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75 lines
2.2 KiB
75 lines
2.2 KiB
'use strict';
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var RedisDistlockLocker = require('./provider/redis-distlock');
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var debug = require('../util/debug')('leader-locker');
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var EventEmitter = require('events').EventEmitter;
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var util = require('util');
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var LOCK = {
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TTL: 5000
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};
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function Locker(locker, ttl) {
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EventEmitter.call(this);
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this.locker = locker;
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this.ttl = (Number.isFinite(ttl) && ttl > 0) ? ttl : LOCK.TTL;
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this.renewInterval = this.ttl / 5;
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this.intervalIds = {};
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}
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util.inherits(Locker, EventEmitter);
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module.exports = Locker;
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Locker.prototype.lock = function(resource, callback) {
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var self = this;
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debug('Locker.lock(%s, %d)', resource, this.ttl);
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this.locker.lock(resource, this.ttl, function (err, lock) {
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if (!err) {
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self.startRenewal(resource);
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}
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return callback(err, lock);
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});
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};
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Locker.prototype.unlock = function(resource, callback) {
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var self = this;
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debug('Locker.unlock(%s)', resource);
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this.locker.unlock(resource, function(err) {
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self.stopRenewal(resource);
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return callback(err);
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});
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};
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Locker.prototype.startRenewal = function(resource) {
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var self = this;
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if (!this.intervalIds.hasOwnProperty(resource)) {
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this.intervalIds[resource] = setInterval(function() {
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debug('Trying to extend lock resource=%s', resource);
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self.locker.lock(resource, self.ttl, function(err, _lock) {
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if (err) {
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self.emit('error', err, resource);
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return self.stopRenewal(resource);
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}
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if (_lock) {
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debug('Extended lock resource=%s', resource);
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}
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});
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}, this.renewInterval);
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}
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};
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Locker.prototype.stopRenewal = function(resource) {
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if (this.intervalIds.hasOwnProperty(resource)) {
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clearInterval(this.intervalIds[resource]);
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delete this.intervalIds[resource];
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}
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};
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module.exports.create = function createLocker(type, config) {
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if (type !== 'redis-distlock') {
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throw new Error('Invalid type Locker type. Valid types are: "redis-distlock"');
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}
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var locker = new RedisDistlockLocker(config.pool);
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return new Locker(locker, config.ttl);
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};
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