node-simple-queue/lib/worker_process.js

A simple queue for NodeJS, with usage similar to Resque in RoR

"use strict"
var path        = require('path');
var DB          = require(path.resolve('.', __dirname + '/db.js')).DB;
var db          = {};
var queue       = "";
var JOB_TIMEOUT = 120000;
/**
 * @desc Start worker process
 * @param worker
 * @constructor
 */
function WorkerProcess(worker){
	// console.log('In worker process process message');
	
	queue = worker.queue;
	try{
		if(worker.JOB_TIMEOUT){
			JOB_TIMEOUT = worker.JOB_TIMEOUT;
		}
		db = new DB('MongoDB', worker.db_config);
		enqueueStoppedJobs();
		setTimeout(checkForJob, 2000);
	} catch(e){
		console.error(e);
		process.exit(200);
	}
};
/**
 * @desc enqueue stopped jobs
 */
function enqueueStoppedJobs(){
	db.Job.getStuckedJobs(JOB_TIMEOUT, function(err, jobs){
		if(!err){
			for(var key in jobs){
				db.Job.retry(jobs[key]._id, function(error, resp){
				});
			}
		}
	});
}

/**
 * @desc Recursion function to check for new job
 */
function checkForJob(){
	
	// Get jobs from db
	db.Job.getNextJobsToDo(queue, process.pid, function(err, job){
		// If new jobs found then process else wait for the job
		if(job){
			//
			// console.log('Queue : ' + queue);
			try{
				db.Worker.MarkBusy(process.pid, function(err, resp){
				});
				require(path.resolve('./job_handlers', job['CLASS_NAME'] + '.js'));
				var jobTimeout = setInterval(function(){
					job.STATUS = 'E';
					job.ERROR  = 'JOB_TIMED_OUT';
					console.error('Job Time Out');
					// If job takes more time than worker then mark job as error and make worker free
					job.save(function(err, status){
						db.Worker.RemoveWorkerByPID(process.pid, function(){
							process.exit(200);
						});
					});
				}, JOB_TIMEOUT);
				// console.log('Job Executed by worker : ' + process.pid)
				
				//Execute perform method of custom class
				GLOBAL[job['CLASS_NAME']].perform(job.PARAMS, function(error, success){
					if(success){
						job.remove(function(err, job){
						});
					}
					else{
						job.STATUS = 'E';
						job.ERROR  = error;
						
						console.error('Error occur while processing job : ' + error);
						job.save(function(err, status){
						});
					}
					db.Worker.MarkFree(process.pid, function(err, resp){
					});
					clearInterval(jobTimeout);
					jobTimeout = null;
					setTimeout(checkForJob, 500);
				});
			} catch(e){
				console.error(e);
				job.STATUS = 'E';
				job.ERROR  = e.toString();
				
				job.save(function(err, status){
				});
				db.Worker.MarkFree(process.pid, function(err, resp){
				});
				setTimeout(checkForJob, 500);
			}
		} else{
			setTimeout(checkForJob, 2000);
		}
	});
}

exports.WorkerProcess = WorkerProcess;