A JavaScript singleton object to handle asynchronous jobs.

jobs

/**
 * A JavaScript singleton object to handle asynchronous jobs.
 * Give it a callback to i.e. know when to close the database connection.
 * @author Jacob Friis Saxberg
 */

module.exports = new function () {

	this.debug = true;
	var jobs = 0;
	var done = false;
	var callback = null;

	function callable () {
		if (done && jobs == 0 && callback != null) {
			callback();
		}
	}

	/**
	 * @param functionName The function to call when all jobs are done
	 */	
	this.setCallback = function (functionName) {
		if (typeof(functionName) != 'function') {
			console.error('callback must be a function');
			return false;
		}
		callback = functionName;
	}

	/**
	 * Call this when all jobs have been started.
	 */
	this.done = function () {
		if (this.debug) {
			console.log('Jobs done');
		}
		done = true;
		callable();
	}
	
	/**
	 * Call this when a job starts.
	 */
	this.start = function () {
		jobs++;
		if (this.debug) {
			console.log('Job start ' + jobs);
		}
	}

	/**
	 * Call this when a job ends.
	 */
	this.end = function () {
		jobs--;
		if (this.debug) {
			console.log('Job end');
		}
		callable();
	}
	
}