CoffeeQ - Simple queuing library implemented on redis

CoffeeQ is a simple queueing library for node.js implemented on top of redis and inspired by resque. It was inspired by Coffee-Resque and implemented to satisfy the needs of a specific development project for a fast backend queueing library. The use of redis build in pub/sub functionality makes the processing of new queue items very fast and eliminates the need to poll redis for changes.

CoffeeQ uses redis built in pub/sub functionality and lists to provide a reliable and fast queueing mechanism. A client can enqueue and job which will add the job to a queue and publish a change message to the queue's pub/sub channel, any workers set to work on that queue will try to pickup the job from the queue - only one worker is able to take any given item from a queue.

Workers listen to the pub/sub channel for a given queue and whenever a new job is queued will attempt to dequeue the job to be processed, if successful they will perform the action defined by the job.

Installation

CoffeeQ is available via npm

npm install coffeeq

It's only dependency is redis which will be installed by npm along with the module.

Usage

CoffeeQ allows you to define workers dedicated to processing tasks for a given queue, a job can be any arbitrary coffeescript/javascript function. You can use the node client to enqueue items on a queue for processing by passing in the name of the job and the parameters for the job in an array.

Defining tasks to be performed

You can define the tasks to be performed as functions, in the simplest case you can

CoffeeScript:

jobs =       
  succeed: (callback) ->
    console.log "callback succeed"
    callback()
  fail: (callback) ->
    console.log "callback fail"
    callback()
  multiply: (a, b, callback) ->
    console.log "callback multiply #{a} * #{b}"
    callback(a * b)

JS:

var jobs = {
  succeed: function(callback) {
    console.log("callback succeed");
    callback();
  },
  fail: function(callback) {
    console.log("callback fail");
    callback();
  },
  multiply: function(a,b,callback) {
    console.log('callback multiply' + a + ' * ' + 'b');
    callback(a*b);      
  }      
}

Adding items to a Queue

To add an job to a queue you create a CoffeeQ client and enqueue the task for the given queue.

CoffeeScript:

CoffeeQ = require 'coffeeq'
client = new CoffeeQ
client.enqueue "test_queue", "add", [1,4]

JS:

var CoffeeQ = require('coffeeq');
var client = new CoffeeQ();
client.enqueue("test_queue", "add", [1, 4]);

Implementing Workers

Workers can watch a single queue at a time (as of this writing - this may be changed in a future version) and process any items that are pushed onto this queue. The worker responds to any of the functions that are defined by the jobs passed into it on initialization.

CoffeeScript:

  Worker = require('coffeeq').Worker

  jobs =              
    succeed: (callback) ->
      console.log "callback succeed"
      callback()
    fail: (callback) ->
      console.log "callback fail"
      callback()
    multiply: (a, b, callback) ->
      console.log "callback add #{a} * #{b}"
      callback(a * b)

  worker = new Worker("test_queue", jobs)

  worker.on 'message', (worker, queue) ->
    console.log("message fired")
  worker.on 'job', (worker, queue) ->
    console.log("job fired")
  worker.on 'error', (worker, queue) ->
    console.log("error fired")
  worker.on 'success', (worker, queue, job, result) ->
    console.log("success fired with result #{result}")

  worker.start()

JS:

var Worker = require('coffeeq').Worker;
var jobs = {
  succeed: function(callback) {
    console.log("callback succeed");
    callback();
  },
  fail: function(callback) {
    console.log("callback fail");
    callback();
  },
  multiply: function(a,b,callback) {
    console.log('callback multiply' + a + ' * ' + 'b');
    callback(a*b);      
  }
}

var worker = new Worker("test_queue", jobs);

worker.on('message', function(worker, queue){
  console.log("message fired");
});
worker.on('job', function(worker, queue){
  console.log("job fired");
});
worker.on('error', function(worker, queue){
  console.log("error fired");
});
worker.on('success', function(worker, queue){
  console.log("success fired");
});

worker.start();

Ruby Client

See https://github.com/pcrawfor/coffeeq-rubyclient for a ruby client implementation to use with the CoffeeQ queueing system.

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Credits

Credit to technoweenie much inspiration and insight was taken from his resque and coffee-resque libraries which I originally looked at.