
 import errors from '../../errors';
 import * as http from 'http';
--- a/lib/s3routes/routes/routePOST.ts
+++ b/lib/s3routes/routes/routePOST.ts
@ -1,5 +1,3 @@
 import { RequestLogger } from 'werelogs';
 import * as routesUtils from '../routesUtils';
 import errors from '../../errors';
 import * as http from 'http';
--- a/lib/s3routes/routes/routePUT.ts
+++ b/lib/s3routes/routes/routePUT.ts
@ -1,5 +1,3 @@
 import { RequestLogger } from 'werelogs';
 import * as routesUtils from '../routesUtils';
 import errors from '../../errors';
 import * as http from 'http';
@ -105,13 +103,6 @@ export default function routePUT(
                    return routesUtils.responseNoBody(err, corsHeaders,
                        response, 200, log);
                });
        } else if (query.quota !== undefined) {
            api.callApiMethod('bucketUpdateQuota', request, response,
                log, (err, resHeaders) => {
                    routesUtils.statsReport500(err, statsClient);
                    return routesUtils.responseNoBody(err, resHeaders, response,
                        200, log);
                });
        } else {
            // PUT bucket
            return api.callApiMethod('bucketPut', request, response, log,
--- a/lib/s3routes/routes/routeWebsite.ts
+++ b/lib/s3routes/routes/routeWebsite.ts
@ -1,5 +1,3 @@
 import { RequestLogger } from 'werelogs';
 import * as routesUtils from '../routesUtils';
 import errors from '../../errors';
 import * as http from 'http';
@ -29,11 +27,6 @@ export default function routerWebsite(
                routesUtils.statsReport500(err, statsClient);
                // request being redirected
                if (redirectInfo) {
                    if (err && redirectInfo.withError) {
                        return routesUtils.redirectRequestOnError(err,
                            'GET', redirectInfo, dataGetInfo, dataRetrievalParams,
                            response, resMetaHeaders, log)
                    }
                    // note that key might have been modified in websiteGet
                    // api to add index document
                    return routesUtils.redirectRequest(redirectInfo,
@ -64,11 +57,6 @@ export default function routerWebsite(
            (err, resMetaHeaders, redirectInfo, key) => {
                routesUtils.statsReport500(err, statsClient);
                if (redirectInfo) {
                    if (err && redirectInfo.withError) {
                        return routesUtils.redirectRequestOnError(err,
                            'HEAD', redirectInfo, null, dataRetrievalParams,
                            response, resMetaHeaders, log)
                    }
                    return routesUtils.redirectRequest(redirectInfo,
                        // TODO ARSN-217 encrypted does not exists in request.connection
                        // @ts-ignore
--- a/lib/s3routes/routesUtils.ts
+++ b/lib/s3routes/routesUtils.ts
@ -1,13 +1,10 @@
 import * as url from 'url';
 import * as http from 'http';
 import { eachSeries } from 'async';
 import { RequestLogger } from 'werelogs';
 import * as ipCheck from '../ipCheck';
 import errors, { ArsenalError } from '../errors';
 import * as constants from '../constants';
 import { eachSeries } from 'async';
 import DataWrapper from '../storage/data/DataWrapper';
 import * as http from 'http';
 import StatsClient from '../metrics/StatsClient';
 import { objectKeyByteLimit } from '../constants';
 const jsutil = require('../jsutil');
@ -694,8 +691,6 @@ export function streamUserErrorPage(
    log: RequestLogger,
 ) {
    setCommonResponseHeaders(corsHeaders, response, log);
    response.setHeader('x-amz-error-code', err.message);
    response.setHeader('x-amz-error-message', err.description);
    response.writeHead(err.code, { 'Content-type': 'text/html' });
    response.on('finish', () => {
        // TODO ARSN-216 Fix logger
@ -878,7 +873,7 @@ export function redirectRequest(
    }
    let redirectLocation = justPath ? `/${redirectKey}` :
        `${redirectProtocol}://${redirectHostName}/${redirectKey}`;
-    if (!redirectKey && redirectLocationHeader && redirectLocation !== '/') {
+    if (!redirectKey && redirectLocationHeader) {
        // remove hanging slash
        redirectLocation = redirectLocation.slice(0, -1);
    }
@ -895,52 +890,6 @@ export function redirectRequest(
    return undefined;
 }
 /**
 * redirectRequestOnError - redirect with an error body
 * @param err - arsenal error object
 * @param method - HTTP method
 * @param routingInfo - info for routing
 * @param [routingInfo.withError] - flag to differentiate from routing rules
 * @param [routingInfo.location] - location header
 * @param dataLocations --
 *   - array of locations to get streams from backend
 * @param retrieveDataParams - params to create instance of
 * data retrieval function
 * @param response - response object
 * @param corsHeaders - CORS-related response headers
 * @param log - Werelogs instance
 */
 export function redirectRequestOnError(
    err: ArsenalError,
    method: 'HEAD' | 'GET',
    routingInfo: {
        withError: true;
        location: string;
    },
    dataLocations: { size: string | number }[] | null,
    retrieveDataParams: any,
    response: http.ServerResponse,
    corsHeaders: { [key: string]: string },
    log: RequestLogger,
 ) {
    response.setHeader('Location', routingInfo.location);
    if (!dataLocations && err.is.Found) {
        if (method === 'HEAD') {
            return errorHeaderResponse(err, response, corsHeaders, log);
        }
        response.setHeader('x-amz-error-code', err.message);
        response.setHeader('x-amz-error-message', err.description);
        return errorHtmlResponse(err, false, '', response, corsHeaders, log);
    }
    // This is reached only for website error document (GET only)
    const overrideErrorCode = err.flatten();
    overrideErrorCode.code = 301;
    return streamUserErrorPage(ArsenalError.unflatten(overrideErrorCode)!,
        dataLocations || [], retrieveDataParams, response, corsHeaders, log);
 }
 /**
 * Get bucket name and object name from the request
 * @param request - http request object
--- a/lib/storage/data/DataWrapper.js
+++ b/lib/storage/data/DataWrapper.js
@ -2,8 +2,6 @@ const async = require('async');
 const PassThrough = require('stream').PassThrough;
 const assert = require('assert');
 const { Logger } = require('werelogs');
 const errors = require('../../errors').default;
 const MD5Sum = require('../../s3middleware/MD5Sum').default;
 const NullStream = require('../../s3middleware/nullStream').default;
@ -29,7 +27,6 @@ class DataWrapper {
        this.metadata = metadata;
        this.locStorageCheckFn = locStorageCheckFn;
        this.vault = vault;
        this.logger = new Logger('DataWrapper');
    }
    put(cipherBundle, value, valueSize, keyContext, backendInfo, log, cb) {
@ -130,7 +127,7 @@ class DataWrapper {
    }
    delete(objectGetInfo, log, cb) {
-        const callback = cb || (() => {});
+        const callback = cb || log.end;
        const isMdModelVersion2 = typeof(objectGetInfo) === 'string';
        const isRequiredStringKey =
            constants.clientsRequireStringKey[this.implName];
@ -179,9 +176,7 @@ class DataWrapper {
            newObjDataStoreName)) {
            return process.nextTick(cb);
        }
-        const delLog = this.logger.newRequestLoggerFromSerializedUids(
+        log.trace('initiating batch delete', {
            log.getSerializedUids());
        delLog.trace('initiating batch delete', {
            keys: locations,
            implName: this.implName,
            method: 'batchDelete',
@ -207,21 +202,21 @@ class DataWrapper {
            return false;
        });
        if (shouldBatchDelete && keys.length > 1) {
-            return this.client.batchDelete(backendName, { keys }, delLog, cb);
+            return this.client.batchDelete(backendName, { keys }, log, cb);
        }
        return async.eachLimit(locations, 5, (loc, next) => {
-            process.nextTick(() => this.delete(loc, delLog, next));
+            process.nextTick(() => this.delete(loc, log, next));
        },
        err => {
            if (err) {
-                delLog.end().error('batch delete failed', { error: err });
+                log.end().error('batch delete failed', { error: err });
                // deletion of non-existing objects result in 204
                if (err.code === 404) {
                    return cb();
                }
                return cb(err);
            }
-            delLog.end().trace('batch delete successfully completed');
+            log.end().trace('batch delete successfully completed');
            return cb();
        });
    }
--- a/lib/storage/data/LocationConstraintParser.js
+++ b/lib/storage/data/LocationConstraintParser.js
@ -1,10 +1,10 @@
 const { http, https } = require('httpagent');
 const url = require('url');
 const AWS = require('aws-sdk');
 const Sproxy = require('sproxydclient');
 const Hyperdrive = require('hdclient');
 const HttpsProxyAgent = require('https-proxy-agent');
 require("aws-sdk/lib/maintenance_mode_message").suppress = true;
 const constants = require('../../constants');
 const DataFileBackend = require('./file/DataFileInterface');
 const inMemory = require('./in_memory/datastore').backend;
@ -25,13 +25,8 @@ function parseLC(config, vault) {
        if (locationObj.type === 'file') {
            clients[location] = new DataFileBackend(config);
        }
        if (locationObj.type === 'vitastor') {
            const VitastorBackend = require('./vitastor/VitastorBackend');
            clients[location] = new VitastorBackend(location, locationObj.details);
        }
        if (locationObj.type === 'scality') {
            if (locationObj.details.connector.sproxyd) {
                const Sproxy = require('sproxydclient');
                clients[location] = new Sproxy({
                    bootstrap: locationObj.details.connector
                        .sproxyd.bootstrap,
@ -46,7 +41,6 @@ function parseLC(config, vault) {
                });
                clients[location].clientType = 'scality';
            } else if (locationObj.details.connector.hdclient) {
                const Hyperdrive = require('hdclient');
                clients[location] = new Hyperdrive.hdcontroller.HDProxydClient(
                    locationObj.details.connector.hdclient);
                clients[location].clientType = 'scality';
--- a/lib/storage/data/MultipleBackendGateway.js
+++ b/lib/storage/data/MultipleBackendGateway.js
@ -5,7 +5,6 @@ const { parseTagFromQuery } = require('../../s3middleware/tagging');
 const { externalBackendHealthCheckInterval } = require('../../constants');
 const DataFileBackend = require('./file/DataFileInterface');
 const { createLogger, checkExternalBackend } = require('./external/utils');
 const jsutil = require('../../jsutil');
 class MultipleBackendGateway {
    constructor(clients, metadata, locStorageCheckFn) {
@ -200,12 +199,11 @@ class MultipleBackendGateway {
    uploadPart(request, streamingV4Params, stream, size, location, key,
        uploadId, partNumber, bucketName, log, cb) {
        const client = this.clients[location];
        const cbOnce = jsutil.once(cb);
        if (client.uploadPart) {
            return this.locStorageCheckFn(location, size, log, err => {
                if (err) {
-                    return cbOnce(err);
+                    return cb(err);
                }
                return client.uploadPart(request, streamingV4Params, stream,
                    size, key, uploadId, partNumber, bucketName, log,
@ -219,14 +217,14 @@ class MultipleBackendGateway {
                                    'metric following object PUT failure',
                                        { error: error.message });
                                    }
-                                    return cbOnce(err);
+                                    return cb(err);
                                });
                        }
-                        return cbOnce(null, partInfo);
+                        return cb(null, partInfo);
                    });
            });
        }
-        return cbOnce();
+        return cb();
    }
    listParts(key, uploadId, location, bucketName, partNumberMarker, maxParts,
--- a/lib/storage/data/external/AwsClient.js
+++ b/lib/storage/data/external/AwsClient.js
@ -8,7 +8,6 @@ const getMetaHeaders =
 const { prepareStream } = require('../../../s3middleware/prepareStream');
 const { createLogger, logHelper, removeQuotes, trimXMetaPrefix } =
    require('./utils');
 const jsutil = require('../../../jsutil');
 const missingVerIdInternalError = errors.InternalError.customizeDescription(
    'Invalid state. Please ensure versioning is enabled ' +
@ -318,11 +317,9 @@ class AwsClient {
    uploadPart(request, streamingV4Params, stream, size, key, uploadId,
        partNumber, bucketName, log, callback) {
        let hashedStream = stream;
        const cbOnce = jsutil.once(callback);
        if (request) {
            const partStream = prepareStream(request, streamingV4Params,
-                this._vault, log, cbOnce);
+                this._vault, log, callback);
            hashedStream = new MD5Sum();
            partStream.pipe(hashedStream);
        }
@ -336,7 +333,7 @@ class AwsClient {
            if (err) {
                logHelper(log, 'error', 'err from data backend ' +
                    'on uploadPart', err, this._dataStoreName, this.clientType);
-                return cbOnce(errors.ServiceUnavailable
+                return callback(errors.ServiceUnavailable
                    .customizeDescription('Error returned from ' +
                    `${this.type}: ${err.message}`),
                );
@ -350,7 +347,7 @@ class AwsClient {
                dataStoreName: this._dataStoreName,
                dataStoreETag: noQuotesETag,
            };
-            return cbOnce(null, dataRetrievalInfo);
+            return callback(null, dataRetrievalInfo);
        });
    }
--- a/lib/storage/data/vitastor/VitastorBackend.ts
+++ b/lib/storage/data/vitastor/VitastorBackend.ts
@ -1,696 +0,0 @@
 // Zenko CloudServer Vitastor data storage backend adapter
 // Copyright (c) Vitaliy Filippov, 2019+
 // License: VNPL-1.1 (see README.md for details)
 const stream = require('stream');
 const vitastor = require('vitastor');
 const VOLUME_MAGIC = 'VstS3Vol';
 const OBJECT_MAGIC = 'VstS3Obj';
 const FLAG_DELETED = 2n;
 type Volume = {
    id: number,
    partial_sectors: {
        [key: string]: {
            buffer: Buffer,
            refs: number,
        },
    },
    header: {
        location: string,
        bucket: string,
        max_size: number,
        create_ts: number,
        used_ts: number,
        size: number,
        objects: number,
        removed_objects: number,
        object_bytes: number,
        removed_bytes: number,
    },
 };
 type ObjectHeader = {
    size: number,
    key: string,
    part_num?: number,
 };
 class VitastorBackend
 {
    locationName: string;
    config: {
        pool_id: number,
        metadata_image: string,
        metadata_pool_id: number,
        metadata_inode_num: number,
        size_buckets: number[],
        size_bucket_mul: number,
        id_batch_size: number,
        sector_size: number,
        write_chunk_size: number,
        read_chunk_size: number,
        pack_objects: boolean,
        // and also other parameters for vitastor itself
    };
    next_id: number;
    alloc_id: number;
    opened: boolean;
    on_open: ((...args: any[]) => void)[] | null;
    open_error: Error | null;
    cli: any;
    kv: any;
    volumes: {
        [bucket: string]: {
            [max_size: string]: Volume,
        },
    };
    volumes_by_id: {
        [id: string]: Volume,
    };
    volume_delete_stats: {
        [id: string]: {
            count: number,
            bytes: number,
        },
    };
    constructor(locationName, config)
    {
        this.locationName = locationName;
        this.config = config;
        // validate config
        this.config.pool_id = Number(this.config.pool_id) || 0;
        if (!this.config.pool_id)
            throw new Error('pool_id is required for Vitastor');
        if (!this.config.metadata_image && (!this.config.metadata_pool_id || !this.config.metadata_inode_num))
            throw new Error('metadata_image or metadata_inode is required for Vitastor');
        if (!this.config.size_buckets || !this.config.size_buckets.length)
            this.config.size_buckets = [ 32*1024, 128*1024, 512*1024, 2*1024, 8*1024 ];
        this.config.size_bucket_mul = Number(this.config.size_bucket_mul) || 2;
        this.config.id_batch_size = Number(this.config.id_batch_size) || 100;
        this.config.sector_size = Number(this.config.sector_size) || 0;
        if (this.config.sector_size < 4096)
            this.config.sector_size = 4096;
        this.config.write_chunk_size = Number(this.config.write_chunk_size) || 0;
        if (this.config.write_chunk_size < this.config.sector_size)
            this.config.write_chunk_size = 4*1024*1024; // 4 MB
        this.config.read_chunk_size = Number(this.config.read_chunk_size) || 0;
        if (this.config.read_chunk_size < this.config.sector_size)
            this.config.read_chunk_size = 4*1024*1024; // 4 MB
        this.config.pack_objects = !!this.config.pack_objects;
        // state
        this.next_id = 1;
        this.alloc_id = 0;
        this.opened = false;
        this.on_open = null;
        this.open_error = null;
        this.cli = new vitastor.Client(config);
        this.kv = new vitastor.KV(this.cli);
        // we group objects into volumes by bucket and size
        this.volumes = {};
        this.volumes_by_id = {};
        this.volume_delete_stats = {};
    }
    async _makeVolumeId()
    {
        if (this.next_id <= this.alloc_id)
        {
            return this.next_id++;
        }
        const id_key = 'id'+this.config.pool_id;
        const [ err, prev ] = await new Promise<[ any, string ]>(ok => this.kv.get(id_key, (err, value) => ok([ err, value ])));
        if (err && err != vitastor.ENOENT)
        {
            throw new Error(err);
        }
        const new_id = (parseInt(prev) || 0) + 1;
        this.next_id = new_id;
        this.alloc_id = this.next_id + this.config.id_batch_size - 1;
        await new Promise((ok, no) => this.kv.set(id_key, this.alloc_id, err => (err ? no(new Error(err)) : ok(null)), cas_old => cas_old === prev));
        return this.next_id;
    }
    async _getVolume(bucketName, size)
    {
        if (!this.opened)
        {
            if (this.on_open)
            {
                await new Promise(ok => this.on_open!.push(ok));
            }
            else
            {
                this.on_open = [];
                if (this.config.metadata_image)
                {
                    const img = new vitastor.Image(this.cli, this.config.metadata_image);
                    const info = await new Promise<{ pool_id: number, inode_num: number }>(ok => img.get_info(ok));
                    this.config.metadata_pool_id = info.pool_id;
                    this.config.metadata_inode_num = info.inode_num;
                }
                const kv_config = {};
                for (const key in this.config)
                {
                    if (key.substr(0, 3) === 'kv_')
                        kv_config[key] = this.config[key];
                }
                this.open_error = await new Promise(ok => this.kv.open(
                    this.config.metadata_pool_id, this.config.metadata_inode_num,
                    kv_config, err => ok(err ? new Error(err) : null)
                ));
                this.opened = true;
                this.on_open.map(cb => setImmediate(cb));
                this.on_open = null;
            }
        }
        if (this.open_error)
        {
            throw this.open_error;
        }
        let i;
        for (i = 0; i < this.config.size_buckets.length && size >= this.config.size_buckets[i]; i++) {}
        let s;
        if (i < this.config.size_buckets.length)
            s = this.config.size_buckets[i];
        else if (this.config.size_bucket_mul > 1)
        {
            while (size >= s)
                s = Math.floor(this.config.size_bucket_mul * s);
        }
        if (!this.volumes[bucketName])
        {
            this.volumes[bucketName] = {};
        }
        if (this.volumes[bucketName][s])
        {
            return this.volumes[bucketName][s];
        }
        const new_id = await this._makeVolumeId();
        const new_vol = this.volumes[bucketName][s] = {
            id: new_id,
            // FIXME: partial_sectors should be written with CAS because otherwise we may lose quick deletes
            partial_sectors: {},
            header: {
                location: this.locationName,
                bucket: bucketName,
                max_size: s,
                create_ts: Date.now(),
                used_ts: Date.now(),
                size: this.config.sector_size, // initial position is right after header
                objects: 0,
                removed_objects: 0,
                object_bytes: 0,
                removed_bytes: 0,
            },
        };
        this.volumes_by_id[new_id] = new_vol;
        const header_text = JSON.stringify(this.volumes[bucketName][s].header);
        const buf = Buffer.alloc(this.config.sector_size);
        buf.write(VOLUME_MAGIC + header_text, 0);
        await new Promise((ok, no) => this.cli.write(
            this.config.pool_id, new_id, 0, buf, err => (err ? no(new Error(err)) : ok(null))
        ));
        await new Promise((ok, no) => this.kv.set(
            'vol_'+this.config.pool_id+'_'+new_id, header_text, err => (err ? no(new Error(err)) : ok(null)), cas_old => !cas_old
        ));
        return new_vol;
    }
    toObjectGetInfo(objectKey, bucketName, storageLocation)
    {
        return null;
    }
    _bufferStart(vol, cur_pos, cur_size, cur_chunks, sector_refs)
    {
        if ((cur_pos % this.config.sector_size) ||
            Math.floor((cur_pos + cur_size) / this.config.sector_size) == Math.floor(cur_pos / this.config.sector_size))
        {
            const sect_pos = Math.floor(cur_pos / this.config.sector_size) * this.config.sector_size;
            const sect = vol.partial_sectors[sect_pos]
                ? vol.partial_sectors[sect_pos].buffer
                : Buffer.alloc(this.config.sector_size);
            if (this.config.pack_objects)
            {
                // Save only if <pack_objects>
                if (!vol.partial_sectors[sect_pos])
                    vol.partial_sectors[sect_pos] = { buffer: sect, refs: 0 };
                vol.partial_sectors[sect_pos].refs++;
                sector_refs.push(sect_pos);
            }
            let off = cur_pos % this.config.sector_size;
            let i = 0;
            for (; i < cur_chunks.length; i++)
            {
                let copy_len = this.config.sector_size - off;
                copy_len = copy_len > cur_chunks[i].length ? cur_chunks[i].length : copy_len;
                cur_chunks[i].copy(sect, off, 0, copy_len);
                off += copy_len;
                if (copy_len < cur_chunks[i].length)
                {
                    cur_chunks[i] = cur_chunks[i].slice(copy_len);
                    cur_size -= copy_len;
                    break;
                }
                else
                    cur_size -= cur_chunks[i].length;
            }
            cur_chunks.splice(0, i, sect);
            cur_size += this.config.sector_size;
            cur_pos = sect_pos;
        }
        return [ cur_pos, cur_size ];
    }
    _bufferEnd(vol, cur_pos, cur_size, cur_chunks, sector_refs, write_all)
    {
        const write_pos = cur_pos;
        const write_chunks = cur_chunks;
        let write_size = cur_size;
        cur_chunks = [];
        cur_pos += cur_size;
        cur_size = 0;
        let remain = (cur_pos % this.config.sector_size);
        if (remain > 0)
        {
            cur_pos -= remain;
            let last_sect = null;
            if (write_all)
            {
                last_sect = vol.partial_sectors[cur_pos]
                    ? vol.partial_sectors[cur_pos].buffer
                    : Buffer.alloc(this.config.sector_size);
                if (this.config.pack_objects)
                {
                    // Save only if <pack_objects>
                    if (!vol.partial_sectors[cur_pos])
                        vol.partial_sectors[cur_pos] = { buffer: last_sect, refs: 0 };
                    vol.partial_sectors[cur_pos].refs++;
                    sector_refs.push(cur_pos);
                }
            }
            write_size -= remain;
            if (write_size < 0)
                write_size = 0;
            for (let i = write_chunks.length-1; i >= 0 && remain > 0; i--)
            {
                if (write_chunks[i].length <= remain)
                {
                    remain -= write_chunks[i].length;
                    if (write_all)
                        write_chunks[i].copy(last_sect, remain);
                    else
                        cur_chunks.unshift(write_chunks[i]);
                    write_chunks.pop();
                }
                else
                {
                    if (write_all)
                        write_chunks[i].copy(last_sect, 0, write_chunks[i].length - remain);
                    else
                        cur_chunks.unshift(write_chunks[i].slice(write_chunks[i].length - remain));
                    write_chunks[i] = write_chunks[i].slice(0, write_chunks[i].length - remain);
                    remain = 0;
                    i++;
                }
            }
            if (write_all)
            {
                write_chunks.push(last_sect);
                write_size += this.config.sector_size;
            }
        }
        for (const chunk of cur_chunks)
        {
            cur_size += chunk.length;
        }
        return [ write_pos, write_chunks, write_size, cur_pos, cur_size, cur_chunks ];
    }
    /**
     * reqUids: string, // request-ids for log, usually joined by ':'
     * keyContext: {
     *     // a lot of shit, basically all metadata
     *     bucketName,
     *     objectKey,
     *     owner?,
     *     namespace?,
     *     partNumber?,
     *     uploadId?,
     *     metaHeaders?,
     *     isDeleteMarker?,
     *     tagging?,
     *     contentType?,
     *     cacheControl?,
     *     contentDisposition?,
     *     contentEncoding?,
     * },
     * callback: (error, objectGetInfo: any) => void,
     */
    put(stream, size, keyContext, reqUids, callback)
    {
        callback = once(callback);
        this._getVolume(keyContext.bucketName, size)
            .then(vol => this._put(vol, stream, size, keyContext, reqUids, callback))
            .catch(callback);
    }
    _put(vol, stream, size, keyContext, reqUids, callback)
    {
        const object_header: ObjectHeader = {
            size,
            key: keyContext.objectKey,
        };
        if (keyContext.partNumber)
        {
            object_header.part_num = keyContext.partNumber;
        }
        // header is: <8 bytes magic> <8 bytes flags> <8 bytes json length> <json>
        const hdr_begin_buf = Buffer.alloc(24);
        const hdr_json_buf = Buffer.from(JSON.stringify(object_header), 'utf-8');
        hdr_begin_buf.write(OBJECT_MAGIC);
        hdr_begin_buf.writeBigInt64LE(BigInt(hdr_json_buf.length), 16);
        const object_header_buf = Buffer.concat([ hdr_begin_buf, hdr_json_buf ]);
        const object_pos = vol.header.size;
        const object_get_info = { volume: vol.id, offset: object_pos, hdrlen: object_header_buf.length, size };
        let cur_pos = object_pos;
        let cur_chunks = [ object_header_buf ];
        let cur_size = object_header_buf.length;
        let err: Error|null = null;
        let waiting = 1; // 1 for end or error, 1 for each write request
        vol.header.size += object_header_buf.length + size;
        if (!this.config.pack_objects && (vol.header.size % this.config.sector_size))
        {
            vol.header.size += this.config.sector_size - (vol.header.size % this.config.sector_size);
        }
        const writeChunk = (last) =>
        {
            const sector_refs = [];
            // Handle partial beginning
            [ cur_pos, cur_size ] = this._bufferStart(vol, cur_pos, cur_size, cur_chunks, sector_refs);
            // Handle partial end
            let write_pos, write_chunks, write_size;
            [ write_pos, write_chunks, write_size, cur_pos, cur_size, cur_chunks ] = this._bufferEnd(vol, cur_pos, cur_size, cur_chunks, sector_refs, last);
            waiting++;
            // FIXME: pool_id: maybe it should be stored in volume metadata to allow to migrate volumes?
            this.cli.write(this.config.pool_id, vol.id, write_pos, write_chunks, (res) =>
            {
                for (const sect of sector_refs)
                {
                    vol.partial_sectors[sect].refs--;
                    if (!vol.partial_sectors[sect].refs &&
                        vol.header.size >= sect+this.config.sector_size)
                    {
                        // Forget partial data when it's not needed anymore
                        delete(vol.partial_sectors[sect]);
                    }
                }
                waiting--;
                if (res)
                {
                    err = new Error(res);
                    waiting--;
                }
                if (!waiting)
                {
                    callback(err, err ? null : object_get_info);
                }
            });
        };
        // Stream data
        stream.on('error', (e) =>
        {
            err = e;
            waiting--;
            if (!waiting)
            {
                callback(err, null);
            }
        });
        stream.on('end', () =>
        {
            if (err)
            {
                return;
            }
            waiting--;
            if (cur_size)
            {
                // write last chunk
                writeChunk(true);
            }
            if (!waiting)
            {
                callback(null, object_get_info);
            }
        });
        stream.on('data', (chunk) =>
        {
            if (err)
            {
                return;
            }
            cur_chunks.push(chunk);
            cur_size += chunk.length;
            if (cur_size >= this.config.write_chunk_size)
            {
                // got a complete chunk, write it out
                writeChunk(false);
            }
        });
    }
    /**
     * objectGetInfo: {
     *   key: { volume, offset, hdrlen, size }, // from put
     *   size,
     *   start,
     *   dataStoreName,
     *   dataStoreETag,
     *   range,
     *   response: ServerResponse,
     * },
     * range?: [ start, end ], // like in HTTP - first byte index, last byte index
     * callback: (error, readStream) => void,
     */
    get(objectGetInfo, range, reqUids, callback)
    {
        if (!(objectGetInfo instanceof Object) || !objectGetInfo.key ||
            !(objectGetInfo.key instanceof Object) || !objectGetInfo.key.volume ||
            !objectGetInfo.key.offset || !objectGetInfo.key.hdrlen || !objectGetInfo.key.size)
        {
            throw new Error('objectGetInfo must be { key: { volume, offset, hdrlen, size } }, but is '+JSON.stringify(objectGetInfo));
        }
        const [ start, end ] = range || [];
        if (start < 0 || end < 0 || end != null && start != null && end < start || start >= objectGetInfo.key.size)
        {
            throw new Error('Invalid range: '+start+'-'+end);
        }
        let offset = objectGetInfo.key.offset + objectGetInfo.key.hdrlen + (start || 0);
        let len = objectGetInfo.key.size - (start || 0);
        if (end)
        {
            const len2 = end - (start || 0) + 1;
            if (len2 < len)
                len = len2;
        }
        callback(null, new VitastorReadStream(this.cli, objectGetInfo.key.volume, offset, len, this.config));
    }
    /**
     * objectGetInfo: {
     *   key: { volume, offset, hdrlen, size }, // from put
     *   size,
     *   start,
     *   dataStoreName,
     *   dataStoreETag,
     *   range,
     *   response: ServerResponse,
     * },
     * callback: (error) => void,
     */
    delete(objectGetInfo, reqUids, callback)
    {
        callback = once(callback);
        this._delete(objectGetInfo, reqUids)
            .then(callback)
            .catch(callback);
    }
    async _delete(objectGetInfo, reqUids)
    {
        if (!(objectGetInfo instanceof Object) || !objectGetInfo.key ||
            !(objectGetInfo.key instanceof Object) || !objectGetInfo.key.volume ||
            !objectGetInfo.key.offset || !objectGetInfo.key.hdrlen || !objectGetInfo.key.size)
        {
            throw new Error('objectGetInfo must be { key: { volume, offset, hdrlen, size } }, but is '+JSON.stringify(objectGetInfo));
        }
        const in_sect_pos = (objectGetInfo.key.offset % this.config.sector_size);
        const sect_pos = objectGetInfo.key.offset - in_sect_pos;
        const vol = this.volumes_by_id[objectGetInfo.key.volume];
        if (vol && vol.partial_sectors[sect_pos])
        {
            // The sector may still be written to in corner cases
            const sect = vol.partial_sectors[sect_pos];
            const flags = sect.buffer.readBigInt64LE(in_sect_pos + 8);
            if (!(flags & FLAG_DELETED))
            {
                const del_stat = this.volume_delete_stats[vol.id] = (this.volume_delete_stats[vol.id] || { count: 0, bytes: 0 });
                del_stat.count++;
                del_stat.bytes += objectGetInfo.key.size;
                sect.buffer.writeBigInt64LE(flags | FLAG_DELETED, in_sect_pos + 8);
                sect.refs++;
                const err = await new Promise<any>(ok => this.cli.write(this.config.pool_id, objectGetInfo.key.volume, sect_pos, sect.buffer, ok));
                sect.refs--;
                if (err)
                {
                    sect.buffer.writeBigInt64LE(0n, in_sect_pos + 8);
                    throw new Error(err);
                }
            }
        }
        else
        {
            // RMW with CAS
            const [ err, buf, version ] = await new Promise<[ any, Buffer, bigint ]>(ok => this.cli.read(
                this.config.pool_id, objectGetInfo.key.volume, sect_pos, this.config.sector_size,
                (err, buf, version) => ok([ err, buf, version ])
            ));
            if (err)
            {
                throw new Error(err);
            }
            // FIXME What if JSON crosses sector boundary? Prevent it if we want to pack objects
            const magic = buf.slice(in_sect_pos, in_sect_pos+8).toString();
            const flags = buf.readBigInt64LE(in_sect_pos+8);
            const json_len = Number(buf.readBigInt64LE(in_sect_pos+16));
            let json_hdr;
            if (in_sect_pos+24+json_len <= buf.length)
            {
                try
                {
                    json_hdr = JSON.parse(buf.slice(in_sect_pos+24, in_sect_pos+24+json_len).toString());
                }
                catch (e)
                {
                }
            }
            if (magic !== OBJECT_MAGIC || !json_hdr || json_hdr.size !== objectGetInfo.key.size)
            {
                throw new Error(
                    'header of object with size '+objectGetInfo.key.size+
                    ' bytes not found in volume '+objectGetInfo.key.volume+' at '+objectGetInfo.key.offset
                );
            }
            else if (!(flags & FLAG_DELETED))
            {
                buf.writeBigInt64LE(flags | FLAG_DELETED, in_sect_pos + 8);
                const err = await new Promise<any>(ok => this.cli.write(this.config.pool_id, objectGetInfo.key.volume, sect_pos, buf, { version: version+1n }, ok));
                if (err == vitastor.EINTR)
                {
                    // Retry
                    await this._delete(objectGetInfo, reqUids);
                }
                else if (err)
                {
                    throw new Error(err);
                }
                else
                {
                    // FIXME: Write deletion statistics to volumes
                    // FIXME: Implement defragmentation
                    const del_stat = this.volume_delete_stats[objectGetInfo.key.volume] = (this.volume_delete_stats[objectGetInfo.key.volume] || { count: 0, bytes: 0 });
                    del_stat.count++;
                    del_stat.bytes += objectGetInfo.key.size;
                }
            }
        }
    }
    /**
     * config: full zenko server config,
     * callback: (error, stats) => void, // stats is the returned statistics in arbitrary format
     */
    getDiskUsage(config, reqUids, callback)
    {
        // FIXME: Iterate all volumes and return its sizes and deletion statistics, or maybe just sizes
        callback(null, {});
    }
 }
 class VitastorReadStream extends stream.Readable
 {
    constructor(cli, volume_id, offset, len, config, options = undefined)
    {
        super(options);
        this.cli = cli;
        this.volume_id = volume_id;
        this.offset = offset;
        this.end = offset + len;
        this.pos = offset;
        this.config = config;
        this._reading = false;
    }
    _read(n)
    {
        if (this._reading)
        {
            return;
        }
        // FIXME: Validate object header
        const chunk_size = n && this.config.read_chunk_size < n ? n : this.config.read_chunk_size;
        const read_offset = this.pos;
        const round_offset = read_offset - (read_offset % this.config.sector_size);
        let read_end = this.end <= read_offset+chunk_size ? this.end : read_offset+chunk_size;
        const round_end = (read_end % this.config.sector_size)
            ? read_end + this.config.sector_size - (read_end % this.config.sector_size)
            : read_end;
        if (round_end <= this.end)
            read_end = round_end;
        this.pos = read_end;
        if (read_end <= read_offset)
        {
            // EOF
            this.push(null);
            return;
        }
        this._reading = true;
        this.cli.read(this.config.pool_id, this.volume_id, round_offset, round_end-round_offset, (err, buf, version) =>
        {
            this._reading = false;
            if (err)
            {
                this.destroy(new Error(err));
                return;
            }
            if (read_offset != round_offset || round_end != read_end)
            {
                buf = buf.subarray(read_offset-round_offset, buf.length-(round_end-read_end));
            }
            if (this.push(buf))
            {
                this._read(n);
            }
        });
    }
 }
 function once(callback)
 {
    let called = false;
    return function()
    {
        if (!called)
        {
            called = true;
            callback.apply(null, arguments);
        }
    };
 }
 module.exports = VitastorBackend;
--- a/lib/storage/metadata/MetadataWrapper.js
+++ b/lib/storage/metadata/MetadataWrapper.js
@ -226,19 +226,6 @@ class MetadataWrapper {
        });
    }
    getBucketQuota(bucketName, log, cb) {
        log.debug('getting bucket quota from metadata');
        this.client.getBucketAttributes(bucketName, log, (err, data) => {
            if (err) {
                log.debug('error from metadata', { implName: this.implName,
                    error: err });
                return cb(err);
            }
            const bucketInfo = BucketInfo.fromObj(data);
            return cb(err, { quota: bucketInfo.getQuota() });
        });
    }
    deleteBucket(bucketName, log, cb) {
        log.debug('deleting bucket from metadata');
        this.client.deleteBucket(bucketName, log, err => {
@ -292,25 +279,6 @@ class MetadataWrapper {
            });
    }
    getObjectsMD(bucketName, objNamesWithParams, log, cb) {
        if (typeof this.client.getObjects !== 'function') {
            log.debug('backend does not support get object metadata with batching', {
                implName: this.implName,
            });
            return cb(errors.NotImplemented);
        }
        log.debug('getting objects from metadata', { objects: objNamesWithParams });
        return this.client.getObjects(bucketName, objNamesWithParams, log, (err, data) => {
            if (err) {
                log.debug('error getting objects from metadata', { implName: this.implName, objects: objNamesWithParams,
                    err });
                return cb(err);
            }
            log.debug('objects retrieved from metadata', { objects: objNamesWithParams });
            return cb(err, data);
        });
    }
    getObjectMD(bucketName, objName, params, log, cb) {
        log.debug('getting object from metadata');
        this.client.getObject(bucketName, objName, params, log, (err, data) => {
@ -324,7 +292,7 @@ class MetadataWrapper {
        });
    }
-    deleteObjectMD(bucketName, objName, params, log, cb, originOp = 's3:ObjectRemoved:Delete') {
+    deleteObjectMD(bucketName, objName, params, log, cb) {
        log.debug('deleting object from metadata');
        this.client.deleteObject(bucketName, objName, params, log, err => {
            if (err) {
@ -334,7 +302,7 @@ class MetadataWrapper {
            }
            log.debug('object deleted from metadata');
            return cb(err);
-        }, originOp);
+        });
    }
    listObject(bucketName, listingParams, log, cb) {
@ -548,139 +516,6 @@ class MetadataWrapper {
                return cb();
            });
    }
    /**
     * Put bucket indexes
     *
     * indexSpec format:
     * [
     *      { key:[ { key: "", order: 1 } ... ], name: <id 1>, ... , < backend options> },
     *      ...
     *      { key:[ { key: "", order: 1 } ... ], name: <id n>, ... },
     * ]
     *
     *
     * @param {String} bucketName bucket name
     * @param {Array<Object>} indexSpecs index specification
     * @param {Object} log logger
     * @param {Function} cb callback
     * @return {undefined}
     */
    putBucketIndexes(bucketName, indexSpecs, log, cb) {
        log.debug('put bucket indexes');
        if (typeof this.client.putBucketIndexes !== 'function') {
            log.error('error from metadata', {
                method: 'putBucketIndexes',
                error: errors.NotImplemented,
                implName: this.implName,
            });
            return cb(errors.NotImplemented);
        }
        return this.client.putBucketIndexes(bucketName, indexSpecs, log, err => {
            if (err) {
                log.debug('error from metadata', {
                    method: 'putBucketIndexes',
                    error: err,
                    implName: this.implName,
                });
                return cb(err);
            }
            return cb(null);
        });
    }
    /**
     * Delete bucket indexes
     *
     * indexSpec format:
     * [
     *      { key:[ { key: "", order: 1 } ... ], name: <id 1>, ... , < backend options> },
     *      ...
     *      { key:[ { key: "", order: 1 } ... ], name: <id n>, ...  },
     * ]
     *
     *
     * @param {String} bucketName bucket name
     * @param {Array<Object>} indexSpecs index specification
     * @param {Object} log logger
     * @param {Function} cb callback
     * @return {undefined}
     */
    deleteBucketIndexes(bucketName, indexSpecs, log, cb) {
        log.debug('delete bucket indexes');
        if (typeof this.client.deleteBucketIndexes !== 'function') {
            log.error('error from metadata', {
                method: 'deleteBucketIndexes',
                error: errors.NotImplemented,
                implName: this.implName,
            });
            return cb(errors.NotImplemented);
        }
        return this.client.deleteBucketIndexes(bucketName, indexSpecs, log, err => {
            if (err) {
                log.error('error from metadata', {
                    method: 'deleteBucketIndexes',
                    error: err,
                    implName: this.implName,
                });
                return cb(err);
            }
            return cb(null);
        });
    }
    getBucketIndexes(bucketName, log, cb) {
        log.debug('get bucket indexes');
        if (typeof this.client.getBucketIndexes !== 'function') {
            log.debug('error from metadata', {
                method: 'getBucketIndexes',
                error: errors.NotImplemented,
                implName: this.implName,
            });
            return cb(errors.NotImplemented);
        }
        return this.client.getBucketIndexes(bucketName, log, (err, res) => {
            if (err) {
                log.debug('error from metadata', {
                    method: 'getBucketIndexes',
                    error: err,
                    implName: this.implName,
                });
                return cb(err);
            }
            return cb(null, res);
        });
    }
    getIndexingJobs(log, cb) {
        if (typeof this.client.getIndexingJobs !== 'function') {
            log.debug('error from metadata', {
                method: 'getIndexingJobs',
                error: errors.NotImplemented,
                implName: this.implName,
            });
            return cb(errors.NotImplemented);
        }
        return this.client.getIndexingJobs(log, (err, res) => {
            if (err) {
                log.debug('error from metadata', {
                    method: 'getBucketIndexes',
                    error: err,
                    implName: this.implName,
                });
                return cb(err);
            }
            return cb(null, res);
        });
    }
 }
 module.exports = MetadataWrapper;
--- a/lib/storage/metadata/bucketclient/BucketClientInterface.js
+++ b/lib/storage/metadata/bucketclient/BucketClientInterface.js
@ -1,5 +1,6 @@
 const assert = require('assert');
 const errors = require('../../../errors').default;
 const BucketInfo = require('../../../models/BucketInfo').default;
 class BucketClientInterface {
@ -111,14 +112,7 @@ class BucketClientInterface {
    }
    listLifecycleObject(bucketName, params, log, cb) {
-        this.client.listObject(bucketName, log.getSerializedUids(), params,
+        return process.nextTick(cb, errors.NotImplemented);
            (err, data) => {
                if (err) {
                    return cb(err);
                }
                return cb(null, JSON.parse(data));
            });
        return null;
    }
    listMultipartUploads(bucketName, params, log, cb) {
--- a/lib/storage/metadata/file/BucketFileInterface.js
+++ b/lib/storage/metadata/file/BucketFileInterface.js
@ -326,7 +326,7 @@ class BucketFileInterface {
    }
    listLifecycleObject(bucketName, params, log, cb) {
-        return this.internalListObject(bucketName, params, log, cb);
+        return process.nextTick(cb, errors.NotImplemented);
    }
    listMultipartUploads(bucketName, params, log, cb) {
--- a/lib/storage/metadata/mongoclient/MongoClientInterface.js
+++ b/lib/storage/metadata/mongoclient/MongoClientInterface.js
--- a/lib/storage/metadata/mongoclient/readStream.js
+++ b/lib/storage/metadata/mongoclient/readStream.js
@ -63,14 +63,6 @@ class MongoReadStream extends Readable {
            }
        }
        if (options.dataStoreName) {
            query['value.dataStoreName'] = {};
            if (options.dataStoreName.ne) {
                query['value.dataStoreName'].$ne = options.dataStoreName.ne;
            }
        }
        if (!Object.keys(query._id).length) {
            delete query._id;
        }
@ -85,8 +77,7 @@ class MongoReadStream extends Readable {
            Object.assign(query, searchOptions);
        }
-        const projection = { 'value.location': 0 };
+        this._cursor = c.find(query).sort({
        this._cursor = c.find(query, { projection }).sort({
            _id: options.reverse ? -1 : 1,
        });
        if (options.limit && options.limit !== -1) {
@ -102,10 +93,15 @@ class MongoReadStream extends Readable {
            return;
        }
-        this._cursor.next().then(doc => {
+        this._cursor.next((err, doc) => {
            if (this._destroyed) {
                return;
            }
            if (err) {
                this.emit('error', err);
                return;
            }
            let key = undefined;
            let value = undefined;
@ -129,12 +125,6 @@ class MongoReadStream extends Readable {
                    value,
                });
            }
        }).catch(err => {
            if (this._destroyed) {
                return;
            }
            this.emit('error', err);
            return;
        });
    }
@ -144,7 +134,7 @@ class MongoReadStream extends Readable {
        }
        this._destroyed = true;
-        this._cursor.close().catch(err => {
+        this._cursor.close(err => {
            if (err) {
                this.emit('error', err);
                return;
--- a/lib/storage/metadata/mongoclient/utils.js
+++ b/lib/storage/metadata/mongoclient/utils.js
@ -185,48 +185,6 @@ function formatVersionKey(key, versionId, vFormat) {
    return formatVersionKeyV0(key, versionId);
 }
 function indexFormatMongoArrayToObject(mongoIndexArray) {
    const indexObj = [];
    for (const idx of mongoIndexArray) {
        const keys = [];
        let entries = [];
        if (idx.key instanceof Map) {
            entries = idx.key.entries();
        } else {
            entries = Object.entries(idx.key);
        }
        for (const k of entries) {
            keys.push({ key: k[0], order: k[1] });
        }
        indexObj.push({ name: idx.name, keys });
    }
    return indexObj;
 }
 function indexFormatObjectToMongoArray(indexObj) {
    const mongoIndexArray = [];
    for (const idx of indexObj) {
        const key = new Map();
        for (const k of idx.keys) {
            key.set(k.key, k.order);
        }
        // copy all field except keys from idx
        // eslint-disable-next-line
        const { keys: _, ...toCopy } = idx;
        mongoIndexArray.push(Object.assign(toCopy, { name: idx.name, key }));
    }
    return mongoIndexArray;
 }
 module.exports = {
    credPrefix,
@ -237,6 +195,4 @@ module.exports = {
    translateConditions,
    formatMasterKey,
    formatVersionKey,
    indexFormatMongoArrayToObject,
    indexFormatObjectToMongoArray,
 };
--- a/lib/storage/utils.js
+++ b/lib/storage/utils.js
@ -10,21 +10,21 @@ function trySetDirSyncFlag(path) {
    const GETFLAGS = 2148034049;
    const SETFLAGS = 1074292226;
-    const FS_DIRSYNC_FL = 65536n;
+    const FS_DIRSYNC_FL = 65536;
    const buffer = Buffer.alloc(8, 0);
    const pathFD = fs.openSync(path, 'r');
    const status = ioctl(pathFD, GETFLAGS, buffer);
    assert.strictEqual(status, 0);
-    const currentFlags = buffer.readBigInt64LE(0);
+    const currentFlags = buffer.readUIntLE(0, 8);
    const flags = currentFlags | FS_DIRSYNC_FL;
-    buffer.writeBigInt64LE(flags, 0);
+    buffer.writeUIntLE(flags, 0, 8);
    const status2 = ioctl(pathFD, SETFLAGS, buffer);
    assert.strictEqual(status2, 0);
    fs.closeSync(pathFD);
    const pathFD2 = fs.openSync(path, 'r');
    const confirmBuffer = Buffer.alloc(8, 0);
    ioctl(pathFD2, GETFLAGS, confirmBuffer);
-    assert.strictEqual(confirmBuffer.readBigInt64LE(0),
+    assert.strictEqual(confirmBuffer.readUIntLE(0, 8),
        currentFlags | FS_DIRSYNC_FL, 'FS_DIRSYNC_FL not set');
    fs.closeSync(pathFD2);
 }
--- a/lib/versioning/Version.ts
+++ b/lib/versioning/Version.ts
@ -3,7 +3,7 @@ import { VersioningConstants } from './constants';
 const VID_SEP = VersioningConstants.VersionId.Separator;
 /**
 * Class for manipulating an object version.
- * The format of a version: { isNull, isNull2, isDeleteMarker, versionId, otherInfo }
+ * The format of a version: { isNull, isDeleteMarker, versionId, otherInfo }
 *
 * @note Some of these functions are optimized based on string search
 * prior to a full JSON parse/stringify. (Vinh: 18K op/s are achieved
@ -13,31 +13,24 @@ const VID_SEP = VersioningConstants.VersionId.Separator;
 export class Version {
    version: {
        isNull?: boolean;
        isNull2?: boolean;
        isDeleteMarker?: boolean;
        versionId?: string;
        isPHD?: boolean;
        nullVersionId?: string;
    };
    /**
     * Create a new version instantiation from its data object.
     * @param version - the data object to instantiate
     * @param version.isNull - is a null version
     * @param version.isNull2 - Whether new version is null or not AND has
     * been put with a Cloudserver handling null keys (i.e. supporting
     * S3C-7352)
     * @param version.isDeleteMarker - is a delete marker
     * @param version.versionId - the version id
     * @constructor
     */
    constructor(version?: {
        isNull?: boolean;
        isNull2?: boolean;
        isDeleteMarker?: boolean;
        versionId?: string;
        isPHD?: boolean;
        nullVersionId?: string;
    }) {
        this.version = version || {};
    }
@ -90,33 +83,6 @@ export class Version {
        return `{ "isPHD": true, "versionId": "${versionId}" }`;
    }
    /**
     * Appends a key-value pair to a JSON object represented as a string. It adds
     * a comma if the object is not empty (i.e., not just '{}'). It assumes the input
     * string is formatted as a JSON object.
     *
     * @param {string} stringifiedObject The JSON object as a string to which the key-value pair will be appended.
     * @param {string} key The key to append to the JSON object.
     * @param {string} value The value associated with the key to append to the JSON object.
     * @returns {string} The updated JSON object as a string with the new key-value pair appended.
     * @example
     * _jsonAppend('{"existingKey":"existingValue"}', 'newKey', 'newValue');
     * // returns '{"existingKey":"existingValue","newKey":"newValue"}'
     */
    static _jsonAppend(stringifiedObject: string, key: string, value: string): string {
        // stringifiedObject value has the format of '{...}'
        let index = stringifiedObject.length - 2;
        while (stringifiedObject.charAt(index) === ' ') {
            index -= 1;
        }
        const needComma = stringifiedObject.charAt(index) !== '{';
        return (
            `${stringifiedObject.slice(0, stringifiedObject.length - 1)}` +
            (needComma ? ',' : '') +
            `"${key}":"${value}"}`
        );
    }
    /**
     * Put versionId into an object in the (cheap) way of string manipulation,
     * instead of the more expensive alternative parsing and stringification.
@ -127,32 +93,14 @@ export class Version {
     */
    static appendVersionId(value: string, versionId: string): string {
        // assuming value has the format of '{...}'
-        return Version._jsonAppend(value, 'versionId', versionId);
+        let index = value.length - 2;
-    }
+        while (value.charAt(index--) === ' ');
-
+        const comma = value.charAt(index + 1) !== '{';
-    /**
+        return (
-    * Updates or appends a `nullVersionId` property to a JSON-formatted string.
+            `${value.slice(0, value.length - 1)}` + // eslint-disable-line
-    * This function first checks if the `nullVersionId` property already exists within the input string.
+            (comma ? ',' : '') +
-    * If it exists, the function updates the `nullVersionId` with the new value provided.
+            `"versionId":"${versionId}"}`
-    * If it does not exist, the function appends a `nullVersionId` property with the provided value.
+        );
    *
    * @static
    * @param {string} value - The JSON-formatted string that may already contain a `nullVersionId` property.
    * @param {string} nullVersionId - The new value for the `nullVersionId` property to be updated or appended.
    * @returns {string} The updated JSON-formatted string with the new `nullVersionId` value.
    */
    static updateOrAppendNullVersionId(value: string, nullVersionId: string): string {
        // Check if "nullVersionId" already exists in the string
        const nullVersionIdPattern = /"nullVersionId":"[^"]*"/;
        const nullVersionIdExists = nullVersionIdPattern.test(value);
        if (nullVersionIdExists) {
            // Replace the existing nullVersionId with the new one
            return value.replace(nullVersionIdPattern, `"nullVersionId":"${nullVersionId}"`);
        } else {
            // Append nullVersionId
            return Version._jsonAppend(value, 'nullVersionId', nullVersionId);
        }
    }
    /**
@ -173,19 +121,6 @@ export class Version {
        return this.version.isNull ?? false;
    }
    /**
     * Check if a version is a null version and has
     * been put with a Cloudserver handling null keys (i.e. supporting
     * S3C-7352).
     *
     * @return - stating if the value is a null version and has
     * been put with a Cloudserver handling null keys (i.e. supporting
     * S3C-7352).
     */
    isNull2Version(): boolean {
        return this.version.isNull2 ?? false;
    }
    /**
     * Check if a stringified object is a delete marker.
     *
@ -255,19 +190,6 @@ export class Version {
        return this;
    }
    /**
     * Mark that the null version has been put with a Cloudserver handling null keys (i.e. supporting S3C-7352)
     * 
     * If `isNull2` is set, `isNull` is also set to maintain consistency.
     * Explicitly setting both avoids misunderstandings and mistakes in future updates or fixes.
     * @return - the updated version
     */
    setNull2Version() {
        this.version.isNull2 = true;
        this.version.isNull = true;
        return this;
    }
    /**
     * Serialize the version.
     *
--- a/lib/versioning/VersioningRequestProcessor.ts
+++ b/lib/versioning/VersioningRequestProcessor.ts
@ -1,8 +1,6 @@
 import { RequestLogger } from 'werelogs';
 import errors, { ArsenalError } from '../errors';
 import { Version } from './Version';
-import { generateVersionId as genVID, getInfVid } from './VersionID';
+import { generateVersionId as genVID } from './VersionID';
 import WriteCache from './WriteCache';
 import WriteGatheringManager from './WriteGatheringManager';
@ -483,113 +481,19 @@ export default class VersioningRequestProcessor {
            const versionId = request.options.versionId;
            const versionKey = formatVersionKey(key, versionId);
            const ops: any = [];
-            const masterVersion = data !== undefined &&
+            if (!request.options.isNull) {
-                  Version.from(data);
+                ops.push({ key: versionKey, value: request.value });
            // push a version key if we're not updating the null
            // version (or in legacy Cloudservers not sending the
            // 'isNull' parameter, but this has an issue, see S3C-7526)
            if (request.options.isNull !== true) {
                const versionOp = { key: versionKey, value: request.value };
                ops.push(versionOp);
            }
-            if (masterVersion) {
+            if (data === undefined ||
-                // master key exists
+                (Version.from(data).getVersionId() ?? '') >= versionId) {
-                // note that older versions have a greater version ID
+                // master does not exist or is not newer than put
-                const versionIdFromMaster = masterVersion.getVersionId();
+                // version and needs to be updated as well.
-                if (versionIdFromMaster === undefined ||
+                // Note that older versions have a greater version ID.
-                    versionIdFromMaster >= versionId) {
+                ops.push({ key: request.key, value: request.value });
-                    let value = request.value;
+            } else if (request.options.isNull) {
                    logger.debug('version to put is not older than master');
                    // Delete the deprecated, null key for backward compatibility
                    // to avoid storing both deprecated and new null keys.
                    // If master null version was put with an older Cloudserver (or in compat mode),
                    // there is a possibility that it also has a null versioned key
                    // associated, so we need to delete it as we write the null key.
                    // Deprecated null key gets deleted when the new CloudServer:
                    // - updates metadata of a null master (options.isNull=true)
                    // - puts metadata on top of a master null key (options.isNull=false)
                    if (request.options.isNull !== undefined && // new null key behavior when isNull is defined.
                        masterVersion.isNullVersion() && // master is null
                        !masterVersion.isNull2Version()) { // master does not support the new null key behavior yet.
                        const masterNullVersionId = masterVersion.getVersionId();
                        // The deprecated null key is referenced in the "versionId" property of the master key.
                        if (masterNullVersionId) {
                            const oldNullVersionKey = formatVersionKey(key, masterNullVersionId);
                            ops.push({ key: oldNullVersionKey, type: 'del' });
                        }
                    }
                    // new behavior when isNull is defined is to only
                    // update the master key if it is the latest
                    // version, old behavior needs to copy master to
                    // the null version because older Cloudservers
                    // rely on version-specific PUT to copy master
                    // contents to a new null version key (newer ones
                    // use special versionId="null" requests for this
                    // purpose).
                    if (versionIdFromMaster !== versionId ||
                        request.options.isNull === undefined) {
                        // master key is strictly older than the put version
                        let masterVersionId;
                        if (masterVersion.isNullVersion() && versionIdFromMaster) {
                            logger.debug('master key is a null version');
                            masterVersionId = versionIdFromMaster;
                        } else if (versionIdFromMaster === undefined) {
                            logger.debug('master key is nonversioned');
                            // master key does not have a versionID
                            // => create one with the "infinite" version ID
                            masterVersionId = getInfVid(this.replicationGroupId);
                            masterVersion.setVersionId(masterVersionId);
                        } else {
                            logger.debug('master key is a regular version');
                        }
                        if (request.options.isNull === true) {
                            if (!masterVersionId) {
                                // master is a regular version: delete the null key that
                                // may exist (older null version)
                                logger.debug('delete null key');
                                const nullKey = formatVersionKey(key, '');
                                ops.push({ key: nullKey, type: 'del' });
                            }
                        } else if (masterVersionId) {
                            logger.debug('create version key from master version');
                            // isNull === false means Cloudserver supports null keys,
                            // so create a null key in this case, and a version key otherwise
                            const masterKeyVersionId = request.options.isNull === false ?
                                  '' : masterVersionId;
                            const masterVersionKey = formatVersionKey(key, masterKeyVersionId);
                            masterVersion.setNullVersion();
                            // isNull === false means Cloudserver supports null keys,
                            // so create a null key with the isNull2 flag
                            if (request.options.isNull === false) {
                                masterVersion.setNull2Version();
                            // else isNull === undefined means Cloudserver does not support null keys,
                            // and versionIdFromMaster !== versionId means that a version is PUT on top of a null version
                            // hence set/update the new master nullVersionId for backward compatibility
                            } else if (versionIdFromMaster !== versionId) {
                                // => set the nullVersionId to the master version if put version on top of null version.
                                value = Version.updateOrAppendNullVersionId(request.value, masterVersionId);
                            }
                            ops.push({ key: masterVersionKey,
                                       value: masterVersion.toString() });
                        }
                    } else {
                        logger.debug('version to put is the master');
                    }
                    ops.push({ key, value: value });
                } else {
                    logger.debug('version to put is older than master');
                    if (request.options.isNull === true && !masterVersion.isNullVersion()) {
                logger.debug('create or update null key');
                const nullKey = formatVersionKey(key, '');
-                        const nullKeyOp = { key: nullKey, value: request.value };
+                ops.push({ key: nullKey, value: request.value });
                        ops.push(nullKeyOp);
                        // for backward compatibility: remove null version key
                        ops.push({ key: versionKey, type: 'del' });
                    }
                }
            } else {
                // master key does not exist: create it
                ops.push({ key, value: request.value });
            }
            return callback(null, ops, versionId);
        });
--- a/lib/versioning/WriteCache.ts
+++ b/lib/versioning/WriteCache.ts
@ -1,5 +1,3 @@
 import { RequestLogger } from 'werelogs';
 import errors, { ArsenalError } from '../errors';
 import WriteGatheringManager from './WriteGatheringManager';
--- a/lib/versioning/WriteGatheringManager.ts
+++ b/lib/versioning/WriteGatheringManager.ts
@ -1,5 +1,3 @@
 import { RequestLogger } from 'werelogs';
 import { ArsenalError } from '../errors';
 const WG_TIMEOUT = 5; // batching period in milliseconds
--- a/package.json
+++ b/package.json
@ -3,7 +3,7 @@
  "engines": {
    "node": ">=16"
  },
-  "version": "8.1.134",
+  "version": "8.1.93",
  "description": "Common utilities for the S3 project components",
  "main": "build/index.js",
  "repository": {
@ -19,38 +19,39 @@
  "dependencies": {
    "@azure/identity": "^3.1.1",
    "@azure/storage-blob": "^12.12.0",
-    "@js-sdsl/ordered-set": "^4.4.2",
+    "@types/async": "^3.2.12",
-    "@swc/cli": "^0.4.0",
+    "@types/utf8": "^3.0.1",
-    "@swc/core": "^1.7.4",
+    "JSONStream": "^1.0.0",
    "agentkeepalive": "^4.1.3",
-    "ajv": "^6.12.3",
+    "ajv": "6.12.3",
-    "async": "^2.6.4",
+    "async": "~2.6.4",
    "aws-sdk": "^2.1005.0",
    "backo": "^1.1.0",
-    "base-x": "^3.0.8",
+    "base-x": "3.0.8",
-    "base62": "^2.0.1",
+    "base62": "2.0.1",
-    "bson": "^4.0.0",
+    "bson": "4.0.0",
-    "debug": "^4.1.0",
+    "debug": "~4.1.0",
    "diskusage": "^1.1.1",
-    "fcntl": "git+https://git.yourcmc.ru/vitalif/zenko-fcntl.git",
+    "fcntl": "github:scality/node-fcntl#0.2.0",
-    "httpagent": "git+https://git.yourcmc.ru/vitalif/zenko-httpagent.git#development/1.0",
+    "hdclient": "scality/hdclient#1.1.5",
    "httpagent": "scality/httpagent#1.0.6",
    "https-proxy-agent": "^2.2.0",
    "ioredis": "^4.28.5",
-    "ipaddr.js": "^1.9.1",
+    "ipaddr.js": "1.9.1",
    "joi": "^17.6.0",
-    "JSONStream": "^1.0.0",
+    "level": "~5.0.1",
-    "level": "^5.0.1",
+    "level-sublevel": "~6.6.5",
-    "level-sublevel": "^6.6.5",
+    "mongodb": "^3.0.1",
    "mongodb": "^5.2.0",
    "node-forge": "^1.3.0",
-    "prom-client": "^14.2.0",
+    "prom-client": "14.2.0",
    "simple-glob": "^0.2.0",
-    "socket.io": "^4.6.1",
+    "socket.io": "2.4.1",
-    "socket.io-client": "^4.6.1",
+    "socket.io-client": "2.4.0",
-    "utf8": "^3.0.0",
+    "sproxydclient": "github:scality/sproxydclient#8.0.8",
    "utf8": "3.0.0",
    "uuid": "^3.0.1",
-    "werelogs": "git+https://git.yourcmc.ru/vitalif/zenko-werelogs.git#development/8.1",
+    "werelogs": "scality/werelogs#8.1.2",
-    "xml2js": "^0.4.23"
+    "xml2js": "~0.4.23"
  },
  "optionalDependencies": {
    "ioctl": "^2.0.2"
@ -59,24 +60,22 @@
    "@babel/preset-env": "^7.16.11",
    "@babel/preset-typescript": "^7.16.7",
    "@sinonjs/fake-timers": "^6.0.1",
    "@types/async": "^3.2.12",
    "@types/utf8": "^3.0.1",
    "@types/ioredis": "^4.28.10",
    "@types/jest": "^27.4.1",
-    "@types/node": "^18.19.41",
+    "@types/node": "^17.0.21",
    "@types/xml2js": "^0.4.11",
-    "eslint": "^8.14.0",
+    "eslint": "^8.12.0",
-    "eslint-config-airbnb-base": "^15.0.0",
+    "eslint-config-airbnb": "6.2.0",
-    "eslint-config-scality": "git+https://git.yourcmc.ru/vitalif/zenko-eslint-config-scality.git",
+    "eslint-config-scality": "scality/Guidelines#ec33dfb",
    "eslint-plugin-react": "^4.3.0",
    "jest": "^27.5.1",
-    "mongodb-memory-server": "^8.12.2",
+    "mongodb-memory-server": "^6.0.2",
    "nyc": "^15.1.0",
    "sinon": "^9.0.2",
-    "temp": "^0.9.1",
+    "temp": "0.9.1",
    "ts-jest": "^27.1.3",
    "ts-node": "^10.6.0",
-    "typescript": "^4.9.5"
+    "typescript": "^4.6.2"
  },
  "scripts": {
    "lint": "eslint $(git ls-files '*.js')",
@ -84,11 +83,10 @@
    "lint_yml": "yamllint $(git ls-files '*.yml')",
    "test": "jest tests/unit",
    "build": "tsc",
-    "prepack": "tsc",
+    "prepare": "yarn build",
    "postinstall": "[ -d build ] || swc -d build --copy-files package.json index.ts lib",
    "ft_test": "jest tests/functional --testTimeout=120000 --forceExit",
    "coverage": "nyc --clean jest tests --coverage --testTimeout=120000 --forceExit",
-    "build_doc": "cd documentation/listingAlgos/pics; dot -Tsvg delimiterStateChart.dot > delimiterStateChart.svg; dot -Tsvg delimiterMasterV0StateChart.dot > delimiterMasterV0StateChart.svg; dot -Tsvg delimiterVersionsStateChart.dot > delimiterVersionsStateChart.svg"
+    "build_doc": "cd documentation/listingAlgos/pics; dot -Tsvg delimiterVersionsStateChart.dot > delimiterVersionsStateChart.svg"
  },
  "private": true,
  "jest": {
--- a/tests/functional/clustering/ClusterRPC-test-server.js
+++ b/tests/functional/clustering/ClusterRPC-test-server.js
@ -1,356 +0,0 @@
 const async = require('async');
 const assert = require('assert');
 const cluster = require('cluster');
 const http = require('http');
 const errors = require('../../../build/lib/errors').default;
 const {
    setupRPCPrimary,
    setupRPCWorker,
    sendWorkerCommand,
    getPendingCommandsCount,
 } = require('../../../build/lib/clustering/ClusterRPC');
 /* eslint-disable prefer-const */
 let SERVER_PORT;
 let N_WORKERS;
 /* eslint-enable prefer-const */
 /* eslint-disable no-console */
 function genUIDS() {
    return Math.trunc(Math.random() * 0x10000).toString(16);
 }
 // for testing robustness: regularly pollute the message channel with
 // unrelated IPC messages
 function sendPollutionMessage(message) {
    if (cluster.isPrimary) {
        const randomWorker = Math.trunc(Math.random() * cluster.workers.length);
        const worker = cluster.workers[randomWorker];
        if (worker) {
            worker.send(message);
        }
    } else {
        process.send(message);
    }
 }
 const ipcPolluterIntervals = [
    setInterval(
        () => sendPollutionMessage('string pollution'), 1500),
    setInterval(
        () => sendPollutionMessage({ pollution: 'bar' }), 2321),
    setInterval(
        () => sendPollutionMessage({ type: 'pollution', foo: { bar: 'baz' } }), 2777),
 ];
 function someTestHandlerFunc(payload, uids, callback) {
    setTimeout(() => callback(null, { someResponsePayload: 'bar' }), 10);
 }
 function testHandlerWithFailureFunc(payload, uids, callback) {
    setTimeout(() => {
        // exactly one of the workers fails to execute this command
        if (cluster.worker.id === 1) {
            callback(errors.ServiceFailure);
        } else {
            callback(null, { someResponsePayload: 'bar' });
        }
    }, 10);
 }
 const rpcHandlers = {
    SomeTestHandler: someTestHandlerFunc,
    TestHandlerWithFailure: testHandlerWithFailureFunc,
    TestHandlerWithNoResponse: () => {},
 };
 const primaryHandlers = {
    echoHandler: (worker, payload, uids, callback) => {
        callback(null, { workerId: worker.id, payload, uids });
    },
    errorWithHttpCodeHandler: (_worker, _payload, _uids, callback) => {
        callback({ name: 'ErrorMock', code: 418, message: 'An error message from primary' });
    },
 };
 function respondOnTestFailure(message, error, results) {
    console.error('After sendWorkerCommand() resolve/reject: ' +
                  `${message}, error=${error}, results=${JSON.stringify(results)}`);
    console.trace();
    throw errors.InternalError;
 }
 async function successfulCommandTestGeneric(nWorkers) {
    try {
        const results = await sendWorkerCommand('*', 'SomeTestHandler', genUIDS(), {});
        if (results.length !== nWorkers) {
            return respondOnTestFailure(
                `expected ${nWorkers} worker results, got ${results.length}`,
                null, results);
        }
        for (const result of results) {
            if (typeof result !== 'object' || result === null) {
                return respondOnTestFailure('not all results are objects', null, results);
            }
            if (result.error !== null) {
                return respondOnTestFailure(
                    'one or more workers had an unexpected error',
                    null, results);
            }
            if (typeof result.result !== 'object' || result.result === null) {
                return respondOnTestFailure(
                    'one or more workers did not return a result object',
                    null, results);
            }
            if (result.result.someResponsePayload !== 'bar') {
                return respondOnTestFailure(
                    'one or more workers did not return the expected payload',
                    null, results);
            }
        }
        return undefined;
    } catch (err) {
        return respondOnTestFailure(`returned unexpected error ${err}`, err, null);
    }
 }
 async function successfulCommandTest() {
    return successfulCommandTestGeneric(N_WORKERS);
 }
 async function successfulCommandWithExtraWorkerTest() {
    return successfulCommandTestGeneric(N_WORKERS + 1);
 }
 async function unsupportedToWorkersTest() {
    try {
        const results = await sendWorkerCommand('badToWorkers', 'SomeTestHandler', genUIDS(), {});
        return respondOnTestFailure('expected an error', null, results);
    } catch (err) {
        if (!err.is.NotImplemented) {
            return respondOnTestFailure('expected a NotImplemented error', err, null);
        }
        return undefined;
    }
 }
 async function unsupportedHandlerTest() {
    try {
        const results = await sendWorkerCommand('*', 'AWrongTestHandler', genUIDS(), {});
        if (results.length !== N_WORKERS) {
            return respondOnTestFailure(
                `expected ${N_WORKERS} worker results, got ${results.length}`,
                null, results);
        }
        for (const result of results) {
            if (typeof result !== 'object' || result === null) {
                return respondOnTestFailure('not all results are objects', null, results);
            }
            if (result.error === null || !result.error.is.NotImplemented) {
                return respondOnTestFailure(
                    'one or more workers did not return the expected NotImplemented error',
                    null, results);
            }
        }
        return undefined;
    } catch (err) {
        return respondOnTestFailure(`returned unexpected error ${err}`, err, null);
    }
 }
 async function missingUidsTest() {
    try {
        const results = await sendWorkerCommand('*', 'SomeTestHandler', undefined, {});
        return respondOnTestFailure('expected an error', null, results);
    } catch (err) {
        if (!err.is.MissingParameter) {
            return respondOnTestFailure('expected a MissingParameter error', err, null);
        }
        return undefined;
    }
 }
 async function duplicateUidsTest() {
    const dupUIDS = genUIDS();
    const promises = [
        sendWorkerCommand('*', 'SomeTestHandler', dupUIDS, {}),
        sendWorkerCommand('*', 'SomeTestHandler', dupUIDS, {}),
    ];
    const results = await Promise.allSettled(promises);
    if (results[1].status !== 'rejected') {
        return respondOnTestFailure('expected an error from the second call', null, null);
    }
    if (!results[1].reason.is.OperationAborted) {
        return respondOnTestFailure(
            'expected a OperationAborted error', results[1].reason, null);
    }
    return undefined;
 }
 async function unsuccessfulWorkerTest() {
    try {
        const results = await sendWorkerCommand('*', 'TestHandlerWithFailure', genUIDS(), {});
        if (results.length !== N_WORKERS) {
            return respondOnTestFailure(
                `expected ${N_WORKERS} worker results, got ${results.length}`,
                null, results);
        }
        const nServiceFailures = results.filter(result => (
            result.error && result.error.is.ServiceFailure
        )).length;
        if (nServiceFailures !== 1) {
            return respondOnTestFailure(
                'expected exactly one worker result to be ServiceFailure error',
                null, results);
        }
        return undefined;
    } catch (err) {
        return respondOnTestFailure(`returned unexpected error ${err}`, err, null);
    }
 }
 async function workerTimeoutTest() {
    try {
        const results = await sendWorkerCommand(
            '*', 'TestHandlerWithNoResponse', genUIDS(), {}, 1000);
        return respondOnTestFailure('expected an error', null, results);
    } catch (err) {
        if (!err.is.RequestTimeout) {
            return respondOnTestFailure('expected a RequestTimeout error', err, null);
        }
        return undefined;
    }
 }
 async function workerToPrimaryEcho() {
    const uids = genUIDS();
    const payload = { testing: true };
    const expected = { workerId: cluster.worker.id, payload, uids };
    const results = await sendWorkerCommand('PRIMARY', 'echoHandler', uids, payload);
    assert.strictEqual(results.length, 1, 'There is 1 and only 1 primary');
    assert.ifError(results[0].error);
    assert.deepStrictEqual(results[0].result, expected);
 }
 async function workerToPrimaryErrorWithHttpCode() {
    const uids = genUIDS();
    const payload = { testing: true };
    const results = await sendWorkerCommand('PRIMARY', 'errorWithHttpCodeHandler', uids, payload);
    assert.strictEqual(results.length, 1, 'There is 1 and only 1 primary');
    assert.ok(results[0].error);
    assert.strictEqual(results[0].error.message, 'An error message from primary');
    assert.strictEqual(results[0].error.code, 418);
 }
 const TEST_URLS = {
    '/successful-command': successfulCommandTest,
    '/successful-command-with-extra-worker': successfulCommandWithExtraWorkerTest,
    '/unsupported-to-workers': unsupportedToWorkersTest,
    '/unsupported-handler': unsupportedHandlerTest,
    '/missing-uids': missingUidsTest,
    '/duplicate-uids': duplicateUidsTest,
    '/unsuccessful-worker': unsuccessfulWorkerTest,
    '/worker-timeout': workerTimeoutTest,
    '/worker-to-primary/echo': workerToPrimaryEcho,
    '/worker-to-primary/error-with-http-code': workerToPrimaryErrorWithHttpCode,
 };
 if (process.argv.length !== 4) {
    console.error('ClusterRPC test server: GET requests on test URLs trigger test runs\n\n' +
                  'Usage: node ClusterRPC-test-server.js <port> <nb-workers>\n\n' +
                  'Available test URLs:');
    console.error(`${Object.keys(TEST_URLS).map(url => `- ${url}\n`).join('')}`);
    process.exit(2);
 }
 /* eslint-disable prefer-const */
 [
    SERVER_PORT,
    N_WORKERS,
 ] = process.argv.slice(2, 4).map(value => Number.parseInt(value, 10));
 /* eslint-enable prefer-const */
 let server;
 if (cluster.isPrimary) {
    async.timesSeries(
        N_WORKERS,
        (i, wcb) => cluster.fork().on('online', wcb),
        () => {
            setupRPCPrimary(primaryHandlers);
        },
    );
 } else {
    // in worker
    server = http.createServer((req, res) => {
        if (req.url in TEST_URLS) {
            return TEST_URLS[req.url]().then(() => {
                if (getPendingCommandsCount() !== 0) {
                    console.error(`There are still ${getPendingCommandsCount()} pending ` +
                                  `RPC commands after test ${req.url} completed`);
                    throw errors.InternalError;
                }
                res.writeHead(200);
                res.end();
            }).catch(err => {
                // serialize AssertionError to be displayed nicely in jest
                if (err instanceof assert.AssertionError) {
                    const serializedErr = JSON.stringify({
                        code: err.code,
                        message: err.message,
                        stack: err.stack,
                        actual: err.actual,
                        expected: err.expected,
                        operator: err.operator,
                    });
                    res.writeHead(500);
                    res.end(serializedErr);
                } else {
                    res.writeHead(err.code || 500);
                    res.end(err.message);
                }
            });
        }
        console.error(`Invalid test URL ${req.url}`);
        res.writeHead(400);
        res.end();
        return undefined;
    });
    server.listen(SERVER_PORT);
    server.on('listening', () => {
        console.log('Worker is listening');
    });
    setupRPCWorker(rpcHandlers);
 }
 function stop(signal) {
    if (cluster.isPrimary) {
        console.log(`Handling signal ${signal}`);
        for (const worker of Object.values(cluster.workers)) {
            worker.kill(signal);
            worker.on('exit', () => {
                console.log(`Worker ${worker.id} exited`);
            });
        }
    }
    for (const interval of ipcPolluterIntervals) {
        clearInterval(interval);
    }
 }
 process.on('SIGTERM', stop);
 process.on('SIGINT', stop);
 process.on('SIGPIPE', () => {});
 // for testing: spawn a new worker each time SIGUSR1 is received
 function spawnNewWorker() {
    if (cluster.isPrimary) {
        cluster.fork();
    }
 }
 process.on('SIGUSR1', spawnNewWorker);
--- a/tests/functional/clustering/ClusterRPC.spec.js
+++ b/tests/functional/clustering/ClusterRPC.spec.js
@ -1,151 +0,0 @@
 'use strict'; // eslint-disable-line
 const assert = require('assert');
 const http = require('http');
 const readline = require('readline');
 const spawn = require('child_process').spawn;
 const TEST_SERVER_PORT = 8800;
 const NB_WORKERS = 4;
 let testServer = null;
 /*
 * jest tests don't correctly support cluster mode with child forked
 * processes, instead we use an external test server that launches
 * each test based on the provided URL, and returns either 200 for
 * success or 500 for failure. A crash would also cause a failure
 * from the client side.
 */
 function startTestServer(done) {
    testServer = spawn('node', [
        `${__dirname}/ClusterRPC-test-server.js`,
        TEST_SERVER_PORT,
        NB_WORKERS,
    ]);
    // gather server stderr to display test failures info
    testServer.stdout.pipe(process.stdout);
    testServer.stderr.pipe(process.stderr);
    const rl = readline.createInterface({
        input: testServer.stdout,
    });
    let nbListeningWorkers = 0;
    rl.on('line', line => {
        if (line === 'Worker is listening') {
            nbListeningWorkers++;
            if (nbListeningWorkers === NB_WORKERS) {
                rl.close();
                done();
            }
        }
    });
 }
 function stopTestServer(done) {
    testServer.kill('SIGTERM');
    testServer.on('close', done);
 }
 /**
 * Try to deserialize and recreate AssertionError with stackTrace from spawned server
 * @param {string} responseBody maybe serialized AssertionError
 * @throws {assert.AssertionError}
 * @returns {undefined}
 */
 function handleAssertionError(responseBody) {
    let parsed;
    try {
        parsed = JSON.parse(responseBody);
    } catch (_) {
        return;
    }
    if (parsed && parsed.code === 'ERR_ASSERTION') {
        const err = new assert.AssertionError(parsed);
        err.stack = parsed.stack;
        throw err;
    }
 }
 function runTest(testUrl, cb) {
    const req = http.request(`http://localhost:${TEST_SERVER_PORT}/${testUrl}`, res => {
        let responseBody = '';
        res
            .on('data', (chunk) => {
                responseBody += chunk;
            })
            .on('end', () => {
                try {
                    handleAssertionError(responseBody);
                    expect(res.statusCode).toEqual(200);
                } catch (err) {
                    if (!(err instanceof assert.AssertionError)) {
                        err.message += `\n\nBody:\n${responseBody}`;
                    }
                    return cb(err);
                }
                return cb();
            })
            .on('error', err => cb(err));
    });
    req
        .end()
        .on('error', err => cb(err));
 }
 describe('ClusterRPC', () => {
    beforeAll(done => startTestServer(done));
    afterAll(done => stopTestServer(done));
    it('should send a successful command to all workers', done => {
        runTest('successful-command', done);
    });
    it('should error if "toWorkers" field is not "*"', done => {
        runTest('unsupported-to-workers', done);
    });
    it('should error if handler name is not known', done => {
        runTest('unsupported-handler', done);
    });
    it('should error if "uids" field is not passed', done => {
        runTest('missing-uids', done);
    });
    it('should error if two simultaneous commands with same "uids" field are sent', done => {
        runTest('duplicate-uids', done);
    });
    it('should timeout if one or more workers don\'t respond in allocated time', done => {
        runTest('worker-timeout', done);
    });
    it('should return worker errors in results array', done => {
        runTest('unsuccessful-worker', done);
    });
    it('should send a successful command to all workers after an extra worker is spawned', done => {
        const rl = readline.createInterface({
            input: testServer.stdout,
        });
        rl.on('line', line => {
            if (line === 'Worker is listening') {
                rl.close();
                runTest('successful-command-with-extra-worker', done);
            }
        });
        // The test server spawns a new worker when it receives SIGUSR1
        testServer.kill('SIGUSR1');
    });
    describe('worker to primary', () => {
        it('should succeed and return a result', done => {
            runTest('worker-to-primary/echo', done);
        });
        it('should return an error with a code', done => {
            runTest('worker-to-primary/error-with-http-code', done);
        });
    });
 });
--- a/tests/functional/metadata/mongodb/delObject.spec.js
+++ b/tests/functional/metadata/mongodb/delObject.spec.js
@ -44,24 +44,29 @@ describe('MongoClientInterface::metadata.deleteObjectMD', () => {
    let collection;
    function getObjectCount(cb) {
-        collection.countDocuments()
+        collection.countDocuments((err, count) => {
-            .then(count => cb(null, count))
+            if (err) {
-            .catch(err => cb(err));
+                cb(err);
            }
            cb(null, count);
        });
    }
    function getObject(key, cb) {
        collection.findOne({
            _id: key,
-        }, {}).then(doc => {
+        }, {}, (err, doc) => {
            if (err) {
                return cb(err);
            }
            if (!doc) {
                return cb(errors.NoSuchKey);
            }
            return cb(null, doc.value);
-        }).catch(err => cb(err));
+        });
    }
    beforeAll(done => {
        mongoserver.start().then(() => {
        mongoserver.waitUntilRunning().then(() => {
            const opts = {
                mongodb: {
@ -76,7 +81,6 @@ describe('MongoClientInterface::metadata.deleteObjectMD', () => {
            metadata.setup(done);
        });
    });
    });
    afterAll(done => {
        async.series([
@ -454,48 +458,6 @@ describe('MongoClientInterface::metadata.deleteObjectMD', () => {
                    },
                ], done);
            });
            it('should delete the object directly if params.doesNotNeedOpogUpdate is true', done => {
                const objName = 'object-to-delete';
                const objVal = {
                    key: 'object-to-delete',
                    versionId: 'null',
                };
                const versionParams = {
                    versioning: false,
                    versionId: null,
                    repairMaster: null,
                };
                async.series([
                    next => {
                        metadata.putObjectMD(BUCKET_NAME, objName, objVal, versionParams, logger, next);
                    },
                    next => {
                        metadata.deleteObjectMD(BUCKET_NAME, objName, { doesNotNeedOpogUpdate: true }, logger, next);
                    },
                    next => {
                        metadata.getObjectMD(BUCKET_NAME, objName, null, logger, err => {
                            assert.deepStrictEqual(err, errors.NoSuchKey);
                            return next();
                        });
                    },
                    next => {
                        getObjectCount((err, count) => {
                            assert.deepStrictEqual(err, null);
                            assert.strictEqual(count, 0);
                            return next();
                        });
                    },
                ], done);
            });
            it('should throw an error if params.doesNotNeedOpogUpdate is true and object does not exist', done => {
                const objName = 'non-existent-object';
                metadata.deleteObjectMD(BUCKET_NAME, objName, { doesNotNeedOpogUpdate: true }, logger, err => {
                    assert.deepStrictEqual(err, errors.InternalError);
                    return done();
                });
            });
        });
    });
 });
--- a/tests/functional/metadata/mongodb/getObject.spec.js
+++ b/tests/functional/metadata/mongodb/getObject.spec.js
@ -74,7 +74,13 @@ describe('MongoClientInterface::metadata.getObjectMD', () => {
            {
                $set: { _id: mKey, value: objVal },
            },
-            { upsert: true }).then(() => cb(null)).catch(err => cb(err));
+            { upsert: true },
            err => {
                if (err) {
                    return cb(err);
                }
                return cb(null);
            });
    }
    /**
@ -87,11 +93,10 @@ describe('MongoClientInterface::metadata.getObjectMD', () => {
        collection.updateMany(
            { 'value.key': key },
            { $set: { 'value.deleted': true } },
-            { upsert: false }).then(() => cb()).catch(err => cb(err));
+            { upsert: false }, cb);
    }
    beforeAll(done => {
        mongoserver.start().then(() => {
        mongoserver.waitUntilRunning().then(() => {
            const opts = {
                mongodb: {
@ -106,7 +111,6 @@ describe('MongoClientInterface::metadata.getObjectMD', () => {
            metadata.setup(done);
        });
    });
    });
    afterAll(done => {
        async.series([
--- a/tests/functional/metadata/mongodb/getObjects.spec.js
+++ b/tests/functional/metadata/mongodb/getObjects.spec.js
@ -1,331 +0,0 @@
 const async = require('async');
 const assert = require('assert');
 const werelogs = require('werelogs');
 const { MongoMemoryReplSet } = require('mongodb-memory-server');
 const { versioning } = require('../../../../index');
 const logger = new werelogs.Logger('MongoClientInterface', 'debug', 'debug');
 const BucketInfo = require('../../../../lib/models/BucketInfo').default;
 const MetadataWrapper =
    require('../../../../lib/storage/metadata/MetadataWrapper');
 const genVID = versioning.VersionID.generateVersionId;
 const { BucketVersioningKeyFormat } = versioning.VersioningConstants;
 const { formatMasterKey, formatVersionKey } = require('../../../../lib/storage/metadata/mongoclient/utils');
 const IMPL_NAME = 'mongodb';
 const DB_NAME = 'metadata';
 const BUCKET_NAME = 'test-bucket-batching';
 const replicationGroupId = 'RG001';
 const N = 10;
 const mongoserver = new MongoMemoryReplSet({
    debug: false,
    instanceOpts: [
        { port: 27019 },
    ],
    replSet: {
        name: 'rs0',
        count: 1,
        DB_NAME,
        storageEngine: 'ephemeralForTest',
    },
 });
 let uidCounter = 0;
 function generateVersionId() {
    return genVID(`${process.pid}.${uidCounter++}`,
        replicationGroupId);
 }
 const variations = [
    { it: '(v0)', vFormat: BucketVersioningKeyFormat.v0, versioning: false },
    { it: '(v0)', vFormat: BucketVersioningKeyFormat.v0, versioning: true },
    { it: '(v1)', vFormat: BucketVersioningKeyFormat.v1, versioning: false },
    { it: '(v1)', vFormat: BucketVersioningKeyFormat.v1, versioning: true },
 ];
 describe('MongoClientInterface::metadata.getObjectsMD', () => {
    let metadata;
    let collection;
    let versionId2;
    const params = {
        key: 'pfx1-test-object',
        objVal: {
            key: 'pfx1-test-object',
            versionId: 'null',
        },
    };
    function updateMasterObject(objName, versionId, objVal, vFormat, cb) {
        const mKey = formatMasterKey(objName, vFormat);
        collection.updateOne(
            {
                _id: mKey,
                $or: [{
                    'value.versionId': {
                        $exists: false,
                    },
                },
                {
                    'value.versionId': {
                        $gt: versionId,
                    },
                },
                ],
            },
            {
                $set: { _id: mKey, value: objVal },
            },
            { upsert: true }).then(() => cb(null)).catch(err => cb(err));
    }
    /**
     * Sets the "deleted" property to true
     * @param {string} key object name
     * @param {Function} cb callback
     * @return {undefined}
     */
    function flagObjectForDeletion(key, cb) {
        collection.updateMany(
            { 'value.key': key },
            { $set: { 'value.deleted': true } },
            { upsert: false }).then(() => cb()).catch(err => cb(err));
    }
    beforeAll(done => {
        mongoserver.start().then(() => {
            mongoserver.waitUntilRunning().then(() => {
                const opts = {
                    mongodb: {
                        replicaSetHosts: 'localhost:27019',
                        writeConcern: 'majority',
                        replicaSet: 'rs0',
                        readPreference: 'primary',
                        database: DB_NAME,
                    },
                };
                metadata = new MetadataWrapper(IMPL_NAME, opts, null, logger);
                metadata.setup(done);
            });
        });
    });
    afterAll(done => {
        async.series([
            next => metadata.close(next),
            next => mongoserver.stop()
                .then(() => next())
                .catch(next),
        ], done);
    });
    variations.forEach(variation => {
        const itOnlyInV1 = variation.vFormat === 'v1' && variation.versioning ? it : it.skip;
        describe(`vFormat : ${variation.vFormat}, versioning: ${variation.versioning}`, () => {
            let paramsArr = [];
            beforeEach(done => {
                // reset params
                paramsArr = Array.from({ length: N }, (_, i) => ({
                    key: `pfx1-test-object${i + 1}`,
                    objVal: {
                        key: `pfx1-test-object${i + 1}`,
                        versionId: 'null',
                    },
                }));
                const bucketMD = BucketInfo.fromObj({
                    _name: BUCKET_NAME,
                    _owner: 'testowner',
                    _ownerDisplayName: 'testdisplayname',
                    _creationDate: new Date().toJSON(),
                    _acl: {
                        Canned: 'private',
                        FULL_CONTROL: [],
                        WRITE: [],
                        WRITE_ACP: [],
                        READ: [],
                        READ_ACP: [],
                    },
                    _mdBucketModelVersion: 10,
                    _transient: false,
                    _deleted: false,
                    _serverSideEncryption: null,
                    _versioningConfiguration: null,
                    _locationConstraint: 'us-east-1',
                    _readLocationConstraint: null,
                    _cors: null,
                    _replicationConfiguration: null,
                    _lifecycleConfiguration: null,
                    _uid: '',
                    _isNFS: null,
                    ingestion: null,
                });
                const versionParams = {
                    versioning: variation.versioning,
                    versionId: null,
                    repairMaster: null,
                };
                async.series([
                    next => {
                        metadata.client.defaultBucketKeyFormat = variation.vFormat;
                        return next();
                    },
                    next => metadata.createBucket(BUCKET_NAME, bucketMD, logger, err => {
                        if (err) {
                            return next(err);
                        }
                        collection = metadata.client.getCollection(BUCKET_NAME);
                        return next();
                    }),
                    next => {
                        async.eachSeries(paramsArr, (params, eachCb) => {
                            metadata.putObjectMD(BUCKET_NAME, params.key, params.objVal,
                                versionParams, logger, (err, res) => {
                                    if (err) {
                                        return eachCb(err);
                                    }
                                    if (variation.versioning) {
                                        // eslint-disable-next-line no-param-reassign
                                        params.versionId = JSON.parse(res).versionId;
                                    }
                                    return eachCb(null);
                                });
                        }, next);
                    },
                    next => {
                        metadata.putObjectMD(BUCKET_NAME, paramsArr[N - 1].key, paramsArr[N - 1].objVal,
                            versionParams, logger, (err, res) => {
                                if (err) {
                                    return next(err);
                                }
                                if (variation.versioning) {
                                    versionId2 = JSON.parse(res).versionId;
                                } else {
                                    versionId2 = 'null';
                                }
                                return next(null);
                            });
                    },
                ], done);
            });
            afterEach(done => {
                metadata.deleteBucket(BUCKET_NAME, logger, done);
            });
            it(`should get ${N} objects${variation.versioning ? '' : ' master'} versions using batching`, done => {
                const request = paramsArr.map(({ key, objVal }) => ({
                    key,
                    params: {
                        versionId: variation.versioning ? objVal.versionId : null,
                    },
                }));
                metadata.getObjectsMD(BUCKET_NAME, request, logger, (err, objects) => {
                    assert.strictEqual(err, null);
                    assert.strictEqual(objects.length, N);
                    objects.forEach((obj, i) => {
                        assert.strictEqual(obj.doc.key, paramsArr[i].key);
                        if (variation.versioning) {
                            assert.strictEqual(obj.doc.versionId, paramsArr[i].objVal.versionId);
                        }
                    });
                    return done();
                });
            });
            it('should not throw an error if object or version is inexistent and return null doc', done => {
                const request = [{
                    key: 'nonexistent',
                    params: {
                        versionId: variation.versioning ? 'nonexistent' : null,
                    },
                }];
                metadata.getObjectsMD(BUCKET_NAME, request, logger, (err, objects) => {
                    assert.strictEqual(err, null);
                    assert.strictEqual(objects.length, 1);
                    assert.strictEqual(objects[0].doc, null);
                    done();
                });
            });
            it(`should return latest version when master is PHD ${variation.it}`, done => {
                if (!variation.versioning) {
                    return done();
                }
                const request = paramsArr.map(({ key, objVal }) => ({
                    key,
                    params: {
                        versionId: variation.versioning ? objVal.versionId : null,
                    },
                }));
                return async.series([
                    next => {
                        let objectName = null;
                        if (variations.versioning) {
                            objectName =
                                formatVersionKey(paramsArr[N - 1].key, paramsArr[N - 1].versionId, variation.vFormat);
                        } else {
                            objectName = formatMasterKey(paramsArr[N - 1].key, variation.vFormat);
                        }
                        // adding isPHD flag to master
                        const phdVersionId = generateVersionId();
                        paramsArr[N - 1].objVal.versionId = phdVersionId;
                        paramsArr[N - 1].objVal.isPHD = true;
                        updateMasterObject(objectName, phdVersionId, paramsArr[N - 1].objVal,
                            variation.vFormat, next);
                    },
                    // Should return latest object version
                    next => metadata.getObjectsMD(BUCKET_NAME, request, logger, (err, objects) => {
                        assert.deepStrictEqual(err, null);
                        objects.forEach((obj, i) => {
                            assert.strictEqual(obj.doc.key, paramsArr[i].objVal.key);
                            if (variation.versioning && i === N - 1) {
                                assert.strictEqual(obj.doc.versionId, versionId2);
                            } else {
                                assert.strictEqual(obj.doc.versionId, paramsArr[i].objVal.versionId);
                            }
                        });
                        delete params.isPHD;
                        return next();
                    }),
                ], done);
            });
            it('should fail to get an object tagged for deletion', done => {
                const key = paramsArr[0].key;
                flagObjectForDeletion(key, err => {
                    assert(err);
                    metadata.getObjectsMD(BUCKET_NAME, [{ key }], logger, (err, object) => {
                        assert.strictEqual(err, null);
                        assert.strictEqual(object[0].doc, null);
                        done();
                    });
                });
            });
            itOnlyInV1(`Should return last version when master deleted ${variation.vFormat}`, done => {
                const versioningParams = {
                    versioning: true,
                    versionId: null,
                    repairMaster: null,
                };
                async.series([
                    // putting a delete marker as last version
                    next => {
                        paramsArr[0].versionId = null;
                        paramsArr[0].objVal.isDeleteMarker = true;
                        return metadata.putObjectMD(BUCKET_NAME, paramsArr[0].key, paramsArr[0].objVal,
                            versioningParams, logger, next);
                    },
                    next => metadata.getObjectsMD(BUCKET_NAME, [{ key: paramsArr[0].key }], logger, (err, objects) => {
                        assert.strictEqual(err, null);
                        assert.strictEqual(objects[0].doc.key, paramsArr[0].key);
                        assert.strictEqual(objects[0].doc.isDeleteMarker, true);
                        paramsArr[0].objVal.isDeleteMarker = null;
                        return next();
                    }),
                ], done);
            });
        });
    });
 });
--- a/tests/functional/metadata/mongodb/listLifecycleObject/current.spec.js
+++ b/tests/functional/metadata/mongodb/listLifecycleObject/current.spec.js
@ -4,10 +4,10 @@ const werelogs = require('werelogs');
 const { MongoMemoryReplSet } = require('mongodb-memory-server');
 const logger = new werelogs.Logger('MongoClientInterface', 'debug', 'debug');
 const MetadataWrapper =
-    require('../../../../../lib/storage/metadata/MetadataWrapper');
+require('../../../../../lib/storage/metadata/MetadataWrapper');
 const { versioning } = require('../../../../../index');
 const { BucketVersioningKeyFormat } = versioning.VersioningConstants;
-const { assertContents, flagObjectForDeletion, makeBucketMD, putBulkObjectVersions } = require('./utils');
+const { flagObjectForDeletion, makeBucketMD, putBulkObjectVersions } = require('./utils');
 const IMPL_NAME = 'mongodb';
 const DB_NAME = 'metadata';
@ -25,15 +25,12 @@ const mongoserver = new MongoMemoryReplSet({
        storageEngine: 'ephemeralForTest',
    },
 });
 describe('MongoClientInterface::metadata.listLifecycleObject::current', () => {
    let metadata;
    let collection;
    const expectedVersionIds = {};
    const location1 = 'loc1';
    const location2 = 'loc2';
    beforeAll(done => {
        mongoserver.start().then(() => {
        mongoserver.waitUntilRunning().then(() => {
            const opts = {
                mongodb: {
@ -45,10 +42,10 @@ describe('MongoClientInterface::metadata.listLifecycleObject::current', () => {
                },
            };
            metadata = new MetadataWrapper(IMPL_NAME, opts, null, logger);
            metadata.client.defaultBucketKeyFormat = BucketVersioningKeyFormat.v1;
            metadata.setup(done);
        });
    });
    });
    afterAll(done => {
        async.series([
@ -59,8 +56,6 @@ describe('MongoClientInterface::metadata.listLifecycleObject::current', () => {
        ], done);
    });
    [BucketVersioningKeyFormat.v0, BucketVersioningKeyFormat.v1].forEach(v => {
        describe(`bucket format version: ${v}`, () => {
    beforeEach(done => {
        const bucketMD = makeBucketMD(BUCKET_NAME);
        const versionParams = {
@ -68,7 +63,6 @@ describe('MongoClientInterface::metadata.listLifecycleObject::current', () => {
            versionId: null,
            repairMaster: null,
        };
                metadata.client.defaultBucketKeyFormat = v;
        async.series([
            next => metadata.createBucket(BUCKET_NAME, bucketMD, logger, err => {
                if (err) {
@ -79,20 +73,17 @@ describe('MongoClientInterface::metadata.listLifecycleObject::current', () => {
                return next();
            }),
            next => {
-                        const objName = 'pfx1-test-object';
+                const params = {
-                        const objVal = {
+                    objName: 'pfx1-test-object',
                    objVal: {
                        key: 'pfx1-test-object',
                        versionId: 'null',
-                            dataStoreName: location1,
+                    },
                    nbVersions: 5,
                };
                        const nbVersions = 5;
                const timestamp = 0;
-                        putBulkObjectVersions(metadata, BUCKET_NAME, objName, objVal, versionParams,
+                putBulkObjectVersions(metadata, BUCKET_NAME, params.objName, params.objVal, versionParams,
-                            nbVersions, timestamp, logger, (err, data) => {
+                    params.nbVersions, timestamp, logger, next);
                                expectedVersionIds[objName] = data.lastVersionId;
                                return next(err);
                            });
                /* eslint-disable max-len */
                // The following versions are created:
                // { "_id" : "Mpfx1-test-object", "value" : { "key" : "pfx1-test-object", "versionId" : "vid4", "last-modified" : "1970-01-01T00:00:00.005Z" } }
@ -104,19 +95,17 @@ describe('MongoClientInterface::metadata.listLifecycleObject::current', () => {
                /* eslint-enable max-len */
            },
            next => {
-                        const objName = 'pfx2-test-object';
+                const params = {
-                        const objVal = {
+                    objName: 'pfx2-test-object',
                    objVal: {
                        key: 'pfx2-test-object',
                        versionId: 'null',
-                            dataStoreName: location2,
+                    },
                    nbVersions: 5,
                };
                        const nbVersions = 5;
                const timestamp = 2000;
-                        putBulkObjectVersions(metadata, BUCKET_NAME, objName, objVal, versionParams,
+                putBulkObjectVersions(metadata, BUCKET_NAME, params.objName, params.objVal, versionParams,
-                            nbVersions, timestamp, logger, (err, data) => {
+                    params.nbVersions, timestamp, logger, next);
                                expectedVersionIds[objName] = data.lastVersionId;
                                return next(err);
                            });
                /* eslint-disable max-len */
                // The following versions are created:
                // { "_id" : "Mpfx2-test-object", "value" : { "key" : "pfx2-test-object", "versionId" : "vid4", "last-modified" : "1970-01-01T00:00:02.005Z" } }
@ -128,19 +117,17 @@ describe('MongoClientInterface::metadata.listLifecycleObject::current', () => {
                /* eslint-enable max-len */
            },
            next => {
-                        const objName = 'pfx3-test-object';
+                const params = {
-                        const objVal = {
+                    objName: 'pfx3-test-object',
                    objVal: {
                        key: 'pfx3-test-object',
                        versionId: 'null',
-                            dataStoreName: location1,
+                    },
                    nbVersions: 5,
                };
                        const nbVersions = 5;
                const timestamp = 1000;
-                        putBulkObjectVersions(metadata, BUCKET_NAME, objName, objVal, versionParams,
+                putBulkObjectVersions(metadata, BUCKET_NAME, params.objName, params.objVal, versionParams,
-                            nbVersions, timestamp, logger, (err, data) => {
+                    params.nbVersions, timestamp, logger, next);
                                expectedVersionIds[objName] = data.lastVersionId;
                                return next(err);
                            });
                /* eslint-disable max-len */
                // The following versions are created:
                // { "_id" : "Mpfx3-test-object", "value" : { "key" : "pfx3-test-object", "versionId" : "vid4", "last-modified" : "1970-01-01T00:00:01.005Z" } }
@ -166,150 +153,14 @@ describe('MongoClientInterface::metadata.listLifecycleObject::current', () => {
            assert.ifError(err);
            assert.strictEqual(data.IsTruncated, false);
            assert.strictEqual(data.Contents.length, 3);
-                    const expected = [
+            assert.strictEqual(data.Contents[0].key, 'pfx1-test-object');
-                        {
+            assert.strictEqual(data.Contents[1].key, 'pfx2-test-object');
-                            key: 'pfx1-test-object',
+            assert.strictEqual(data.Contents[2].key, 'pfx3-test-object');
                            LastModified: '1970-01-01T00:00:00.005Z',
                            dataStoreName: location1,
                            VersionId: expectedVersionIds['pfx1-test-object'],
                        },
                        {
                            key: 'pfx2-test-object',
                            LastModified: '1970-01-01T00:00:02.005Z',
                            dataStoreName: location2,
                            VersionId: expectedVersionIds['pfx2-test-object'],
                        },
                        {
                            key: 'pfx3-test-object',
                            LastModified: '1970-01-01T00:00:01.005Z',
                            dataStoreName: location1,
                            VersionId: expectedVersionIds['pfx3-test-object'],
                        },
                    ];
                    assertContents(data.Contents, expected);
            return done();
        });
    });
            it('Should list current versions of objects excluding keys stored in location2', done => {
                const params = {
                    listingType: 'DelimiterCurrent',
                    excludedDataStoreName: location2,
                };
                return metadata.listLifecycleObject(BUCKET_NAME, params, logger, (err, data) => {
                    assert.ifError(err);
                    assert.strictEqual(data.IsTruncated, false);
                    assert.strictEqual(data.Contents.length, 2);
                    const expected = [
                        {
                            key: 'pfx1-test-object',
                            LastModified: '1970-01-01T00:00:00.005Z',
                            dataStoreName: location1,
                            VersionId: expectedVersionIds['pfx1-test-object'],
                        },
                        {
                            key: 'pfx3-test-object',
                            LastModified: '1970-01-01T00:00:01.005Z',
                            dataStoreName: location1,
                            VersionId: expectedVersionIds['pfx3-test-object'],
                        },
                    ];
                    assertContents(data.Contents, expected);
                    return done();
                });
            });
            it('Should list current versions of objects excluding keys stored in location1', done => {
                const params = {
                    listingType: 'DelimiterCurrent',
                    excludedDataStoreName: location1,
                };
                return metadata.listLifecycleObject(BUCKET_NAME, params, logger, (err, data) => {
                    assert.ifError(err);
                    assert.strictEqual(data.IsTruncated, false);
                    assert.strictEqual(data.Contents.length, 1);
                    const expected = [
                        {
                            key: 'pfx2-test-object',
                            LastModified: '1970-01-01T00:00:02.005Z',
                            dataStoreName: location2,
                            VersionId: expectedVersionIds['pfx2-test-object'],
                        },
                    ];
                    assertContents(data.Contents, expected);
                    return done();
                });
            });
            it('Should list current versions of objects with prefix and excluding keys stored in location2', done => {
                const params = {
                    listingType: 'DelimiterCurrent',
                    excludedDataStoreName: location2,
                    prefix: 'pfx3',
                };
                return metadata.listLifecycleObject(BUCKET_NAME, params, logger, (err, data) => {
                    assert.ifError(err);
                    assert.strictEqual(data.IsTruncated, false);
                    assert.strictEqual(data.Contents.length, 1);
                    const expected = [
                        {
                            key: 'pfx3-test-object',
                            LastModified: '1970-01-01T00:00:01.005Z',
                            dataStoreName: location1,
                            VersionId: expectedVersionIds['pfx3-test-object'],
                        },
                    ];
                    assertContents(data.Contents, expected);
                    return done();
                });
            });
            it('Should return trucated list of current versions excluding keys stored in location2', done => {
                const params = {
                    listingType: 'DelimiterCurrent',
                    excludedDataStoreName: location2,
                    maxKeys: 1,
                };
                return metadata.listLifecycleObject(BUCKET_NAME, params, logger, (err, data) => {
                    assert.ifError(err);
                    assert.strictEqual(data.IsTruncated, true);
                    assert.strictEqual(data.Contents.length, 1);
                    assert.strictEqual(data.NextMarker, 'pfx1-test-object');
                    const expected = [
                        {
                            key: 'pfx1-test-object',
                            LastModified: '1970-01-01T00:00:00.005Z',
                            dataStoreName: location1,
                            VersionId: expectedVersionIds['pfx1-test-object'],
                        },
                    ];
                    assertContents(data.Contents, expected);
                    params.marker = 'pfx1-test-object';
                    return metadata.listLifecycleObject(BUCKET_NAME, params, logger, (err, data) => {
                        assert.ifError(err);
                        assert.strictEqual(data.IsTruncated, false);
                        assert.strictEqual(data.Contents.length, 1);
                        const expected = [
                            {
                                key: 'pfx3-test-object',
                                LastModified: '1970-01-01T00:00:01.005Z',
                                dataStoreName: location1,
                                VersionId: expectedVersionIds['pfx3-test-object'],
                            },
                        ];
                        assertContents(data.Contents, expected);
                        return done();
                    });
                });
            });
    it('Should return empty list when beforeDate is before the objects creation date', done => {
        const params = {
            listingType: 'DelimiterCurrent',
@ -333,15 +184,7 @@ describe('MongoClientInterface::metadata.listLifecycleObject::current', () => {
            assert.ifError(err);
            assert.strictEqual(data.IsTruncated, false);
            assert.strictEqual(data.Contents.length, 1);
-                    const expected = [
+            assert.strictEqual(data.Contents[0].key, 'pfx1-test-object');
                        {
                            key: 'pfx1-test-object',
                            LastModified: '1970-01-01T00:00:00.005Z',
                            dataStoreName: location1,
                            VersionId: expectedVersionIds['pfx1-test-object'],
                        },
                    ];
                    assertContents(data.Contents, expected);
            return done();
        });
@ -356,21 +199,8 @@ describe('MongoClientInterface::metadata.listLifecycleObject::current', () => {
            assert.ifError(err);
            assert.strictEqual(data.IsTruncated, false);
            assert.strictEqual(data.Contents.length, 2);
-                    const expected = [
+            assert.strictEqual(data.Contents[0].key, 'pfx1-test-object');
-                        {
+            assert.strictEqual(data.Contents[1].key, 'pfx3-test-object');
                            key: 'pfx1-test-object',
                            LastModified: '1970-01-01T00:00:00.005Z',
                            dataStoreName: location1,
                            VersionId: expectedVersionIds['pfx1-test-object'],
                        },
                        {
                            key: 'pfx3-test-object',
                            LastModified: '1970-01-01T00:00:01.005Z',
                            dataStoreName: location1,
                            VersionId: expectedVersionIds['pfx3-test-object'],
                        },
                    ];
                    assertContents(data.Contents, expected);
            return done();
        });
@ -385,27 +215,9 @@ describe('MongoClientInterface::metadata.listLifecycleObject::current', () => {
            assert.ifError(err);
            assert.strictEqual(data.IsTruncated, false);
            assert.strictEqual(data.Contents.length, 3);
-                    const expected = [
+            assert.strictEqual(data.Contents[0].key, 'pfx1-test-object');
-                        {
+            assert.strictEqual(data.Contents[1].key, 'pfx2-test-object');
-                            key: 'pfx1-test-object',
+            assert.strictEqual(data.Contents[2].key, 'pfx3-test-object');
                            LastModified: '1970-01-01T00:00:00.005Z',
                            dataStoreName: location1,
                            VersionId: expectedVersionIds['pfx1-test-object'],
                        },
                        {
                            key: 'pfx2-test-object',
                            LastModified: '1970-01-01T00:00:02.005Z',
                            dataStoreName: location2,
                            VersionId: expectedVersionIds['pfx2-test-object'],
                        },
                        {
                            key: 'pfx3-test-object',
                            LastModified: '1970-01-01T00:00:01.005Z',
                            dataStoreName: location1,
                            VersionId: expectedVersionIds['pfx3-test-object'],
                        },
                    ];
                    assertContents(data.Contents, expected);
            return done();
        });
@ -421,16 +233,8 @@ describe('MongoClientInterface::metadata.listLifecycleObject::current', () => {
            assert.ifError(err);
            assert.strictEqual(data.IsTruncated, true);
            assert.strictEqual(data.Contents.length, 1);
            assert.strictEqual(data.Contents[0].key, 'pfx1-test-object');
            assert.strictEqual(data.NextMarker, 'pfx1-test-object');
                    const expected = [
                        {
                            key: 'pfx1-test-object',
                            LastModified: '1970-01-01T00:00:00.005Z',
                            dataStoreName: location1,
                            VersionId: expectedVersionIds['pfx1-test-object'],
                        },
                    ];
                    assertContents(data.Contents, expected);
            params.marker = 'pfx1-test-object';
@ -438,15 +242,7 @@ describe('MongoClientInterface::metadata.listLifecycleObject::current', () => {
                assert.ifError(err);
                assert.strictEqual(data.IsTruncated, false);
                assert.strictEqual(data.Contents.length, 1);
-                        const expected = [
+                assert.strictEqual(data.Contents[0].key, 'pfx3-test-object');
                            {
                                key: 'pfx3-test-object',
                                LastModified: '1970-01-01T00:00:01.005Z',
                                dataStoreName: location1,
                                VersionId: expectedVersionIds['pfx3-test-object'],
                            },
                        ];
                        assertContents(data.Contents, expected);
                return done();
            });
@ -463,21 +259,8 @@ describe('MongoClientInterface::metadata.listLifecycleObject::current', () => {
            assert.strictEqual(data.IsTruncated, true);
            assert.strictEqual(data.NextMarker, 'pfx2-test-object');
            assert.strictEqual(data.Contents.length, 2);
-                    const expected = [
+            assert.strictEqual(data.Contents[0].key, 'pfx1-test-object');
-                        {
+            assert.strictEqual(data.Contents[1].key, 'pfx2-test-object');
                            key: 'pfx1-test-object',
                            LastModified: '1970-01-01T00:00:00.005Z',
                            dataStoreName: location1,
                            VersionId: expectedVersionIds['pfx1-test-object'],
                        },
                        {
                            key: 'pfx2-test-object',
                            LastModified: '1970-01-01T00:00:02.005Z',
                            dataStoreName: location2,
                            VersionId: expectedVersionIds['pfx2-test-object'],
                        },
                    ];
                    assertContents(data.Contents, expected);
            return done();
        });
@ -492,15 +275,7 @@ describe('MongoClientInterface::metadata.listLifecycleObject::current', () => {
            assert.ifError(err);
            assert.strictEqual(data.IsTruncated, false);
            assert.strictEqual(data.Contents.length, 1);
-                    const expected = [
+            assert.strictEqual(data.Contents[0].key, 'pfx3-test-object');
                        {
                            key: 'pfx3-test-object',
                            LastModified: '1970-01-01T00:00:01.005Z',
                            dataStoreName: location1,
                            VersionId: expectedVersionIds['pfx3-test-object'],
                        },
                    ];
                    assertContents(data.Contents, expected);
            return done();
        });
@ -515,22 +290,13 @@ describe('MongoClientInterface::metadata.listLifecycleObject::current', () => {
            assert.ifError(err);
            assert.strictEqual(data.IsTruncated, false);
            assert.strictEqual(data.Contents.length, 1);
-                    const expected = [
+            assert.strictEqual(data.Contents[0].key, 'pfx2-test-object');
                        {
                            key: 'pfx2-test-object',
                            LastModified: '1970-01-01T00:00:02.005Z',
                            dataStoreName: location2,
                            VersionId: expectedVersionIds['pfx2-test-object'],
                        },
                    ];
                    assertContents(data.Contents, expected);
            return done();
        });
    });
-            it('Should return the list of current versions modified before 1970-01-01T00:00:01.010Z with prefix pfx1',
+    it('Should return the list of current versions modified before 1970-01-01T00:00:01.010Z with prefix pfx1', done => {
                done => {
        const params = {
            listingType: 'DelimiterCurrent',
            beforeDate: '1970-01-01T00:00:01.010Z',
@ -541,21 +307,13 @@ describe('MongoClientInterface::metadata.listLifecycleObject::current', () => {
            assert.ifError(err);
            assert.strictEqual(data.IsTruncated, false);
            assert.strictEqual(data.Contents.length, 1);
-                        const expected = [
+            assert.strictEqual(data.Contents[0].key, 'pfx1-test-object');
                            {
                                key: 'pfx1-test-object',
                                LastModified: '1970-01-01T00:00:00.005Z',
                                dataStoreName: location1,
                                VersionId: expectedVersionIds['pfx1-test-object'],
                            },
                        ];
                        assertContents(data.Contents, expected);
            return done();
        });
    });
-            it('Should not list deleted version', done => {
+    it('Should not list deleted object', done => {
        const objVal = {
            'key': 'pfx4-test-object',
            'last-modified': new Date(0).toISOString(),
@ -566,89 +324,16 @@ describe('MongoClientInterface::metadata.listLifecycleObject::current', () => {
        const params = {
            listingType: 'DelimiterCurrent',
        };
                let deletedVersionId;
        async.series([
            next => metadata.putObjectMD(BUCKET_NAME, objVal.key, objVal, versionParams,
-                        logger, (err, res) => {
+                logger, next),
-                            if (err) {
+            next => metadata.deleteObjectMD(BUCKET_NAME, objVal.key, null, logger, next),
-                                return next(err);
+            next => metadata.listObject(BUCKET_NAME, params, logger, (err, data) => {
                            }
                            deletedVersionId = JSON.parse(res).versionId;
                            return next(null);
                        }),
                    next => metadata.deleteObjectMD(BUCKET_NAME, objVal.key,
                        { versionId: deletedVersionId }, logger, next),
                    next => metadata.listLifecycleObject(BUCKET_NAME, params, logger, (err, data) => {
                assert.ifError(err);
                assert.strictEqual(data.Contents.length, 3);
-                        const expected = [
+                assert.strictEqual(data.Contents[0].key, 'pfx1-test-object');
-                            {
+                assert.strictEqual(data.Contents[1].key, 'pfx2-test-object');
-                                key: 'pfx1-test-object',
+                assert.strictEqual(data.Contents[2].key, 'pfx3-test-object');
                                LastModified: '1970-01-01T00:00:00.005Z',
                                dataStoreName: location1,
                                VersionId: expectedVersionIds['pfx1-test-object'],
                            },
                            {
                                key: 'pfx2-test-object',
                                LastModified: '1970-01-01T00:00:02.005Z',
                                dataStoreName: location2,
                                VersionId: expectedVersionIds['pfx2-test-object'],
                            },
                            {
                                key: 'pfx3-test-object',
                                LastModified: '1970-01-01T00:00:01.005Z',
                                dataStoreName: location1,
                                VersionId: expectedVersionIds['pfx3-test-object'],
                            },
                        ];
                        assertContents(data.Contents, expected);
                        return next();
                    }),
                ], done);
            });
            it('Should not list object with delete marker', done => {
                const objVal = {
                    'key': 'pfx4-test-object',
                    'last-modified': new Date(0).toISOString(),
                };
                const dmObjVal = { ...objVal, isDeleteMarker: true };
                const versionParams = {
                    versioning: true,
                };
                const params = {
                    listingType: 'DelimiterCurrent',
                };
                async.series([
                    next => metadata.putObjectMD(BUCKET_NAME, objVal.key, objVal, versionParams, logger, next),
                    next => metadata.putObjectMD(BUCKET_NAME, objVal.key, dmObjVal, versionParams, logger, next),
                    next => metadata.listLifecycleObject(BUCKET_NAME, params, logger, (err, data) => {
                        assert.ifError(err);
                        assert.strictEqual(data.Contents.length, 3);
                        const expected = [
                            {
                                key: 'pfx1-test-object',
                                LastModified: '1970-01-01T00:00:00.005Z',
                                dataStoreName: location1,
                                VersionId: expectedVersionIds['pfx1-test-object'],
                            },
                            {
                                key: 'pfx2-test-object',
                                LastModified: '1970-01-01T00:00:02.005Z',
                                dataStoreName: location2,
                                VersionId: expectedVersionIds['pfx2-test-object'],
                            },
                            {
                                key: 'pfx3-test-object',
                                LastModified: '1970-01-01T00:00:01.005Z',
                                dataStoreName: location1,
                                VersionId: expectedVersionIds['pfx3-test-object'],
                            },
                        ];
                        assertContents(data.Contents, expected);
                return next();
            }),
        ], done);
@ -711,34 +396,14 @@ describe('MongoClientInterface::metadata.listLifecycleObject::current', () => {
            next => metadata.putObjectMD(BUCKET_NAME, objVal.key, objVal, versionParams,
                logger, next),
            next => flagObjectForDeletion(collection, objVal.key, next),
-                    next => metadata.listLifecycleObject(BUCKET_NAME, params, logger, (err, data) => {
+            next => metadata.listObject(BUCKET_NAME, params, logger, (err, data) => {
                assert.ifError(err);
                assert.strictEqual(data.Contents.length, 3);
-                        const expected = [
+                assert.strictEqual(data.Contents[0].key, 'pfx1-test-object');
-                            {
+                assert.strictEqual(data.Contents[1].key, 'pfx2-test-object');
-                                key: 'pfx1-test-object',
+                assert.strictEqual(data.Contents[2].key, 'pfx3-test-object');
                                LastModified: '1970-01-01T00:00:00.005Z',
                                dataStoreName: location1,
                                VersionId: expectedVersionIds['pfx1-test-object'],
                            },
                            {
                                key: 'pfx2-test-object',
                                LastModified: '1970-01-01T00:00:02.005Z',
                                dataStoreName: location2,
                                VersionId: expectedVersionIds['pfx2-test-object'],
                            },
                            {
                                key: 'pfx3-test-object',
                                LastModified: '1970-01-01T00:00:01.005Z',
                                dataStoreName: location1,
                                VersionId: expectedVersionIds['pfx3-test-object'],
                            },
                        ];
                        assertContents(data.Contents, expected);
                return next();
            }),
        ], done);
    });
        });
    });
 });
--- a/tests/functional/metadata/mongodb/listLifecycleObject/global.spec.js
+++ b/tests/functional/metadata/mongodb/listLifecycleObject/global.spec.js
@ -0,0 +1,102 @@
 const async = require('async');
 const assert = require('assert');
 const werelogs = require('werelogs');
 const { MongoMemoryReplSet } = require('mongodb-memory-server');
 const logger = new werelogs.Logger('MongoClientInterface', 'debug', 'debug');
 const MetadataWrapper =
 require('../../../../../lib/storage/metadata/MetadataWrapper');
 const { versioning } = require('../../../../../index');
 const { BucketVersioningKeyFormat } = versioning.VersioningConstants;
 const { makeBucketMD } = require('./utils');
 const IMPL_NAME = 'mongodb';
 const DB_NAME = 'metadata';
 const BUCKET_NAME = 'test-lifecycle-list-bucket-v0';
 const mongoserver = new MongoMemoryReplSet({
    debug: false,
    instanceOpts: [
        { port: 27020 },
    ],
    replSet: {
        name: 'rs0',
        count: 1,
        DB_NAME,
        storageEngine: 'ephemeralForTest',
    },
 });
 describe('MongoClientInterface::metadata.listLifecycleObject::global', () => {
    let metadata;
    beforeAll(done => {
        mongoserver.waitUntilRunning().then(() => {
            const opts = {
                mongodb: {
                    replicaSetHosts: 'localhost:27020',
                    writeConcern: 'majority',
                    replicaSet: 'rs0',
                    readPreference: 'primary',
                    database: DB_NAME,
                },
            };
            metadata = new MetadataWrapper(IMPL_NAME, opts, null, logger);
            metadata.client.defaultBucketKeyFormat = BucketVersioningKeyFormat.v0;
            metadata.setup(done);
        });
    });
    afterAll(done => {
        async.series([
            next => metadata.close(next),
            next => mongoserver.stop()
                .then(() => next())
                .catch(next),
        ], done);
    });
    beforeEach(done => {
        const bucketMD = makeBucketMD(BUCKET_NAME);
        return metadata.createBucket(BUCKET_NAME, bucketMD, logger, done);
    });
    afterEach(done => {
        metadata.deleteBucket(BUCKET_NAME, logger, done);
    });
    it('Should return error listing current versions if v0 key format', done => {
        const params = {
            listingType: 'DelimiterCurrent',
        };
        return metadata.listLifecycleObject(BUCKET_NAME, params, logger, (err, data) => {
            assert(err.NotImplemented);
            assert(!data);
            return done();
        });
    });
    it('Should return error listing non-current versions if v0 key format', done => {
        const params = {
            listingType: 'DelimiterNonCurrent',
        };
        return metadata.listLifecycleObject(BUCKET_NAME, params, logger, (err, data) => {
            assert(err.NotImplemented);
            assert(!data);
            return done();
        });
    });
    it('Should return error listing orphan delete markers if v0 key format', done => {
        const params = {
            listingType: 'DelimiterOrphanDeleteMarker',
        };
        return metadata.listLifecycleObject(BUCKET_NAME, params, logger, (err, data) => {
            assert(err.NotImplemented);
            assert(!data);
            return done();
        });
    });
 });
--- a/tests/functional/metadata/mongodb/listLifecycleObject/noncurrent.spec.js
+++ b/tests/functional/metadata/mongodb/listLifecycleObject/noncurrent.spec.js
@ -4,7 +4,7 @@ const werelogs = require('werelogs');
 const { MongoMemoryReplSet } = require('mongodb-memory-server');
 const logger = new werelogs.Logger('MongoClientInterface', 'debug', 'debug');
 const MetadataWrapper =
-    require('../../../../../lib/storage/metadata/MetadataWrapper');
+require('../../../../../lib/storage/metadata/MetadataWrapper');
 const { versioning } = require('../../../../../index');
 const { BucketVersioningKeyFormat } = versioning.VersioningConstants;
 const { assertContents, makeBucketMD, putBulkObjectVersions, flagObjectForDeletion } = require('./utils');
@ -33,11 +33,8 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
    const key1 = 'pfx1-test-object';
    const key2 = 'pfx2-test-object';
    const key3 = 'pfx3-test-object';
    const location1 = 'loc1';
    const location2 = 'loc2';
    beforeAll(done => {
        mongoserver.start().then(() => {
        mongoserver.waitUntilRunning().then(() => {
            const opts = {
                mongodb: {
@ -49,10 +46,10 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
                },
            };
            metadata = new MetadataWrapper(IMPL_NAME, opts, null, logger);
            metadata.client.defaultBucketKeyFormat = BucketVersioningKeyFormat.v1;
            metadata.setup(done);
        });
    });
    });
    afterAll(done => {
        async.series([
@ -63,8 +60,6 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
        ], done);
    });
    [BucketVersioningKeyFormat.v0, BucketVersioningKeyFormat.v1].forEach(v => {
        describe(`bucket format version: ${v}`, () => {
    beforeEach(done => {
        const bucketMD = makeBucketMD(BUCKET_NAME);
        const versionParams = {
@ -72,7 +67,6 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
            versionId: null,
            repairMaster: null,
        };
                metadata.client.defaultBucketKeyFormat = v;
        async.series([
            next => metadata.createBucket(BUCKET_NAME, bucketMD, logger, err => {
                if (err) {
@ -83,16 +77,18 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
                return next();
            }),
            next => {
-                        const objVal = {
+                const params = {
                    objName: key1,
                    objVal: {
                        key: key1,
                        versionId: 'null',
-                            dataStoreName: location1,
+                    },
                    nbVersions: 5,
                };
                        const nbVersions = 5;
                const timestamp = 0;
-                        putBulkObjectVersions(metadata, BUCKET_NAME, key1, objVal, versionParams,
+                putBulkObjectVersions(metadata, BUCKET_NAME, params.objName, params.objVal, versionParams,
-                            nbVersions, timestamp, logger, (err, data) => {
+                    params.nbVersions, timestamp, logger, (err, data) => {
-                                expectedVersionIds[key1] = data.expectedVersionIds;
+                        expectedVersionIds[key1] = data;
                        return next(err);
                    });
                /* eslint-disable max-len */
@ -105,16 +101,18 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
                /* eslint-enable max-len */
            },
            next => {
-                        const objVal = {
+                const params = {
                    objName: key2,
                    objVal: {
                        key: key2,
                        versionId: 'null',
-                            dataStoreName: location2,
+                    },
                    nbVersions: 5,
                };
                        const nbVersions = 5;
                const timestamp = 0;
-                        putBulkObjectVersions(metadata, BUCKET_NAME, key2, objVal, versionParams,
+                putBulkObjectVersions(metadata, BUCKET_NAME, params.objName, params.objVal, versionParams,
-                            nbVersions, timestamp, logger, (err, data) => {
+                    params.nbVersions, timestamp, logger, (err, data) => {
-                                expectedVersionIds[key2] = data.expectedVersionIds;
+                        expectedVersionIds[key2] = data;
                        return next(err);
                    });
                /* eslint-disable max-len */
@ -127,16 +125,18 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
                /* eslint-enable max-len */
            },
            next => {
-                        const objVal = {
+                const params = {
                    objName: key3,
                    objVal: {
                        key: key3,
                        versionId: 'null',
-                            dataStoreName: location1,
+                    },
                    nbVersions: 5,
                };
                        const nbVersions = 5;
                const timestamp = 0;
-                        putBulkObjectVersions(metadata, BUCKET_NAME, key3, objVal, versionParams,
+                putBulkObjectVersions(metadata, BUCKET_NAME, params.objName, params.objVal, versionParams,
-                            nbVersions, timestamp, logger, (err, data) => {
+                    params.nbVersions, timestamp, logger, (err, data) => {
-                                expectedVersionIds[key3] = data.expectedVersionIds;
+                        expectedVersionIds[key3] = data;
                        return next(err);
                    });
                /* eslint-disable max-len */
@ -166,73 +166,61 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
                    key: key1,
                    LastModified: '1970-01-01T00:00:00.004Z',
                    staleDate: '1970-01-01T00:00:00.005Z',
                            dataStoreName: location1,
                },
                {
                    key: key1,
                    LastModified: '1970-01-01T00:00:00.003Z',
                    staleDate: '1970-01-01T00:00:00.004Z',
                            dataStoreName: location1,
                },
                {
                    key: key1,
                    LastModified: '1970-01-01T00:00:00.002Z',
                    staleDate: '1970-01-01T00:00:00.003Z',
                            dataStoreName: location1,
                },
                {
                    key: key1,
                    LastModified: '1970-01-01T00:00:00.001Z',
                    staleDate: '1970-01-01T00:00:00.002Z',
                            dataStoreName: location1,
                },
                {
                    key: key2,
                    LastModified: '1970-01-01T00:00:00.004Z',
                    staleDate: '1970-01-01T00:00:00.005Z',
                            dataStoreName: location2,
                },
                {
                    key: key2,
                    LastModified: '1970-01-01T00:00:00.003Z',
                    staleDate: '1970-01-01T00:00:00.004Z',
                            dataStoreName: location2,
                },
                {
                    key: key2,
                    LastModified: '1970-01-01T00:00:00.002Z',
                    staleDate: '1970-01-01T00:00:00.003Z',
                            dataStoreName: location2,
                },
                {
                    key: key2,
                    LastModified: '1970-01-01T00:00:00.001Z',
                    staleDate: '1970-01-01T00:00:00.002Z',
                            dataStoreName: location2,
                },
                {
                    key: key3,
                    LastModified: '1970-01-01T00:00:00.004Z',
                    staleDate: '1970-01-01T00:00:00.005Z',
                            dataStoreName: location1,
                },
                {
                    key: key3,
                    LastModified: '1970-01-01T00:00:00.003Z',
                    staleDate: '1970-01-01T00:00:00.004Z',
                            dataStoreName: location1,
                },
                {
                    key: key3,
                    LastModified: '1970-01-01T00:00:00.002Z',
                    staleDate: '1970-01-01T00:00:00.003Z',
                            dataStoreName: location1,
                },
                {
                    key: key3,
                    LastModified: '1970-01-01T00:00:00.001Z',
                    staleDate: '1970-01-01T00:00:00.002Z',
                            dataStoreName: location1,
                },
            ];
            assertContents(data.Contents, expected);
@ -264,157 +252,6 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
        });
    });
            it('Should list non-current versions excluding keys stored in location1', done => {
                const params = {
                    listingType: 'DelimiterNonCurrent',
                    excludedDataStoreName: location1,
                };
                return metadata.listLifecycleObject(BUCKET_NAME, params, logger, (err, data) => {
                    assert.deepStrictEqual(err, null);
                    assert.strictEqual(data.IsTruncated, false);
                    assert.strictEqual(data.Contents.length, 4);
                    const expected = [
                        {
                            key: key2,
                            LastModified: '1970-01-01T00:00:00.004Z',
                            staleDate: '1970-01-01T00:00:00.005Z',
                            VersionId: expectedVersionIds[key2][0],
                            dataStoreName: location2,
                        },
                        {
                            key: key2,
                            LastModified: '1970-01-01T00:00:00.003Z',
                            staleDate: '1970-01-01T00:00:00.004Z',
                            VersionId: expectedVersionIds[key2][1],
                            dataStoreName: location2,
                        },
                        {
                            key: key2,
                            LastModified: '1970-01-01T00:00:00.002Z',
                            staleDate: '1970-01-01T00:00:00.003Z',
                            VersionId: expectedVersionIds[key2][2],
                            dataStoreName: location2,
                        },
                        {
                            key: key2,
                            LastModified: '1970-01-01T00:00:00.001Z',
                            staleDate: '1970-01-01T00:00:00.002Z',
                            VersionId: expectedVersionIds[key2][3],
                            dataStoreName: location2,
                        },
                    ];
                    assertContents(data.Contents, expected);
                    const key2VersionIds = data.Contents.filter(k => k.key === key2).map(k => k.value.VersionId);
                    assert.deepStrictEqual(key2VersionIds, expectedVersionIds[key2]);
                    return done();
                });
            });
            it('Should list non-current versions older than a specific date and excluding keys stored in location1',
                done => {
                    const params = {
                        listingType: 'DelimiterNonCurrent',
                        excludedDataStoreName: location1,
                        beforeDate: '1970-01-01T00:00:00.004Z',
                    };
                    return metadata.listLifecycleObject(BUCKET_NAME, params, logger, (err, data) => {
                        assert.deepStrictEqual(err, null);
                        assert.strictEqual(data.IsTruncated, false);
                        assert.strictEqual(data.Contents.length, 2);
                        const expected = [
                            {
                                key: key2,
                                LastModified: '1970-01-01T00:00:00.002Z',
                                staleDate: '1970-01-01T00:00:00.003Z',
                                VersionId: expectedVersionIds[key2][2],
                                dataStoreName: location2,
                            },
                            {
                                key: key2,
                                LastModified: '1970-01-01T00:00:00.001Z',
                                staleDate: '1970-01-01T00:00:00.002Z',
                                VersionId: expectedVersionIds[key2][3],
                                dataStoreName: location2,
                            },
                        ];
                        assertContents(data.Contents, expected);
                        return done();
                    });
                });
            it('Should return trucated list of non-current versions excluding keys stored in location1', done => {
                const params = {
                    listingType: 'DelimiterNonCurrent',
                    excludedDataStoreName: location1,
                    maxKeys: 2,
                };
                return metadata.listLifecycleObject(BUCKET_NAME, params, logger, (err, data) => {
                    assert.deepStrictEqual(err, null);
                    assert.strictEqual(data.IsTruncated, true);
                    assert.strictEqual(data.NextKeyMarker, key2);
                    assert.strictEqual(data.NextVersionIdMarker, data.Contents[1].value.VersionId);
                    assert.strictEqual(data.Contents.length, 2);
                    const expected = [
                        {
                            key: key2,
                            LastModified: '1970-01-01T00:00:00.004Z',
                            staleDate: '1970-01-01T00:00:00.005Z',
                            VersionId: expectedVersionIds[key2][0],
                            dataStoreName: location2,
                        },
                        {
                            key: key2,
                            LastModified: '1970-01-01T00:00:00.003Z',
                            staleDate: '1970-01-01T00:00:00.004Z',
                            VersionId: expectedVersionIds[key2][1],
                            dataStoreName: location2,
                        },
                    ];
                    assertContents(data.Contents, expected);
                    params.keyMarker = data.NextKeyMarker;
                    params.versionIdMarker = data.NextVersionIdMarker;
                    return metadata.listLifecycleObject(BUCKET_NAME, params, logger, (err, data) => {
                        assert.deepStrictEqual(err, null);
                        assert.strictEqual(data.IsTruncated, true);
                        assert.strictEqual(data.NextKeyMarker, key2);
                        assert.strictEqual(data.NextVersionIdMarker, data.Contents[1].value.VersionId);
                        assert.strictEqual(data.Contents.length, 2);
                        const expected = [
                            {
                                key: key2,
                                LastModified: '1970-01-01T00:00:00.002Z',
                                staleDate: '1970-01-01T00:00:00.003Z',
                                VersionId: expectedVersionIds[key2][2],
                                dataStoreName: location2,
                            },
                            {
                                key: key2,
                                LastModified: '1970-01-01T00:00:00.001Z',
                                staleDate: '1970-01-01T00:00:00.002Z',
                                VersionId: expectedVersionIds[key2][3],
                                dataStoreName: location2,
                            },
                        ];
                        assertContents(data.Contents, expected);
                        params.keyMarker = data.NextKeyMarker;
                        params.versionIdMarker = data.NextVersionIdMarker;
                        return metadata.listLifecycleObject(BUCKET_NAME, params, logger, (err, data) => {
                            assert.deepStrictEqual(err, null);
                            assert.strictEqual(data.IsTruncated, false);
                            assert.strictEqual(data.Contents.length, 0);
                            return done();
                        });
                    });
                });
            });
    it('Should return the non-current versions with stale date older than 1970-01-01T00:00:00.003Z', done => {
        const params = {
            listingType: 'DelimiterNonCurrent',
@ -430,21 +267,18 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
                    LastModified: '1970-01-01T00:00:00.001Z',
                    staleDate: '1970-01-01T00:00:00.002Z',
                    VersionId: expectedVersionIds[key1][3],
                            dataStoreName: location1,
                },
                {
                    key: key2,
                    LastModified: '1970-01-01T00:00:00.001Z',
                    staleDate: '1970-01-01T00:00:00.002Z',
                    VersionId: expectedVersionIds[key2][3],
                            dataStoreName: location2,
                },
                {
                    key: key3,
                    LastModified: '1970-01-01T00:00:00.001Z',
                    staleDate: '1970-01-01T00:00:00.002Z',
                    VersionId: expectedVersionIds[key3][3],
                            dataStoreName: location1,
                },
            ];
            assertContents(data.Contents, expected);
@ -472,21 +306,18 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
                        LastModified: '1970-01-01T00:00:00.004Z',
                        staleDate: '1970-01-01T00:00:00.005Z',
                        VersionId: expectedVersionIds[key1][0],
                                dataStoreName: location1,
                    },
                    {
                        key: key1,
                        LastModified: '1970-01-01T00:00:00.003Z',
                        staleDate: '1970-01-01T00:00:00.004Z',
                        VersionId: expectedVersionIds[key1][1],
                                dataStoreName: location1,
                    },
                    {
                        key: key1,
                        LastModified: '1970-01-01T00:00:00.002Z',
                        staleDate: '1970-01-01T00:00:00.003Z',
                        VersionId: expectedVersionIds[key1][2],
                                dataStoreName: location1,
                    },
                ];
                assertContents(data.Contents, expected);
@ -508,21 +339,18 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
                        LastModified: '1970-01-01T00:00:00.001Z',
                        staleDate: '1970-01-01T00:00:00.002Z',
                        VersionId: expectedVersionIds[key1][3],
                                dataStoreName: location1,
                    },
                    {
                        key: key2,
                        LastModified: '1970-01-01T00:00:00.004Z',
                        staleDate: '1970-01-01T00:00:00.005Z',
                        VersionId: expectedVersionIds[key2][0],
                                dataStoreName: location2,
                    },
                    {
                        key: key2,
                        LastModified: '1970-01-01T00:00:00.003Z',
                        staleDate: '1970-01-01T00:00:00.004Z',
                        VersionId: expectedVersionIds[key2][1],
                                dataStoreName: location2,
                    },
                ];
                assertContents(data.Contents, expected);
@ -544,21 +372,18 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
                        LastModified: '1970-01-01T00:00:00.002Z',
                        staleDate: '1970-01-01T00:00:00.003Z',
                        VersionId: expectedVersionIds[key2][2],
                                dataStoreName: location2,
                    },
                    {
                        key: key2,
                        LastModified: '1970-01-01T00:00:00.001Z',
                        staleDate: '1970-01-01T00:00:00.002Z',
                        VersionId: expectedVersionIds[key2][3],
                                dataStoreName: location2,
                    },
                    {
                        key: key3,
                        LastModified: '1970-01-01T00:00:00.004Z',
                        staleDate: '1970-01-01T00:00:00.005Z',
                        VersionId: expectedVersionIds[key3][0],
                                dataStoreName: location1,
                    },
                ];
                assertContents(data.Contents, expected);
@ -578,21 +403,18 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
                        LastModified: '1970-01-01T00:00:00.003Z',
                        staleDate: '1970-01-01T00:00:00.004Z',
                        VersionId: expectedVersionIds[key3][1],
                                dataStoreName: location1,
                    },
                    {
                        key: key3,
                        LastModified: '1970-01-01T00:00:00.002Z',
                        staleDate: '1970-01-01T00:00:00.003Z',
                        VersionId: expectedVersionIds[key3][2],
                                dataStoreName: location1,
                    },
                    {
                        key: key3,
                        LastModified: '1970-01-01T00:00:00.001Z',
                        staleDate: '1970-01-01T00:00:00.002Z',
                        VersionId: expectedVersionIds[key3][3],
                                dataStoreName: location1,
                    },
                ];
                assertContents(data.Contents, expected);
@ -622,25 +444,21 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
                        key: key1,
                        LastModified: '1970-01-01T00:00:00.004Z',
                        staleDate: '1970-01-01T00:00:00.005Z',
                                dataStoreName: location1,
                    },
                    {
                        key: key1,
                        LastModified: '1970-01-01T00:00:00.003Z',
                        staleDate: '1970-01-01T00:00:00.004Z',
                                dataStoreName: location1,
                    },
                    {
                        key: key1,
                        LastModified: '1970-01-01T00:00:00.002Z',
                        staleDate: '1970-01-01T00:00:00.003Z',
                                dataStoreName: location1,
                    },
                    {
                        key: key1,
                        LastModified: '1970-01-01T00:00:00.001Z',
                        staleDate: '1970-01-01T00:00:00.002Z',
                                dataStoreName: location1,
                    },
                ];
@ -665,25 +483,21 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
                        key: key2,
                        LastModified: '1970-01-01T00:00:00.004Z',
                        staleDate: '1970-01-01T00:00:00.005Z',
                                dataStoreName: location2,
                    },
                    {
                        key: key2,
                        LastModified: '1970-01-01T00:00:00.003Z',
                        staleDate: '1970-01-01T00:00:00.004Z',
                                dataStoreName: location2,
                    },
                    {
                        key: key2,
                        LastModified: '1970-01-01T00:00:00.002Z',
                        staleDate: '1970-01-01T00:00:00.003Z',
                                dataStoreName: location2,
                    },
                    {
                        key: key2,
                        LastModified: '1970-01-01T00:00:00.001Z',
                        staleDate: '1970-01-01T00:00:00.002Z',
                                dataStoreName: location2,
                    },
                ];
                assertContents(data.Contents, expected);
@ -705,25 +519,21 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
                        key: key3,
                        LastModified: '1970-01-01T00:00:00.004Z',
                        staleDate: '1970-01-01T00:00:00.005Z',
                                dataStoreName: location1,
                    },
                    {
                        key: key3,
                        LastModified: '1970-01-01T00:00:00.003Z',
                        staleDate: '1970-01-01T00:00:00.004Z',
                                dataStoreName: location1,
                    },
                    {
                        key: key3,
                        LastModified: '1970-01-01T00:00:00.002Z',
                        staleDate: '1970-01-01T00:00:00.003Z',
                                dataStoreName: location1,
                    },
                    {
                        key: key3,
                        LastModified: '1970-01-01T00:00:00.001Z',
                        staleDate: '1970-01-01T00:00:00.002Z',
                                dataStoreName: location1,
                    },
                ];
                assertContents(data.Contents, expected);
@ -758,14 +568,12 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
                        LastModified: '1970-01-01T00:00:00.004Z',
                        staleDate: '1970-01-01T00:00:00.005Z',
                        VersionId: expectedVersionIds[key2][0],
                                dataStoreName: location2,
                    },
                    {
                        key: key2,
                        LastModified: '1970-01-01T00:00:00.003Z',
                        staleDate: '1970-01-01T00:00:00.004Z',
                        VersionId: expectedVersionIds[key2][1],
                                dataStoreName: location2,
                    },
                ];
@ -786,14 +594,12 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
                        LastModified: '1970-01-01T00:00:00.002Z',
                        staleDate: '1970-01-01T00:00:00.003Z',
                        VersionId: expectedVersionIds[key2][2],
                                dataStoreName: location2,
                    },
                    {
                        key: key2,
                        LastModified: '1970-01-01T00:00:00.001Z',
                        staleDate: '1970-01-01T00:00:00.002Z',
                        VersionId: expectedVersionIds[key2][3],
                                dataStoreName: location2,
                    },
                ];
                assertContents(data.Contents, expected);
@ -824,25 +630,21 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
                    key: key2,
                    LastModified: '1970-01-01T00:00:00.004Z',
                    staleDate: '1970-01-01T00:00:00.005Z',
                            dataStoreName: location2,
                },
                {
                    key: key2,
                    LastModified: '1970-01-01T00:00:00.003Z',
                    staleDate: '1970-01-01T00:00:00.004Z',
                            dataStoreName: location2,
                },
                {
                    key: key2,
                    LastModified: '1970-01-01T00:00:00.002Z',
                    staleDate: '1970-01-01T00:00:00.003Z',
                            dataStoreName: location2,
                },
                {
                    key: key2,
                    LastModified: '1970-01-01T00:00:00.001Z',
                    staleDate: '1970-01-01T00:00:00.002Z',
                            dataStoreName: location2,
                },
            ];
            assertContents(data.Contents, expected);
@ -867,25 +669,21 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
                key: key2,
                LastModified: '1970-01-01T00:00:00.004Z',
                staleDate: '1970-01-01T00:00:00.005Z',
                        dataStoreName: location2,
            },
            {
                key: key2,
                LastModified: '1970-01-01T00:00:00.003Z',
                staleDate: '1970-01-01T00:00:00.004Z',
                        dataStoreName: location2,
            },
            {
                key: key2,
                LastModified: '1970-01-01T00:00:00.002Z',
                staleDate: '1970-01-01T00:00:00.003Z',
                        dataStoreName: location2,
            },
            {
                key: key2,
                LastModified: '1970-01-01T00:00:00.001Z',
                staleDate: '1970-01-01T00:00:00.002Z',
                        dataStoreName: location2,
            }];
            assertContents(data.Contents, expected);
@ -912,7 +710,6 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
                LastModified: '1970-01-01T00:00:00.001Z',
                staleDate: '1970-01-01T00:00:00.002Z',
                VersionId: expectedVersionIds[key2][3],
                        dataStoreName: location2,
            }];
            assertContents(data.Contents, expected);
@ -920,8 +717,7 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
        });
    });
-            it('Should truncate list of non-current versions that start with prefix and older than beforedate',
+    it('Should truncate list of non-current versions that start with prefix and older than beforedate', done => {
                done => {
        const params = {
            listingType: 'DelimiterNonCurrent',
            prefix: 'pfx2',
@ -939,14 +735,12 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
                    LastModified: '1970-01-01T00:00:00.003Z',
                    staleDate: '1970-01-01T00:00:00.004Z',
                    VersionId: expectedVersionIds[key2][1],
                                dataStoreName: location2,
                },
                {
                    key: key2,
                    LastModified: '1970-01-01T00:00:00.002Z',
                    staleDate: '1970-01-01T00:00:00.003Z',
                    VersionId: expectedVersionIds[key2][2],
                                dataStoreName: location2,
                },
            ];
            assert.strictEqual(data.Contents.length, 2);
@ -1024,63 +818,10 @@ describe('MongoClientInterface::metadata.listLifecycleObject::noncurrent', () =>
            next => flagObjectForDeletion(collection, 'pfx4-test-object', next),
            next => metadata.listLifecycleObject(BUCKET_NAME, params, logger, (err, data) => {
                assert.ifError(err);
                assert.strictEqual(data.IsTruncated, false);
                assert.strictEqual(data.Contents.length, 0);
                return next();
            }),
        ], done);
    });
            it('Should exclude keys stored in location1', done => {
                let expectedId;
                const objLoc1 = {
                    'key': 'pfx4-test-object',
                    'versionId': 'null',
                    'dataStoreName': location1,
                    'last-modified': new Date(0).toISOString(),
                };
                const objLoc2 = {
                    'key': 'pfx4-test-object',
                    'versionId': 'null',
                    'dataStoreName': location2,
                    'last-modified': new Date(0).toISOString(),
                };
                const versionParams = {
                    versioning: true,
                };
                const params = {
                    listingType: 'DelimiterNonCurrent',
                    prefix: 'pfx4',
                    excludedDataStoreName: location1,
                };
                async.series([
                    next => metadata.putObjectMD(BUCKET_NAME, 'pfx4-test-object', objLoc1, versionParams,
                        logger, next),
                    next => metadata.putObjectMD(BUCKET_NAME, 'pfx4-test-object', objLoc2, versionParams,
                        logger, (err, data) => {
                            expectedId = JSON.parse(data).versionId;
                            return next(err);
                        }),
                    next => metadata.putObjectMD(BUCKET_NAME, 'pfx4-test-object', objLoc1, versionParams,
                        logger, next),
                    next => metadata.putObjectMD(BUCKET_NAME, 'pfx4-test-object', objLoc2, versionParams,
                        logger, next),
                    next => metadata.listLifecycleObject(BUCKET_NAME, params, logger, (err, data) => {
                        assert.ifError(err);
                        assert.strictEqual(data.IsTruncated, false);
                        assert.strictEqual(data.Contents.length, 1);
                        const firstKey = data.Contents[0];
                        assert.strictEqual(firstKey.key, 'pfx4-test-object');
                        assert.strictEqual(firstKey.value.VersionId, expectedId);
                        assert.strictEqual(firstKey.value.dataStoreName, location2);
                        return next();
                    }),
                ], done);
            });
        });
    });
 });
--- a/tests/functional/metadata/mongodb/listLifecycleObject/nullVersion.spec.js
+++ b/tests/functional/metadata/mongodb/listLifecycleObject/nullVersion.spec.js
@ -4,7 +4,7 @@ const werelogs = require('werelogs');
 const { MongoMemoryReplSet } = require('mongodb-memory-server');
 const logger = new werelogs.Logger('MongoClientInterface', 'debug', 'debug');
 const MetadataWrapper =
-    require('../../../../../lib/storage/metadata/MetadataWrapper');
+require('../../../../../lib/storage/metadata/MetadataWrapper');
 const { versioning } = require('../../../../../index');
 const { BucketVersioningKeyFormat } = versioning.VersioningConstants;
 const { makeBucketMD } = require('./utils');
@ -31,7 +31,6 @@ describe('MongoClientInterface::metadata.listLifecycleObject::nullVersion', () =
    let metadata;
    beforeAll(done => {
        mongoserver.start().then(() => {
        mongoserver.waitUntilRunning().then(() => {
            const opts = {
                mongodb: {
@ -43,10 +42,10 @@ describe('MongoClientInterface::metadata.listLifecycleObject::nullVersion', () =
                },
            };
            metadata = new MetadataWrapper(IMPL_NAME, opts, null, logger);
            metadata.client.defaultBucketKeyFormat = BucketVersioningKeyFormat.v1;
            metadata.setup(done);
        });
    });
    });
    afterAll(done => {
        async.series([
@ -57,8 +56,11 @@ describe('MongoClientInterface::metadata.listLifecycleObject::nullVersion', () =
        ], done);
    });
-    [BucketVersioningKeyFormat.v0, BucketVersioningKeyFormat.v1].forEach(v => {
+    beforeEach(done => {
-        describe(`bucket format version: ${v}`, () => {
+        const bucketMD = makeBucketMD(BUCKET_NAME);
        return metadata.createBucket(BUCKET_NAME, bucketMD, logger, done);
    });
    beforeEach(done => {
        const bucketMD = makeBucketMD(BUCKET_NAME);
        const versionParams = {
@ -66,7 +68,6 @@ describe('MongoClientInterface::metadata.listLifecycleObject::nullVersion', () =
            versionId: null,
            repairMaster: null,
        };
                metadata.client.defaultBucketKeyFormat = v;
        async.series([
            next => metadata.createBucket(BUCKET_NAME, bucketMD, logger, next),
            next => {
@ -102,65 +103,17 @@ describe('MongoClientInterface::metadata.listLifecycleObject::nullVersion', () =
                const lastModified = new Date(timestamp).toISOString();
                const objVal = {
                    'key': objName,
                    'versionId': 'null',
                    'last-modified': lastModified,
                };
                return metadata.putObjectMD(BUCKET_NAME, objName, objVal, versionParams, logger, next);
            },
                    // key2 simulates a scenario where:
                    // 1) bucket is versioned
                    // 2) put object key2
                    // 3) bucket versioning gets suspended
                    // 4) put object key2
                    // result:
                    // {
                    //     "_id" : "Mkey0",
                    //     "value" : {
                    //         "key" : "key2",
                    //         "isNull" : true,
                    //         "versionId" : "<VersionId2>",
                    //         "last-modified" : "2023-07-11T14:16:00.151Z",
                    //     }
                    // },
                    // {
                    //     "_id" : "Vkey0\u0000<VersionId1>",
                    //     "value" : {
                    //         "key" : "key2",
                    //         "versionId" : "<VersionId1>",
                    //         "tags" : {
                    //         },
                    //         "last-modified" : "2023-07-11T14:15:36.713Z",
                    //     }
                    // },
                    next => {
                        const objName = 'key2';
                        const timestamp = 0;
                        const lastModified = new Date(timestamp).toISOString();
                        const objVal = {
                            'key': objName,
                            'last-modified': lastModified,
                        };
                        return metadata.putObjectMD(BUCKET_NAME, objName, objVal, versionParams, logger, next);
                    },
                    next => {
                        const objName = 'key2';
                        const timestamp = 0;
                        const params = {
                            versionId: '',
                        };
                        const lastModified = new Date(timestamp).toISOString();
                        const objVal = {
                            'key': objName,
                            'last-modified': lastModified,
                            'isNull': true,
                        };
                        return metadata.putObjectMD(BUCKET_NAME, objName, objVal, params, logger, next);
                    },
        ], done);
    });
-            afterEach(done => metadata.deleteBucket(BUCKET_NAME, logger, done));
+    afterEach(done => {
        metadata.deleteBucket(BUCKET_NAME, logger, done);
    });
    it('Should list the null current version and set IsNull to true', done => {
        const params = {
@ -169,22 +122,17 @@ describe('MongoClientInterface::metadata.listLifecycleObject::nullVersion', () =
        return metadata.listLifecycleObject(BUCKET_NAME, params, logger, (err, data) => {
            assert.ifError(err);
            assert.strictEqual(data.IsTruncated, false);
-                    assert.strictEqual(data.Contents.length, 3);
+            assert.strictEqual(data.Contents.length, 2);
            // check that key0 has a null current version
            const firstKey = data.Contents[0];
            assert.strictEqual(firstKey.key, 'key0');
            assert.strictEqual(firstKey.value.IsNull, true);
-                    // check that key1 has no null current version
+            // check that key1 has not a null current version
            const secondKey = data.Contents[1];
            assert.strictEqual(secondKey.key, 'key1');
            assert(!secondKey.value.IsNull);
                    // check that key2 has a null current version
                    const thirdKey = data.Contents[2];
                    assert.strictEqual(thirdKey.key, 'key2');
                    assert.strictEqual(thirdKey.value.IsNull, true);
            return done();
        });
    });
@ -196,20 +144,13 @@ describe('MongoClientInterface::metadata.listLifecycleObject::nullVersion', () =
        return metadata.listLifecycleObject(BUCKET_NAME, params, logger, (err, data) => {
            assert.deepStrictEqual(err, null);
            assert.strictEqual(data.IsTruncated, false);
-                    assert.strictEqual(data.Contents.length, 2);
+            assert.strictEqual(data.Contents.length, 1);
            // check that key1 has a null non-current version
            const firstKey = data.Contents[0];
            assert.strictEqual(firstKey.key, 'key1');
            assert.strictEqual(firstKey.value.IsNull, true);
                    // check that key2 has no null non-current version
                    const secondKey = data.Contents[1];
                    assert.strictEqual(secondKey.key, 'key2');
                    assert(!secondKey.value.IsNull);
            return done();
        });
    });
        });
    });
 });
--- a/tests/functional/metadata/mongodb/listLifecycleObject/orphanDeleteMarker.spec.js
+++ b/tests/functional/metadata/mongodb/listLifecycleObject/orphanDeleteMarker.spec.js
@ -4,7 +4,7 @@ const werelogs = require('werelogs');
 const { MongoMemoryReplSet } = require('mongodb-memory-server');
 const logger = new werelogs.Logger('MongoClientInterface', 'debug', 'debug');
 const MetadataWrapper =
-    require('../../../../../lib/storage/metadata/MetadataWrapper');
+require('../../../../../lib/storage/metadata/MetadataWrapper');
 const { versioning } = require('../../../../../index');
 const { BucketVersioningKeyFormat } = versioning.VersioningConstants;
 const { makeBucketMD, putBulkObjectVersions } = require('./utils');
@ -30,7 +30,6 @@ describe('MongoClientInterface::metadata.listLifecycleObject::orphan', () => {
    let metadata;
    beforeAll(done => {
        mongoserver.start().then(() => {
        mongoserver.waitUntilRunning().then(() => {
            const opts = {
                mongodb: {
@ -42,10 +41,10 @@ describe('MongoClientInterface::metadata.listLifecycleObject::orphan', () => {
                },
            };
            metadata = new MetadataWrapper(IMPL_NAME, opts, null, logger);
            metadata.client.defaultBucketKeyFormat = BucketVersioningKeyFormat.v1;
            metadata.setup(done);
        });
    });
    });
    afterAll(done => {
        async.series([
@ -56,8 +55,6 @@ describe('MongoClientInterface::metadata.listLifecycleObject::orphan', () => {
        ], done);
    });
    [BucketVersioningKeyFormat.v0, BucketVersioningKeyFormat.v1].forEach(v => {
        describe(`bucket format version: ${v}`, () => {
    beforeEach(done => {
        const bucketMD = makeBucketMD(BUCKET_NAME);
        const versionParams = {
@ -65,7 +62,6 @@ describe('MongoClientInterface::metadata.listLifecycleObject::orphan', () => {
            versionId: null,
            repairMaster: null,
        };
                metadata.client.defaultBucketKeyFormat = v;
        async.series([
            next => metadata.createBucket(BUCKET_NAME, bucketMD, logger, next),
            next => {
@ -395,8 +391,7 @@ describe('MongoClientInterface::metadata.listLifecycleObject::orphan', () => {
        });
    });
-            it('Should return the truncated list of orphan delete markers older than 1970-01-01T00:00:00.006Z',
+    it('Should return the truncated list of orphan delete markers older than 1970-01-01T00:00:00.006Z', done => {
                done => {
        const params = {
            listingType: 'DelimiterOrphanDeleteMarker',
            maxKeys: 2,
@ -414,8 +409,7 @@ describe('MongoClientInterface::metadata.listLifecycleObject::orphan', () => {
        });
    });
-            it('Should return the following list of orphan delete markers older than 1970-01-01T00:00:00.006Z',
+    it('Should return the following list of orphan delete markers older than 1970-01-01T00:00:00.006Z', done => {
                done => {
        const params = {
            listingType: 'DelimiterOrphanDeleteMarker',
            maxKeys: 2,
@ -432,8 +426,7 @@ describe('MongoClientInterface::metadata.listLifecycleObject::orphan', () => {
        });
    });
-            it('Should return the truncated list of orphan delete markers older than 1970-01-01T00:00:00.001Z',
+    it('Should return the truncated list of orphan delete markers older than 1970-01-01T00:00:00.001Z', done => {
                done => {
        const params = {
            listingType: 'DelimiterOrphanDeleteMarker',
            maxKeys: 2,
@ -450,6 +443,4 @@ describe('MongoClientInterface::metadata.listLifecycleObject::orphan', () => {
            return done();
        });
    });
        });
    });
 });
--- a/tests/functional/metadata/mongodb/listLifecycleObject/utils.js
+++ b/tests/functional/metadata/mongodb/listLifecycleObject/utils.js
@ -30,10 +30,10 @@ function putBulkObjectVersions(metadata, bucketName, objName, objVal, params, ve
            });
        }, (err, expectedVersionIds) => {
            // The last version is removed since it represents the current version.
-            const lastVersionId = expectedVersionIds.pop();
+            expectedVersionIds.pop();
            // array is reversed to be alligned with the version order (latest to oldest).
            expectedVersionIds.reverse();
-            return cb(err, { lastVersionId, expectedVersionIds });
+            return cb(err, expectedVersionIds);
        });
 }
@ -68,12 +68,10 @@ function makeBucketMD(bucketName) {
 }
 function assertContents(contents, expected) {
    assert.strictEqual(contents.length, expected.length);
    contents.forEach((c, i) => {
        assert.strictEqual(c.key, expected[i].key);
        assert.strictEqual(c.value.LastModified, expected[i].LastModified);
        assert.strictEqual(c.value.staleDate, expected[i].staleDate);
        assert.strictEqual(c.value.dataStoreName, expected[i].dataStoreName);
        if (expected[i].VersionId) {
            assert.strictEqual(c.value.VersionId, expected[i].VersionId);
        }
@ -91,9 +89,7 @@ function flagObjectForDeletion(collection, key, cb) {
    collection.updateMany(
        { 'value.key': key },
        { $set: { 'value.deleted': true } },
-        { upsert: false })
+        { upsert: false }, cb);
        .then(() => cb())
        .catch(err => cb(err));
 }
 module.exports = {
--- a/tests/functional/metadata/mongodb/listObject.spec.js
+++ b/tests/functional/metadata/mongodb/listObject.spec.js
@ -5,11 +5,9 @@ const { MongoMemoryReplSet } = require('mongodb-memory-server');
 const logger = new werelogs.Logger('MongoClientInterface', 'debug', 'debug');
 const BucketInfo = require('../../../../lib/models/BucketInfo').default;
 const MetadataWrapper =
-    require('../../../../lib/storage/metadata/MetadataWrapper');
+require('../../../../lib/storage/metadata/MetadataWrapper');
 const { versioning } = require('../../../../index');
 const { BucketVersioningKeyFormat } = versioning.VersioningConstants;
 const sinon = require('sinon');
 const MongoReadStream = require('../../../../lib/storage/metadata/mongoclient/readStream');
 const IMPL_NAME = 'mongodb';
 const DB_NAME = 'metadata';
@ -69,18 +67,10 @@ describe('MongoClientInterface::metadata.listObject', () => {
        collection.updateMany(
            { 'value.key': key },
            { $set: { 'value.deleted': true } },
-            { upsert: false }).then(() => cb()).catch(err => cb(err));
+            { upsert: false }, cb);
    }
    function customListingParser(entries) {
        return entries.map(entry => {
            const tmp = JSON.parse(entry.value);
            return tmp;
        });
    }
    beforeAll(done => {
        mongoserver.start().then(() => {
        mongoserver.waitUntilRunning().then(() => {
            const opts = {
                mongodb: {
@ -95,7 +85,6 @@ describe('MongoClientInterface::metadata.listObject', () => {
            metadata.setup(done);
        });
    });
    });
    afterAll(done => {
        async.series([
@ -159,12 +148,6 @@ describe('MongoClientInterface::metadata.listObject', () => {
                            objVal: {
                                key: 'pfx1-test-object',
                                versionId: 'null',
                                location: [{
                                    start: 0,
                                    size: 150,
                                    dataStoreETag: 'etag',
                                    dataStoreVersionId: 'versionId',
                                }],
                            },
                            nbVersions: 5,
                        };
@ -492,81 +475,6 @@ describe('MongoClientInterface::metadata.listObject', () => {
                    }),
                ], done);
            });
            it('Should properly destroy the MongoDBReadStream', done => {
                // eslint-disable-next-line func-names
                const destroyStub = sinon.stub(MongoReadStream.prototype, 'destroy').callsFake(function (...args) {
                    // You can add extra logic here if needed
                    MongoReadStream.prototype.destroy.wrappedMethod.apply(this, ...args);
                });
                const params = {
                    listingType: 'DelimiterMaster',
                    maxKeys: 100,
                };
                return metadata.listObject(BUCKET_NAME, params, logger, err => {
                    assert.ifError(err);
                    assert(destroyStub.called, 'Destroy should have been called on MongoReadStream');
                    // Restore original destroy method
                    destroyStub.restore();
                    return done();
                });
            });
            it('Should properly destroy the MongoDBReadStream on error', done => {
                // eslint-disable-next-line func-names
                const destroyStub = sinon.stub(MongoReadStream.prototype, 'destroy').callsFake(function (...args) {
                    // You can add extra logic here if needed
                    MongoReadStream.prototype.destroy.wrappedMethod.apply(this, ...args);
                });
                // stub the cursor creation to emit an error
                // eslint-disable-next-line func-names
                const readStub = sinon.stub(MongoReadStream.prototype, '_read').callsFake(function () {
                    this.emit('error', new Error('error'));
                });
                const params = {
                    listingType: 'DelimiterMaster',
                    maxKeys: 100,
                };
                return metadata.listObject(BUCKET_NAME, params, logger, err => {
                    assert(err, 'Expected an error');
                    assert(destroyStub.called, 'Destroy should have been called on MongoReadStream');
                    destroyStub.restore();
                    readStub.restore();
                    return done();
                });
            });
            it('Should not include location in listing result and use custom listing parser', done => {
                const opts = {
                    mongodb: {
                        replicaSetHosts: 'localhost:27020',
                        writeConcern: 'majority',
                        replicaSet: 'rs0',
                        readPreference: 'primary',
                        database: DB_NAME,
                    },
                    customListingParser,
                };
                const parserSpy = sinon.spy(opts, 'customListingParser');
                const md = new MetadataWrapper(IMPL_NAME, opts, null, logger);
                md.setup(() => {
                    const params = {
                        listingType: 'DelimiterMaster',
                        maxKeys: 100,
                    };
                    return md.listObject(BUCKET_NAME, params, logger, (err, data) => {
                        assert.ifError(err);
                        assert.strictEqual(data.Contents.length, 3);
                        assert.strictEqual(data.Contents[0].key, 'pfx1-test-object');
                        assert.strictEqual(data.Contents[0].location, undefined);
                        assert(parserSpy.called);
                        return done();
                    });
                });
            });
        });
    });
 });
--- a/tests/functional/metadata/mongodb/putObject.spec.js
+++ b/tests/functional/metadata/mongodb/putObject.spec.js
@ -40,22 +40,27 @@ describe('MongoClientInterface:metadata.putObjectMD', () => {
    function getObject(key, cb) {
        collection.findOne({
            _id: key,
-        }, {}).then(doc => {
+        }, {}, (err, doc) => {
            if (err) {
                return cb(err);
            }
            if (!doc) {
                return cb(errors.NoSuchKey);
            }
            return cb(null, doc.value);
-        }).catch(err => cb(err));
+        });
    }
    function getObjectCount(cb) {
-        collection.countDocuments()
+        collection.countDocuments((err, count) => {
-            .then(count => cb(null, count))
+            if (err) {
-            .catch(err => cb(err));
+                cb(err);
            }
            cb(null, count);
        });
    }
    beforeAll(done => {
        mongoserver.start().then(() => {
        mongoserver.waitUntilRunning().then(() => {
            const opts = {
                mongodb: {
@ -70,7 +75,6 @@ describe('MongoClientInterface:metadata.putObjectMD', () => {
            metadata.setup(done);
        });
    });
    });
    afterAll(done => {
        async.series([
--- a/tests/functional/metadata/mongodb/withCond.spec.js
+++ b/tests/functional/metadata/mongodb/withCond.spec.js
@ -35,7 +35,6 @@ describe('MongoClientInterface:withCond', () => {
    ];
    beforeAll(done => {
        mongoserver.start().then(() => {
        mongoserver.waitUntilRunning().then(() => {
            const opts = {
                mongodb: {
@ -50,7 +49,6 @@ describe('MongoClientInterface:withCond', () => {
            metadata.setup(done);
        });
    });
    });
    afterAll(done => {
        async.series([
@ -220,10 +218,6 @@ describe('MongoClientInterface:withCond', () => {
        });
        describe('::deleteObjectWithCond', () => {
            afterEach(done => {
                metadata.deleteBucket(BUCKET_NAME, logger, done);
            });
            const tests = [
                [
                    `should return no such key if the object does not exist ${variation.it}`,
--- a/tests/unit/algos/cache/GapCache.spec.ts
+++ b/tests/unit/algos/cache/GapCache.spec.ts
@ -1,265 +0,0 @@
 import GapCache from '../../../../lib/algos/cache/GapCache';
 describe('GapCache', () => {
    let gapCache;
    beforeEach(() => {
        // exposureDelayMs=100, maxGaps=10, maxGapWeight=100
        gapCache = new GapCache(100, 10, 100);
        gapCache.start();
    });
    afterEach(() => {
        gapCache.stop();
    });
    describe('getters and setters', () => {
        it('maxGapWeight getter', () => {
            expect(gapCache.maxGapWeight).toEqual(100);
        });
        it('maxGapWeight setter', () => {
            gapCache.maxGapWeight = 123;
            expect(gapCache.maxGapWeight).toEqual(123);
            // check that internal gap sets have also been updated
            expect(gapCache._stagingUpdates.newGaps.maxWeight).toEqual(123);
            expect(gapCache._frozenUpdates.newGaps.maxWeight).toEqual(123);
        });
        it('exposureDelayMs getter', () => {
            expect(gapCache.exposureDelayMs).toEqual(100);
        });
        it('exposureDelayMs setter', async () => {
            // insert a first gap
            gapCache.setGap('bar', 'baz', 10);
            // change the exposure delay to 50ms
            gapCache.exposureDelayMs = 50;
            expect(gapCache.exposureDelayMs).toEqual(50);
            gapCache.setGap('qux', 'quz', 10);
            // wait for more than twice the new exposure delay
            await new Promise(resolve => setTimeout(resolve, 200));
            // only the second gap should have been exposed, due to the change of
            // exposure delay subsequent to the first call to setGap()
            expect(await gapCache.lookupGap('ape', 'zoo')).toEqual(
                { firstKey: 'qux', lastKey: 'quz', weight: 10 }
            );
        });
    });
    describe('clear()', () => {
        it('should clear all exposed gaps', async () => {
            gapCache.setGap('bar', 'baz', 10);
            gapCache.setGap('qux', 'quz', 20);
            await new Promise(resolve => setTimeout(resolve, 300));
            expect(await gapCache.lookupGap('ape', 'zoo')).toEqual(
                { firstKey: 'bar', lastKey: 'baz', weight: 10 }
            );
            gapCache.clear();
            expect(await gapCache.lookupGap('ape', 'zoo')).toBeNull();
        });
        it('should clear all staging gaps', async () => {
            gapCache.setGap('bar', 'baz', 10);
            gapCache.setGap('qux', 'quz', 20);
            gapCache.clear();
            await new Promise(resolve => setTimeout(resolve, 300));
            expect(await gapCache.lookupGap('ape', 'zoo')).toBeNull();
        });
        it('should keep existing invalidating updates against the next new gaps', async () => {
            // invalidate future gaps containing 'dog'
            expect(gapCache.removeOverlappingGaps(['dog'])).toEqual(0);
            // then, clear the cache
            gapCache.clear();
            // wait for 50ms (half of exposure delay of 100ms) before
            // setting a new gap overlapping with 'dog'
            await new Promise(resolve => setTimeout(resolve, 50));
            gapCache.setGap('cat', 'fox', 10);
            // also set a non-overlapping gap to make sure it is not invalidated
            gapCache.setGap('goat', 'hog', 20);
            // wait an extra 250ms to ensure all valid gaps have been exposed
            await new Promise(resolve => setTimeout(resolve, 250));
            // the next gap is indeed 'goat'... because 'cat'... should have been invalidated
            expect(await gapCache.lookupGap('bat', 'zoo')).toEqual(
                { firstKey: 'goat', lastKey: 'hog', weight: 20 });
        });
    });
    it('should expose gaps after at least exposureDelayMs milliseconds', async () => {
        gapCache.setGap('bar', 'baz', 10);
        expect(await gapCache.lookupGap('ape', 'cat')).toBeNull();
        // wait for 50ms which is half of the minimum time to exposure
        await new Promise(resolve => setTimeout(resolve, 50));
        // the gap should not be exposed yet
        expect(await gapCache.lookupGap('ape', 'cat')).toBeNull();
        // wait for an extra 250ms (total 300ms): the upper bound for exposure of any
        // setGap() call is twice the exposureDelayMs value, so 200ms, wait an extra
        // 100ms to cope with scheduling uncertainty and GapSet processing time, after
        // which the gap introduced by setGap() should always be exposed.
        await new Promise(resolve => setTimeout(resolve, 250));
        expect(await gapCache.lookupGap('ape', 'cat')).toEqual(
            { firstKey: 'bar', lastKey: 'baz', weight: 10 });
        // check getters
        expect(gapCache.maxGaps).toEqual(10);
        expect(gapCache.maxGapWeight).toEqual(100);
        expect(gapCache.size).toEqual(1);
        // check iteration over the exposed gaps
        let nGaps = 0;
        for (const gap of gapCache) {
            expect(gap).toEqual({ firstKey: 'bar', lastKey: 'baz', weight: 10 });
            nGaps += 1;
        }
        expect(nGaps).toEqual(1);
        // check toArray()
        expect(gapCache.toArray()).toEqual([
            { firstKey: 'bar', lastKey: 'baz', weight: 10 },
        ]);
    });
    it('removeOverlappingGaps() should invalidate all overlapping gaps that are already exposed',
    async () => {
        gapCache.setGap('cat', 'fox', 10);
        gapCache.setGap('lion', 'seal', 20);
        // wait for 3x100ms to ensure all setGap() calls have been exposed
        await new Promise(resolve => setTimeout(resolve, 300));
        // expect 0 gap removed because 'hog' is not in any gap
        expect(gapCache.removeOverlappingGaps(['hog'])).toEqual(0);
        // expect 1 gap removed because 'cat' -> 'fox' should be already exposed
        expect(gapCache.removeOverlappingGaps(['dog'])).toEqual(1);
        // the gap should have been invalidated permanently
        expect(await gapCache.lookupGap('dog', 'fox')).toBeNull();
        // the other gap should still be present
        expect(await gapCache.lookupGap('rat', 'tiger')).toEqual(
            { firstKey: 'lion', lastKey: 'seal', weight: 20 });
    });
    it('removeOverlappingGaps() should invalidate all overlapping gaps that are not yet exposed',
    async () => {
        gapCache.setGap('cat', 'fox', 10);
        gapCache.setGap('lion', 'seal', 20);
        // make the following calls asynchronous for the sake of the
        // test, but not waiting for the exposure delay
        await new Promise(resolve => setImmediate(resolve));
        // expect 0 gap removed because 'hog' is not in any gap
        expect(gapCache.removeOverlappingGaps(['hog'])).toEqual(0);
        // expect 0 gap removed because 'cat' -> 'fox' is not exposed yet,
        // but internally it should have been removed from the staging or
        // frozen gap set
        expect(gapCache.removeOverlappingGaps(['dog'])).toEqual(0);
        // wait for 3x100ms to ensure all non-invalidated setGap() calls have been exposed
        await new Promise(resolve => setTimeout(resolve, 300));
        // the gap should have been invalidated permanently
        expect(await gapCache.lookupGap('dog', 'fox')).toBeNull();
        // the other gap should now be exposed
        expect(await gapCache.lookupGap('rat', 'tiger')).toEqual(
            { firstKey: 'lion', lastKey: 'seal', weight: 20 });
    });
    it('removeOverlappingGaps() should invalidate gaps created later by setGap() but ' +
    'within the exposure delay', async () => {
        // wait for 80ms (slightly less than exposure delay of 100ms)
        // before calling removeOverlappingGaps(), so that the next
        // exposure timer kicks in before the call to setGap()
        await new Promise(resolve => setTimeout(resolve, 80));
        // there is no exposed gap yet, so expect 0 gap removed
        expect(gapCache.removeOverlappingGaps(['dog'])).toEqual(0);
        // wait for 50ms (half of exposure delay of 100ms) before
        // setting a new gap overlapping with 'dog'
        await new Promise(resolve => setTimeout(resolve, 50));
        gapCache.setGap('cat', 'fox', 10);
        // also set a non-overlapping gap to make sure it is not invalidated
        gapCache.setGap('goat', 'hog', 20);
        // wait an extra 250ms to ensure all valid gaps have been exposed
        await new Promise(resolve => setTimeout(resolve, 250));
        // the next gap is indeed 'goat'... because 'cat'... should have been invalidated
        expect(await gapCache.lookupGap('bat', 'zoo')).toEqual(
            { firstKey: 'goat', lastKey: 'hog', weight: 20 });
    });
    it('removeOverlappingGaps() should not invalidate gaps created more than twice ' +
    'the exposure delay later', async () => {
        // there is no exposed gap yet, so expect 0 gap removed
        expect(gapCache.removeOverlappingGaps(['dog'])).toEqual(0);
        // wait for 250ms (more than twice the exposure delay of 100ms) before
        // setting a new gap overlapping with 'dog'
        await new Promise(resolve => setTimeout(resolve, 250));
        gapCache.setGap('cat', 'fox', 10);
        // also set a non-overlapping gap to make sure it is not invalidated
        gapCache.setGap('goat', 'hog', 20);
        // wait for an extra 250ms to ensure the new gap is exposed
        await new Promise(resolve => setTimeout(resolve, 250));
        // should find the inserted gap as it should not have been invalidated
        expect(await gapCache.lookupGap('bat', 'zoo')).toEqual(
            { firstKey: 'cat', lastKey: 'fox', weight: 10 });
    });
    it('exposed gaps should be merged when possible', async () => {
        gapCache.setGap('bar', 'baz', 10);
        gapCache.setGap('baz', 'qux', 10);
        // wait until the merged gap is exposed
        await new Promise(resolve => setTimeout(resolve, 300));
        expect(await gapCache.lookupGap('ape', 'cat')).toEqual(
            { firstKey: 'bar', lastKey: 'qux', weight: 20 });
    });
    it('exposed gaps should be split when above maxGapWeight', async () => {
        gapCache.setGap('bar', 'baz', gapCache.maxGapWeight - 1);
        gapCache.setGap('baz', 'qux', 10);
        // wait until the gaps are exposed
        await new Promise(resolve => setTimeout(resolve, 300));
        expect(await gapCache.lookupGap('cat', 'dog')).toEqual(
            { firstKey: 'baz', lastKey: 'qux', weight: 10 });
    });
    it('gaps should not be exposed when reaching the maxGaps limit', async () => {
        const gapsArray = new Array(gapCache.maxGaps).fill(undefined).map(
            (_, i) => {
                const firstKey = `0000${i}`.slice(-4);
                return {
                    firstKey,
                    lastKey: `${firstKey}foo`,
                    weight: 10,
                };
            }
        );
        for (const gap of gapsArray) {
            gapCache.setGap(gap.firstKey, gap.lastKey, gap.weight);
        }
        // wait until the gaps are exposed
        await new Promise(resolve => setTimeout(resolve, 300));
        expect(gapCache.size).toEqual(gapCache.maxGaps);
        gapCache.setGap('noroomforthisgap', 'noroomforthisgapfoo');
        // wait until the gaps are exposed
        await new Promise(resolve => setTimeout(resolve, 300));
        // the number of gaps should still be 'maxGaps'
        expect(gapCache.size).toEqual(gapCache.maxGaps);
        // the gaps should correspond to the original array
        expect(gapCache.toArray()).toEqual(gapsArray);
    });
 });
--- a/tests/unit/algos/cache/GapSet.spec.ts
+++ b/tests/unit/algos/cache/GapSet.spec.ts
@ -1,878 +0,0 @@
 import { OrderedSet } from '@js-sdsl/ordered-set';
 import GapSet from '../../../../lib/algos/cache/GapSet';
 function genRandomKey(): string {
    const CHARS = 'abcdefghijklmnopqrstuvwxyz0123456789';
    return new Array(16).fill(undefined).map(
        () => CHARS[Math.trunc(Math.random() * CHARS.length)]
    ).join('');
 }
 function genRandomUnchainedGaps(nGaps) {
    const gapBounds = new Array(nGaps * 2).fill(undefined).map(
        () => genRandomKey()
    );
    gapBounds.sort();
    const gapsArray = new Array(nGaps).fill(undefined).map(
        (_, i) => ({
            firstKey: gapBounds[2 * i],
            lastKey: gapBounds[2 * i + 1],
            weight: 10,
        })
    );
    return gapsArray;
 }
 function genRandomChainedGaps(nGaps) {
    const gapBounds = new Array(nGaps + 1).fill(undefined).map(
        () => genRandomKey()
    );
    gapBounds.sort();
    const gapsArray = new Array(nGaps).fill(undefined).map(
        (_, i) => ({
            firstKey: gapBounds[i],
            lastKey: gapBounds[i + 1],
            weight: 10,
        })
    );
    return gapsArray;
 }
 /**
 * Shuffle an array in-place
 *
 * @param {any[]} - The array to shuffle
 * @return {undefined}
 */
 function shuffleArray(array) {
    for (let i = array.length - 1; i > 0; i--) {
        const randIndex = Math.trunc(Math.random() * (i + 1));
        /* eslint-disable no-param-reassign */
        const randIndexVal = array[randIndex];
        array[randIndex] = array[i];
        array[i] = randIndexVal;
        /* eslint-enable no-param-reassign */
    }
 }
 describe('GapSet', () => {
    const INITIAL_GAPSET = [
        { firstKey: 'bar', lastKey: 'baz', weight: 10 },
        { firstKey: 'qux', lastKey: 'quz', weight: 20 },
    ];
    const INITIAL_GAPSET_WITH_CHAIN = [
        // single-key gap
        { firstKey: 'ape', lastKey: 'ape', weight: 1 },
        // start of chain
        { firstKey: 'bar', lastKey: 'baz', weight: 10 },
        { firstKey: 'baz', lastKey: 'qux', weight: 15 },
        { firstKey: 'qux', lastKey: 'quz', weight: 20 },
        { firstKey: 'quz', lastKey: 'rat', weight: 25 },
        { firstKey: 'rat', lastKey: 'yak', weight: 30 },
        // end of chain
    ]
    let gapsArray;
    let gapSet;
    let gapsArrayWithChain;
    let gapSetWithChain;
    beforeEach(() => {
        gapsArray = JSON.parse(
            JSON.stringify(INITIAL_GAPSET)
        );
        gapSet = GapSet.createFromArray(gapsArray, 100);
        gapsArrayWithChain = JSON.parse(
            JSON.stringify(INITIAL_GAPSET_WITH_CHAIN)
        );
        gapSetWithChain = GapSet.createFromArray(gapsArrayWithChain, 100);
    });
    describe('GapSet::size', () => {
        it('should return 0 for an empty gap set', () => {
            const emptyGapSet = new GapSet(100);
            expect(emptyGapSet.size).toEqual(0);
        });
        it('should return the size of the gap set', () => {
            expect(gapSet.size).toEqual(2);
        });
        it('should reflect the new size after removal of gaps', () => {
            gapSet._gaps.eraseElementByKey({ firstKey: 'bar' });
            expect(gapSet.size).toEqual(1);
        });
    });
    describe('GapSet::maxWeight', () => {
        it('getter', () => {
            const emptyGapSet = new GapSet(123);
            expect(emptyGapSet.maxWeight).toEqual(123);
        });
        it('setter', () => {
            const emptyGapSet = new GapSet(123);
            emptyGapSet.maxWeight = 456;
            expect(emptyGapSet.maxWeight).toEqual(456);
        });
    });
    describe('GapSet::setGap()', () => {
        it('should start a gap with a single key in empty gap set', () => {
            const emptyGapSet = new GapSet(100);
            const gap = emptyGapSet.setGap('foo', 'foo', 1);
            expect(gap).toEqual({ firstKey: 'foo', lastKey: 'foo', weight: 1 });
            expect(emptyGapSet.toArray()).toEqual([
                { firstKey: 'foo', lastKey: 'foo', weight: 1 },
            ]);
        });
        it('should start a gap with a single key in non-empty gap set', () => {
            const gap = gapSet.setGap('foo', 'foo', 1);
            expect(gap).toEqual({ firstKey: 'foo', lastKey: 'foo', weight: 1 });
            expect(gapSet.toArray()).toEqual([
                { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                { firstKey: 'foo', lastKey: 'foo', weight: 1 },
                { firstKey: 'qux', lastKey: 'quz', weight: 20 },
            ]);
        });
        it('should start a gap with multiple keys in empty gap set', () => {
            const emptyGapSet = new GapSet(100);
            const gap = emptyGapSet.setGap('foo', 'qux', 5);
            expect(gap).toEqual({ firstKey: 'foo', lastKey: 'qux', weight: 5 });
            expect(emptyGapSet.toArray()).toEqual([
                { firstKey: 'foo', lastKey: 'qux', weight: 5 },
            ]);
        });
        it('should return a new object rather than a gap managed by GapSet', () => {
            const emptyGapSet = new GapSet(100);
            const gap = emptyGapSet.setGap('foo', 'qux', 5);
            gap.lastKey = 'quz';
            // check that modifying the returned gap doesn't affect the GapSet
            expect(emptyGapSet.toArray()).toEqual([
                { firstKey: 'foo', lastKey: 'qux', weight: 5 },
            ]);
        });
        it('should return an existing gap that includes the wanted gap', () => {
            const gap = gapSet.setGap('bat', 'bay', 5);
            expect(gap).toEqual({ firstKey: 'bar', lastKey: 'baz', weight: 10 });
            expect(gapSet.toArray()).toEqual(INITIAL_GAPSET);
        });
        it('should return an existing gap that starts with the wanted gap first key', () => {
            const gap = gapSet.setGap('bar', 'bay', 5);
            expect(gap).toEqual({ firstKey: 'bar', lastKey: 'baz', weight: 10 });
            expect(gapSet.toArray()).toEqual(INITIAL_GAPSET);
        });
        it('should return an existing gap that ends with the wanted gap last key', () => {
            const gap = gapSet.setGap('bat', 'baz', 5);
            expect(gap).toEqual({ firstKey: 'bar', lastKey: 'baz', weight: 10 });
            expect(gapSet.toArray()).toEqual(INITIAL_GAPSET);
        });
        it('should return the existing chained gap that starts with the first key', () => {
            const gap = gapSetWithChain.setGap('baz', 'quo', 10);
            expect(gap).toEqual({ firstKey: 'baz', lastKey: 'qux', weight: 15 });
            expect(gapSetWithChain.toArray()).toEqual(INITIAL_GAPSET_WITH_CHAIN);
        });
        it('should extend a single-key gap with no other gap', () => {
            const singleKeyGap = { firstKey: 'foo', lastKey: 'foo', weight: 1 };
            const singleKeyGapSet = GapSet.createFromArray([singleKeyGap], 100);
            const extendedGap = singleKeyGapSet.setGap('foo', 'qux', 30);
            expect(extendedGap).toEqual({ firstKey: 'foo', lastKey: 'qux', weight: 31 });
            expect(singleKeyGapSet.toArray()).toEqual([
                { firstKey: 'foo', lastKey: 'qux', weight: 31 },
            ]);
        });
        it('should extend a gap with no next gap', () => {
            // existing gap: 'qux' -> 'quz'
            const extendedGap = gapSet.setGap('qux', 'rat', 25);
            expect(extendedGap).toEqual({ firstKey: 'qux', lastKey: 'rat', weight: 25 });
            expect(gapSet.toArray()).toEqual([
                { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                { firstKey: 'qux', lastKey: 'rat', weight: 25 },
            ]);
        });
        it('should extend a gap without overlap with next gap', () => {
            // existing gap: 'bar' -> 'baz'
            const extendedGap = gapSet.setGap('bar', 'dog', 15);
            expect(extendedGap).toEqual({ firstKey: 'bar', lastKey: 'dog', weight: 15 });
            expect(gapSet.toArray()).toEqual([
                { firstKey: 'bar', lastKey: 'dog', weight: 15 },
                { firstKey: 'qux', lastKey: 'quz', weight: 20 },
            ]);
        });
        it('should extend a gap starting from its last key', () => {
            // existing gap: 'qux' -> 'quz'
            const extendedGap = gapSet.setGap('quz', 'rat', 5);
            expect(extendedGap).toEqual({ firstKey: 'qux', lastKey: 'rat', weight: 25 });
            expect(gapSet.toArray()).toEqual([
                { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                { firstKey: 'qux', lastKey: 'rat', weight: 25 },
            ]);
        });
        it('should merge with next gap with single-key overlap if total weight is ' +
        'under maxWeight', () => {
            const extendedGap = gapSet.setGap('bar', 'qux', 80);
            // updated weight is accurately set as the sum of
            // overlapping individual gap weights
            expect(extendedGap).toEqual({ firstKey: 'bar', lastKey: 'quz', weight: 80 + 20 });
            expect(gapSet.toArray()).toEqual([
                { firstKey: 'bar', lastKey: 'quz', weight: 80 + 20 },
            ]);
        });
        it('should chain with next gap with single-key overlap if total weight is ' +
        'above maxWeight', () => {
            const extendedGap = gapSet.setGap('bar', 'qux', 90);
            expect(extendedGap).toEqual({ firstKey: 'qux', lastKey: 'quz', weight: 20 });
            expect(gapSet.toArray()).toEqual([
                { firstKey: 'bar', lastKey: 'qux', weight: 90 },
                { firstKey: 'qux', lastKey: 'quz', weight: 20 },
            ]);
        });
        it('should merge with both previous and next gap if bounds overlap by a ' +
        'single key and total weight is under maxWeight', () => {
            const extendedGap = gapSet.setGap('baz', 'qux', 30);
            // updated weight is accurately set as the sum of
            // overlapping individual gap weights
            expect(extendedGap).toEqual({ firstKey: 'bar', lastKey: 'quz', weight: 10 + 30 + 20 });
            expect(gapSet.toArray()).toEqual([
                { firstKey: 'bar', lastKey: 'quz', weight: 10 + 30 + 20 },
            ]);
        });
        it('should merge with previous gap and chain with next gap if bounds overlap by a ' +
        'single key on either side and weight is above maxWeight when merging on right side', () => {
            const extendedGap = gapSet.setGap('baz', 'qux', 90);
            expect(extendedGap).toEqual({ firstKey: 'qux', lastKey: 'quz', weight: 20 });
            expect(gapSet.toArray()).toEqual([
                { firstKey: 'bar', lastKey: 'qux', weight: 100 },
                { firstKey: 'qux', lastKey: 'quz', weight: 20 },
            ]);
        });
        it('should chain with previous gap and merge with next gap if bounds overlap by a ' +
        'single key on either side and weight is above maxWeight when merging on left side', () => {
            // modified version of the common test set with increased weight
            // for 'bar' -> 'baz'
            const gapSet = GapSet.createFromArray([
                { firstKey: 'bar', lastKey: 'baz', weight: 80 },
                { firstKey: 'qux', lastKey: 'quz', weight: 20 },
            ], 100);
            const extendedGap = gapSet.setGap('baz', 'qux', 70);
            expect(extendedGap).toEqual({ firstKey: 'baz', lastKey: 'quz', weight: 90 });
            expect(gapSet.toArray()).toEqual([
                { firstKey: 'bar', lastKey: 'baz', weight: 80 },
                { firstKey: 'baz', lastKey: 'quz', weight: 90 },
            ]);
        });
        it('should merge with both previous and next gap if left bound overlaps by a ' +
        'single key and total weight is under maxWeight', () => {
            const extendedGap = gapSet.setGap('baz', 'quxxx', 40);
            // updated weight is heuristically set as the sum of the
            // previous chained gap's weight and the new weight
            // (excluding the overlapping gap on right side)
            expect(extendedGap).toEqual({ firstKey: 'bar', lastKey: 'quz', weight: 10 + 40 });
            expect(gapSet.toArray()).toEqual([
                { firstKey: 'bar', lastKey: 'quz', weight: 10 + 40 },
            ]);
        });
        it('should chain with previous gap and merge with next gap if left bound overlaps by a ' +
        'single key and total weight is above maxWeight', () => {
            const extendedGap = gapSet.setGap('baz', 'quxxx', 95);
            // updated weight is accurately set as the sum of
            // overlapping individual gap weights
            expect(extendedGap).toEqual({ firstKey: 'baz', lastKey: 'quz', weight: 95 });
            expect(gapSet.toArray()).toEqual([
                { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                { firstKey: 'baz', lastKey: 'quz', weight: 95 },
            ]);
        });
        it('should extend a gap with overlap with next gap and large weight', () => {
            const extendedGap = gapSet.setGap('bar', 'quxxx', 80);
            // updated weight is heuristically chosen to be the new
            // gap weight which is larger than the sum of the existing merged
            // gap weights
            expect(extendedGap).toEqual({ firstKey: 'bar', lastKey: 'quz', weight: 80 });
            expect(gapSet.toArray()).toEqual([
                { firstKey: 'bar', lastKey: 'quz', weight: 80 },
            ]);
        });
        it('should extend a gap with overlap with next gap and small weight', () => {
            const extendedGap = gapSet.setGap('bar', 'quxxx', 11);
            // updated weight is heuristically chosen to be the sum of the existing merged
            // gap weights which is larger than the new gap weight
            expect(extendedGap).toEqual({ firstKey: 'bar', lastKey: 'quz', weight: 10 + 20 });
            expect(gapSet.toArray()).toEqual([
                { firstKey: 'bar', lastKey: 'quz', weight: 10 + 20 },
            ]);
        });
        it('should extend a gap with overlap beyond last key of next gap', () => {
            const extendedGap = gapSet.setGap('bar', 'rat', 80);
            // updated weight is the new gap weight
            expect(extendedGap).toEqual({ firstKey: 'bar', lastKey: 'rat', weight: 80 });
            expect(gapSet.toArray()).toEqual([
                { firstKey: 'bar', lastKey: 'rat', weight: 80 },
            ]);
        });
        it('should extend a gap with overlap beyond last key of next gap with a chained gap ' +
        'if above maxWeight', () => {
            // gapSet was initialized with maxWeight=100
            const extendedGap = gapSet.setGap('bar', 'rat', 105);
            // returned new gap is the right-side chained gap
            // updated weight is the new gap weight minus the left-side chained gap's weight
            expect(extendedGap).toEqual({ firstKey: 'baz', lastKey: 'rat', weight: 105 - 10 });
            expect(gapSet.toArray()).toEqual([
                { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                { firstKey: 'baz', lastKey: 'rat', weight: 105 - 10 },
            ]);
        });
        it('should extend a single-key gap with overlap on chained gaps', () => {
            // existing gap: 'ape' -> 'ape' (weight=1)
            const extendedGap = gapSetWithChain.setGap('ape', 'dog', 30);
            // updated weight heuristically including the new gap
            // weight, which is larger than the overlapping gaps cumulated
            // weights (10+15=25)
            expect(extendedGap).toEqual({ firstKey: 'ape', lastKey: 'qux', weight: 30 });
            expect(gapSetWithChain.toArray()).toEqual([
                { firstKey: 'ape', lastKey: 'qux', weight: 30 },
                { firstKey: 'qux', lastKey: 'quz', weight: 20 },
                { firstKey: 'quz', lastKey: 'rat', weight: 25 },
                { firstKey: 'rat', lastKey: 'yak', weight: 30 },
            ]);
        });
        it('should merge and extend + update weight a gap with overlap not past end of chained gaps',
        () => {
            const extendedGap = gapSetWithChain.setGap('baz', 'sea', 80);
            expect(extendedGap).toEqual({ firstKey: 'baz', lastKey: 'yak', weight: 90 });
            expect(gapSetWithChain.toArray()).toEqual([
                { firstKey: 'ape', lastKey: 'ape', weight: 1 },
                { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                { firstKey: 'baz', lastKey: 'yak', weight: 90 },
            ]);
        });
        it('should merge and extend + update weight a gap with overlap past end of chained gaps',
        () => {
            const extendedGap = gapSetWithChain.setGap('baz', 'zoo', 95);
            expect(extendedGap).toEqual({ firstKey: 'baz', lastKey: 'zoo', weight: 95 });
            expect(gapSetWithChain.toArray()).toEqual([
                { firstKey: 'ape', lastKey: 'ape', weight: 1 },
                { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                { firstKey: 'baz', lastKey: 'zoo', weight: 95 },
            ]);
        });
        it('should extend gap + update weight with overlap past end of chained gaps and ' +
        'above maxWeight', () => {
            const extendedGap = gapSetWithChain.setGap('baz', 'zoo', 105);
            // updated weight is the new gap weight minus the left-side chained gap's weight
            expect(extendedGap).toEqual({ firstKey: 'qux', lastKey: 'zoo', weight: 105 - 15 });
            expect(gapSetWithChain.toArray()).toEqual([
                { firstKey: 'ape', lastKey: 'ape', weight: 1 },
                { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                { firstKey: 'baz', lastKey: 'qux', weight: 15 },
                { firstKey: 'qux', lastKey: 'zoo', weight: 105 - 15 },
            ]);
        });
        it('should return existing chained gap with overlap above maxWeight', () => {
            const chainedGapsArray = [
                { firstKey: 'ant', lastKey: 'cat', weight: 90 },
                { firstKey: 'cat', lastKey: 'fox', weight: 40 },
            ];
            const chainedGapsSet = GapSet.createFromArray(chainedGapsArray, 100);
            const extendedGap = chainedGapsSet.setGap('bat', 'dog', 105);
            expect(extendedGap).toEqual({ firstKey: 'cat', lastKey: 'fox', weight: 40 });
            expect(chainedGapsSet.toArray()).toEqual([
                { firstKey: 'ant', lastKey: 'cat', weight: 90 },
                { firstKey: 'cat', lastKey: 'fox', weight: 40 },
            ]);
        });
        it('should merge but not extend nor update weight with overlap on chained gaps', () => {
            // existing chained gap: 'baz' -> 'qux'
            const extendedGap = gapSetWithChain.setGap('baz', 'quxxx', 25);
            // updated weight is the sum of the two merged gap's weights
            expect(extendedGap).toEqual({ firstKey: 'baz', lastKey: 'quz', weight: 15 + 20 });
            expect(gapSetWithChain.toArray()).toEqual([
                { firstKey: 'ape', lastKey: 'ape', weight: 1 },
                { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                { firstKey: 'baz', lastKey: 'quz', weight: 15 + 20 },
                { firstKey: 'quz', lastKey: 'rat', weight: 25 },
                { firstKey: 'rat', lastKey: 'yak', weight: 30 },
            ]);
        });
    });
    describe('GapSet::removeOverlappingGaps()', () => {
        describe('with zero key as parameter', () => {
            it('passed in an array: should not remove any gap', () => {
                const nRemoved = gapSet.removeOverlappingGaps([]);
                expect(nRemoved).toEqual(0);
                expect(gapSet.toArray()).toEqual(INITIAL_GAPSET);
            });
            it('passed in a OrderedSet: should not remove any gap', () => {
                const nRemoved = gapSet.removeOverlappingGaps(new OrderedSet());
                expect(nRemoved).toEqual(0);
                expect(gapSet.toArray()).toEqual(INITIAL_GAPSET);
            });
        });
        describe('with an array of one key as parameter', () => {
            it('should not remove any gap if no overlap', () => {
                const nRemoved = gapSet.removeOverlappingGaps(['rat']);
                expect(nRemoved).toEqual(0);
                expect(gapSet.toArray()).toEqual(INITIAL_GAPSET);
            });
            it('should remove a single gap if overlaps', () => {
                const nRemoved = gapSet.removeOverlappingGaps(['bat']);
                expect(nRemoved).toEqual(1);
                expect(gapSet.toArray()).toEqual([
                    // removed: { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                    { firstKey: 'qux', lastKey: 'quz', weight: 20 },
                ]);
            });
            it('should remove a single gap if overlaps with first key of first gap', () => {
                const nRemoved = gapSet.removeOverlappingGaps(['bar']);
                expect(nRemoved).toEqual(1);
                expect(gapSet.toArray()).toEqual([
                    // removed: { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                    { firstKey: 'qux', lastKey: 'quz', weight: 20 },
                ]);
            });
            it('should remove a single gap if overlaps with first key of non-first gap', () => {
                const nRemoved = gapSet.removeOverlappingGaps(['qux']);
                expect(nRemoved).toEqual(1);
                expect(gapSet.toArray()).toEqual([
                    { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                    // removed: { firstKey: 'qux', lastKey: 'quz', weight: 20 },
                ]);
            });
            it('should remove a single gap if overlaps with last key', () => {
                const nRemoved = gapSet.removeOverlappingGaps(['quz']);
                expect(nRemoved).toEqual(1);
                expect(gapSet.toArray()).toEqual([
                    { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                    // removed: { firstKey: 'qux', lastKey: 'quz', weight: 20 },
                ]);
            });
            it('should remove a single gap in chain if overlaps with one chained gap', () => {
                const nRemoved = gapSetWithChain.removeOverlappingGaps(['dog']);
                expect(nRemoved).toEqual(1);
                expect(gapSetWithChain.toArray()).toEqual([
                    { firstKey: 'ape', lastKey: 'ape', weight: 1 },
                    { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                    // removed: { firstKey: 'baz', lastKey: 'qux', weight: 15 },
                    { firstKey: 'qux', lastKey: 'quz', weight: 20 },
                    { firstKey: 'quz', lastKey: 'rat', weight: 25 },
                    { firstKey: 'rat', lastKey: 'yak', weight: 30 },
                ]);
            });
            it('should remove two gaps in chain if overlaps with two chained gap', () => {
                const nRemoved = gapSetWithChain.removeOverlappingGaps(['qux']);
                expect(nRemoved).toEqual(2);
                expect(gapSetWithChain.toArray()).toEqual([
                    { firstKey: 'ape', lastKey: 'ape', weight: 1 },
                    { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                    // removed: { firstKey: 'baz', lastKey: 'qux', weight: 15 },
                    // removed: { firstKey: 'qux', lastKey: 'quz', weight: 20 },
                    { firstKey: 'quz', lastKey: 'rat', weight: 25 },
                    { firstKey: 'rat', lastKey: 'yak', weight: 30 },
                ]);
            });
        });
        describe('with an array of two keys as parameter', () => {
            it('should not remove any gap if no overlap', () => {
                const nRemoved = gapSet.removeOverlappingGaps(['rat', `rat\0v100`]);
                expect(nRemoved).toEqual(0);
                expect(gapSet.toArray()).toEqual(INITIAL_GAPSET);
            });
            it('should remove a single gap if both keys overlap', () => {
                const nRemoved = gapSet.removeOverlappingGaps(['bat', 'bat\0v100']);
                expect(nRemoved).toEqual(1);
                expect(gapSet.toArray()).toEqual([
                    // removed: { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                    { firstKey: 'qux', lastKey: 'quz', weight: 20 },
                ]);
            });
            it('should remove a single gap if min key overlaps with first key of first gap', () => {
                const nRemoved = gapSet.removeOverlappingGaps(['bar\0v100', 'bar']);
                expect(nRemoved).toEqual(1);
                expect(gapSet.toArray()).toEqual([
                    // removed: { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                    { firstKey: 'qux', lastKey: 'quz', weight: 20 },
                ]);
            });
            it('should remove a single gap if max key overlaps with first key of first gap', () => {
                const nRemoved = gapSet.removeOverlappingGaps(['ape', 'bar']);
                expect(nRemoved).toEqual(1);
                expect(gapSet.toArray()).toEqual([
                    // removed: { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                    { firstKey: 'qux', lastKey: 'quz', weight: 20 },
                ]);
            });
            it('should not remove any gap if both keys straddle an existing gap without overlap',
            () => {
                const nRemoved = gapSet.removeOverlappingGaps(['cow', 'ape']);
                expect(nRemoved).toEqual(0);
                expect(gapSet.toArray()).toEqual([
                    { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                    { firstKey: 'qux', lastKey: 'quz', weight: 20 },
                ]);
            });
            it('should remove the two last gaps in chained gaps if last gap bounds match ' +
            'the two keys', () => {
                const nRemoved = gapSetWithChain.removeOverlappingGaps(['yak', 'rat']);
                expect(nRemoved).toEqual(2);
                expect(gapSetWithChain.toArray()).toEqual([
                    { firstKey: 'ape', lastKey: 'ape', weight: 1 },
                    { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                    { firstKey: 'baz', lastKey: 'qux', weight: 15 },
                    { firstKey: 'qux', lastKey: 'quz', weight: 20 },
                    // removed: { firstKey: 'quz', lastKey: 'rat', weight: 25 },
                    // removed: { firstKey: 'rat', lastKey: 'yak', weight: 30 },
                ]);
            });
            it('should remove first and last gap in chained gaps if their bounds match ' +
            'the two keys', () => {
                const nRemoved = gapSetWithChain.removeOverlappingGaps(['yak', 'bar']);
                expect(nRemoved).toEqual(2);
                expect(gapSetWithChain.toArray()).toEqual([
                    { firstKey: 'ape', lastKey: 'ape', weight: 1 },
                    // removed: { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                    { firstKey: 'baz', lastKey: 'qux', weight: 15 },
                    { firstKey: 'qux', lastKey: 'quz', weight: 20 },
                    { firstKey: 'quz', lastKey: 'rat', weight: 25 },
                    // removed: { firstKey: 'rat', lastKey: 'yak', weight: 30 },
                ]);
            });
        });
        describe('with an array of three keys as parameter', () => {
            it('should remove a single gap if only median key overlaps with gap', () => {
                const nRemoved = gapSet.removeOverlappingGaps(['ape', 'bat', 'cow']);
                expect(nRemoved).toEqual(1);
                expect(gapSet.toArray()).toEqual([
                    // removed: { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                    { firstKey: 'qux', lastKey: 'quz', weight: 20 },
                ]);
            });
            it('should remove a single-key gap and two contiguous chained gaps each overlapping' +
            'with one key', () => {
                const nRemoved = gapSetWithChain.removeOverlappingGaps(['ape', 'bat', 'cow']);
                expect(nRemoved).toEqual(3);
                expect(gapSetWithChain.toArray()).toEqual([
                    // removed: { firstKey: 'ape', lastKey: 'ape', weight: 1 },
                    // removed: { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                    // removed: { firstKey: 'baz', lastKey: 'qux', weight: 15 },
                    { firstKey: 'qux', lastKey: 'quz', weight: 20 },
                    { firstKey: 'quz', lastKey: 'rat', weight: 25 },
                    { firstKey: 'rat', lastKey: 'yak', weight: 30 },
                ]);
            });
            it('should not remove any gap if all keys are intermingled but do not overlap', () => {
                const nRemoved = gapSet.removeOverlappingGaps(['ape', 'rat', 'cow']);
                expect(nRemoved).toEqual(0);
                expect(gapSet.toArray()).toEqual([
                    { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                    { firstKey: 'qux', lastKey: 'quz', weight: 20 },
                ]);
            });
            it('should remove three discontiguous chained gaps each overlapping with one key', () => {
                const nRemoved = gapSetWithChain.removeOverlappingGaps(['bat', 'quxxx', 'tiger']);
                expect(nRemoved).toEqual(3);
                expect(gapSetWithChain.toArray()).toEqual([
                    { firstKey: 'ape', lastKey: 'ape', weight: 1 },
                    // removed: { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                    { firstKey: 'baz', lastKey: 'qux', weight: 15 },
                    // removed: { firstKey: 'qux', lastKey: 'quz', weight: 20 },
                    { firstKey: 'quz', lastKey: 'rat', weight: 25 },
                    // { firstKey: 'rat', lastKey: 'yak', weight: 30 },
                ]);
            });
        });
        describe('with a OrderedSet of three keys as parameter', () => {
            it('should remove a single gap if only median key overlaps with gap', () => {
                const nRemoved = gapSet.removeOverlappingGaps(
                    new OrderedSet(['ape', 'bat', 'cow']));
                expect(nRemoved).toEqual(1);
                expect(gapSet.toArray()).toEqual([
                    // removed: { firstKey: 'bar', lastKey: 'baz', weight: 10 },
                    { firstKey: 'qux', lastKey: 'quz', weight: 20 },
                ]);
            });
        });
        // this helper checks that:
        // - the gaps not overlapping with any key are still present in newGapsArray
        // - and the gaps overlapping with at least one key have been removed from oldGapsArray
        // NOTE: It uses a sorted list of keys for efficiency, otherwise it would require
        // O(n^2) compute time which would be expensive with 50K keys.
        function checkOverlapInvariant(sortedKeys, oldGapsArray, newGapsArray) {
            let oldGapIdx = 0;
            let newGapIdx = 0;
            for (const key of sortedKeys) {
                // for all gaps not overlapping with any key in 'sortedKeys',
                // check that they are still in 'newGapsArray'
                while (oldGapIdx < oldGapsArray.length &&
                       oldGapsArray[oldGapIdx].lastKey < key) {
                    expect(oldGapsArray[oldGapIdx]).toEqual(newGapsArray[newGapIdx]);
                    oldGapIdx += 1;
                    newGapIdx += 1;
                }
                // for the gap(s) overlapping with the current key,
                // check that they have been removed from 'newGapsArray'
                while (oldGapIdx < oldGapsArray.length &&
                       oldGapsArray[oldGapIdx].firstKey <= key) {
                    if (newGapIdx < newGapsArray.length) {
                        expect(oldGapsArray[oldGapIdx]).not.toEqual(newGapsArray[newGapIdx]);
                    }
                    ++oldGapIdx;
                }
            }
            // check the range after the last key in 'sortedKeys'
            while (oldGapIdx < oldGapsArray.length) {
                expect(oldGapsArray[oldGapIdx]).toEqual(newGapsArray[newGapIdx]);
                oldGapIdx += 1;
                newGapIdx += 1;
            }
            // check that no extra range is in newGapsArray
            expect(newGapIdx).toEqual(newGapsArray.length);
        }
        [false, true].forEach(chained => {
            describe(`with 10K random ${chained ? 'chained' : 'unchained'} gaps`, () => {
                let largeGapsArray;
                let largeGapSet;
                beforeEach(() => {
                    largeGapsArray = chained ?
                        genRandomChainedGaps(10000) :
                        genRandomUnchainedGaps(10000);
                    largeGapSet = GapSet.createFromArray(largeGapsArray, 100);
                });
                [{
                    desc: 'equal to their first key',
                    getGapKey: gap => gap.firstKey,
                }, {
                    desc: 'equal to their last key',
                    getGapKey: gap => gap.lastKey,
                }, {
                    desc: 'neither their first nor last key',
                    getGapKey: gap => `${gap.firstKey}/foo`,
                }].forEach(testCase => {
                    it(`should remove the overlapping gap(s) with one key ${testCase.desc}`, () => {
                        const gapIndex = 5000;
                        const gap = largeGapsArray[gapIndex];
                        const overlappingKey = testCase.getGapKey(gap);
                        const nRemoved = largeGapSet.removeOverlappingGaps([overlappingKey]);
                        let firstRemovedGapIndex, lastRemovedGapIndex;
                        if (chained && overlappingKey === gap.firstKey) {
                            expect(nRemoved).toEqual(2);
                            [firstRemovedGapIndex, lastRemovedGapIndex] = [4999, 5000];
                        } else if (chained && overlappingKey === gap.lastKey) {
                            expect(nRemoved).toEqual(2);
                            [firstRemovedGapIndex, lastRemovedGapIndex] = [5000, 5001];
                        } else {
                            expect(nRemoved).toEqual(1);
                            [firstRemovedGapIndex, lastRemovedGapIndex] = [5000, 5000];
                        }
                        const expectedGaps = [
                            ...largeGapsArray.slice(0, firstRemovedGapIndex),
                            ...largeGapsArray.slice(lastRemovedGapIndex + 1)
                        ];
                        const newGaps = largeGapSet.toArray();
                        expect(newGaps).toEqual(expectedGaps);
                    });
                    it(`should remove all gaps when they all overlap with one key ${testCase.desc}`,
                       () => {
                           // simulate a scenario made of 200 batches of 50 operations, each with
                           // random keys scattered across all gaps that each overlaps a distinct gap
                           // (supposedly a worst-case performance scenario for such batch sizes)
                           const overlappingKeys = largeGapsArray.map(testCase.getGapKey);
                           shuffleArray(overlappingKeys);
                           for (let i = 0; i < overlappingKeys.length; i += 50) {
                               const nRemoved = largeGapSet.removeOverlappingGaps(
                                   overlappingKeys.slice(i, i + 50));
                               // with unchained gaps, we expect to have removed exactly
                               // 50 gaps (the size of 'overlappingKeys').
                               if (!chained) {
                                   expect(nRemoved).toEqual(50);
                               }
                           }
                           const newGaps = largeGapSet.toArray();
                           expect(newGaps).toEqual([]);
                       });
                });
                it('should remove only and all overlapping gaps with 50K randomized keys', () => {
                    const randomizedKeys = new Array(50000).fill(undefined).map(
                        () => genRandomKey()
                    );
                    for (let i = 0; i < randomizedKeys.length; i += 50) {
                        largeGapSet.removeOverlappingGaps(
                            randomizedKeys.slice(i, i + 50));
                    }
                    const newGaps = largeGapSet.toArray();
                    randomizedKeys.sort();
                    checkOverlapInvariant(randomizedKeys, largeGapsArray, newGaps);
                });
            });
        });
    });
    describe('GapSet::_coalesceGapChain()', () => {
        afterEach(() => {
            // check that the gap sets were not modified by the operation
            expect(gapSet.toArray()).toEqual(INITIAL_GAPSET);
            expect(gapSetWithChain.toArray()).toEqual(INITIAL_GAPSET_WITH_CHAIN);
        });
        it('should not coalesce if gaps are not chained', async () => {
            const gap = { firstKey: 'bar', lastKey: 'baz', weight: 10 };
            const coalescedGap = await gapSet._coalesceGapChain(gap);
            expect(coalescedGap).toEqual({ firstKey: 'bar', lastKey: 'baz', weight: 10 });
        });
        it('should coalesce one chained gap', async () => {
            const gap = { firstKey: 'quz', lastKey: 'rat', weight: 25 };
            const coalescedGap = await gapSetWithChain._coalesceGapChain(gap);
            expect(coalescedGap).toEqual({ firstKey: 'quz', lastKey: 'yak', weight: 55 });
        });
        it('should coalesce a chain of five gaps', async () => {
            const gap = { firstKey: 'bar', lastKey: 'baz', weight: 10 };
            const coalescedGap = await gapSetWithChain._coalesceGapChain(gap);
            expect(coalescedGap).toEqual({ firstKey: 'bar', lastKey: 'yak', weight: 100 });
        });
        it('should coalesce a chain of one thousand gaps', async () => {
            const getKey = i => `000${i}`.slice(-4);
            const thousandGapsArray = new Array(1000).fill(undefined).map(
                (_, i) => ({ firstKey: getKey(i), lastKey: getKey(i + 1), weight: 10 })
            );
            const thousandGapsSet = GapSet.createFromArray(thousandGapsArray, 100);
            const gap = { firstKey: '0000', lastKey: '0001', weight: 10 };
            const coalescedGap = await thousandGapsSet._coalesceGapChain(gap);
            expect(coalescedGap).toEqual({ firstKey: '0000', lastKey: '1000', weight: 10000 });
        });
        it('should coalesce a single-key gap', async () => {
            const singleKeyGapSet = GapSet.createFromArray([
                { firstKey: '0000', lastKey: '0000', weight: 1 },
            ], 100);
            const gap = { firstKey: '0000', lastKey: '0000', weight: 1 };
            const coalescedGap = await singleKeyGapSet._coalesceGapChain(gap);
            expect(coalescedGap).toEqual({ firstKey: '0000', lastKey: '0000', weight: 1 });
        });
        it('should coalesce a chain of two gaps ending with a single-key gap', async () => {
            const singleKeyGapSet = GapSet.createFromArray([
                { firstKey: '0000', lastKey: '0003', weight: 9 },
                { firstKey: '0003', lastKey: '0003', weight: 1 },
            ], 100);
            const gap = { firstKey: '0000', lastKey: '0003', weight: 9 };
            const coalescedGap = await singleKeyGapSet._coalesceGapChain(gap);
            expect(coalescedGap).toEqual({ firstKey: '0000', lastKey: '0003', weight: 9 });
        });
    });
    describe('GapSet::lookupGap()', () => {
        afterEach(() => {
            // check that the gap sets were not modified by the operation
            expect(gapSet.toArray()).toEqual(INITIAL_GAPSET);
            expect(gapSetWithChain.toArray()).toEqual(INITIAL_GAPSET_WITH_CHAIN);
        });
        it('should return null with empty cache', async () => {
            const emptyGapSet = new GapSet(100);
            const gap = await emptyGapSet.lookupGap('cat', 'dog');
            expect(gap).toBeNull();
        });
        it('should return null if no gap overlaps [minKey, maxKey]', async () => {
            const gap = await gapSet.lookupGap('cat', 'dog');
            expect(gap).toBeNull();
        });
        it('should return the first gap that overlaps if all gaps overlap', async () => {
            const gap = await gapSet.lookupGap('ape', 'zoo');
            expect(gap).toEqual({ firstKey: 'bar', lastKey: 'baz', weight: 10 });
        });
        it('should return an existing gap that contains [minKey, maxKey]', async () => {
            const gap1 = await gapSet.lookupGap('bat', 'bay');
            expect(gap1).toEqual({ firstKey: 'bar', lastKey: 'baz', weight: 10 });
            const gap2 = await gapSet.lookupGap('quxxx', 'quy');
            expect(gap2).toEqual({ firstKey: 'qux', lastKey: 'quz', weight: 20 });
        });
        it('should return an existing gap that overlaps with minKey but not maxKey', async () => {
            const gap = await gapSet.lookupGap('ape', 'bat');
            expect(gap).toEqual({ firstKey: 'bar', lastKey: 'baz', weight: 10 });
        });
        it('should return an existing gap that overlaps just with minKey when no maxKey is provided',
        async () => {
            const gap = await gapSet.lookupGap('ape');
            expect(gap).toEqual({ firstKey: 'bar', lastKey: 'baz', weight: 10 });
        });
        it('should return an existing gap that overlaps with maxKey but not minKey', async () => {
            const gap = await gapSet.lookupGap('bat', 'cat');
            expect(gap).toEqual({ firstKey: 'bar', lastKey: 'baz', weight: 10 });
        });
        it('should return an existing gap that is contained in [minKey, maxKey] strictly', async () => {
            const gap = await gapSet.lookupGap('dog', 'rat');
            expect(gap).toEqual({ firstKey: 'qux', lastKey: 'quz', weight: 20 });
        });
        it('should return a coalesced gap from chained gaps that fully overlaps [minKey, maxKey]', async () => {
            const gap = await gapSetWithChain.lookupGap('bat', 'zoo');
            expect(gap).toEqual({ firstKey: 'bar', lastKey: 'yak', weight: 100 });
        });
        it('should return a coalesced gap from chained gaps that contain [minKey, maxKey] strictly',
        async () => {
            const gap = await gapSetWithChain.lookupGap('bog', 'dog');
            expect(gap).toEqual({ firstKey: 'baz', lastKey: 'yak', weight: 90 });
        });
    });
 });
--- a/tests/unit/algos/list/delimiter.spec.js
+++ b/tests/unit/algos/list/delimiter.spec.js
@ -7,17 +7,23 @@ const DelimiterMaster =
    require('../../../../lib/algos/list/delimiterMaster').DelimiterMaster;
 const Werelogs = require('werelogs').Logger;
 const logger = new Werelogs('listTest');
 const performListing = require('../../../utils/performListing');
 const zpad = require('../../helpers').zpad;
 const { inc } = require('../../../../lib/algos/list/tools');
 const VSConst = require('../../../../lib/versioning/constants').VersioningConstants;
 const { DbPrefixes } = VSConst;
 class Test {
-    constructor(name, input, genMDParams, output) {
+    constructor(name, input, genMDParams, output, filter) {
        this.name = name;
        this.input = input;
        this.genMDParams = genMDParams;
        this.output = output;
        this.filter = filter || this._defaultFilter;
    }
    _defaultFilter() {
        return true;
    }
 }
@ -27,7 +33,7 @@ const valueDeleteMarker = '{"hello":"world","isDeleteMarker":"true"}';
 const data = [
    { key: 'Pâtisserie=中文-español-English', value },
    { key: 'notes/spring/1.txt', value },
-    { key: 'notes/spring/4.txt', value },
+    { key: 'notes/spring/2.txt', value },
    { key: 'notes/spring/march/1.txt', value },
    { key: 'notes/summer/1.txt', value },
    { key: 'notes/summer/2.txt', value },
@ -50,9 +56,6 @@ const dataVersioned = [
    { key: 'notes/spring/2.txt\0foo', value },
    { key: 'notes/spring/3.txt', value: valueDeleteMarker },
    { key: 'notes/spring/3.txt\0foo', value },
    { key: 'notes/spring/4.txt', value: valuePHD },
    { key: 'notes/spring/4.txt\0bar', value },
    { key: 'notes/spring/4.txt\0foo', value },
    { key: 'notes/spring/march/1.txt', value },
    { key: 'notes/spring/march/1.txt\0bar', value },
    { key: 'notes/spring/march/1.txt\0foo', value },
@ -75,8 +78,15 @@ const dataVersioned = [
    { key: 'notes/yore.rs', value },
    { key: 'notes/zaphod/Beeblebrox.txt', value },
 ];
 const nonAlphabeticalData = [
    { key: 'zzz', value },
    { key: 'aaa', value },
 ];
 const receivedData = data.map(item => ({ key: item.key, value: item.value }));
 const receivedNonAlphaData = nonAlphabeticalData.map(
    item => ({ key: item.key, value: item.value }),
 );
 const tests = [
    new Test('all elements', {}, {
@ -114,7 +124,7 @@ const tests = [
        Delimiter: undefined,
        IsTruncated: false,
        NextMarker: undefined,
-    }),
+    }, (e, input) => e.key > input.marker),
    new Test('with bad marker', {
        marker: 'zzzz',
        delimiter: '/',
@ -132,7 +142,7 @@ const tests = [
        Delimiter: '/',
        IsTruncated: false,
        NextMarker: undefined,
-    }),
+    }, (e, input) => e.key > input.marker),
    new Test('with makKeys', {
        maxKeys: 3,
    }, {
@ -209,12 +219,12 @@ const tests = [
        marker: 'notes/summer0',
    }, {
        v0: {
-            gt: 'notes/summer0',
+            gt: `notes/summer${inc('/')}`,
-            lt: 'notes/summer0',
+            lt: `notes/summer${inc('/')}`,
        },
        v1: {
-            gt: `${DbPrefixes.Master}notes/summer0`,
+            gt: `${DbPrefixes.Master}notes/summer${inc('/')}`,
-            lt: `${DbPrefixes.Master}notes/summer0`,
+            lt: `${DbPrefixes.Master}notes/summer${inc('/')}`,
        },
    }, {
        Contents: [],
@ -222,18 +232,18 @@ const tests = [
        Delimiter: '/',
        IsTruncated: false,
        NextMarker: undefined,
-    }),
+    }, (e, input) => e.key > input.marker),
    new Test('delimiter and prefix (related to #147)', {
        delimiter: '/',
        prefix: 'notes/',
    }, {
        v0: {
            gte: 'notes/',
-            lt: 'notes0',
+            lt: `notes${inc('/')}`,
        },
        v1: {
            gte: `${DbPrefixes.Master}notes/`,
-            lt: `${DbPrefixes.Master}notes0`,
+            lt: `${DbPrefixes.Master}notes${inc('/')}`,
        },
    }, {
        Contents: [
@ -256,11 +266,11 @@ const tests = [
    }, {
        v0: {
            gt: 'notes/year.txt',
-            lt: 'notes0',
+            lt: `notes${inc('/')}`,
        },
        v1: {
            gt: `${DbPrefixes.Master}notes/year.txt`,
-            lt: `${DbPrefixes.Master}notes0`,
+            lt: `${DbPrefixes.Master}notes${inc('/')}`,
        },
    }, {
        Contents: [
@ -272,8 +282,8 @@ const tests = [
        Delimiter: '/',
        IsTruncated: false,
        NextMarker: undefined,
-    }),
+    }, (e, input) => e.key > input.marker),
-    new Test('all parameters 1/5', {
+    new Test('all parameters 1/3', {
        delimiter: '/',
        prefix: 'notes/',
        marker: 'notes/',
@ -281,11 +291,11 @@ const tests = [
    }, {
        v0: {
            gt: 'notes/',
-            lt: 'notes0',
+            lt: `notes${inc('/')}`,
        },
        v1: {
            gt: `${DbPrefixes.Master}notes/`,
-            lt: `${DbPrefixes.Master}notes0`,
+            lt: `${DbPrefixes.Master}notes${inc('/')}`,
        },
    }, {
        Contents: [],
@ -293,21 +303,21 @@ const tests = [
        Delimiter: '/',
        IsTruncated: true,
        NextMarker: 'notes/spring/',
-    }),
+    }, (e, input) => e.key > input.marker),
-    new Test('all parameters 2/5', {
+    new Test('all parameters 2/3', {
        delimiter: '/',
-        prefix: 'notes/',
+        prefix: 'notes/', // prefix
        marker: 'notes/spring/',
        maxKeys: 1,
    }, {
        v0: {
-            gte: 'notes/spring0',
+            gt: 'notes/spring/',
-            lt: 'notes0',
+            lt: `notes${inc('/')}`,
        },
        v1: {
-            gte: `${DbPrefixes.Master}notes/spring0`,
+            gt: `${DbPrefixes.Master}notes/spring/`,
-            lt: `${DbPrefixes.Master}notes0`,
+            lt: `${DbPrefixes.Master}notes${inc('/')}`,
        },
    }, {
        Contents: [],
@ -315,21 +325,21 @@ const tests = [
        Delimiter: '/',
        IsTruncated: true,
        NextMarker: 'notes/summer/',
-    }),
+    }, (e, input) => e.key > input.marker),
-    new Test('all parameters 3/5', {
+    new Test('all parameters 3/3', {
        delimiter: '/',
-        prefix: 'notes/',
+        prefix: 'notes/', // prefix
        marker: 'notes/summer/',
        maxKeys: 1,
    }, {
        v0: {
-            gte: 'notes/summer0',
+            gt: 'notes/summer/',
-            lt: 'notes0',
+            lt: `notes${inc('/')}`,
        },
        v1: {
-            gte: `${DbPrefixes.Master}notes/summer0`,
+            gt: `${DbPrefixes.Master}notes/summer/`,
-            lt: `${DbPrefixes.Master}notes0`,
+            lt: `${DbPrefixes.Master}notes${inc('/')}`,
        },
    }, {
        Contents: [
@ -339,21 +349,21 @@ const tests = [
        Delimiter: '/',
        IsTruncated: true,
        NextMarker: 'notes/year.txt',
-    }),
+    }, (e, input) => e.key > input.marker),
-    new Test('all parameters 4/5', {
+    new Test('all parameters 4/3', {
        delimiter: '/',
-        prefix: 'notes/',
+        prefix: 'notes/', // prefix
        marker: 'notes/year.txt',
        maxKeys: 1,
    }, {
        v0: {
            gt: 'notes/year.txt',
-            lt: 'notes0',
+            lt: `notes${inc('/')}`,
        },
        v1: {
            gt: `${DbPrefixes.Master}notes/year.txt`,
-            lt: `${DbPrefixes.Master}notes0`,
+            lt: `${DbPrefixes.Master}notes${inc('/')}`,
        },
    }, {
        Contents: [
@ -363,9 +373,9 @@ const tests = [
        Delimiter: '/',
        IsTruncated: true,
        NextMarker: 'notes/yore.rs',
-    }),
+    }, (e, input) => e.key > input.marker),
-    new Test('all parameters 5/5', {
+    new Test('all parameters 5/3', {
        delimiter: '/',
        prefix: 'notes/',
        marker: 'notes/yore.rs',
@ -373,11 +383,11 @@ const tests = [
    }, {
        v0: {
            gt: 'notes/yore.rs',
-            lt: 'notes0',
+            lt: `notes${inc('/')}`,
        },
        v1: {
            gt: `${DbPrefixes.Master}notes/yore.rs`,
-            lt: `${DbPrefixes.Master}notes0`,
+            lt: `${DbPrefixes.Master}notes${inc('/')}`,
        },
    }, {
        Contents: [],
@ -385,29 +395,7 @@ const tests = [
        Delimiter: '/',
        IsTruncated: false,
        NextMarker: undefined,
-    }),
+    }, (e, input) => e.key > input.marker),
    new Test('marker inside common prefix', {
        delimiter: '/',
        prefix: 'notes/',
        marker: 'notes/spring/1.txt',
        maxKeys: 1,
    }, {
        v0: {
            gte: 'notes/spring0',
            lt: 'notes0',
        },
        v1: {
            gte: `${DbPrefixes.Master}notes/spring0`,
            lt: `${DbPrefixes.Master}notes0`,
        },
    }, {
        Contents: [],
        CommonPrefixes: ['notes/summer/'],
        Delimiter: '/',
        IsTruncated: true,
        NextMarker: 'notes/summer/',
    }),
    new Test('all elements v2', {
        v2: true,
@ -447,7 +435,7 @@ const tests = [
        Delimiter: undefined,
        IsTruncated: false,
        NextContinuationToken: undefined,
-    }),
+    }, (e, input) => e.key > input.startAfter),
    new Test('with bad startAfter', {
        startAfter: 'zzzz',
        delimiter: '/',
@ -466,7 +454,7 @@ const tests = [
        Delimiter: '/',
        IsTruncated: false,
        NextContinuationToken: undefined,
-    }),
+    }, (e, input) => e.key > input.startAfter),
    new Test('with valid continuationToken', {
        continuationToken: receivedData[4].key,
        v2: true,
@ -490,7 +478,7 @@ const tests = [
        Delimiter: undefined,
        IsTruncated: false,
        NextContinuationToken: undefined,
-    }),
+    }, (e, input) => e.key > input.continuationToken),
    new Test('with bad continuationToken', {
        continuationToken: 'zzzz',
        delimiter: '/',
@ -509,49 +497,47 @@ const tests = [
        Delimiter: '/',
        IsTruncated: false,
        NextContinuationToken: undefined,
-    }),
+    }, (e, input) => e.key > input.continuationToken),
    new Test('bad startAfter and good prefix', {
        delimiter: '/',
        prefix: 'notes/summer/',
        startAfter: 'notes/summer0',
        v2: true,
    }, {
        v0: {
-            gt: 'notes/summer0',
+            gte: 'notes/summer/',
-            lt: 'notes/summer0',
+            lt: `notes/summer${inc('/')}`,
        },
        v1: {
-            gt: `${DbPrefixes.Master}notes/summer0`,
+            gte: `${DbPrefixes.Master}notes/summer/`,
-            lt: `${DbPrefixes.Master}notes/summer0`,
+            lt: `${DbPrefixes.Master}notes/summer${inc('/')}`,
        },
    }, {
        Contents: [],
        CommonPrefixes: [],
        Delimiter: '/',
        IsTruncated: false,
-        NextContinuationToken: undefined,
+        NextMarker: undefined,
-    }),
+    }, (e, input) => e.key > input.startAfter),
    new Test('bad continuation token and good prefix', {
        delimiter: '/',
        prefix: 'notes/summer/',
        continuationToken: 'notes/summer0',
        v2: true,
    }, {
        v0: {
-            gt: 'notes/summer0',
+            gte: 'notes/summer/',
-            lt: 'notes/summer0',
+            lt: `notes/summer${inc('/')}`,
        },
        v1: {
-            gt: `${DbPrefixes.Master}notes/summer0`,
+            gte: `${DbPrefixes.Master}notes/summer/`,
-            lt: `${DbPrefixes.Master}notes/summer0`,
+            lt: `${DbPrefixes.Master}notes/summer${inc('/')}`,
        },
    }, {
        Contents: [],
        CommonPrefixes: [],
        Delimiter: '/',
        IsTruncated: false,
-        NextContinuationToken: undefined,
+        NextMarker: undefined,
-    }),
+    }, (e, input) => e.key > input.continuationToken),
    new Test('no delimiter v2', {
        startAfter: 'notes/year.txt',
@ -573,9 +559,9 @@ const tests = [
        Delimiter: undefined,
        IsTruncated: true,
        NextContinuationToken: 'notes/yore.rs',
-    }),
+    }, (e, input) => e.key > input.startAfter),
-    new Test('all parameters v2 1/5', {
+    new Test('all parameters v2 1/6', {
        delimiter: '/',
        prefix: 'notes/',
        startAfter: 'notes/',
@ -584,11 +570,11 @@ const tests = [
    }, {
        v0: {
            gt: 'notes/',
-            lt: 'notes0',
+            lt: `notes${inc('/')}`,
        },
        v1: {
            gt: `${DbPrefixes.Master}notes/`,
-            lt: `${DbPrefixes.Master}notes0`,
+            lt: `${DbPrefixes.Master}notes${inc('/')}`,
        },
    }, {
        Contents: [],
@ -596,9 +582,9 @@ const tests = [
        Delimiter: '/',
        IsTruncated: true,
        NextContinuationToken: 'notes/spring/',
-    }),
+    }, (e, input) => e.key > input.startAfter),
-    new Test('all parameters v2 2/5', {
+    new Test('all parameters v2 2/6', {
        delimiter: '/',
        prefix: 'notes/',
        continuationToken: 'notes/spring/',
@ -606,12 +592,12 @@ const tests = [
        v2: true,
    }, {
        v0: {
-            gte: 'notes/spring0',
+            gt: 'notes/spring/',
-            lt: 'notes0',
+            lt: `notes${inc('/')}`,
        },
        v1: {
-            gte: `${DbPrefixes.Master}notes/spring0`,
+            gt: `${DbPrefixes.Master}notes/spring/`,
-            lt: `${DbPrefixes.Master}notes0`,
+            lt: `${DbPrefixes.Master}notes${inc('/')}`,
        },
    }, {
        Contents: [],
@ -619,7 +605,7 @@ const tests = [
        Delimiter: '/',
        IsTruncated: true,
        NextContinuationToken: 'notes/summer/',
-    }),
+    }, (e, input) => e.key > input.continuationToken),
    new Test('all parameters v2 3/5', {
        delimiter: '/',
@ -629,12 +615,12 @@ const tests = [
        v2: true,
    }, {
        v0: {
-            gte: 'notes/summer0',
+            gt: 'notes/summer/',
-            lt: 'notes0',
+            lt: `notes${inc('/')}`,
        },
        v1: {
-            gte: `${DbPrefixes.Master}notes/summer0`,
+            gt: `${DbPrefixes.Master}notes/summer/`,
-            lt: `${DbPrefixes.Master}notes0`,
+            lt: `${DbPrefixes.Master}notes${inc('/')}`,
        },
    }, {
        Contents: [
@ -644,7 +630,7 @@ const tests = [
        Delimiter: '/',
        IsTruncated: true,
        NextContinuationToken: 'notes/year.txt',
-    }),
+    }, (e, input) => e.key > input.continuationToken),
    new Test('all parameters v2 4/5', {
        delimiter: '/',
@ -655,11 +641,11 @@ const tests = [
    }, {
        v0: {
            gt: 'notes/year.txt',
-            lt: 'notes0',
+            lt: `notes${inc('/')}`,
        },
        v1: {
            gt: `${DbPrefixes.Master}notes/year.txt`,
-            lt: `${DbPrefixes.Master}notes0`,
+            lt: `${DbPrefixes.Master}notes${inc('/')}`,
        },
    }, {
        Contents: [
@ -669,7 +655,7 @@ const tests = [
        Delimiter: '/',
        IsTruncated: true,
        NextContinuationToken: 'notes/yore.rs',
-    }),
+    }, (e, input) => e.key > input.startAfter),
    new Test('all parameters v2 5/5', {
        delimiter: '/',
@ -680,11 +666,11 @@ const tests = [
    }, {
        v0: {
            gt: 'notes/yore.rs',
-            lt: 'notes0',
+            lt: `notes${inc('/')}`,
        },
        v1: {
            gt: `${DbPrefixes.Master}notes/yore.rs`,
-            lt: `${DbPrefixes.Master}notes0`,
+            lt: `${DbPrefixes.Master}notes${inc('/')}`,
        },
    }, {
        Contents: [],
@ -692,11 +678,35 @@ const tests = [
        Delimiter: '/',
        IsTruncated: false,
        NextContinuationToken: undefined,
-    }),
+    }, (e, input) => e.key > input.startAfter),
 ];
-function getTestListing(mdParams, data, vFormat) {
+const alphabeticalOrderTests = [
    {
        params: {},
        expectedValue: true,
    }, {
        params: {
            alphabeticalOrder: undefined,
        },
        expectedValue: true,
    }, {
        params: {
            alphabeticalOrder: true,
        },
        expectedValue: true,
    }, {
        params: {
            alphabeticalOrder: false,
        },
        expectedValue: false,
    },
 ];
 function getTestListing(test, data, vFormat) {
    return data
        .filter(e => test.filter(e, test.input))
        .map(obj => {
            if (vFormat === 'v0') {
                return obj;
@ -708,12 +718,7 @@ function getTestListing(mdParams, data, vFormat) {
                };
            }
            return assert.fail(`bad format ${vFormat}`);
-        })
+        });
        .filter(e =>
            (!mdParams.gt || e.key > mdParams.gt) &&
            (!mdParams.gte || e.key >= mdParams.gte) &&
            (!mdParams.lt || e.key < mdParams.lt),
        );
 }
 ['v0', 'v1'].forEach(vFormat => {
@ -727,7 +732,16 @@ function getTestListing(mdParams, data, vFormat) {
                });
            }
            assert.strictEqual(delimiter.skipping(),
-                `${vFormat === 'v1' ? DbPrefixes.Master : ''}foo0`);
+                `${vFormat === 'v1' ? DbPrefixes.Master : ''}foo/`);
        });
        it('Should set Delimiter alphabeticalOrder field to the expected value', () => {
            alphabeticalOrderTests.forEach(test => {
                const delimiter = new Delimiter(test.params);
                assert.strictEqual(delimiter.alphabeticalOrder,
                    test.expectedValue,
                    `${JSON.stringify(test.params)}`);
            });
        });
        tests.forEach(test => {
@ -737,13 +751,9 @@ function getTestListing(mdParams, data, vFormat) {
                assert.deepStrictEqual(params, test.genMDParams[vFormat]);
            });
            it(`Should list ${test.name}`, () => {
-                const listing = new Delimiter(test.input, logger, vFormat);
+                // Simulate skip scan done by LevelDB
-                const mdParams = listing.genMDParams();
+                const d = getTestListing(test, data, vFormat);
-                const rawEntries = getTestListing(mdParams, data, vFormat);
+                const res = performListing(d, Delimiter, test.input, logger, vFormat);
                for (const entry of rawEntries) {
                    listing.filter(entry);
                }
                const res = listing.result();
                assert.deepStrictEqual(res, test.output);
            });
        });
@ -752,16 +762,49 @@ function getTestListing(mdParams, data, vFormat) {
        if (vFormat === 'v0') {
            tests.forEach(test => {
                it(`Should list master versions ${test.name}`, () => {
-                    const listing = new DelimiterMaster(test.input, logger, vFormat);
+                    // Simulate skip scan done by LevelDB
-                    const mdParams = listing.genMDParams();
+                    const d = dataVersioned.filter(e => test.filter(e, test.input));
-                    const rawEntries = getTestListing(mdParams, dataVersioned, vFormat);
+                    const res = performListing(d, DelimiterMaster, test.input, logger, vFormat);
                    for (const entry of rawEntries) {
                        listing.filter(entry);
                    }
                    const res = listing.result();
                    assert.deepStrictEqual(res, test.output);
                });
            });
        }
        it('Should filter values according to alphabeticalOrder parameter', () => {
            let test = new Test('alphabeticalOrder parameter set', {
                delimiter: '/',
                alphabeticalOrder: true,
            }, {
            }, {
                Contents: [
                    receivedNonAlphaData[0],
                ],
                Delimiter: '/',
                CommonPrefixes: [],
                IsTruncated: false,
                NextMarker: undefined,
            });
            let d = getTestListing(test, nonAlphabeticalData, vFormat);
            let res = performListing(d, Delimiter, test.input, logger, vFormat);
            assert.deepStrictEqual(res, test.output);
            test = new Test('alphabeticalOrder parameter set', {
                delimiter: '/',
                alphabeticalOrder: false,
            }, {
            }, {
                Contents: [
                    receivedNonAlphaData[0],
                    receivedNonAlphaData[1],
                ],
                Delimiter: '/',
                CommonPrefixes: [],
                IsTruncated: false,
                NextMarker: undefined,
            });
            d = getTestListing(test, nonAlphabeticalData, vFormat);
            res = performListing(d, Delimiter, test.input, logger, vFormat);
            assert.deepStrictEqual(res, test.output);
        });
    });
 });
--- a/Show More
+++ b/Show More