libraries/bugcore/js/src/concurrent/Lock.js
/*
* Copyright (c) 2016 airbug Inc. http://airbug.com
*
* bugcore may be freely distributed under the MIT license.
*/
//-------------------------------------------------------------------------------
// Annotations
//-------------------------------------------------------------------------------
//@Export('Lock')
//@Require('Class')
//@Require('Event')
//@Require('EventDispatcher')
//@Require('Queue')
//@Require('Tracer')
//-------------------------------------------------------------------------------
// Context
//-------------------------------------------------------------------------------
require('bugpack').context("*", function(bugpack) {
//-------------------------------------------------------------------------------
// BugPack
//-------------------------------------------------------------------------------
var Class = bugpack.require('Class');
var Event = bugpack.require('Event');
var EventDispatcher = bugpack.require('EventDispatcher');
var Queue = bugpack.require('Queue');
var Tracer = bugpack.require('Tracer');
//-------------------------------------------------------------------------------
// Simplify References
//-------------------------------------------------------------------------------
var $trace = Tracer.$trace;
//-------------------------------------------------------------------------------
// Declare Class
//-------------------------------------------------------------------------------
/**
* @class
* @extends {EventDispatcher}
*/
var Lock = Class.extend(EventDispatcher, {
_name: "Lock",
//-------------------------------------------------------------------------------
// Constructor
//-------------------------------------------------------------------------------
/**
* @constructs
*/
_constructor: function() {
this._super();
//-------------------------------------------------------------------------------
// Private Properties
//-------------------------------------------------------------------------------
/**
* @private
* @type {Queue.<function()>}
*/
this.acquisitionQueue = new Queue();
/**
* @private
* @type {boolean}
*/
this.locked = false;
},
//-------------------------------------------------------------------------------
// Public Methods
//-------------------------------------------------------------------------------
/**
* @return {boolean}
*/
hasWaiters: function() {
return this.acquisitionQueue.getCount() > 0;
},
/**
* @return {boolean}
*/
isLocked: function() {
return this.locked;
},
/**
* @return {boolean}
*/
tryLock: function() {
if (this.isLocked()) {
return false;
} else {
this.acquireLock();
return true;
}
},
/**
*
*/
unlock: function() {
this.releaseLock();
},
/**
* @param {function(*=)=} method
*/
waitLock: function(method) {
this.queueAcquisition(method);
this.processQueue();
},
//-------------------------------------------------------------------------------
// Private Methods
//-------------------------------------------------------------------------------
/**
* @private
* @param {function(*=)=} method
*/
acquireLock: function(method) {
this.locked = true;
if (method) {
method();
}
},
/**
* @private
*/
processQueue: function() {
if (!this.isLocked()) {
if (this.acquisitionQueue.getCount() > 0) {
var nextMethod = this.acquisitionQueue.dequeue();
this.acquireLock(nextMethod);
} else {
this.dispatchEvent(new Event(Lock.EventTypes.EMPTY));
}
}
},
/**
* @private
* @param {function()} method
*/
queueAcquisition: function(method) {
this.acquisitionQueue.enqueue(method);
},
/**
* @private
*/
releaseLock: function() {
this.locked = false;
this.dispatchEvent(new Event(Lock.EventTypes.RELEASED));
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);
}
});
//-------------------------------------------------------------------------------
// Static Properties
//-------------------------------------------------------------------------------
/**
* @static
* @enum {string}
*/
Lock.EventTypes = {
EMPTY: "Lock:Empty",
RELEASED: "Lock:Released"
};
//-------------------------------------------------------------------------------
// Exports
//-------------------------------------------------------------------------------
bugpack.export('Lock', Lock);
});