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// Copyright 2006 The Closure Library Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS-IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
/**
* @fileoverview Datastructure: Priority Pool.
*
*
* An extending of Pool that handles queueing and prioritization.
*/
goog.provide('goog.structs.PriorityPool');
goog.require('goog.structs.Pool');
goog.require('goog.structs.PriorityQueue');
/**
* A generic pool class. If max is greater than min, an error is thrown.
* @param {number=} opt_minCount Min. number of objects (Default: 1).
* @param {number=} opt_maxCount Max. number of objects (Default: 10).
* @constructor
* @extends {goog.structs.Pool}
*/
goog.structs.PriorityPool = function(opt_minCount, opt_maxCount) {
/**
* Queue of requests for pool objects.
* @type {goog.structs.PriorityQueue}
* @private
*/
this.requestQueue_ = new goog.structs.PriorityQueue();
// Must break convention of putting the super-class's constructor first. This
// is because the super-class constructor calls adjustForMinMax, which this
// class overrides. In this class's implementation, it assumes that there
// is a requestQueue_, and will error if not present.
goog.structs.Pool.call(this, opt_minCount, opt_maxCount);
};
goog.inherits(goog.structs.PriorityPool, goog.structs.Pool);
/**
* The key for the most recent timeout created.
* @type {number|undefined}
* @private
*/
goog.structs.PriorityPool.prototype.delayTimeout_;
/**
* Default priority for pool objects requests.
* @type {number}
* @private
*/
goog.structs.PriorityPool.DEFAULT_PRIORITY_ = 100;
/** @override */
goog.structs.PriorityPool.prototype.setDelay = function(delay) {
goog.base(this, 'setDelay', delay);
// If the pool hasn't been accessed yet, no need to do anything.
if (!goog.isDefAndNotNull(this.lastAccess)) {
return;
}
goog.global.clearTimeout(this.delayTimeout_);
this.delayTimeout_ = goog.global.setTimeout(
goog.bind(this.handleQueueRequests_, this),
this.delay + this.lastAccess - goog.now());
// Handle all requests.
this.handleQueueRequests_();
};
/**
* Get a new object from the the pool, if there is one available, otherwise
* return undefined.
* @param {Function=} opt_callback The function to callback when an object is
* available. This could be immediately. If this is not present, then an
* object is immediately returned if available, or undefined if not.
* @param {*=} opt_priority The priority of the request. A smaller value means a
* higher priority.
* @return {Object|undefined} The new object from the pool if there is one
* available and a callback is not given. Otherwise, undefined.
* @override
*/
goog.structs.PriorityPool.prototype.getObject = function(opt_callback,
opt_priority) {
if (!opt_callback) {
var result = goog.base(this, 'getObject');
if (result && this.delay) {
this.delayTimeout_ = goog.global.setTimeout(
goog.bind(this.handleQueueRequests_, this),
this.delay);
}
return result;
}
var priority = goog.isDef(opt_priority) ? opt_priority :
goog.structs.PriorityPool.DEFAULT_PRIORITY_;
this.requestQueue_.enqueue(priority, opt_callback);
// Handle all requests.
this.handleQueueRequests_();
return undefined;
};
/**
* Handles the request queue. Tries to fires off as many queued requests as
* possible.
* @private
*/
goog.structs.PriorityPool.prototype.handleQueueRequests_ = function() {
var requestQueue = this.requestQueue_;
while (requestQueue.getCount() > 0) {
var obj = this.getObject();
if (!obj) {
return;
} else {
var requestCallback = requestQueue.dequeue();
requestCallback.apply(this, [obj]);
}
}
};
/**
* Adds an object to the collection of objects that are free. If the object can
* not be added, then it is disposed.
*
* NOTE: This method does not remove the object from the in use collection.
*
* @param {Object} obj The object to add to the collection of free objects.
* @override
*/
goog.structs.PriorityPool.prototype.addFreeObject = function(obj) {
goog.structs.PriorityPool.superClass_.addFreeObject.call(this, obj);
// Handle all requests.
this.handleQueueRequests_();
};
/**
* Adjusts the objects held in the pool to be within the min/max constraints.
*
* NOTE: It is possible that the number of objects in the pool will still be
* greater than the maximum count of objects allowed. This will be the case
* if no more free objects can be disposed of to get below the minimum count
* (i.e., all objects are in use).
* @override
*/
goog.structs.PriorityPool.prototype.adjustForMinMax = function() {
goog.structs.PriorityPool.superClass_.adjustForMinMax.call(this);
// Handle all requests.
this.handleQueueRequests_();
};
/** @override */
goog.structs.PriorityPool.prototype.disposeInternal = function() {
goog.structs.PriorityPool.superClass_.disposeInternal.call(this);
goog.global.clearTimeout(this.delayTimeout_);
this.requestQueue_.clear();
this.requestQueue_ = null;
};
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