mirror of https://github.com/perkeep/perkeep.git
102 lines
3.0 KiB
JavaScript
102 lines
3.0 KiB
JavaScript
/*
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Copyright 2014 The Perkeep Authors
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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goog.provide('cam.WorkerMessageRouter');
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goog.require('goog.string');
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// Convenience for sending request/response style messages to and from workers.
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// @param {!Worker} worker The DOM worker to wrap.
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// @constructor
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cam.WorkerMessageRouter = function(worker) {
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this.worker_ = worker;
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this.nextMessageId_ = 1;
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// name->handler - See registerHandler()
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// @type Object.<string, function(*, function(*))>
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this.handlers_ = {};
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// messageid->callback - See sendMessage()
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// @type Object.<number, function(*)>
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this.pendingMessages_ = {};
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this.worker_.addEventListener('message', this.handleMessage_.bind(this));
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};
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// Send a message over the worker, optionally expecting a response.
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// @param {!string} name The name of the message to send.
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// @param {!*} msg The message content
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// @param {?function(*)} opt_callback The function to receive the response.
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cam.WorkerMessageRouter.prototype.sendMessage = function(name, msg, opt_callback) {
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var messageId = 0;
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if (opt_callback) {
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messageId = this.nextMessageId_++;
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this.pendingMessages_[messageId] = opt_callback;
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}
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this.worker_.postMessage({
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messageId: messageId,
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name: name,
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message: msg
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});
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};
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// Registers a function to handle a particular named message type.
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// @param {!string} name The name of the message type to handle.
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// @param {!function(*, function(*))} handler The function to call to return the reply to the client.
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cam.WorkerMessageRouter.prototype.registerHandler = function(name, handler) {
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this.handlers_[name] = handler;
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};
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cam.WorkerMessageRouter.prototype.handleMessage_ = function(e) {
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if (!goog.isObject(e.data) || !goog.isDef(e.data.messageId)) {
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return;
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}
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if (goog.isDef(e.data.name)) {
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this.handleRequest_(e.data);
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} else {
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this.handleReply_(e.data);
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}
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};
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cam.WorkerMessageRouter.prototype.handleRequest_ = function(request) {
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var handler = this.handlers_[request.name];
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if (!handler) {
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throw new Error(goog.string.subs('No registered handler with name: %s', request.name));
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}
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var sendReply = function(reply) {
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if (!request.messageId) {
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return;
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}
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this.worker_.postMessage({
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messageId: request.messageId,
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message: reply
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});
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}.bind(this);
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handler(request.message, sendReply);
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};
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cam.WorkerMessageRouter.prototype.handleReply_ = function(reply) {
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var callback = this.pendingMessages_[reply.messageId];
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if (!callback) {
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throw new Error('Could not find callback for pending message: %s', reply.messageId);
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}
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delete this.pendingMessages_[reply.messageId];
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callback(reply.message);
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};
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