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