technoweenie/coffee-resque

Coffee-Resque

Coffeescript/Node.js port of Resque.

USAGE

First, you'll want to queue some jobs in your app:

var resque = require('coffee-resque').connect({
  host: redisHost,
  port: redisPort
});
resque.enqueue('math', 'add', [1,2], function(err, remainingJobs) {
  console.log('New job queued. Remaining jobs in queue: ' + remainingJobs);
});

Next, you'll want to setup a worker to handle these jobs.

Upon completion of the job, invoke the passed callback with a result (if a result was produced by the job) or an Error (if an error was encountered). If an Error is received, resque fails the job. In all other cases resque assumes the job is successful.

The callback is important—it notifies resque that the worker has completed the current job and is ready for another. Neglecting to invoke the callback will result in worker starvation.

// implement your job functions.
var myJobs = {
  add: function(a, b, callback) { callback(a + b); },
  succeed: function(arg, callback) { callback(); },
  fail: function(arg, callback) { callback(new Error('fail')); }
}

// setup a worker
var worker = require('coffee-resque').connect({
  host: redisHost,
  port: redisPort
}).worker('*', myJobs)

// some global event listeners
//
// Triggered every time the Worker polls.
worker.on('poll', function(worker, queue) {})

// Triggered before a Job is attempted.
worker.on('job', function(worker, queue, job) {})

// Triggered every time a Job errors.
worker.on('error', function(err, worker, queue, job) {})

// Triggered on every successful Job run.
worker.on('success', function(worker, queue, job, result) {})

worker.start()

Worker Polling Mechanism

As of v0.1.9, workers poll the given queues similar to Ruby Resque:

start
loop do
  if job = reserve
    job.process
  else
    sleep 5 # Polling frequency = 5
  end
end
shutdown

This ensures that multiple queues are polled in the priority mentioned. Eg: If a worker is started on "queue1,queue2", queue1 is drained completely before jobs in queue2 are processed.

Prior to v0.1.9, workers used to poll the queues in a round-robin fashion.

Development

All code is written in Coffee Script and converted to javascript as it's published to npm.

For normal development, all you need to be concerned about is testing:

$ make test

If you need to generate javascript for production purposes and don't want to use npm packages, you can use:

$ make generate-js
$ make remove-js

You can also have coffeescript watch the src directory and generate Javascript files as they're updated.

$ make dev

TODO

• Generic failure handling
• Better polling