2PL

In-memory two-phase locking for asynchronous JavaScript functions.

npm install 2pl

Multiple lock keys can be acquired during the lifetime of a lock instance, where release is done in one operation.

var lock = require('2pl')
var shared = {} // in-memory lock object shared across instances

var l = lock(shared, { ttl: 5000 }) // new instance, 5 seconds timeout

l.acquire('a', function (err) {
  // a is locked
  l.acquire('b', function (err) {
    // b is locked
    l.release(function (err) {
      // a and b are released
    })
  })
})

API

var l = lock(shared, [options])

Create a new instance with shared object holding the in-memory locks. Accepts following options:

• ttl: Time to live (milliseconds) of lock instance for liveness. Defaults to 20 seconds.

l.acquire(key, [callback])

Attempts to acquire a lock, given a string key. Accepts an optional callback function, invoked on success or error.

l.extend(ttl, [callback])

Attempts to extend ttl of lock in milliseconds. Accepts an optional callback function, invoked on success or error.

l.release([callback])

Attempts to release lock. Accepts an optional callback function, invoked on success or error.

var createLock = lock.creator([options])

Returns a factory function createLock([options]) that create instances under the same shared lock object.

var createLock = lock.creator({ ttl: 5000 })

var l1 = createLock() // ttl 5000
var l2 = createLock({ ttl: 500 }) // ttl 500

License

MIT