libraries/bugcore/js/src/concurrent/Semaphore.js
/*
* Copyright (c) 2016 airbug Inc. http://airbug.com
*
* bugcore may be freely distributed under the MIT license.
*/
//-------------------------------------------------------------------------------
// Annotations
//-------------------------------------------------------------------------------
//@Export('Semaphore')
//@Require('Class')
//@Require('Obj')
//@Require('Queue')
//@Require('Tracer')
//-------------------------------------------------------------------------------
// Context
//-------------------------------------------------------------------------------
require('bugpack').context("*", function(bugpack) {
//-------------------------------------------------------------------------------
// BugPack
//-------------------------------------------------------------------------------
var Class = bugpack.require('Class');
var Obj = bugpack.require('Obj');
var Queue = bugpack.require('Queue');
var Tracer = bugpack.require('Tracer');
//-------------------------------------------------------------------------------
// Simplify References
//-------------------------------------------------------------------------------
var $trace = Tracer.$trace;
//-------------------------------------------------------------------------------
// Declare Class
//-------------------------------------------------------------------------------
/**
* @class
* @extends {Obj}
*/
var Semaphore = Class.extend(Obj, {
_name: "Semaphore",
//-------------------------------------------------------------------------------
// Constructor
//-------------------------------------------------------------------------------
/**
* @constructs
* @param {number} numberPermits
*/
_constructor: function(numberPermits) {
this._super();
//-------------------------------------------------------------------------------
// Private Properties
//-------------------------------------------------------------------------------
/**
* @private
* @type {Queue.<function()>}
*/
this.acquisitionQueue = new Queue();
/**
* @private
* @type {number}
*/
this.numberPermitsAcquired = 0;
/**
* @private
* @type {number}
*/
this.numberPermits = numberPermits;
},
//-------------------------------------------------------------------------------
// Public Methods
//-------------------------------------------------------------------------------
/**
* @param {function()} method
*/
acquire: function(method) {
this.queueAcquisition(method);
this.processQueue();
},
/**
*
*/
release: function() {
this.releasePermit();
},
//-------------------------------------------------------------------------------
// Private Methods
//-------------------------------------------------------------------------------
/**
* @private
*/
acquirePermit: function(method) {
this.numberPermitsAcquired++;
method();
},
/**
* @private
*/
processQueue: function() {
while (this.numberPermitsAcquired < this.numberPermits && this.acquisitionQueue.getCount() > 0) {
var nextMethod = this.acquisitionQueue.dequeue();
this.acquirePermit(nextMethod);
}
},
/**
* @private
* @param {function()} method
*/
queueAcquisition: function(method) {
this.acquisitionQueue.enqueue(method);
},
/**
* @private
*/
releasePermit: function() {
this.numberPermitsAcquired--;
var _this = this;
// NOTE BRN: We use a setTimeout here to help prevent stack overflows when it comes to the processing of the
// queue.
setTimeout($trace(function() {
_this.processQueue();
}), 0);
}
});
//-------------------------------------------------------------------------------
// Exports
//-------------------------------------------------------------------------------
bugpack.export('Semaphore', Semaphore);
});