gecko/browser/components/sessionstore/nsSessionStartup.js

351 lines
12 KiB
JavaScript

/* 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";
/**
* Session Storage and Restoration
*
* Overview
* This service reads user's session file at startup, and makes a determination
* as to whether the session should be restored. It will restore the session
* under the circumstances described below. If the auto-start Private Browsing
* mode is active, however, the session is never restored.
*
* Crash Detection
* The CrashMonitor is used to check if the final session state was successfully
* written at shutdown of the last session. If we did not reach
* 'sessionstore-final-state-write-complete', then it's assumed that the browser
* has previously crashed and we should restore the session.
*
* Forced Restarts
* In the event that a restart is required due to application update or extension
* installation, set the browser.sessionstore.resume_session_once pref to true,
* and the session will be restored the next time the browser starts.
*
* Always Resume
* This service will always resume the session if the integer pref
* browser.startup.page is set to 3.
*/
/* :::::::: Constants and Helpers ::::::::::::::: */
const Cc = Components.classes;
const Ci = Components.interfaces;
const Cr = Components.results;
const Cu = Components.utils;
Cu.import("resource://gre/modules/XPCOMUtils.jsm");
Cu.import("resource://gre/modules/Services.jsm");
Cu.import("resource://gre/modules/TelemetryStopwatch.jsm");
Cu.import("resource://gre/modules/PrivateBrowsingUtils.jsm");
Cu.import("resource://gre/modules/Promise.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "console",
"resource://gre/modules/devtools/Console.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "SessionFile",
"resource:///modules/sessionstore/SessionFile.jsm");
XPCOMUtils.defineLazyModuleGetter(this, "CrashMonitor",
"resource://gre/modules/CrashMonitor.jsm");
const STATE_RUNNING_STR = "running";
// 'browser.startup.page' preference value to resume the previous session.
const BROWSER_STARTUP_RESUME_SESSION = 3;
function debug(aMsg) {
aMsg = ("SessionStartup: " + aMsg).replace(/\S{80}/g, "$&\n");
Services.console.logStringMessage(aMsg);
}
function warning(aMsg, aException) {
let consoleMsg = Cc["@mozilla.org/scripterror;1"].createInstance(Ci.nsIScriptError);
consoleMsg.init(aMsg, aException.fileName, null, aException.lineNumber, 0, Ci.nsIScriptError.warningFlag, "component javascript");
Services.console.logMessage(consoleMsg);
}
let gOnceInitializedDeferred = (function () {
let deferred = {};
deferred.promise = new Promise((resolve, reject) => {
deferred.resolve = resolve;
deferred.reject = reject;
});
return deferred;
})();
/* :::::::: The Service ::::::::::::::: */
function SessionStartup() {
}
SessionStartup.prototype = {
// the state to restore at startup
_initialState: null,
_sessionType: Ci.nsISessionStartup.NO_SESSION,
_initialized: false,
// Stores whether the previous session crashed.
_previousSessionCrashed: null,
/* ........ Global Event Handlers .............. */
/**
* Initialize the component
*/
init: function sss_init() {
Services.obs.notifyObservers(null, "sessionstore-init-started", null);
// do not need to initialize anything in auto-started private browsing sessions
if (PrivateBrowsingUtils.permanentPrivateBrowsing) {
this._initialized = true;
gOnceInitializedDeferred.resolve();
return;
}
SessionFile.read().then(
this._onSessionFileRead.bind(this),
console.error
);
},
// Wrap a string as a nsISupports
_createSupportsString: function ssfi_createSupportsString(aData) {
let string = Cc["@mozilla.org/supports-string;1"]
.createInstance(Ci.nsISupportsString);
string.data = aData;
return string;
},
/**
* Complete initialization once the Session File has been read
*
* @param source The Session State string read from disk.
* @param parsed The object obtained by parsing |source| as JSON.
*/
_onSessionFileRead: function ({source, parsed, noFilesFound}) {
this._initialized = true;
// Let observers modify the state before it is used
let supportsStateString = this._createSupportsString(source);
Services.obs.notifyObservers(supportsStateString, "sessionstore-state-read", "");
let stateString = supportsStateString.data;
if (stateString != source) {
// The session has been modified by an add-on, reparse.
try {
this._initialState = JSON.parse(stateString);
} catch (ex) {
// That's not very good, an add-on has rewritten the initial
// state to something that won't parse.
warning("Observer rewrote the state to something that won't parse", ex);
}
} else {
// No need to reparse
this._initialState = parsed;
}
if (this._initialState == null) {
// No valid session found.
this._sessionType = Ci.nsISessionStartup.NO_SESSION;
Services.obs.notifyObservers(null, "sessionstore-state-finalized", "");
gOnceInitializedDeferred.resolve();
return;
}
let shouldResumeSessionOnce = Services.prefs.getBoolPref("browser.sessionstore.resume_session_once");
let shouldResumeSession = shouldResumeSessionOnce ||
Services.prefs.getIntPref("browser.startup.page") == BROWSER_STARTUP_RESUME_SESSION;
// If this is a normal restore then throw away any previous session
if (!shouldResumeSessionOnce && this._initialState) {
delete this._initialState.lastSessionState;
}
let resumeFromCrash = Services.prefs.getBoolPref("browser.sessionstore.resume_from_crash");
CrashMonitor.previousCheckpoints.then(checkpoints => {
if (checkpoints) {
// If the previous session finished writing the final state, we'll
// assume there was no crash.
this._previousSessionCrashed = !checkpoints["sessionstore-final-state-write-complete"];
} else {
// If the Crash Monitor could not load a checkpoints file it will
// provide null. This could occur on the first run after updating to
// a version including the Crash Monitor, or if the checkpoints file
// was removed, or on first startup with this profile, or after Firefox Reset.
if (noFilesFound) {
// There was no checkpoints file and no sessionstore.js or its backups
// so we will assume that this was a fresh profile.
this._previousSessionCrashed = false;
} else {
// If this is the first run after an update, sessionstore.js should
// still contain the session.state flag to indicate if the session
// crashed. If it is not present, we will assume this was not the first
// run after update and the checkpoints file was somehow corrupted or
// removed by a crash.
//
// If the session.state flag is present, we will fallback to using it
// for crash detection - If the last write of sessionstore.js had it
// set to "running", we crashed.
let stateFlagPresent = (this._initialState.session &&
this._initialState.session.state);
this._previousSessionCrashed = !stateFlagPresent ||
(this._initialState.session.state == STATE_RUNNING_STR);
}
}
// Report shutdown success via telemetry. Shortcoming here are
// being-killed-by-OS-shutdown-logic, shutdown freezing after
// session restore was written, etc.
Services.telemetry.getHistogramById("SHUTDOWN_OK").add(!this._previousSessionCrashed);
// set the startup type
if (this._previousSessionCrashed && resumeFromCrash)
this._sessionType = Ci.nsISessionStartup.RECOVER_SESSION;
else if (!this._previousSessionCrashed && shouldResumeSession)
this._sessionType = Ci.nsISessionStartup.RESUME_SESSION;
else if (this._initialState)
this._sessionType = Ci.nsISessionStartup.DEFER_SESSION;
else
this._initialState = null; // reset the state
Services.obs.addObserver(this, "sessionstore-windows-restored", true);
if (this._sessionType != Ci.nsISessionStartup.NO_SESSION)
Services.obs.addObserver(this, "browser:purge-session-history", true);
// We're ready. Notify everyone else.
Services.obs.notifyObservers(null, "sessionstore-state-finalized", "");
gOnceInitializedDeferred.resolve();
});
},
/**
* Handle notifications
*/
observe: function sss_observe(aSubject, aTopic, aData) {
switch (aTopic) {
case "app-startup":
Services.obs.addObserver(this, "final-ui-startup", true);
Services.obs.addObserver(this, "quit-application", true);
break;
case "final-ui-startup":
Services.obs.removeObserver(this, "final-ui-startup");
Services.obs.removeObserver(this, "quit-application");
this.init();
break;
case "quit-application":
// no reason for initializing at this point (cf. bug 409115)
Services.obs.removeObserver(this, "final-ui-startup");
Services.obs.removeObserver(this, "quit-application");
if (this._sessionType != Ci.nsISessionStartup.NO_SESSION)
Services.obs.removeObserver(this, "browser:purge-session-history");
break;
case "sessionstore-windows-restored":
Services.obs.removeObserver(this, "sessionstore-windows-restored");
// free _initialState after nsSessionStore is done with it
this._initialState = null;
break;
case "browser:purge-session-history":
Services.obs.removeObserver(this, "browser:purge-session-history");
// reset all state on sanitization
this._sessionType = Ci.nsISessionStartup.NO_SESSION;
break;
}
},
/* ........ Public API ................*/
get onceInitialized() {
return gOnceInitializedDeferred.promise;
},
/**
* Get the session state as a jsval
*/
get state() {
return this._initialState;
},
/**
* Determines whether there is a pending session restore. Should only be
* called after initialization has completed.
* @returns bool
*/
doRestore: function sss_doRestore() {
return this._willRestore();
},
/**
* Determines whether automatic session restoration is enabled for this
* launch of the browser. This does not include crash restoration. In
* particular, if session restore is configured to restore only in case of
* crash, this method returns false.
* @returns bool
*/
isAutomaticRestoreEnabled: function () {
return Services.prefs.getBoolPref("browser.sessionstore.resume_session_once") ||
Services.prefs.getIntPref("browser.startup.page") == BROWSER_STARTUP_RESUME_SESSION;
},
/**
* Determines whether there is a pending session restore.
* @returns bool
*/
_willRestore: function () {
return this._sessionType == Ci.nsISessionStartup.RECOVER_SESSION ||
this._sessionType == Ci.nsISessionStartup.RESUME_SESSION;
},
/**
* Returns whether we will restore a session that ends up replacing the
* homepage. The browser uses this to not start loading the homepage if
* we're going to stop its load anyway shortly after.
*
* This is meant to be an optimization for the average case that loading the
* session file finishes before we may want to start loading the default
* homepage. Should this be called before the session file has been read it
* will just return false.
*
* @returns bool
*/
get willOverrideHomepage() {
if (this._initialState && this._willRestore()) {
let windows = this._initialState.windows || null;
// If there are valid windows with not only pinned tabs, signal that we
// will override the default homepage by restoring a session.
return windows && windows.some(w => w.tabs.some(t => !t.pinned));
}
return false;
},
/**
* Get the type of pending session store, if any.
*/
get sessionType() {
return this._sessionType;
},
/**
* Get whether the previous session crashed.
*/
get previousSessionCrashed() {
return this._previousSessionCrashed;
},
/* ........ QueryInterface .............. */
QueryInterface : XPCOMUtils.generateQI([Ci.nsIObserver,
Ci.nsISupportsWeakReference,
Ci.nsISessionStartup]),
classID: Components.ID("{ec7a6c20-e081-11da-8ad9-0800200c9a66}")
};
this.NSGetFactory = XPCOMUtils.generateNSGetFactory([SessionStartup]);