Implement FallbackSignalStrategy.

remoting/webapp/crd/js/fallback_signal_strategy.js

Index: remoting/webapp/crd/js/fallback_signal_strategy.js
diff --git a/remoting/webapp/crd/js/fallback_signal_strategy.js b/remoting/webapp/crd/js/fallback_signal_strategy.js
new file mode 100644
index 0000000000000000000000000000000000000000..bb58e4d45ae63da3adcf558a4581b61009ffb3bd
--- /dev/null
+++ b/remoting/webapp/crd/js/fallback_signal_strategy.js
@@ -0,0 +1,329 @@
+// Copyright 2015 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.
+
+'use strict';
+
+/** @suppress {duplicate} */
+var remoting = remoting || {};
+
+/**
+ * A signal strategy encapsulating a primary and a back-up strategy. If the
+ * primary fails or times out, then the secondary is used. Information about
+ * which strategy was used, and why, is returned via |onProgressCallback|.
+ *
+ * @param {function(
+ *             function(remoting.SignalStrategy.State)
+ *         ):remoting.SignalStrategy} primaryFactory
+ * @param {function(
+ *             function(remoting.SignalStrategy.State)
+ *         ):remoting.SignalStrategy} secondaryFactory
+ * @param {function(remoting.SignalStrategy.State):void} onStateChangedCallback
+ * @param {function(remoting.FallbackSignalStrategy.Progress)}
+ *     onProgressCallback
+ *
+ * @implements {remoting.SignalStrategy}
+ * @constructor
+ */
+remoting.FallbackSignalStrategy = function(
+    primaryFactory, secondaryFactory,
+    onStateChangedCallback, onProgressCallback) {
+  /**
+   * @type {remoting.SignalStrategy}
+   * @private
+   */
+  this.primary_ = primaryFactory(this.onPrimaryStateChanged_.bind(this));
+
+  /**
+   * @type {remoting.SignalStrategy}
+   * @private
+   */
+  this.secondary_ = secondaryFactory(this.onSecondaryStateChanged_.bind(this));
+
+  /**
+   * @type {function(remoting.SignalStrategy.State)}
+   * @private
+   */
+  this.onStateChangedCallback_ = onStateChangedCallback;
+
+  /**
+   * @type {function(remoting.FallbackSignalStrategy.Progress)}
+   * @private
+   */
+  this.onProgressCallback_ = onProgressCallback;
+
+  /**
+   * @type {?function(Element):void}
+   * @private
+   */
+  this.onIncomingStanzaCallback_ = null;
+
+  /**
+   * @type {number}
+   * @private
+   * @const
+   */
+  this.PRIMARY_CONNECT_TIMEOUT_MS_ = 10 * 1000;
+
+  /**
+   * @enum {string}
+   * @private
+   */
+  this.State = {
+    NOT_CONNECTED: 'not-connected',
+    PRIMARY_PENDING: 'primary-pending',
+    PRIMARY_SUCCEEDED: 'primary-succeeded',
+    SECONDARY_PENDING: 'secondary-pending',
+    SECONDARY_SUCCEEDED: 'secondary-succeeded',
+    SECONDARY_FAILED: 'secondary-failed',
+    CLOSED: 'closed'
+  };
+
+  /**
+   * @type {string}
+   * @private
+   */
+  this.state_ = this.State.NOT_CONNECTED;
+
+  /**
+   * @type {?remoting.SignalStrategy.State}
+   * @private
+   */
+  this.externalState_ = null;
+
+  /**
+   * @type {string}
+   * @private
+   */
+  this.server_ = '';
+
+  /**
+   * @type {string}
+   * @private
+   */
+  this.username_ = '';
+
+  /**
+   * @type {string}
+   * @private
+   */
+  this.authToken_ = '';
+
+  /**
+   * @type {number}
+   * @private
+   */
+  this.primaryConnectTimerId_ = 0;
+};
+
+/**
+ * @enum {string}
+ */
+remoting.FallbackSignalStrategy.Progress = {
+  PRIMARY_SUCCEEDED: 'primary-succeeded',
+  PRIMARY_FAILED: 'primary-failed',
+  PRIMARY_TIMED_OUT: 'primary-timed-out',
+  PRIMARY_SUCCEEDED_LATE: 'primary-succeeded-late',
+  PRIMARY_FAILED_LATE: 'primary-failed-late',
+  SECONDARY_SUCCEEDED: 'secondary-succeeded',
+  SECONDARY_FAILED: 'secondary-failed'
+};
+
+remoting.FallbackSignalStrategy.prototype.dispose = function() {
+  this.primary_.dispose();
+  this.secondary_.dispose();
+};
+
+/**
+ * @param {?function(Element):void} onIncomingStanzaCallback Callback to call on
+ *     incoming messages.
+ */
+remoting.FallbackSignalStrategy.prototype.setIncomingStanzaCallback =
+    function(onIncomingStanzaCallback) {
+  this.onIncomingStanzaCallback_ = onIncomingStanzaCallback;
+  if (this.state_ == this.State.PRIMARY_PENDING ||
+      this.state_ == this.State.PRIMARY_SUCCEEDED) {
+    this.primary_.setIncomingStanzaCallback(onIncomingStanzaCallback);
+  } else if (this.state_ == this.State.SECONDARY_PENDING ||
+             this.state_ == this.State.SECONDARY_SUCCEEDED) {
+    this.secondary_.setIncomingStanzaCallback(onIncomingStanzaCallback);
+  }
+};
+
+/**
+ * @param {string} server
+ * @param {string} username
+ * @param {string} authToken
+ */
+remoting.FallbackSignalStrategy.prototype.connect =
+    function(server, username, authToken) {
+  base.debug.assert(this.state_ == this.State.NOT_CONNECTED);
+  this.server_ = server;
+  this.username_ = username;
+  this.authToken_ = authToken;
+  this.state_ = this.State.PRIMARY_PENDING;
+  this.primary_.setIncomingStanzaCallback(this.onIncomingStanzaCallback_);
+  this.primary_.connect(server, username, authToken);
+  this.primaryConnectTimerId_ =
+      window.setTimeout(this.onPrimaryTimeout_.bind(this),
+                        this.PRIMARY_CONNECT_TIMEOUT_MS_);
+};
+
+/**
+ * Sends a message. Can be called only in CONNECTED state.
+ * @param {string} message
+ */
+remoting.FallbackSignalStrategy.prototype.sendMessage = function(message) {
+  this.getConnectedSignalStrategy_().sendMessage(message);
+};
+
+/** @return {remoting.SignalStrategy.State} Current state */
+remoting.FallbackSignalStrategy.prototype.getState = function() {
+  return (this.externalState_ === null)
+      ? remoting.SignalStrategy.State.NOT_CONNECTED
+      : this.externalState_;
+};
+
+/** @return {remoting.Error} Error when in FAILED state. */
+remoting.FallbackSignalStrategy.prototype.getError = function() {
+  base.debug.assert(this.state_ == this.State.SECONDARY_FAILED);
+  base.debug.assert(
+      this.secondary_.getState() == remoting.SignalStrategy.State.FAILED);
+  return this.secondary_.getError();
+};
+
+/** @return {string} Current JID when in CONNECTED state. */
+remoting.FallbackSignalStrategy.prototype.getJid = function() {
+  return this.getConnectedSignalStrategy_().getJid();
+};
+
+/**
+ * @return {remoting.SignalStrategy} The active signal strategy, if the
+ *     connection has succeeded.
+ * @private
+ */
+remoting.FallbackSignalStrategy.prototype.getConnectedSignalStrategy_ =
+    function() {
+  if (this.state_ == this.State.PRIMARY_SUCCEEDED) {
+    base.debug.assert(
+        this.primary_.getState() == remoting.SignalStrategy.State.CONNECTED);
+    return this.primary_;
+  } else if (this.state_ == this.State.SECONDARY_SUCCEEDED) {
+    base.debug.assert(
+        this.secondary_.getState() == remoting.SignalStrategy.State.CONNECTED);
+    return this.secondary_;
+  } else {
+    base.debug.assert(
+        false,
+        'getConnectedSignalStrategy called in unconnected state');
+    return null;
+  }
+};
+
+/**
+ * @param {remoting.SignalStrategy.State} state
+ * @private
+ */
+remoting.FallbackSignalStrategy.prototype.onPrimaryStateChanged_ =
+    function(state) {
+  switch (state) {
+    case remoting.SignalStrategy.State.CONNECTED:
+      if (this.state_ == this.State.PRIMARY_PENDING) {
+        window.clearTimeout(this.primaryConnectTimerId_);
+        this.onProgressCallback_(
+            remoting.FallbackSignalStrategy.Progress.PRIMARY_SUCCEEDED);
+        this.state_ = this.State.PRIMARY_SUCCEEDED;
+      } else {
+        this.onProgressCallback_(
+            remoting.FallbackSignalStrategy.Progress.PRIMARY_SUCCEEDED_LATE);
+      }
+      break;
+
+    case remoting.SignalStrategy.State.FAILED:
+      if (this.state_ == this.State.PRIMARY_PENDING) {
+        window.clearTimeout(this.primaryConnectTimerId_);
+        this.onProgressCallback_(
+            remoting.FallbackSignalStrategy.Progress.PRIMARY_FAILED);
+        this.connectSecondary_();
+      } else {
+        this.onProgressCallback_(
+            remoting.FallbackSignalStrategy.Progress.PRIMARY_FAILED_LATE);
+      }
+      return;  // Don't notify the external callback
+
+    case remoting.SignalStrategy.State.CLOSED:
+      this.state_ = this.State.CLOSED;
+      break;
+  }
+
+  this.notifyExternalCallback_(state);
+};
+
+/**
+ * @param {remoting.SignalStrategy.State} state
+ * @private
+ */
+remoting.FallbackSignalStrategy.prototype.onSecondaryStateChanged_ =
+    function(state) {
+  switch (state) {
+    case remoting.SignalStrategy.State.CONNECTED:
+      this.onProgressCallback_(
+          remoting.FallbackSignalStrategy.Progress.SECONDARY_SUCCEEDED);
+      this.state_ = this.State.SECONDARY_SUCCEEDED;
+      break;
+
+    case remoting.SignalStrategy.State.FAILED:
+      this.onProgressCallback_(
+          remoting.FallbackSignalStrategy.Progress.SECONDARY_FAILED);
+      this.state_ = this.State.SECONDARY_FAILED;
+      break;
+
+    case remoting.SignalStrategy.State.CLOSED:
+      this.state_ = this.State.CLOSED;
+      break;
+  }
+
+  this.notifyExternalCallback_(state);
+};
+
+/**
+ * Notify the external callback of a change in state if it's consistent with
+ * the allowed state transitions (ie, if it represents a later stage in the
+ * connection process). Suppress state transitions that would violate this,
+ * for example a CONNECTING -> NOT_CONNECTED transition when we switch from
+ * the primary to the secondary signal strategy.
+ *
+ * @param {remoting.SignalStrategy.State} state
+ * @private
+ */
+remoting.FallbackSignalStrategy.prototype.notifyExternalCallback_ =
+    function(state) {
+  if (this.externalState_ === null || state > this.externalState_) {
+    this.externalState_ = state;
+    this.onStateChangedCallback_(state);
+  }
+};
+
+/**
+ * @private
+ */
+remoting.FallbackSignalStrategy.prototype.connectSecondary_ = function() {
+  base.debug.assert(this.state_ == this.State.PRIMARY_PENDING);
+  base.debug.assert(this.server_ != '');
+  base.debug.assert(this.username_ != '');
+  base.debug.assert(this.authToken_ != '');
+
+  this.state_ = this.State.SECONDARY_PENDING;
+  this.primary_.setIncomingStanzaCallback(null);
+  this.secondary_.setIncomingStanzaCallback(this.onIncomingStanzaCallback_);
+  this.secondary_.connect(this.server_, this.username_, this.authToken_);
+};
+
+/**
+ * @private
+ */
+remoting.FallbackSignalStrategy.prototype.onPrimaryTimeout_ = function() {
+  this.onProgressCallback_(
+      remoting.FallbackSignalStrategy.Progress.PRIMARY_TIMED_OUT);
+  this.connectSecondary_();
+};