Node singleton

/*--------------------------------------
* Original Gist by dimdimbe : https://gist.github.com/dimdimbe/37abbe5b95bbee800dac94b1e6bba144
* After Further reading, it seem's that require break the singleton pattern.
* By the nature of the require cache system, the internal Instance of singleton is preserved... until Garbage collector is triggered.
* The most simple workaround is to "polute" the global scope to store the singleton internal instance, 
* global variables are never disposed of by the GC.
/*--------------------------------------
var SocketInstance  = null
    ;

/**
 @var: __socketSingletonInstance.
 @description: Internal singleton instance, never call this via global use getInstance instead
 */
global.__socketSingletonInstance = null ;

/**
 @class: theObject.
 @description: Factory Function object.
 */
SocketInstance = function(port){

    // Add some object or var
    var _singletonInstance = {};
    _singletonInstance.port = port;
    _singletonInstance.instanceId = Math.random().toString(16).substr(2, 8);
    _singletonInstance.socket = require('socket.io').listen(port);
    return _singletonInstance;
};

/**
 @function: getInstance.
 @description: Return the internal instance, create it if is null
 */
function _getInstance(port){

    if(!global.__socketSingletonInstance || port){
        global.__socketSingletonInstance = new SocketInstance(port);
        console.log ('create a new instance of port');
    }
    return global.__socketSingletonInstance;

}

module.exports = {

    getInstance:_getInstance

};