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// Copyright 2007 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 This represents a Gears worker (background process).
*
* @author arv@google.com (Erik Arvidsson)
*/
goog.provide('goog.gears.Worker');
goog.provide('goog.gears.Worker.EventType');
goog.provide('goog.gears.WorkerEvent');
goog.require('goog.events.Event');
goog.require('goog.events.EventTarget');
/**
* This is an absctraction of workers that can be used with Gears WorkerPool.
* @constructor
* @param {goog.gears.WorkerPool} workerPool WorkerPool object.
* @param {number=} opt_id The id of the worker this represents.
*
* @extends {goog.events.EventTarget}
*/
goog.gears.Worker = function(workerPool, opt_id) {
goog.events.EventTarget.call(this);
/**
* Reference to the worker pool.
* @type {goog.gears.WorkerPool}
* @private
*/
this.workerPool_ = workerPool;
if (opt_id != null) {
this.init(opt_id);
}
};
goog.inherits(goog.gears.Worker, goog.events.EventTarget);
/**
* Called when we receive a message from this worker. The message will
* first be dispatched as a WorkerEvent with type {@code EventType.MESSAGE} and
* then a {@code EventType.COMMAND}. An EventTarget may call
* {@code WorkerEvent.preventDefault()} to stop further dispatches.
* @param {GearsMessageObject} messageObject An object containing all
* information about the message.
*/
goog.gears.Worker.prototype.handleMessage = function(messageObject) {
// First dispatch a message event.
var messageEvent = new goog.gears.WorkerEvent(
goog.gears.Worker.EventType.MESSAGE,
messageObject);
// Allow the user to call prevent default to not process the COMMAND.
if (this.dispatchEvent(messageEvent)) {
if (goog.gears.Worker.isCommandLike(messageObject.body)) {
this.dispatchEvent(new goog.gears.WorkerEvent(
goog.gears.Worker.EventType.COMMAND,
messageObject));
}
}
};
/**
* The ID of the worker we are communicating with.
* @type {?number}
* @private
*/
goog.gears.Worker.prototype.id_ = null;
/**
* Initializes the worker object with a worker id.
* @param {number} id The id of the worker this represents.
*/
goog.gears.Worker.prototype.init = function(id) {
if (this.id_ != null) {
throw Error('Can only set the worker id once');
}
this.id_ = id;
this.workerPool_.registerWorker(this);
};
/**
* Sends a command to the worker.
* @param {number} commandId The ID of the command to
* send.
* @param {Object} params An object to send as the parameters. This object
* must be something that Gears can serialize. This includes JSON as well
* as Gears blobs.
*/
goog.gears.Worker.prototype.sendCommand = function(commandId, params) {
this.sendMessage([commandId, params]);
};
/**
* Sends a message to the worker.
* @param {*} message The message to send to the target worker.
*/
goog.gears.Worker.prototype.sendMessage = function(message) {
this.workerPool_.sendMessage(message, this);
};
/**
* Gets an ID that uniquely identifies this worker. The ID is unique among all
* worker from the same WorkerPool.
*
* @return {number} The ID of the worker. This might be null if the
* worker has not been initialized yet.
*/
goog.gears.Worker.prototype.getId = function() {
if (this.id_ == null) {
throw Error('The worker has not yet been initialized');
}
return this.id_;
};
/**
* Whether an object looks like a command. A command is an array with length 2
* where the first element is a number.
* @param {*} obj The object to test.
* @return {boolean} true if the object looks like a command.
*/
goog.gears.Worker.isCommandLike = function(obj) {
return goog.isArray(obj) && obj.length == 2 &&
goog.isNumber((/** @type {Array} */ obj)[0]);
};
/** @override */
goog.gears.Worker.prototype.disposeInternal = function() {
goog.gears.Worker.superClass_.disposeInternal.call(this);
this.workerPool_.unregisterWorker(this);
this.workerPool_ = null;
};
/**
* Enum for event types fired by the worker.
* @enum {string}
*/
goog.gears.Worker.EventType = {
MESSAGE: 'message',
COMMAND: 'command'
};
/**
* Event used when the worker recieves a message
* @param {string} type The type of event.
* @param {GearsMessageObject} messageObject The message object.
*
* @constructor
* @extends {goog.events.Event}
*/
goog.gears.WorkerEvent = function(type, messageObject) {
goog.events.Event.call(this, type);
/**
* The message sent from the worker.
* @type {*}
*/
this.message = messageObject.body;
/**
* The JSON object sent from the worker.
* @type {*}
* @deprecated Use message instead.
*/
this.json = this.message;
/**
* The object containing all information about the message.
* @type {GearsMessageObject}
*/
this.messageObject = messageObject;
};
goog.inherits(goog.gears.WorkerEvent, goog.events.Event);
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