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Redis Distributed Lock Management
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| // REF: http://redis.io/topics/distlock | |
| var redis = require('redis'); | |
| var Redlock = require('redlock'); | |
| var lock_client = redis.createClient(port, host, { db: 1 }); | |
| var lock_duration = 300000;, // in ms | |
| var redlock = new Redlock( | |
| // you should have one client for each redis node | |
| // in your cluster | |
| [lock_client], | |
| { | |
| // the expected clock drift; for more details | |
| // see http://redis.io/topics/distlock | |
| driftFactor: 0.01, | |
| // the max number of times Redlock will attempt | |
| // to lock a resource before erroring | |
| retryCount: 3, | |
| // the time in ms between attempts | |
| retryDelay: 200 | |
| } | |
| ); | |
| function acquireLock(resource, ttl, callback) { | |
| redlock.lock(resource, ttl, function(err, lock) { | |
| if (err) { | |
| return callback(err, null); | |
| } | |
| var time_to_expire = 0; | |
| lock.extend_timer = setInterval(function() { | |
| time_to_expire = lock.expiration - Date.now(); | |
| logger.debug(S, 'Time to expire: %dms, for: %s', time_to_expire, | |
| lock.resource); | |
| lock.extend(ttl, function(err, lock) { | |
| if (err) { | |
| logger.error(S, 'Failed to extend for:', resource, err); | |
| } else { | |
| logger.debug(S, 'Extended for:', resource); | |
| } | |
| }); | |
| }, (time_to_expire + 0.85 * ttl)); | |
| return callback(null, lock); | |
| }); | |
| } | |
| function releaseLockSync(lock) { | |
| clearInterval(lock.extend_timer); | |
| lock.unlock(); | |
| } |
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