Add a 'NaCl manager' to manage the state of the NaCl hotword detector plugin.

chrome/browser/resources/hotword/nacl_manager.js

+// Copyright (c) 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+cr.define('hotword', function() {
+'use strict';
+
+/**
+ * Class used to manage the state of the NaCl recognizer plugin. Handles all
+ * control of the NaCl plugin, including creation, start, stop, trigger, and
+ * shutdown.
+ *
+ * @constructor
+ * @extends {cr.EventTarget}
+ */
+function NaClManager() {
+  /**
+   * Current state of this manager.
+   * @private {hotword.NaClManager.ManagerState_}
+   */
+  this.recognizerState_ = ManagerState_.UNINITIALIZED;
+
+  /**
+   * The window.timeout ID associated with a pending message.
+   * @private {?number}
+   */
+  this.naclTimeoutId_ = null;
+
+  /**
+   * The expected message that will cancel the current timeout.
+   * @private {?string}
+   */
+  this.expectingMessage_ = null;
+
+  /**
+   * Whether the plugin will be started as soon as it stops.
+   * @private {boolean}
+   */
+  this.restartOnStop_ = false;
+
+  /**
+   * NaCl plugin element on extension background page.
+   * @private {?Nacl}
+   */
+  this.plugin_ = null;
+
+  /**
+   * URL containing hotword-model data file.
+   * @private {string}
+   */
+  this.modelUrl_ = '';
+
+  /**
+   * Media stream containing an audio input track.
+   * @private {?MediaStream}
+   */
+  this.stream_ = null;
+};
+
+/**
+ * States this manager can be in. Since messages to/from the plugin are
+ * asynchronous (and potentially queued), it's not possible to know what state
+ * the plugin is in. However, track a state machine for NaClManager based on
+ * what messages are sent/received.
+ * @enum {number}
+ * @private
+ */
+NaClManager.ManagerState_ = {
+  UNINITIALIZED: 0,
+  LOADING: 1,
+  STOPPING: 2,
+  STOPPED: 3,
+  STARTING: 4,
+  RUNNING: 5,
+  ERROR: 6,
+  SHUTDOWN: 7,
+};
+var ManagerState_ = NaClManager.ManagerState_;
+var Error_ = hotword.constants.Error;
+
+NaClManager.prototype.__proto__ = cr.EventTarget.prototype;
+
+/**
+ * Called when an error occurs. Dispatches an event.
+ * @param {!hotword.constants.Error} error
+ * @private
+ */
+NaClManager.prototype.handleError_ = function(error) {
+  event = new Event(hotword.constants.Event.ERROR);
+  event.data = error;
+  this.dispatchEvent(event);
+};
+
+/**
+ * @return {boolean} True if the recognizer is in a running state.
+ */
+NaClManager.prototype.isRunning = function() {
+  return this.recognizerState_ == ManagerState_.RUNNING;
+};
+
+/**
+ * Set a timeout. Only allow one timeout to exist at any given time.
+ * @param {!function()} func
+ * @param {number} timeout
+ * @private
+ */
+NaClManager.prototype.setTimeout_ = function(func, timeout) {
+  assert(!this.naclTimeoutId_);
+  this.naclTimeoutId_ = window.setTimeout(
+      function() {
+        this.naclTimeoutId_ = null;
+        func();
+      }.bind(this), timeout);
+};
+
+/**
+ * Clears the current timeout.
+ * @private
+ */
+NaClManager.prototype.clearTimeout_ = function() {
+  window.clearTimeout(this.naclTimeoutId_);
+  this.naclTimeoutId_ = null;
+};
+
+/**
+ * Starts a stopped or stopping hotword recognizer (NaCl plugin).
+ */
+NaClManager.prototype.startRecognizer = function() {
+  if (this.recognizerState_ == ManagerState_.STOPPED) {
+    this.recognizerState_ = ManagerState_.STARTING;
+    this.sendDataToPlugin_(hotword.constants.NaClPlugin.RESTART);
+    this.waitForMessage_(hotword.constants.TimeoutMs.LONG,
+                         hotword.constants.NaClPlugin.READY_FOR_AUDIO);
+  } else if (this.recognizerState_ == ManagerState_.STOPPING) {
+    // Wait until the plugin is stopped before trying to start it.
+    this.restartOnStop_ = true;
+  } else {
+    throw 'Attempting to start NaCl recogniser not in STOPPED or STOPPING ' +
+        'state';
+  }
+};
+
+/**
+ * Stops the hotword recognizer.
+ */
+NaClManager.prototype.stopRecognizer = function() {
+  this.sendDataToPlugin_(hotword.constants.NaClPlugin.STOP);
+  this.recognizerState_ = ManagerState_.STOPPING;
+  this.waitForMessage_(hotword.constants.TimeoutMs.NORMAL,
+                       hotword.constants.NaClPlugin.STOPPED);
+};
+
+/**
+ * Checks whether the file at the given path exists.
+ * @param {!string} path Path to a file. Can be any valid URL.
+ * @return {boolean} True if the patch exists.
+ * @private
+ */
+NaClManager.prototype.fileExists_ = function(path) {
+  var xhr = new XMLHttpRequest();
+  xhr.open('HEAD', path, false);
+  try {
+    xhr.send();
+  } catch (err) {
+    return false;
+  }
+  if (xhr.readyState != xhr.DONE || xhr.status != 200) {
+    return false;
+  }
+  return true;
+};
+
+/**
+ * Creates and returns a list of possible languages to check for hotword
+ * support.
+ * @return {!Array.<string>} Array of languages.
+ * @private
+ */
+NaClManager.prototype.getPossibleLanguages_ = function() {
+  // Create array used to search first for language-country, if not found then
+  // search for language, if not found then no language (empty string).
+  // For example, search for 'en-us', then 'en', then ''.
+  var langs = new Array();
+  if (hotword.constants.UI_LANGUAGE) {
+    // Chrome webstore doesn't support uppercase path: crbug.com/353407
+    var language = hotword.constants.UI_LANGUAGE.toLowerCase();
+    langs.push(language);  // Example: 'en-us'.
+    // Remove country to add just the language to array.
+    var hyphen = language.lastIndexOf('-');
+    if (hyphen >= 0) {
+      langs.push(language.substr(0, hyphen));  // Example: 'en'.
+    }
+  }
+  langs.push('');
+  return langs;
+};
+
+/**
+ * Creates a NaCl plugin object and attaches it to the page.
+ * @param {!string} src Location of the plugin.
+ * @return {!Nacl} NaCl plugin DOM object.
+ * @private
+ */
+NaClManager.prototype.createPlugin_ = function(src) {
+  var plugin = document.createElement('embed');
+  plugin.src = src;
+  plugin.type = 'application/x-nacl';
+  document.body.appendChild(plugin);
+  return plugin;
+};
+
+/**
+ * Initializes the NaCl manager.
+ * @param {!string} naclArch Either 'arm', 'x86-32' or 'x86-64'.
+ * @param {!MediaStream} stream A stream containing an audio source track.
+ * @return {boolean} True if the successful.
+ */
+NaClManager.prototype.initialize = function(naclArch, stream) {
+  assert(this.recognizerState_ == ManagerState_.UNINITIALIZED);
+  var langs = this.getPossibleLanguages_();
+  var i, j;
+  // For country-lang variations. For example, when combined with path it will
+  // attempt to find: '/x86-32_en-gb/', else '/x86-32_en/', else '/x86-32_/'.
+  for (i = 0; i < langs.length; i++) {
+    var folder = hotword.constants.SHARED_MODULE_ROOT + '/_platform_specific/' +
+        naclArch + '_' + langs[i] + '/';
+    var dataSrc = folder + hotword.constants.File.RECOGNIZER_CONFIG;
+    var pluginSrc = hotword.constants.SHARED_MODULE_ROOT + '/hotword_' +
+        langs[i] + '.nmf';
+    var dataExists = this.fileExists_(dataSrc) && this.fileExists_(pluginSrc);
+    if (!dataExists) {
+      continue;
+    }
+
+    var plugin = this.createPlugin_(pluginSrc);
+    this.plugin_ = /** @type {Nacl} */ (plugin);
+    if (!this.plugin_ || !this.plugin_.postMessage) {
+      document.body.removeChild(this.plugin_);
+      this.recognizerState_ = ManagerState_.ERROR;
+      return false;
+    }
+    this.modelUrl_ = chrome.extension.getURL(dataSrc);
+    this.stream_ = stream;
+    this.recognizerState_ = ManagerState_.LOADING;
+
+    plugin.addEventListener('message',
+                            this.handlePluginMessage_.bind(this),
+                            false);
+
+    plugin.addEventListener('crash',
+                            this.handleError_.bind(this, Error_.NACL_CRASH),
+                            false);
+    return true;
+  }
+  this.recognizerState_ = ManagerState_.ERROR;
+  return false;
+};
+
+/**
+ * Shuts down the NaCl plugin and frees all resources.
+ */
+NaClManager.prototype.shutdown = function() {
+  if (this.plugin_ != null) {
+    document.body.removeChild(this.plugin_);
+    this.plugin_ = null;
+  }
+  this.clearTimeout_();
+  this.recognizerState_ = ManagerState_.SHUTDOWN;
+  this.stream_ = null;
+};
+
+/**
+ * Sends data to the NaCl plugin.
+ * @param {!string} data Command to be sent to NaCl plugin.
+ * @private
+ */
+NaClManager.prototype.sendDataToPlugin_ = function(data) {
+  assert(this.recognizerState_ != ManagerState_.UNINITIALIZED);
+  this.plugin_.postMessage(data);
+};
+
+/**
+ * Waits, with a timeout, for a message to be received from the plugin. If the
+ * message is not seen within the timeout, dispatch an 'error' event and go into
+ * the ERROR state.
+ * @param {number} timeout Timeout, in milliseconds, to wait for the message.
+ * @param {!string} message Message to wait for.
+ * @private
+ */
+NaClManager.prototype.waitForMessage_ = function(timeout, message) {
+  assert(this.expectingMessage_ == null,
+         'Already waiting for message ' + this.expectingMessage_);
+  this.setTimeout_(
+      function() {
+        this.recognizerState_ = ManagerState_.ERROR;
+        this.handleError_(Error_.TIMEOUT);
+      }.bind(this), timeout);
+  this.expectingMessage_ = message;
+};
+
+/**
+ * Called when a message is received from the plugin. If we're waiting for that
+ * message, cancel the pending timeout.
+ * @param {string} message Message received.
+ * @private
+ */
+NaClManager.prototype.receivedMessage_ = function(message) {
+  if (message == this.expectingMessage_) {
+    this.clearTimeout_();
+    this.expectingMessage_ = null;
+  }
+};
+
+/**
+ * Handle a REQUEST_MODEL message from the plugin.
+ * The plugin sends this message immediately after starting.
+ * @private
+ */
+NaClManager.prototype.handleRequestModel_ = function() {
+  if (this.recognizerState_ != ManagerState_.LOADING) {
+    return;
+  }
+  this.sendDataToPlugin_(
+      hotword.constants.NaClPlugin.MODEL_PREFIX + this.modelUrl_);
+  this.waitForMessage_(hotword.constants.TimeoutMs.LONG,
+                       hotword.constants.NaClPlugin.MODEL_LOADED);
+};
+
+/**
+ * Handle a MODEL_LOADED message from the plugin.
+ * The plugin sends this message after successfully loading the language model.
+ * @private
+ */
+NaClManager.prototype.handleModelLoaded_ = function() {
+  if (this.recognizerState_ != ManagerState_.LOADING) {
+    return;
+  }
+  this.sendDataToPlugin_(this.stream_.getAudioTracks()[0]);
+  this.waitForMessage_(hotword.constants.TimeoutMs.LONG,
+                       hotword.constants.NaClPlugin.MS_CONFIGURED);
+};
+
+/**
+ * Handle a MS_CONFIGURED message from the plugin.
+ * The plugin sends this message after successfully configuring the audio input
+ * stream.
+ * @private
+ */
+NaClManager.prototype.handleMsConfigured_ = function() {
+  if (this.recognizerState_ != ManagerState_.LOADING) {
+    return;
+  }
+  this.recognizerState_ = ManagerState_.STOPPED;
+  this.dispatchEvent(new Event(hotword.constants.Event.READY));
+};
+
+/**
+ * Handle a READY_FOR_AUDIO message from the plugin.
+ * The plugin sends this message after the recognizer is started and
+ * successfully receives and processes audio data.
+ * @private
+ */
+NaClManager.prototype.handleReadyForAudio_ = function() {
+  if (this.recognizerState_ != ManagerState_.STARTING) {
+    return;
+  }
+  this.recognizerState_ = ManagerState_.RUNNING;
+};
+
+/**
+ * Handle a HOTWORD_DETECTED message from the plugin.
+ * The plugin sends this message after detecting the hotword.
+ * @private
+ */
+NaClManager.prototype.handleHotwordDetected_ = function() {
+  if (this.recognizerState_ != ManagerState_.RUNNING) {
+    return;
+  }
+  // We'll receive a STOPPED message very soon.
+  this.recognizerState_ = ManagerState_.STOPPING;
+  this.waitForMessage_(hotword.constants.TimeoutMs.NORMAL,
+                       hotword.constants.NaClPlugin.STOPPED);
+  this.dispatchEvent(new Event(hotword.constants.Event.TRIGGER));
+};
+
+/**
+ * Handle a STOPPED message from the plugin.
+ * This plugin sends this message after stopping the recognizer. This can happen
+ * either in response to a stop request, or after the hotword is detected.
+ * @private
+ */
+NaClManager.prototype.handleStopped_ = function() {
+  this.recognizerState_ = ManagerState_.STOPPED;
+  if (this.restartOnStop_) {
+    this.restartOnStop_ = false;
+    this.startRecognizer();
+  }
+};
+
+/**
+ * Handles a message from the NaCl plugin.
+ * @param {!Event} msg Message from NaCl plugin.
+ * @private
+ */
+NaClManager.prototype.handlePluginMessage_ = function(msg) {
+  if (msg['data']) {
+    this.receivedMessage_(msg['data']);
+    switch (msg['data']) {
+      case hotword.constants.NaClPlugin.REQUEST_MODEL:
+        this.handleRequestModel_();
+        break;
+      case hotword.constants.NaClPlugin.MODEL_LOADED:
+        this.handleModelLoaded_();
+        break;
+      case hotword.constants.NaClPlugin.MS_CONFIGURED:
+        this.handleMsConfigured_();
+        break;
+      case hotword.constants.NaClPlugin.READY_FOR_AUDIO:
+        this.handleReadyForAudio_();
+        break;
+      case hotword.constants.NaClPlugin.HOTWORD_DETECTED:
+        this.handleHotwordDetected_();
+        break;
+      case hotword.constants.NaClPlugin.STOPPED:
+        this.handleStopped_();
+        break;
+    }
+  }
+};
+
+return {
+  NaClManager: NaClManager
+};
+
+});