protex

protex is like a mutex but for Promises. That is, an instance executes one promise at a time and remains locked until the Promise is resolved.

Example:

var protex = require('protex')();

protex.isLocked(); // => false

// Submit a promise chain for execution.
// The protex instance will remain locked until the returned promise is fulfilled.
var promise = protex.exec(function() {
	return Promise.resolve()
		.then(task1)
		.then(function() {
			try {
				protex.exec(function() {
					console.log("i won't run");
				});
			} catch (e) {
				protex.isLocked(); // => true
			}
		})
		.then(task2)
});

promise.then(function() {
	console.log("protex is now unlocked!");
});

Installation

npm

Get it:

npm install protex

Require it:

var protex = require('protex');

UMD etc.

Copy and paste build/protex.js or build/protex.min.js to your project.

API

var prx = protex()

Create a new protex.

prx.isLocked()

Returns true if currently locked, false otherwise.

prx.exec(thing)

Submit thing for execution. Throws an exception if currently locked.

thing can be either a function or a Promise, although functions are preferred - the reason being that Promises begin to execute the moment they are created, i.e. before prx.exec() is called, meaning that it's possible to circumvent the lock. Passing a function will correctly delay the instantation of the Promise until prx.exec() has been called and locking is complete.

If thing is a function and it doesn't return a Promise it is assumed that the function is synchronous and the protex is unlocked immediately after the call returns.

Copyright & License

© 2014 Jason Frame [ @jaz303 / jason@onehackoranother.com ]

Released under the ISC license.