reliable-redis-queue

Redis Queue for Node

This library provides a Node module for a reliable queue for Redis where each value is guaranteed to be processed at least once even in case of failures. The only constraint is that there should be ONLY a single consumer for the queue. The library relies heavily on Promises. The code is fully annotated.

Installation

npm install redis-queue

Usage

var Promise = require('bluebird');
var redis = Promise.promisifyAll(require('redis'));
var Queue = require('redis-queue);

Enqueue

enqueueAsync, which will return a promise that will enqueue values to the queue as follows:

var queue = new Queue('redis://localhost:6379', 'myqueuename');
// to enqueue a single value
queue.enqueueAsync('foo');
// to enqueue multiple values
queue.enqueueAsync(['foo', 'bar']);

Dequeue

Queue's constructor provides a parameter fn that will be called back for each value that is popped-off the queue. It will get called at at least once. It may get called more than once in the even of failures/crashes. The contract is that fn must return a Promise. Once the promise is resolved, it will be popped-off the queue, otherwise, it will get re-queued. var callback = function callback(value) { // do something and return a Promise }

var queue = new Queue(redisClient, 'myqueuename', callback);
queue.startDequeueingAsync();

// if for some reason, you want to stop processing
queue.stopDequeueingAsync();