The Tor Browser: browser/components/sessionstore/src/SessionSaver.jsm@6474c204b198 (annotated)

browser/components/sessionstore/src/SessionSaver.jsm@6474c204b198 (annotated)

browser/components/sessionstore/src/SessionSaver.jsm

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* 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";
 this.EXPORTED_SYMBOLS = ["SessionSaver"];
 const Cu = Components.utils;
 const Cc = Components.classes;
 const Ci = Components.interfaces;
 Cu.import("resource://gre/modules/Timer.jsm", this);
 Cu.import("resource://gre/modules/Services.jsm", this);
 Cu.import("resource://gre/modules/XPCOMUtils.jsm", this);
 Cu.import("resource://gre/modules/TelemetryStopwatch.jsm", this);
 XPCOMUtils.defineLazyModuleGetter(this, "console",
   "resource://gre/modules/devtools/Console.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "PrivacyFilter",
   "resource:///modules/sessionstore/PrivacyFilter.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "SessionStore",
   "resource:///modules/sessionstore/SessionStore.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "SessionFile",
   "resource:///modules/sessionstore/SessionFile.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "PrivateBrowsingUtils",
   "resource://gre/modules/PrivateBrowsingUtils.jsm");
 // Minimal interval between two save operations (in milliseconds).
 XPCOMUtils.defineLazyGetter(this, "gInterval", function () {
   const PREF = "browser.sessionstore.interval";
   // Observer that updates the cached value when the preference changes.
   Services.prefs.addObserver(PREF, () => {
     this.gInterval = Services.prefs.getIntPref(PREF);
     // Cancel any pending runs and call runDelayed() with
     // zero to apply the newly configured interval.
     SessionSaverInternal.cancel();
     SessionSaverInternal.runDelayed(0);
   }, false);
   return Services.prefs.getIntPref(PREF);
 });
 // Notify observers about a given topic with a given subject.
 function notify(subject, topic) {
   Services.obs.notifyObservers(subject, topic, "");
 }
 // TelemetryStopwatch helper functions.
 function stopWatch(method) {
   return function (...histograms) {
     for (let hist of histograms) {
       TelemetryStopwatch[method]("FX_SESSION_RESTORE_" + hist);
     }
   };
 }
 let stopWatchStart = stopWatch("start");
 let stopWatchCancel = stopWatch("cancel");
 let stopWatchFinish = stopWatch("finish");
 /**
  * The external API implemented by the SessionSaver module.
  */
 this.SessionSaver = Object.freeze({
   /**
    * Immediately saves the current session to disk.
    */
   run: function () {
     return SessionSaverInternal.run();
   },
   /**
    * Saves the current session to disk delayed by a given amount of time. Should
    * another delayed run be scheduled already, we will ignore the given delay
    * and state saving may occur a little earlier.
    */
   runDelayed: function () {
     SessionSaverInternal.runDelayed();
   },
   /**
    * Sets the last save time to the current time. This will cause us to wait for
    * at least the configured interval when runDelayed() is called next.
    */
   updateLastSaveTime: function () {
     SessionSaverInternal.updateLastSaveTime();
   },
   /**
    * Sets the last save time to zero. This will cause us to
    * immediately save the next time runDelayed() is called.
    */
   clearLastSaveTime: function () {
     SessionSaverInternal.clearLastSaveTime();
   },
   /**
    * Cancels all pending session saves.
    */
   cancel: function () {
     SessionSaverInternal.cancel();
   }
 });
 /**
  * The internal API.
  */
 let SessionSaverInternal = {
   /**
    * The timeout ID referencing an active timer for a delayed save. When no
    * save is pending, this is null.
    */
   _timeoutID: null,
   /**
    * A timestamp that keeps track of when we saved the session last. We will
    * this to determine the correct interval between delayed saves to not deceed
    * the configured session write interval.
    */
   _lastSaveTime: 0,
   /**
    * Immediately saves the current session to disk.
    */
   run: function () {
     return this._saveState(true /* force-update all windows */);
   },
   /**
    * Saves the current session to disk delayed by a given amount of time. Should
    * another delayed run be scheduled already, we will ignore the given delay
    * and state saving may occur a little earlier.
    *
    * @param delay (optional)
    *        The minimum delay in milliseconds to wait for until we collect and
    *        save the current session.
    */
   runDelayed: function (delay = 2000) {
     // Bail out if there's a pending run.
     if (this._timeoutID) {
       return;
     }
     // Interval until the next disk operation is allowed.
     delay = Math.max(this._lastSaveTime + gInterval - Date.now(), delay, 0);
     // Schedule a state save.
     this._timeoutID = setTimeout(() => this._saveStateAsync(), delay);
   },
   /**
    * Sets the last save time to the current time. This will cause us to wait for
    * at least the configured interval when runDelayed() is called next.
    */
   updateLastSaveTime: function () {
     this._lastSaveTime = Date.now();
   },
   /**
    * Sets the last save time to zero. This will cause us to
    * immediately save the next time runDelayed() is called.
    */
   clearLastSaveTime: function () {
     this._lastSaveTime = 0;
   },
   /**
    * Cancels all pending session saves.
    */
   cancel: function () {
     clearTimeout(this._timeoutID);
     this._timeoutID = null;
   },
   /**
    * Saves the current session state. Collects data and writes to disk.
    *
    * @param forceUpdateAllWindows (optional)
    *        Forces us to recollect data for all windows and will bypass and
    *        update the corresponding caches.
    */
   _saveState: function (forceUpdateAllWindows = false) {
     // Cancel any pending timeouts.
     this.cancel();
     if (PrivateBrowsingUtils.permanentPrivateBrowsing) {
       // Don't save (or even collect) anything in permanent private
       // browsing mode
       this.updateLastSaveTime();
       return Promise.resolve();
     }
     stopWatchStart("COLLECT_DATA_MS", "COLLECT_DATA_LONGEST_OP_MS");
     let state = SessionStore.getCurrentState(forceUpdateAllWindows);
     PrivacyFilter.filterPrivateWindowsAndTabs(state);
     // Make sure that we keep the previous session if we started with a single
     // private window and no non-private windows have been opened, yet.
     if (state.deferredInitialState) {
       state.windows = state.deferredInitialState.windows || [];
       delete state.deferredInitialState;
     }
 #ifndef XP_MACOSX
     // We want to restore closed windows that are marked with _shouldRestore.
     // We're doing this here because we want to control this only when saving
     // the file.
     while (state._closedWindows.length) {
       let i = state._closedWindows.length - 1;
       if (!state._closedWindows[i]._shouldRestore) {
         // We only need to go until _shouldRestore
         // is falsy since we're going in reverse.
         break;
       }
       delete state._closedWindows[i]._shouldRestore;
       state.windows.unshift(state._closedWindows.pop());
     }
 #endif
     stopWatchFinish("COLLECT_DATA_MS", "COLLECT_DATA_LONGEST_OP_MS");
     return this._writeState(state);
   },
   /**
    * Saves the current session state. Collects data asynchronously and calls
    * _saveState() to collect data again (with a cache hit rate of hopefully
    * 100%) and write to disk afterwards.
    */
   _saveStateAsync: function () {
     // Allow scheduling delayed saves again.
     this._timeoutID = null;
     // Write to disk.
     this._saveState();
   },
   /**
    * Write the given state object to disk.
    */
   _writeState: function (state) {
     // Inform observers
     notify(null, "sessionstore-state-write");
     stopWatchStart("SERIALIZE_DATA_MS", "SERIALIZE_DATA_LONGEST_OP_MS", "WRITE_STATE_LONGEST_OP_MS");
     let data = JSON.stringify(state);
     stopWatchFinish("SERIALIZE_DATA_MS", "SERIALIZE_DATA_LONGEST_OP_MS");
     // We update the time stamp before writing so that we don't write again
     // too soon, if saving is requested before the write completes. Without
     // this update we may save repeatedly if actions cause a runDelayed
     // before writing has completed. See Bug 902280
     this.updateLastSaveTime();
     // Write (atomically) to a session file, using a tmp file. Once the session
     // file is successfully updated, save the time stamp of the last save and
     // notify the observers.
     stopWatchStart("SEND_SERIALIZED_STATE_LONGEST_OP_MS");
     let promise = SessionFile.write(data);
     stopWatchFinish("WRITE_STATE_LONGEST_OP_MS",
                     "SEND_SERIALIZED_STATE_LONGEST_OP_MS");
     promise = promise.then(() => {
       this.updateLastSaveTime();
       notify(null, "sessionstore-state-write-complete");
     }, console.error);
     return promise;
   },
 };

The Tor Browser / annotate

browser/components/sessionstore/src/SessionSaver.jsm@6474c204b198 (annotated)

browser/components/sessionstore/src/SessionSaver.jsm