I want to make mini-etcd out of it
parent
a6893ea494
commit
899c06faed
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@ -0,0 +1,393 @@
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const crypto = require('crypto');
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/*type TreeNode = {
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value?: any,
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create_revision?: number,
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mod_revision?: number,
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version?: number,
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lease?: string,
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children: { [string]: TreeNode },
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watchers?: number[],
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key_watchers?: number[],
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};*/
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class EtcTree
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{
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constructor()
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{
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this.state = {};
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this.leases = {};
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this.watchers = {};
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this.watcher_id = 0;
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this.mod_revision = 0;
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}
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check(chk)
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{
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const parts = this.key_parts(chk.key);
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const { cur } = this.get_subtree(parts, false, false);
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let check_value, ref_value;
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if (chk.target === 'MOD')
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{
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check_value = cur.mod_revision || 0;
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ref_value = chk.mod_revision || 0;
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}
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else if (chk.target === 'CREATE')
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{
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check_value = cur.create_revision || 0;
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ref_value = chk.create_revision || 0;
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}
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else if (chk.target === 'VERSION')
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{
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check_value = cur.version || 0;
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ref_value = chk.version || 0;
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}
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else if (chk.target === 'LEASE')
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{
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check_value = cur.lease;
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ref_value = chk.lease;
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}
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else
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{
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throw new Error('Unsupported comparison target: '+chk.target);
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}
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if (chk.result === 'LESS')
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{
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return check_value < ref_value;
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}
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else if (chk.result)
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{
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throw new Error('Unsupported comparison result: '+chk.result);
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}
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return check_value == ref_value;
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}
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key_parts(key)
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{
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const parts = key.replace(/\/\/+/g, '/').replace(/^\/|\/$/g, '');
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return parts === '' ? [] : parts.split('/');
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}
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get_range(req)
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{
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const key = req.key;
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const end = req.range_end;
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if (end != null && (key[key.length-1] != '/' || end[end.length-1] != '0' ||
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end.substr(0, end.length-1) !== key.substr(0, key.length-1)))
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{
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throw new Error('Non-directory range queries are unsupported');
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}
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const parts = this.key_parts(key);
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return { parts, all: end != null };
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}
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get_subtree(parts, create, notify)
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{
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let cur = this.state;
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let watchers = notify ? [] : null;
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for (let k of parts)
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{
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if (notify && cur.watchers)
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{
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watchers.push.apply(watchers, cur.watchers);
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}
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if (!cur.children)
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{
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if (!create)
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{
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return {};
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}
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cur.children = {};
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}
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if (!cur.children[k])
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{
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if (!create)
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{
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return {};
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}
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cur.children[k] = {};
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}
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cur = cur.children[k];
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}
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if (notify && cur.watchers)
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{
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watchers.push.apply(watchers, cur.watchers);
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}
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if (notify && cur.key_watchers)
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{
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watchers.push.apply(watchers, cur.key_watchers);
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}
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return { watchers, cur };
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}
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api_grant_lease(req)
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{
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let id;
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while (!id || this.leases[id])
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{
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id = crypto.randomBytes(8).toString('base64');
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}
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const timer_id = setTimeout(() => this.api_revoke_lease({ ID: id }), req.TTL*1000);
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this.leases[id] = { ttl: req.TTL, timer_id, keys: {} };
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return { ID: id };
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}
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api_keepalive_lease(req)
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{
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const id = req.ID;
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if (!this.leases[id])
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{
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throw new Error('unknown lease');
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}
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clearTimeout(this.leases[id].timer_id);
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const ttl = this.leases[id].TTL;
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this.leases[id].timer_id = setTimeout(() => this.api_revoke_lease({ ID: id }), ttl*1000);
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return { TTL: ttl };
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}
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api_revoke_lease(req)
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{
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if (!this.leases[req.ID])
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{
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throw new Error('unknown lease');
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}
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const next_revision = this.mod_revision + 1;
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const notifications = [];
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for (const key in this.leases[req.ID].keys)
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{
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this.txn_action({ request_delete_range: { key } }, next_revision, notifications);
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}
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this.notify(notifications);
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}
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api_create_watch(req, send)
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{
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const { parts, all } = this.get_range(req);
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if (req.start_revision && req.start_revision < this.mod_revision)
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{
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throw new Error('history storage is not implemented');
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}
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let watch_id = req.watch_id;
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if (watch_id instanceof Object)
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{
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throw new Error('invalid watch_id');
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}
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if (!watch_id)
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{
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watch_id = ++this.watcher_id;
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}
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if (!this.watchers[watch_id])
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{
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this.watchers[watch_id] = {
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paths: [],
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send,
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};
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}
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this.watchers[watch_id].paths.push(parts);
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const { cur } = this.get_subtree(parts, true, false);
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if (all)
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{
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cur.watchers = cur.watchers || [];
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cur.watchers.push(watch_id);
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}
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else
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{
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cur.key_watchers = cur.key_watchers || [];
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cur.key_watchers.push(watch_id);
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}
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return { watch_id, created: true };
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}
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api_cancel_watch(watch_id)
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{
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if (this.watchers[watch_id])
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{
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for (const parts of this.watchers[watch_id].paths)
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{
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const { cur } = this.get_subtree(parts, false, false);
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if (cur)
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{
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if (cur.watchers)
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{
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cur.watchers = cur.watchers.filter(id => id != watch_id);
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if (!cur.watchers.length)
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cur.watchers = null;
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}
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if (cur.key_watchers)
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{
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cur.key_watchers = cur.key_watchers.filter(id => id != watch_id);
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if (!cur.key_watchers.length)
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cur.key_watchers = null;
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}
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// FIXME: cleanup deleted tree paths
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}
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}
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delete this.watchers[watch_id];
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}
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}
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api_txn({ compare, success, failure })
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{
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const failed = (compare || []).filter(chk => !this.check(chk)).length > 0;
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const responses = [];
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const notifications = [];
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const next_revision = this.mod_revision + 1;
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for (const req of (failed ? failure : success) || [])
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{
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responses.push(this.txn_action(req, next_revision, notifications));
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}
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this.notify(notifications);
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return { revision: this.mod_revision, succeeded: !failed, responses };
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}
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notify(notifications)
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{
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if (!notifications.length)
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{
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return;
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}
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const by_watcher = {};
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for (const notif of notifications)
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{
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const watchers = notif.watchers;
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delete notif.watchers;
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for (const wid of watchers)
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{
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if (this.watchers[wid])
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{
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by_watcher[wid] = by_watcher[wid] || { header: { revision: this.mod_revision }, events: {} };
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by_watcher[wid].events[notif.key] = notif;
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}
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}
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}
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for (const wid in by_watcher)
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{
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by_watcher[wid].events = Object.values(by_watcher[wid].events);
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this.watchers[wid].send(by_watcher[wid]);
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}
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}
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txn_action(req, cur_revision, notifications)
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{
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if (req.request_range)
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{
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// FIXME: limit, revision(-), sort_order, sort_target, serializable(-), keys_only,
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// count_only, min_mod_revision, max_mod_revision, min_create_revision, max_create_revision
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const { parts, all } = this.get_range(req.request_range);
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const { cur } = this.get_subtree(parts, false, false);
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const kvs = [];
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if (cur)
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{
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this.get_all(kvs, cur, all, parts.join('/'), req.request_range);
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}
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return { kvs };
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}
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else if (req.request_put)
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{
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// FIXME: prev_kv, ignore_value(?), ignore_lease(?)
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const parts = this.key_parts(req.request_put.key);
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const key = parts.join('/');
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const value = req.request_put.value;
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const { cur, watchers } = this.get_subtree(parts, true, true);
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if (!eq(cur.value, value) || cur.lease != req.request_put.lease)
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{
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if (cur.lease && this.leases[cur.lease])
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{
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delete this.leases[cur.lease].keys[key];
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}
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if (req.request_put.lease)
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{
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if (!this.leases[req.request_put.lease])
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{
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throw new Error('unknown lease: '+req.request_put.lease);
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}
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cur.lease = req.request_put.lease;
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this.leases[req.request_put.lease].keys[key] = true;
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}
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this.mod_revision = cur_revision;
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cur.version = (cur.version||0) + 1;
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cur.mod_revision = cur_revision;
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if (cur.value == null)
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{
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cur.create_revision = cur_revision;
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}
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cur.value = value;
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const notify = { watchers, key, value, mod_revision: cur.mod_revision };
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if (cur.lease)
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{
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notify.lease = cur.lease;
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}
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notifications.push(notify);
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}
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return {};
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}
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else if (req.request_delete_range)
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{
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// FIXME: prev_kv
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const { parts, all } = this.get_range(req.request_delete_range);
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const { cur, watchers } = this.get_subtree(parts, false, true);
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if (cur)
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{
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this.delete_all(notifications, watchers, cur, all, parts.join('/'), cur_revision);
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}
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}
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}
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get_all(kvs, cur, all, prefix, req)
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{
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if (req.limit && kvs.length > req.limit)
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{
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return;
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}
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if (cur.value != null)
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{
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if (req.keys_only)
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{
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kvs.push({ key: prefix, mod_revision: cur.mod_revision });
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}
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else
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{
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kvs.push({ key: prefix, value: cur.value, mod_revision: cur.mod_revision });
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}
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}
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if (all && cur.children)
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{
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for (let k in cur.children)
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{
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this.get_all(kvs, cur.children[k], true, prefix === '' ? k : prefix+'/'+k, req);
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}
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}
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}
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delete_all(notifications, watchers, cur, all, prefix, cur_revision)
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{
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if (cur.value != null)
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{
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// Do not actually forget the key until the deletion is confirmed by all replicas
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cur.value = null;
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cur.create_revision = null;
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cur.mod_revision = cur_revision;
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this.mod_revision = cur_revision;
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notifications.push({ watchers, key: prefix, mod_revision: cur_revision });
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}
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if (all && cur.children)
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{
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for (let k in cur.children)
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{
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const subw = cur.children[k].watchers ? [ ...watchers, ...cur.children[k].watchers ] : watchers;
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this.delete_all(notifications, subw, cur.children[k], true, prefix === '' ? k : prefix+'/'+k, cur_revision);
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}
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}
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}
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}
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function eq(a, b)
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{
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if (a instanceof Object || b instanceof Object)
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{
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return JSON.stringify(a) === JSON.stringify(b);
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}
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return a == b;
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}
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module.exports = EtcTree;
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@ -0,0 +1,59 @@
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const EtcTree = require('./etctree.js');
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describe('EtcTree', () =>
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{
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it('should return the inserted value', () =>
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{
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const t = new EtcTree();
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expect(t.api_txn({ success: [ { request_put: { key: '/vitastor//config/global', value: { hello: 'world' } } } ] }))
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.toEqual({ succeeded: true, revision: 1, responses: [ {} ] });
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expect(t.api_txn({ success: [ { request_range: { key: '/vitastor/config/global' } } ] }))
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.toEqual({ succeeded: true, revision: 1, responses: [ { kvs: [ { key: 'vitastor/config/global', mod_revision: 1, value: { hello: 'world' } } ] } ] });
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expect(t.api_txn({ success: [ { request_range: { key: '/vitastor/config/', range_end: '/vitastor/config0' } } ] }))
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.toEqual({ succeeded: true, revision: 1, responses: [ { kvs: [ { key: 'vitastor/config/global', mod_revision: 1, value: { hello: 'world' } } ] } ] });
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expect(t.api_txn({ success: [ { request_range: { key: '/vitasto/', range_end: '/vitasto0' } } ] }))
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.toEqual({ succeeded: true, revision: 1, responses: [ { kvs: [] } ] });
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expect(t.api_txn({
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compare: [ { key: '/vitastor/config/global', target: 'MOD', mod_revision: 1, result: 'LESS' } ],
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success: [ { request_put: { key: '/vitastor//config/global', value: { hello: 'world' } } } ],
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failure: [ { request_range: { key: 'vitastor/config/global' } } ],
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})).toEqual({ succeeded: false, revision: 1, responses: [ { kvs: [ { key: 'vitastor/config/global', mod_revision: 1, value: { hello: 'world' } } ] } ] });
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expect(t.api_txn({
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compare: [ { key: '/vitastor/config/global', target: 'MOD', mod_revision: 2, result: 'LESS' } ],
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success: [ { request_put: { key: '/vitastor//config/global', value: { hello: 'world2' } } } ]
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})).toEqual({ succeeded: true, revision: 2, responses: [ {} ] });
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expect(t.api_txn({ success: [ { request_range: { key: '/vitastor/config/', range_end: '/vitastor/config0' } } ] }))
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.toEqual({ succeeded: true, revision: 2, responses: [ { kvs: [ { key: 'vitastor/config/global', mod_revision: 2, value: { hello: 'world2' } } ] } ] });
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});
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it('should watch', () =>
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{
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const t = new EtcTree();
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const sent = [];
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const send = (event) => sent.push(event);
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expect(t.api_txn({ success: [ { request_put: { key: '/vitastor//config/global', value: { hello: 'world' } } } ] }))
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.toEqual({ succeeded: true, revision: 1, responses: [ {} ] });
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expect(t.api_create_watch({ watch_id: 1, key: '/vitastor/', range_end: '/vitastor0' }, send))
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.toEqual({ watch_id: 1, created: true });
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expect(sent).toEqual([]);
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expect(t.api_txn({ success: [ { request_put: { key: '/vitastor/osd/state/1', value: { ip: '1.2.3.4' } } } ] }))
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.toEqual({ succeeded: true, revision: 2, responses: [ {} ] });
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expect(sent).toEqual([ { header: { revision: 2 }, events: [ { key: 'vitastor/osd/state/1', mod_revision: 2, value: { ip: '1.2.3.4' } } ] } ]);
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});
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it('should lease', async () =>
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{
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const t = new EtcTree();
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const sent = [];
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const send = (event) => sent.push(event);
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const leaseID = t.api_grant_lease({ TTL: 0.5 }).ID;
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expect(leaseID).not.toBeNull();
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expect(t.api_txn({ success: [ { request_put: { key: '/vitastor/osd/state/1', lease: leaseID, value: { ip: '1.2.3.4' } } } ] }))
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.toEqual({ succeeded: true, revision: 1, responses: [ {} ] });
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expect(t.api_create_watch({ watch_id: 1, key: '/vitastor/', range_end: '/vitastor0' }, send))
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.toEqual({ watch_id: 1, created: true });
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expect(sent).toEqual([]);
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await new Promise(ok => setTimeout(ok, 600));
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expect(sent).toEqual([ { header: { revision: 2 }, events: [ { key: 'vitastor/osd/state/1', mod_revision: 2 } ] } ]);
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});
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});
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