The Tor Browser: browser/components/sessionstore/content/content-sessionStore.js@7e26c7da4463 (annotated)

browser/components/sessionstore/content/content-sessionStore.js@7e26c7da4463 (annotated)

browser/components/sessionstore/content/content-sessionStore.js

Wed, 31 Dec 2014 06:55:50 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:55:50 +0100
changeset 2: 7e26c7da4463
permissions: -rw-r--r--

Added tag UPSTREAM_283F7C6 for changeset ca08bd8f51b2

 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 "use strict";
 function debug(msg) {
   Services.console.logStringMessage("SessionStoreContent: " + msg);
 }
 let Cu = Components.utils;
 let Cc = Components.classes;
 let Ci = Components.interfaces;
 let Cr = Components.results;
 Cu.import("resource://gre/modules/XPCOMUtils.jsm", this);
 Cu.import("resource://gre/modules/Timer.jsm", this);
 XPCOMUtils.defineLazyModuleGetter(this, "DocShellCapabilities",
   "resource:///modules/sessionstore/DocShellCapabilities.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "FormData",
   "resource://gre/modules/FormData.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "PageStyle",
   "resource:///modules/sessionstore/PageStyle.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "ScrollPosition",
   "resource://gre/modules/ScrollPosition.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "SessionHistory",
   "resource:///modules/sessionstore/SessionHistory.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "SessionStorage",
   "resource:///modules/sessionstore/SessionStorage.jsm");
 Cu.import("resource:///modules/sessionstore/FrameTree.jsm", this);
 let gFrameTree = new FrameTree(this);
 Cu.import("resource:///modules/sessionstore/ContentRestore.jsm", this);
 XPCOMUtils.defineLazyGetter(this, 'gContentRestore',
                             () => { return new ContentRestore(this) });
 /**
  * Returns a lazy function that will evaluate the given
  * function |fn| only once and cache its return value.
  */
 function createLazy(fn) {
   let cached = false;
   let cachedValue = null;
   return function lazy() {
     if (!cached) {
       cachedValue = fn();
       cached = true;
     }
     return cachedValue;
   };
 }
 /**
  * Determines whether the given storage event was triggered by changes
  * to the sessionStorage object and not the local or globalStorage.
  */
 function isSessionStorageEvent(event) {
   try {
     return event.storageArea == content.sessionStorage;
   } catch (ex if ex instanceof Ci.nsIException && ex.result == Cr.NS_ERROR_NOT_AVAILABLE) {
     // This page does not have a DOMSessionStorage
     // (this is typically the case for about: pages)
     return false;
   }
 }
 /**
  * Listens for and handles content events that we need for the
  * session store service to be notified of state changes in content.
  */
 let EventListener = {
   init: function () {
     addEventListener("load", this, true);
   },
   handleEvent: function (event) {
     // Ignore load events from subframes.
     if (event.target != content.document) {
       return;
     }
     // If we're in the process of restoring, this load may signal
     // the end of the restoration.
     let epoch = gContentRestore.getRestoreEpoch();
     if (!epoch) {
       return;
     }
     // Restore the form data and scroll position.
     gContentRestore.restoreDocument();
     // Ask SessionStore.jsm to trigger SSTabRestored.
     sendAsyncMessage("SessionStore:restoreDocumentComplete", {epoch: epoch});
   }
 };
 /**
  * Listens for and handles messages sent by the session store service.
  */
 let MessageListener = {
   MESSAGES: [
     "SessionStore:restoreHistory",
     "SessionStore:restoreTabContent",
     "SessionStore:resetRestore",
   ],
   init: function () {
     this.MESSAGES.forEach(m => addMessageListener(m, this));
   },
   receiveMessage: function ({name, data}) {
     switch (name) {
       case "SessionStore:restoreHistory":
         let reloadCallback = () => {
           // Inform SessionStore.jsm about the reload. It will send
           // restoreTabContent in response.
           sendAsyncMessage("SessionStore:reloadPendingTab", {epoch: data.epoch});
         };
         gContentRestore.restoreHistory(data.epoch, data.tabData, reloadCallback);
         // When restoreHistory finishes, we send a synchronous message to
         // SessionStore.jsm so that it can run SSTabRestoring. Users of
         // SSTabRestoring seem to get confused if chrome and content are out of
         // sync about the state of the restore (particularly regarding
         // docShell.currentURI). Using a synchronous message is the easiest way
         // to temporarily synchronize them.
         sendSyncMessage("SessionStore:restoreHistoryComplete", {epoch: data.epoch});
         break;
       case "SessionStore:restoreTabContent":
         let epoch = gContentRestore.getRestoreEpoch();
         let finishCallback = () => {
           // Tell SessionStore.jsm that it may want to restore some more tabs,
           // since it restores a max of MAX_CONCURRENT_TAB_RESTORES at a time.
           sendAsyncMessage("SessionStore:restoreTabContentComplete", {epoch: epoch});
         };
         // We need to pass the value of didStartLoad back to SessionStore.jsm.
         let didStartLoad = gContentRestore.restoreTabContent(finishCallback);
         sendAsyncMessage("SessionStore:restoreTabContentStarted", {epoch: epoch});
         if (!didStartLoad) {
           // Pretend that the load succeeded so that event handlers fire correctly.
           sendAsyncMessage("SessionStore:restoreTabContentComplete", {epoch: epoch});
           sendAsyncMessage("SessionStore:restoreDocumentComplete", {epoch: epoch});
         }
         break;
       case "SessionStore:resetRestore":
         gContentRestore.resetRestore();
         break;
       default:
         debug("received unknown message '" + name + "'");
         break;
     }
   }
 };
 /**
  * On initialization, this handler gets sent to the parent process as a CPOW.
  * The parent will use it only to flush pending data from the frame script
  * when needed, i.e. when closing a tab, closing a window, shutting down, etc.
  *
  * This will hopefully not be needed in the future once we have async APIs for
  * closing windows and tabs.
  */
 let SyncHandler = {
   init: function () {
     // Send this object as a CPOW to chrome. In single-process mode,
     // the synchronous send ensures that the handler object is
     // available in SessionStore.jsm immediately upon loading
     // content-sessionStore.js.
     sendSyncMessage("SessionStore:setupSyncHandler", {}, {handler: this});
   },
   /**
    * This function is used to make the tab process flush all data that
    * hasn't been sent to the parent process, yet.
    *
    * @param id (int)
    *        A unique id that represents the last message received by the chrome
    *        process before flushing. We will use this to determine data that
    *        would be lost when data has been sent asynchronously shortly
    *        before flushing synchronously.
    */
   flush: function (id) {
     MessageQueue.flush(id);
   },
   /**
    * DO NOT USE - DEBUGGING / TESTING ONLY
    *
    * This function is used to simulate certain situations where race conditions
    * can occur by sending data shortly before flushing synchronously.
    */
   flushAsync: function () {
     MessageQueue.flushAsync();
   }
 };
 /**
  * Listens for changes to the session history. Whenever the user navigates
  * we will collect URLs and everything belonging to session history.
  *
  * Causes a SessionStore:update message to be sent that contains the current
  * session history.
  *
  * Example:
  *   {entries: [{url: "about:mozilla", ...}, ...], index: 1}
  */
 let SessionHistoryListener = {
   init: function () {
     // The frame tree observer is needed to handle navigating away from
     // an about page. Currently nsISHistoryListener does not have
     // OnHistoryNewEntry() called for about pages because the history entry is
     // modified to point at the new page. Once Bug 981900 lands the frame tree
     // observer can be removed.
     gFrameTree.addObserver(this);
     // By adding the SHistoryListener immediately, we will unfortunately be
     // notified of every history entry as the tab is restored. We don't bother
     // waiting to add the listener later because these notifications are cheap.
     // We will likely only collect once since we are batching collection on
     // a delay.
     docShell.QueryInterface(Ci.nsIWebNavigation).sessionHistory.
       addSHistoryListener(this);
     // Collect data if we start with a non-empty shistory.
     if (!SessionHistory.isEmpty(docShell)) {
       this.collect();
     }
   },
   uninit: function () {
     let sessionHistory = docShell.QueryInterface(Ci.nsIWebNavigation).sessionHistory;
     if (sessionHistory) {
       sessionHistory.removeSHistoryListener(this);
     }
   },
   collect: function () {
     if (docShell) {
       MessageQueue.push("history", () => SessionHistory.collect(docShell));
     }
   },
   onFrameTreeCollected: function () {
     this.collect();
   },
   onFrameTreeReset: function () {
     this.collect();
   },
   OnHistoryNewEntry: function (newURI) {
     this.collect();
   },
   OnHistoryGoBack: function (backURI) {
     this.collect();
     return true;
   },
   OnHistoryGoForward: function (forwardURI) {
     this.collect();
     return true;
   },
   OnHistoryGotoIndex: function (index, gotoURI) {
     this.collect();
     return true;
   },
   OnHistoryPurge: function (numEntries) {
     this.collect();
     return true;
   },
   OnHistoryReload: function (reloadURI, reloadFlags) {
     this.collect();
     return true;
   },
   OnHistoryReplaceEntry: function (index) {
     this.collect();
   },
   QueryInterface: XPCOMUtils.generateQI([
     Ci.nsISHistoryListener,
     Ci.nsISupportsWeakReference
   ])
 };
 /**
  * Listens for scroll position changes. Whenever the user scrolls the top-most
  * frame we update the scroll position and will restore it when requested.
  *
  * Causes a SessionStore:update message to be sent that contains the current
  * scroll positions as a tree of strings. If no frame of the whole frame tree
  * is scrolled this will return null so that we don't tack a property onto
  * the tabData object in the parent process.
  *
  * Example:
  *   {scroll: "100,100", children: [null, null, {scroll: "200,200"}]}
  */
 let ScrollPositionListener = {
   init: function () {
     addEventListener("scroll", this);
     gFrameTree.addObserver(this);
   },
   handleEvent: function (event) {
     let frame = event.target && event.target.defaultView;
     // Don't collect scroll data for frames created at or after the load event
     // as SessionStore can't restore scroll data for those.
     if (frame && gFrameTree.contains(frame)) {
       MessageQueue.push("scroll", () => this.collect());
     }
   },
   onFrameTreeCollected: function () {
     MessageQueue.push("scroll", () => this.collect());
   },
   onFrameTreeReset: function () {
     MessageQueue.push("scroll", () => null);
   },
   collect: function () {
     return gFrameTree.map(ScrollPosition.collect);
   }
 };
 /**
  * Listens for changes to input elements. Whenever the value of an input
  * element changes we will re-collect data for the current frame tree and send
  * a message to the parent process.
  *
  * Causes a SessionStore:update message to be sent that contains the form data
  * for all reachable frames.
  *
  * Example:
  *   {
  *     formdata: {url: "http://mozilla.org/", id: {input_id: "input value"}},
  *     children: [
  *       null,
  *       {url: "http://sub.mozilla.org/", id: {input_id: "input value 2"}}
  *     ]
  *   }
  */
 let FormDataListener = {
   init: function () {
     addEventListener("input", this, true);
     addEventListener("change", this, true);
     gFrameTree.addObserver(this);
   },
   handleEvent: function (event) {
     let frame = event.target &&
                 event.target.ownerDocument &&
                 event.target.ownerDocument.defaultView;
     // Don't collect form data for frames created at or after the load event
     // as SessionStore can't restore form data for those.
     if (frame && gFrameTree.contains(frame)) {
       MessageQueue.push("formdata", () => this.collect());
     }
   },
   onFrameTreeReset: function () {
     MessageQueue.push("formdata", () => null);
   },
   collect: function () {
     return gFrameTree.map(FormData.collect);
   }
 };
 /**
  * Listens for changes to the page style. Whenever a different page style is
  * selected or author styles are enabled/disabled we send a message with the
  * currently applied style to the chrome process.
  *
  * Causes a SessionStore:update message to be sent that contains the currently
  * selected pageStyle for all reachable frames.
  *
  * Example:
  *   {pageStyle: "Dusk", children: [null, {pageStyle: "Mozilla"}]}
  */
 let PageStyleListener = {
   init: function () {
     Services.obs.addObserver(this, "author-style-disabled-changed", false);
     Services.obs.addObserver(this, "style-sheet-applicable-state-changed", false);
     gFrameTree.addObserver(this);
   },
   uninit: function () {
     Services.obs.removeObserver(this, "author-style-disabled-changed");
     Services.obs.removeObserver(this, "style-sheet-applicable-state-changed");
   },
   observe: function (subject, topic) {
     let frame = subject.defaultView;
     if (frame && gFrameTree.contains(frame)) {
       MessageQueue.push("pageStyle", () => this.collect());
     }
   },
   collect: function () {
     return PageStyle.collect(docShell, gFrameTree);
   },
   onFrameTreeCollected: function () {
     MessageQueue.push("pageStyle", () => this.collect());
   },
   onFrameTreeReset: function () {
     MessageQueue.push("pageStyle", () => null);
   }
 };
 /**
  * Listens for changes to docShell capabilities. Whenever a new load is started
  * we need to re-check the list of capabilities and send message when it has
  * changed.
  *
  * Causes a SessionStore:update message to be sent that contains the currently
  * disabled docShell capabilities (all nsIDocShell.allow* properties set to
  * false) as a string - i.e. capability names separate by commas.
  */
 let DocShellCapabilitiesListener = {
   /**
    * This field is used to compare the last docShell capabilities to the ones
    * that have just been collected. If nothing changed we won't send a message.
    */
   _latestCapabilities: "",
   init: function () {
     gFrameTree.addObserver(this);
   },
   /**
    * onFrameTreeReset() is called as soon as we start loading a page.
    */
   onFrameTreeReset: function() {
     // The order of docShell capabilities cannot change while we're running
     // so calling join() without sorting before is totally sufficient.
     let caps = DocShellCapabilities.collect(docShell).join(",");
     // Send new data only when the capability list changes.
     if (caps != this._latestCapabilities) {
       this._latestCapabilities = caps;
       MessageQueue.push("disallow", () => caps || null);
     }
   }
 };
 /**
  * Listens for changes to the DOMSessionStorage. Whenever new keys are added,
  * existing ones removed or changed, or the storage is cleared we will send a
  * message to the parent process containing up-to-date sessionStorage data.
  *
  * Causes a SessionStore:update message to be sent that contains the current
  * DOMSessionStorage contents. The data is a nested object using host names
  * as keys and per-host DOMSessionStorage data as values.
  */
 let SessionStorageListener = {
   init: function () {
     addEventListener("MozStorageChanged", this);
     Services.obs.addObserver(this, "browser:purge-domain-data", false);
     gFrameTree.addObserver(this);
   },
   uninit: function () {
     Services.obs.removeObserver(this, "browser:purge-domain-data");
   },
   handleEvent: function (event) {
     // Ignore events triggered by localStorage or globalStorage changes.
     if (gFrameTree.contains(event.target) && isSessionStorageEvent(event)) {
       this.collect();
     }
   },
   observe: function () {
     // Collect data on the next tick so that any other observer
     // that needs to purge data can do its work first.
     setTimeout(() => this.collect(), 0);
   },
   collect: function () {
     if (docShell) {
       MessageQueue.push("storage", () => SessionStorage.collect(docShell, gFrameTree));
     }
   },
   onFrameTreeCollected: function () {
     this.collect();
   },
   onFrameTreeReset: function () {
     this.collect();
   }
 };
 /**
  * Listen for changes to the privacy status of the tab.
  * By definition, tabs start in non-private mode.
  *
  * Causes a SessionStore:update message to be sent for
  * field "isPrivate". This message contains
  *  |true| if the tab is now private
  *  |null| if the tab is now public - the field is therefore
  *  not saved.
  */
 let PrivacyListener = {
   init: function() {
     docShell.addWeakPrivacyTransitionObserver(this);
     // Check that value at startup as it might have
     // been set before the frame script was loaded.
     if (docShell.QueryInterface(Ci.nsILoadContext).usePrivateBrowsing) {
       MessageQueue.push("isPrivate", () => true);
     }
   },
   // Ci.nsIPrivacyTransitionObserver
   privateModeChanged: function(enabled) {
     MessageQueue.push("isPrivate", () => enabled || null);
   },
   QueryInterface: XPCOMUtils.generateQI([Ci.nsIPrivacyTransitionObserver,
                                          Ci.nsISupportsWeakReference])
 };
 /**
  * A message queue that takes collected data and will take care of sending it
  * to the chrome process. It allows flushing using synchronous messages and
  * takes care of any race conditions that might occur because of that. Changes
  * will be batched if they're pushed in quick succession to avoid a message
  * flood.
  */
 let MessageQueue = {
   /**
    * A unique, monotonically increasing ID used for outgoing messages. This is
    * important to make it possible to reuse tabs and allow sync flushes before
    * data could be destroyed.
    */
   _id: 1,
   /**
    * A map (string -> lazy fn) holding lazy closures of all queued data
    * collection routines. These functions will return data collected from the
    * docShell.
    */
   _data: new Map(),
   /**
    * A map holding the |this._id| value for every type of data back when it
    * was pushed onto the queue. We will use those IDs to find the data to send
    * and flush.
    */
   _lastUpdated: new Map(),
   /**
    * The delay (in ms) used to delay sending changes after data has been
    * invalidated.
    */
   BATCH_DELAY_MS: 1000,
   /**
    * The current timeout ID, null if there is no queue data. We use timeouts
    * to damp a flood of data changes and send lots of changes as one batch.
    */
   _timeout: null,
   /**
    * Pushes a given |value| onto the queue. The given |key| represents the type
    * of data that is stored and can override data that has been queued before
    * but has not been sent to the parent process, yet.
    *
    * @param key (string)
    *        A unique identifier specific to the type of data this is passed.
    * @param fn (function)
    *        A function that returns the value that will be sent to the parent
    *        process.
    */
   push: function (key, fn) {
     this._data.set(key, createLazy(fn));
     this._lastUpdated.set(key, this._id);
     if (!this._timeout) {
       // Wait a little before sending the message to batch multiple changes.
       this._timeout = setTimeout(() => this.send(), this.BATCH_DELAY_MS);
     }
   },
   /**
    * Sends queued data to the chrome process.
    *
    * @param options (object)
    *        {id: 123} to override the update ID used to accumulate data to send.
    *        {sync: true} to send data to the parent process synchronously.
    */
   send: function (options = {}) {
     // Looks like we have been called off a timeout after the tab has been
     // closed. The docShell is gone now and we can just return here as there
     // is nothing to do.
     if (!docShell) {
       return;
     }
     if (this._timeout) {
       clearTimeout(this._timeout);
       this._timeout = null;
     }
     let sync = options && options.sync;
     let startID = (options && options.id) || this._id;
     // We use sendRpcMessage in the sync case because we may have been called
     // through a CPOW. RPC messages are the only synchronous messages that the
     // child is allowed to send to the parent while it is handling a CPOW
     // request.
     let sendMessage = sync ? sendRpcMessage : sendAsyncMessage;
     let durationMs = Date.now();
     let data = {};
     for (let [key, id] of this._lastUpdated) {
       // There is no data for the given key anymore because
       // the parent process already marked it as received.
       if (!this._data.has(key)) {
         continue;
       }
       if (startID > id) {
         // If the |id| passed by the parent process is higher than the one
         // stored in |_lastUpdated| for the given key we know that the parent
         // received all necessary data and we can remove it from the map.
         this._data.delete(key);
         continue;
       }
       data[key] = this._data.get(key)();
     }
     durationMs = Date.now() - durationMs;
     let telemetry = {
       FX_SESSION_RESTORE_CONTENT_COLLECT_DATA_LONGEST_OP_MS: durationMs
     }
     // Send all data to the parent process.
     sendMessage("SessionStore:update", {
       id: this._id,
       data: data,
       telemetry: telemetry
     });
     // Increase our unique message ID.
     this._id++;
   },
   /**
    * This function is used to make the message queue flush all queue data that
    * hasn't been sent to the parent process, yet.
    *
    * @param id (int)
    *        A unique id that represents the latest message received by the
    *        chrome process. We can use this to determine which messages have not
    *        yet been received because they are still stuck in the event queue.
    */
   flush: function (id) {
     // It's important to always send data, even if there is nothing to flush.
     // The update message will be received by the parent process that can then
     // update its last received update ID to ignore stale messages.
     this.send({id: id + 1, sync: true});
     this._data.clear();
     this._lastUpdated.clear();
   },
   /**
    * DO NOT USE - DEBUGGING / TESTING ONLY
    *
    * This function is used to simulate certain situations where race conditions
    * can occur by sending data shortly before flushing synchronously.
    */
   flushAsync: function () {
     if (!Services.prefs.getBoolPref("browser.sessionstore.debug")) {
       throw new Error("flushAsync() must be used for testing, only.");
     }
     this.send();
   }
 };
 EventListener.init();
 MessageListener.init();
 FormDataListener.init();
 SyncHandler.init();
 PageStyleListener.init();
 SessionHistoryListener.init();
 SessionStorageListener.init();
 ScrollPositionListener.init();
 DocShellCapabilitiesListener.init();
 PrivacyListener.init();
 addEventListener("unload", () => {
   // Remove all registered nsIObservers.
   PageStyleListener.uninit();
   SessionStorageListener.uninit();
   SessionHistoryListener.uninit();
   // We don't need to take care of any gFrameTree observers as the gFrameTree
   // will die with the content script. The same goes for the privacy transition
   // observer that will die with the docShell when the tab is closed.
 });