mutexify

Bike shed mutex lock implementation in node.js

npm install mutexify

Hasn't this been done before? Yes, but the specific semantics of this made some of my code simpler.

Usage

var mutexify = require('mutexify')
var lock = mutexify()

lock(function(release) {
  console.log('i am now locked')
  setTimeout(function() {
    release()
  }, 1000)
})

lock(function(release) {
  console.log('1 second later')
  release()
})

A common pattern is to call a callback after you release the lock. To do this in a one-liner pass the callback and the value to release(cb, err, value)

var write = function(data, cb) {
  lock(function(release) {
    fs.writeFile('locked-file.txt', data, release.bind(null, cb))
  })
}

mutexify guarantees that the order that a mutex was requested in is the order that access will be given.

You can read the lock's current state on the lock.locked property.

Usage with promises

mutexify provides a Promise-based alternative.

const mutexify = require('mutexify/promise')

;(async () => {
  var lock = mutexify()

  var release = await lock()
  console.log('i am now locked')
  setTimeout(function () {
    release()
  }, 1000)

  release = await lock()
  console.log('1 second later')
  release()
})()

License

MIT