89 lines
2.4 KiB
JavaScript
89 lines
2.4 KiB
JavaScript
'use strict';
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var REDIS_DISTLOCK = {
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DB: 5,
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PREFIX: 'batch:locks:'
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};
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var Redlock = require('redlock');
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var debug = require('../../util/debug')('redis-distlock');
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function RedisDistlockLocker(redisPool) {
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this.pool = redisPool;
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this.redlock = null;
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this._locks = {};
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}
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module.exports = RedisDistlockLocker;
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module.exports.type = 'redis-distlock';
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function resourceId(host) {
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return REDIS_DISTLOCK.PREFIX + host;
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}
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RedisDistlockLocker.prototype.lock = function(host, ttl, callback) {
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var self = this;
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debug('RedisDistlockLocker.lock(%s, %d)', host, ttl);
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var resource = resourceId(host);
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var lock = this._getLock(resource);
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function acquireCallback(err, _lock) {
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if (err) {
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return callback(err);
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}
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self._setLock(resource, _lock);
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return callback(null, _lock);
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}
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if (lock) {
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return this._tryExtend(lock, ttl, function(err, _lock) {
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if (err) {
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return self._tryAcquire(resource, ttl, acquireCallback);
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}
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return callback(null, _lock);
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});
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} else {
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return this._tryAcquire(resource, ttl, acquireCallback);
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}
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};
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RedisDistlockLocker.prototype.unlock = function(host, callback) {
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var lock = this._getLock(resourceId(host));
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if (lock && this.redlock) {
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return this.redlock.unlock(lock, callback);
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}
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};
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RedisDistlockLocker.prototype._getLock = function(resource) {
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if (this._locks.hasOwnProperty(resource)) {
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return this._locks[resource];
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}
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return null;
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};
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RedisDistlockLocker.prototype._setLock = function(resource, lock) {
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this._locks[resource] = lock;
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};
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RedisDistlockLocker.prototype._tryExtend = function(lock, ttl, callback) {
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return lock.extend(ttl, function(err, _lock) {
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return callback(err, _lock);
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});
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};
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RedisDistlockLocker.prototype._tryAcquire = function(resource, ttl, callback) {
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var self = this;
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this.pool.acquire(REDIS_DISTLOCK.DB, function (err, client) {
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self.redlock = new Redlock([client], {
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// see http://redis.io/topics/distlock
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driftFactor: 0.01, // time in ms
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// the max number of times Redlock will attempt to lock a resource before failing
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retryCount: 3,
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// the time in ms between attempts
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retryDelay: 200
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});
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self.redlock.lock(resource, ttl, callback);
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});
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};
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