redis-queue.js

var proxmis = require('proxmis');

var parse = function (callback) {
	return function (err, value) {
		if (err) {
			callback(err);
		} else {
			try {
				value = JSON.parse(value);
				callback(null, value);
			} catch (e) {
				callback(e);
			}
		}
	};
};

module.exports = function (redis, listName) {
	if (!redis) {
		throw new Error('Must provide a redis client object');
	}

	if (!listName) {
		throw new Error('Must provide the name of the redis list to queue with.');
	}

	return {
		push: function (value, callback) {
			callback = proxmis(callback);
			redis.rpush(listName, JSON.stringify(value), callback);
			return callback.promise;
		},
		pop: function (callback) {
			callback = proxmis(callback);
			redis.rpop(listName, parse(callback));
			return callback.promise;
		},
		shift: function (value, callback) {
			callback = proxmis(callback);
			redis.lpop(listName, parse(callback));
			return callback.promise;
		},
		unshift: function (value, callback) {
			callback = proxmis(callback);
			redis.lpush(listName, JSON.stringify(value), callback);
			return callback.promise;
		},
		first: function (callback) {
			callback = proxmis(callback);
			redis.lrange(listName, 0, 0, parse(callback));
			return callback.promise;
		},
		last: function (callback) {
			callback = proxmis(callback);
			redis.lrange(listName, -1, -1, parse(callback));
			return callback.promise;
		},
		length: function (callback) {
			callback = proxmis(callback);
			redis.llen(listName, callback);
			return callback.promise;
		}
	};
};