passkey

Shared lock built on top of redis

Reliable locking mechanism on Redis. Performs atomic locking and verifies ownership.

Usage

var redis = require('redis');
var passkey = require('passkey');

var client = redis.createClient();
var key = passkey(client, {
  ttl: 10000
});

key.lock('my-lock')
  .then(function (lock) {

    return doWork()
      .then(function () {
        // extend the lock
        return lock.ttl(10000);
      })
      .then(function () {
        return doMoreWork();
      })
      .then(function () {
        // release the lock
        return lock.unlock();
      });

  })
  .catch(passkey.LockError, function (err) {
    // lock not obtained or expired before ttl/unlock was called
  })

API

var key = passkey(client, [options])

creates a new key that can be used to set locks, expects to be called with a redis client. Options can be an object with following properties

• ttl: time before the lock automatically expires, default: 10000ms

key.lock(key, [ttl])

lock a key, any future call to .lock with the same value will fail with a promise.LockError. The lock will expire after ttl or the default time when unspecified. returns a Lock instance.

Lock.unlock()

Release this lock so it can be obtained by another client. Fails with a promise.LockError if the lock is expired.

Lock.ttl([ttl])

Set a new ttl on this lock. This is useful to extend the lifetime of the lock. Fails with a promise.LockError if the lock is expired. Returns the current ttl when called without arguments.

Lock.extend()

Extends the ttl of the current lock with last used ttl.