1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/toolkit/components/crashmonitor/CrashMonitor.jsm Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,221 @@
1.4 +/* -*- Mode: js; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +/**
1.10 + * Crash Monitor
1.11 + *
1.12 + * Monitors execution of a program to detect possible crashes. After
1.13 + * program termination, the monitor can be queried during the next run
1.14 + * to determine whether the last run exited cleanly or not.
1.15 + *
1.16 + * The monitoring is done by registering and listening for special
1.17 + * notifications, or checkpoints, known to be sent by the monitored
1.18 + * program as different stages in the execution are reached. As they
1.19 + * are observed, these notifications are written asynchronously to a
1.20 + * checkpoint file.
1.21 + *
1.22 + * During next program startup the crash monitor reads the checkpoint
1.23 + * file from the last session. If notifications are missing, a crash
1.24 + * has likely happened. By inspecting the notifications present, it is
1.25 + * possible to determine what stages were reached in the program
1.26 + * before the crash.
1.27 + *
1.28 + * Note that since the file is written asynchronously it is possible
1.29 + * that a received notification is lost if the program crashes right
1.30 + * after a checkpoint, but before crash monitor has been able to write
1.31 + * it to disk. Thus, while the presence of a notification in the
1.32 + * checkpoint file tells us that the corresponding stage was reached
1.33 + * during the last run, the absence of a notification after a crash
1.34 + * does not necessarily tell us that the checkpoint wasn't reached.
1.35 + */
1.36 +
1.37 +this.EXPORTED_SYMBOLS = [ "CrashMonitor" ];
1.38 +
1.39 +const Cu = Components.utils;
1.40 +const Cr = Components.results;
1.41 +
1.42 +Cu.import("resource://gre/modules/Services.jsm");
1.43 +Cu.import("resource://gre/modules/osfile.jsm");
1.44 +Cu.import("resource://gre/modules/Promise.jsm");
1.45 +Cu.import("resource://gre/modules/Task.jsm");
1.46 +Cu.import("resource://gre/modules/AsyncShutdown.jsm");
1.47 +
1.48 +const NOTIFICATIONS = [
1.49 + "final-ui-startup",
1.50 + "sessionstore-windows-restored",
1.51 + "quit-application-granted",
1.52 + "quit-application",
1.53 + "profile-change-net-teardown",
1.54 + "profile-change-teardown",
1.55 + "profile-before-change",
1.56 + "sessionstore-final-state-write-complete"
1.57 +];
1.58 +
1.59 +let CrashMonitorInternal = {
1.60 +
1.61 + /**
1.62 + * Notifications received during the current session.
1.63 + *
1.64 + * Object where a property with a value of |true| means that the
1.65 + * notification of the same name has been received at least once by
1.66 + * the CrashMonitor during this session. Notifications that have not
1.67 + * yet been received are not present as properties. |NOTIFICATIONS|
1.68 + * lists the notifications tracked by the CrashMonitor.
1.69 + */
1.70 + checkpoints: {},
1.71 +
1.72 + /**
1.73 + * Notifications received during previous session.
1.74 + *
1.75 + * Available after |loadPreviousCheckpoints|. Promise which resolves
1.76 + * to an object containing a set of properties, where a property
1.77 + * with a value of |true| means that the notification with the same
1.78 + * name as the property name was received at least once last
1.79 + * session.
1.80 + */
1.81 + previousCheckpoints: null,
1.82 +
1.83 + /* Deferred for AsyncShutdown blocker */
1.84 + profileBeforeChangeDeferred: Promise.defer(),
1.85 +
1.86 + /**
1.87 + * Path to checkpoint file.
1.88 + *
1.89 + * Each time a new notification is received, this file is written to
1.90 + * disc to reflect the information in |checkpoints|. Although Firefox for
1.91 + * Desktop and Metro share the same profile, they need to keep record of
1.92 + * crashes separately.
1.93 + */
1.94 + path: (Services.metro && Services.metro.immersive) ?
1.95 + OS.Path.join(OS.Constants.Path.profileDir, "metro", "sessionCheckpoints.json"):
1.96 + OS.Path.join(OS.Constants.Path.profileDir, "sessionCheckpoints.json"),
1.97 +
1.98 + /**
1.99 + * Load checkpoints from previous session asynchronously.
1.100 + *
1.101 + * @return {Promise} A promise that resolves/rejects once loading is complete
1.102 + */
1.103 + loadPreviousCheckpoints: function () {
1.104 + this.previousCheckpoints = Task.spawn(function*() {
1.105 + let data;
1.106 + try {
1.107 + data = yield OS.File.read(CrashMonitorInternal.path, { encoding: "utf-8" });
1.108 + } catch (ex if ex instanceof OS.File.Error) {
1.109 + if (!ex.becauseNoSuchFile) {
1.110 + Cu.reportError("Error while loading crash monitor data: " + ex.toString());
1.111 + }
1.112 +
1.113 + return null;
1.114 + }
1.115 +
1.116 + let notifications;
1.117 + try {
1.118 + notifications = JSON.parse(data);
1.119 + } catch (ex) {
1.120 + Cu.reportError("Error while parsing crash monitor data: " + ex);
1.121 + return null;
1.122 + }
1.123 +
1.124 + return Object.freeze(notifications);
1.125 + });
1.126 +
1.127 + return this.previousCheckpoints;
1.128 + }
1.129 +};
1.130 +
1.131 +this.CrashMonitor = {
1.132 +
1.133 + /**
1.134 + * Notifications received during previous session.
1.135 + *
1.136 + * Return object containing the set of notifications received last
1.137 + * session as keys with values set to |true|.
1.138 + *
1.139 + * @return {Promise} A promise resolving to previous checkpoints
1.140 + */
1.141 + get previousCheckpoints() {
1.142 + if (!CrashMonitorInternal.initialized) {
1.143 + throw new Error("CrashMonitor must be initialized before getting previous checkpoints");
1.144 + }
1.145 +
1.146 + return CrashMonitorInternal.previousCheckpoints
1.147 + },
1.148 +
1.149 + /**
1.150 + * Initialize CrashMonitor.
1.151 + *
1.152 + * Should only be called from the CrashMonitor XPCOM component.
1.153 + *
1.154 + * @return {Promise}
1.155 + */
1.156 + init: function () {
1.157 + if (CrashMonitorInternal.initialized) {
1.158 + throw new Error("CrashMonitor.init() must only be called once!");
1.159 + }
1.160 +
1.161 + let promise = CrashMonitorInternal.loadPreviousCheckpoints();
1.162 + // Add "profile-after-change" to checkpoint as this method is
1.163 + // called after receiving it
1.164 + CrashMonitorInternal.checkpoints["profile-after-change"] = true;
1.165 +
1.166 + NOTIFICATIONS.forEach(function (aTopic) {
1.167 + Services.obs.addObserver(this, aTopic, false);
1.168 + }, this);
1.169 +
1.170 + // Add shutdown blocker for profile-before-change
1.171 + AsyncShutdown.profileBeforeChange.addBlocker(
1.172 + "CrashMonitor: Writing notifications to file after receiving profile-before-change",
1.173 + CrashMonitorInternal.profileBeforeChangeDeferred.promise
1.174 + );
1.175 +
1.176 + CrashMonitorInternal.initialized = true;
1.177 + if (Services.metro && Services.metro.immersive) {
1.178 + OS.File.makeDir(OS.Path.join(OS.Constants.Path.profileDir, "metro"));
1.179 + }
1.180 + return promise;
1.181 + },
1.182 +
1.183 + /**
1.184 + * Handle registered notifications.
1.185 + *
1.186 + * Update checkpoint file for every new notification received.
1.187 + */
1.188 + observe: function (aSubject, aTopic, aData) {
1.189 + if (!(aTopic in CrashMonitorInternal.checkpoints)) {
1.190 + // If this is the first time this notification is received,
1.191 + // remember it and write it to file
1.192 + CrashMonitorInternal.checkpoints[aTopic] = true;
1.193 + Task.spawn(function() {
1.194 + try {
1.195 + let data = JSON.stringify(CrashMonitorInternal.checkpoints);
1.196 +
1.197 + /* Write to the checkpoint file asynchronously, off the main
1.198 + * thread, for performance reasons. Note that this means
1.199 + * that there's not a 100% guarantee that the file will be
1.200 + * written by the time the notification completes. The
1.201 + * exception is profile-before-change which has a shutdown
1.202 + * blocker. */
1.203 + yield OS.File.writeAtomic(
1.204 + CrashMonitorInternal.path,
1.205 + data, {tmpPath: CrashMonitorInternal.path + ".tmp"});
1.206 +
1.207 + } finally {
1.208 + // Resolve promise for blocker
1.209 + if (aTopic == "profile-before-change") {
1.210 + CrashMonitorInternal.profileBeforeChangeDeferred.resolve();
1.211 + }
1.212 + }
1.213 + });
1.214 + }
1.215 +
1.216 + if (NOTIFICATIONS.every(elem => elem in CrashMonitorInternal.checkpoints)) {
1.217 + // All notifications received, unregister observers
1.218 + NOTIFICATIONS.forEach(function (aTopic) {
1.219 + Services.obs.removeObserver(this, aTopic);
1.220 + }, this);
1.221 + }
1.222 + }
1.223 +};
1.224 +Object.freeze(this.CrashMonitor);
