REDIS-MUTEX

Nodejs mutex implementation using the redis' set nx/xx/px commands.

USAGE

var redis = require("redis");
var client = redis.createClient();

var redisMutex = require("redis-mutex");
var runWithMutex = redisMutex.runWithMutex;

runWithMutex({
    intervalTime: 2000,
    renewTime: 100,
    maxTime: 10000,
    key: "PROCESS_1",
    redisClient: client
}, function(cb) {
    // this is the code of our function
    setTimeout(cb, 1000);
})
.then(function() {
    return "OK";
}, function() {
    return "REJECTED";
});

API

runWithMutex()

Arguments

name	type	description
inervalTime	number	The granularity at which the mutex updates itself in milliseconds.
renewTime	number	How many ms before intervalTime a renew request is sent to redis.
maxTime	number	The maximum time the function is allowed to run before it is killed.
key	string	A string label of the mutex. Only one function with the same key is allowed to run.
redisClient	object	Instance of redisClient from redis, providing the redis connection.
fn	function	The actual processing function.

Return value

The function returns a promise. The promise is rejected when the mutex is locked or fn calls the callback with an error. The promise is resolved once fn calls the callback without an error.

Error states

In case the redis record can't be updated the whole process is terminated since something had to go wrong. When the maxTime is exceeded the process is also terminated since there is no way in nodejs to terminate the function.