207 lines
5.3 KiB
Go
207 lines
5.3 KiB
Go
// Copyright 2015 The etcd Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package backend
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import (
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"bytes"
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"sync"
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"sync/atomic"
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"time"
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"github.com/boltdb/bolt"
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)
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type BatchTx interface {
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Lock()
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Unlock()
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UnsafeCreateBucket(name []byte)
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UnsafePut(bucketName []byte, key []byte, value []byte)
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UnsafeSeqPut(bucketName []byte, key []byte, value []byte)
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UnsafeRange(bucketName []byte, key, endKey []byte, limit int64) (keys [][]byte, vals [][]byte)
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UnsafeDelete(bucketName []byte, key []byte)
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UnsafeForEach(bucketName []byte, visitor func(k, v []byte) error) error
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Commit()
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CommitAndStop()
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}
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type batchTx struct {
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sync.Mutex
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tx *bolt.Tx
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backend *backend
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pending int
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}
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func newBatchTx(backend *backend) *batchTx {
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tx := &batchTx{backend: backend}
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tx.Commit()
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return tx
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}
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func (t *batchTx) UnsafeCreateBucket(name []byte) {
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_, err := t.tx.CreateBucket(name)
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if err != nil && err != bolt.ErrBucketExists {
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plog.Fatalf("cannot create bucket %s (%v)", name, err)
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}
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t.pending++
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}
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// UnsafePut must be called holding the lock on the tx.
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func (t *batchTx) UnsafePut(bucketName []byte, key []byte, value []byte) {
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t.unsafePut(bucketName, key, value, false)
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}
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// UnsafeSeqPut must be called holding the lock on the tx.
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func (t *batchTx) UnsafeSeqPut(bucketName []byte, key []byte, value []byte) {
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t.unsafePut(bucketName, key, value, true)
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}
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func (t *batchTx) unsafePut(bucketName []byte, key []byte, value []byte, seq bool) {
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bucket := t.tx.Bucket(bucketName)
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if bucket == nil {
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plog.Fatalf("bucket %s does not exist", bucketName)
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}
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if seq {
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// it is useful to increase fill percent when the workloads are mostly append-only.
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// this can delay the page split and reduce space usage.
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bucket.FillPercent = 0.9
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}
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if err := bucket.Put(key, value); err != nil {
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plog.Fatalf("cannot put key into bucket (%v)", err)
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}
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t.pending++
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}
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// UnsafeRange must be called holding the lock on the tx.
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func (t *batchTx) UnsafeRange(bucketName []byte, key, endKey []byte, limit int64) (keys [][]byte, vs [][]byte) {
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bucket := t.tx.Bucket(bucketName)
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if bucket == nil {
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plog.Fatalf("bucket %s does not exist", bucketName)
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}
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if len(endKey) == 0 {
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if v := bucket.Get(key); v == nil {
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return keys, vs
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} else {
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return append(keys, key), append(vs, v)
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}
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}
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c := bucket.Cursor()
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for ck, cv := c.Seek(key); ck != nil && bytes.Compare(ck, endKey) < 0; ck, cv = c.Next() {
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vs = append(vs, cv)
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keys = append(keys, ck)
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if limit > 0 && limit == int64(len(keys)) {
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break
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}
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}
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return keys, vs
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}
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// UnsafeDelete must be called holding the lock on the tx.
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func (t *batchTx) UnsafeDelete(bucketName []byte, key []byte) {
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bucket := t.tx.Bucket(bucketName)
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if bucket == nil {
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plog.Fatalf("bucket %s does not exist", bucketName)
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}
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err := bucket.Delete(key)
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if err != nil {
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plog.Fatalf("cannot delete key from bucket (%v)", err)
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}
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t.pending++
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}
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// UnsafeForEach must be called holding the lock on the tx.
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func (t *batchTx) UnsafeForEach(bucketName []byte, visitor func(k, v []byte) error) error {
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b := t.tx.Bucket(bucketName)
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if b == nil {
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// bucket does not exist
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return nil
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}
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return b.ForEach(visitor)
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}
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// Commit commits a previous tx and begins a new writable one.
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func (t *batchTx) Commit() {
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t.Lock()
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defer t.Unlock()
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t.commit(false)
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}
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// CommitAndStop commits the previous tx and do not create a new one.
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func (t *batchTx) CommitAndStop() {
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t.Lock()
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defer t.Unlock()
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t.commit(true)
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}
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func (t *batchTx) Unlock() {
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if t.pending >= t.backend.batchLimit {
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t.commit(false)
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t.pending = 0
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}
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t.Mutex.Unlock()
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}
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func (t *batchTx) commit(stop bool) {
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var err error
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// commit the last tx
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if t.tx != nil {
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if t.pending == 0 && !stop {
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t.backend.mu.RLock()
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defer t.backend.mu.RUnlock()
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// batchTx.commit(true) calls *bolt.Tx.Commit, which
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// initializes *bolt.Tx.db and *bolt.Tx.meta as nil,
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// and subsequent *bolt.Tx.Size() call panics.
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//
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// This nil pointer reference panic happens when:
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// 1. batchTx.commit(false) from newBatchTx
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// 2. batchTx.commit(true) from stopping backend
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// 3. batchTx.commit(false) from inflight mvcc Hash call
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//
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// Check if db is nil to prevent this panic
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if t.tx.DB() != nil {
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atomic.StoreInt64(&t.backend.size, t.tx.Size())
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}
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return
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}
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start := time.Now()
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// gofail: var beforeCommit struct{}
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err = t.tx.Commit()
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// gofail: var afterCommit struct{}
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commitDurations.Observe(time.Since(start).Seconds())
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atomic.AddInt64(&t.backend.commits, 1)
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t.pending = 0
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if err != nil {
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plog.Fatalf("cannot commit tx (%s)", err)
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}
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}
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if stop {
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return
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}
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t.backend.mu.RLock()
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defer t.backend.mu.RUnlock()
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// begin a new tx
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t.tx, err = t.backend.db.Begin(true)
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if err != nil {
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plog.Fatalf("cannot begin tx (%s)", err)
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}
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atomic.StoreInt64(&t.backend.size, t.tx.Size())
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}
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