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/* -*- mode: js; indent-tabs-mode: nil; js-indent-level: 2 -*- */
/* 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
import { AppConstants } from "resource://gre/modules/AppConstants.sys.mjs";
/**
* Elides the middle of a string by replacing it with an elipsis if it is
* longer than `threshold` characters. Does its best to not break up grapheme
* clusters.
*/
function elideMiddleOfString(str, threshold) {
const searchDistance = 5;
const stubLength = threshold / 2 - searchDistance;
if (str.length <= threshold || stubLength < searchDistance) {
return str;
}
function searchElisionPoint(position) {
let unsplittableCharacter = c => /[\p{M}\uDC00-\uDFFF]/u.test(c);
for (let i = 0; i < searchDistance; i++) {
if (!unsplittableCharacter(str[position + i])) {
return position + i;
}
if (!unsplittableCharacter(str[position - i])) {
return position - i;
}
}
return position;
}
let elisionStart = searchElisionPoint(stubLength);
let elisionEnd = searchElisionPoint(str.length - stubLength);
if (elisionStart < elisionEnd) {
str = str.slice(0, elisionStart) + "\u2026" + str.slice(elisionEnd);
}
return str;
}
/**
* This JSM is responsible for observing content process hang reports
* and asking the user what to do about them. See nsIHangReport for
* the platform interface.
*/
export var ProcessHangMonitor = {
/**
* This timeout is the wait period applied after a user selects "Wait" in
* an existing notification.
*/
get WAIT_EXPIRATION_TIME() {
try {
return Services.prefs.getIntPref("browser.hangNotification.waitPeriod");
} catch (ex) {
return 10000;
}
},
/**
* Should only be set to true once the quit-application-granted notification
* has been fired.
*/
_shuttingDown: false,
/**
* Collection of hang reports that haven't expired or been dismissed
* by the user. These are nsIHangReports. They are mapped to objects
* containing:
* - notificationTime: when (Cu.now()) we first showed a notification
* - waitCount: how often the user asked to wait for the script to finish
* - lastReportFromChild: when (Cu.now()) we last got hang info from the
* child.
*/
_activeReports: new Map(),
/**
* Collection of hang reports that have been suppressed for a short
* period of time. Value is an object like in _activeReports, but also
* including a `timer` prop, which is an nsITimer for when the wait time
* expires.
*/
_pausedReports: new Map(),
/**
* Initialize hang reporting. Called once in the parent process.
*/
init() {
Services.obs.addObserver(this, "process-hang-report");
Services.obs.addObserver(this, "clear-hang-report");
Services.obs.addObserver(this, "quit-application-granted");
Services.obs.addObserver(this, "xpcom-shutdown");
Services.ww.registerNotification(this);
},
/**
* Terminate JavaScript associated with the hang being reported for
* the selected browser in |win|.
*/
terminateScript(win) {
this.handleUserInput(win, report => report.terminateScript());
},
/**
* Start devtools debugger for JavaScript associated with the hang
* being reported for the selected browser in |win|.
*/
debugScript(win) {
this.handleUserInput(win, report => {
function callback() {
report.endStartingDebugger();
}
this._recordTelemetryForReport(report, "debugging");
report.beginStartingDebugger();
let svc = Cc["@mozilla.org/dom/slow-script-debug;1"].getService(
Ci.nsISlowScriptDebug
);
let handler = svc.remoteActivationHandler;
handler.handleSlowScriptDebug(report.scriptBrowser, callback);
});
},
/**
* Dismiss the browser notification and invoke an appropriate action based on
* the hang type.
*/
stopIt(win) {
let report = this.findActiveReport(win.gBrowser.selectedBrowser);
if (!report) {
return;
}
this._recordTelemetryForReport(report, "user-aborted");
this.terminateScript(win);
},
/**
* Terminate the script causing this report. This is done without
* updating any report notifications.
*/
stopHang(report, endReason, backupInfo) {
this._recordTelemetryForReport(report, endReason, backupInfo);
report.terminateScript();
},
/**
* Dismiss the notification, clear the report from the active list and set up
* a new timer to track a wait period during which we won't notify.
*/
waitLonger(win) {
let report = this.findActiveReport(win.gBrowser.selectedBrowser);
if (!report) {
return;
}
// Update the other info we keep.
let reportInfo = this._activeReports.get(report);
reportInfo.waitCount++;
// Remove the report from the active list.
this.removeActiveReport(report);
// NOTE, we didn't call userCanceled on nsIHangReport here. This insures
// we don't repeatedly generate and cache crash report data for this hang
// in the process hang reporter. It already has one report for the browser
// process we want it hold onto.
// Create a new wait timer with notify callback
let timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
timer.initWithCallback(
() => {
for (let [stashedReport, pausedInfo] of this._pausedReports) {
if (pausedInfo.timer === timer) {
this.removePausedReport(stashedReport);
// We're still hung, so move the report back to the active
// list and update the UI.
this._activeReports.set(report, pausedInfo);
this.updateWindows();
break;
}
}
},
this.WAIT_EXPIRATION_TIME,
timer.TYPE_ONE_SHOT
);
reportInfo.timer = timer;
this._pausedReports.set(report, reportInfo);
// remove the browser notification associated with this hang
this.updateWindows();
},
/**
* If there is a hang report associated with the selected browser in
* |win|, invoke |func| on that report and stop notifying the user
* about it.
*/
handleUserInput(win, func) {
let report = this.findActiveReport(win.gBrowser.selectedBrowser);
if (!report) {
return null;
}
this.removeActiveReport(report);
return func(report);
},
observe(subject, topic) {
switch (topic) {
case "xpcom-shutdown": {
Services.obs.removeObserver(this, "xpcom-shutdown");
Services.obs.removeObserver(this, "process-hang-report");
Services.obs.removeObserver(this, "clear-hang-report");
Services.obs.removeObserver(this, "quit-application-granted");
Services.ww.unregisterNotification(this);
break;
}
case "quit-application-granted": {
this.onQuitApplicationGranted();
break;
}
case "process-hang-report": {
this.reportHang(subject.QueryInterface(Ci.nsIHangReport));
break;
}
case "clear-hang-report": {
this.clearHang(subject.QueryInterface(Ci.nsIHangReport));
break;
}
case "domwindowopened": {
// Install event listeners on the new window in case one of
// its tabs is already hung.
let win = subject;
let listener = () => {
win.removeEventListener("load", listener, true);
this.updateWindows();
};
win.addEventListener("load", listener, true);
break;
}
case "domwindowclosed": {
let win = subject;
this.onWindowClosed(win);
break;
}
}
},
/**
* Called early on in the shutdown sequence. We take this opportunity to
* take any pre-existing hang reports, and terminate them. We also put
* ourselves in a state so that if any more hang reports show up while
* we're shutting down, we terminate them immediately.
*/
onQuitApplicationGranted() {
this._shuttingDown = true;
this.stopAllHangs("quit-application-granted");
this.updateWindows();
},
onWindowClosed(win) {
let maybeStopHang = report => {
let hungBrowserWindow = null;
try {
hungBrowserWindow = report.scriptBrowser.ownerGlobal;
} catch (e) {
// Ignore failures to get the script browser - we'll be
// conservative, and assume that if we cannot access the
// window that belongs to this report that we should stop
// the hang.
}
if (!hungBrowserWindow || hungBrowserWindow == win) {
this.stopHang(report, "window-closed");
return true;
}
return false;
};
// If there are any script hangs for browsers that are in this window
// that is closing, we can stop them now.
for (let [report] of this._activeReports) {
if (maybeStopHang(report)) {
this._activeReports.delete(report);
}
}
for (let [pausedReport] of this._pausedReports) {
if (maybeStopHang(pausedReport)) {
this.removePausedReport(pausedReport);
}
}
this.updateWindows();
},
stopAllHangs(endReason) {
for (let [report] of this._activeReports) {
this.stopHang(report, endReason);
}
this._activeReports = new Map();
for (let [pausedReport] of this._pausedReports) {
this.stopHang(pausedReport, endReason);
this.removePausedReport(pausedReport);
}
},
/**
* Find a active hang report for the given <browser> element.
*/
findActiveReport(browser) {
let frameLoader = browser.frameLoader;
for (let report of this._activeReports.keys()) {
if (report.isReportForBrowserOrChildren(frameLoader)) {
return report;
}
}
return null;
},
/**
* Find a paused hang report for the given <browser> element.
*/
findPausedReport(browser) {
let frameLoader = browser.frameLoader;
for (let [report] of this._pausedReports) {
if (report.isReportForBrowserOrChildren(frameLoader)) {
return report;
}
}
return null;
},
/**
* Tell telemetry about the report.
*/
_recordTelemetryForReport(report, endReason, backupInfo) {
let info =
this._activeReports.get(report) ||
this._pausedReports.get(report) ||
backupInfo;
if (!info) {
return;
}
try {
let uri_type;
if (report.addonId) {
uri_type = "extension";
} else if (report.scriptFileName?.startsWith("debugger")) {
uri_type = "devtools";
} else {
try {
let url = new URL(report.scriptFileName);
if (url.protocol == "chrome:" || url.protocol == "resource:") {
uri_type = "browser";
} else {
uri_type = "content";
}
} catch (ex) {
console.error(ex);
uri_type = "unknown";
}
}
let uptime = 0;
if (info.notificationTime) {
uptime = Cu.now() - info.notificationTime;
}
uptime = "" + uptime;
// We combine the duration of the hang in the content process with the
// time since we were last told about the hang in the parent. This is
// not the same as the time we showed a notification, as we only do that
// for the currently selected browser. It's as messy as it is because
// there is no cross-process monotonically increasing timestamp we can
// use. :-(
let hangDuration =
report.hangDuration + Cu.now() - info.lastReportFromChild;
Glean.slowScriptWarning.shownContent.record({
end_reason: endReason,
hang_duration: hangDuration,
n_tab_deselect: info.deselectCount,
uri_type,
uptime,
wait_count: info.waitCount,
});
} catch (ex) {
console.error(ex);
}
},
/**
* Remove an active hang report from the active list and cancel the timer
* associated with it.
*/
removeActiveReport(report) {
this._activeReports.delete(report);
this.updateWindows();
},
/**
* Remove a paused hang report from the paused list and cancel the timer
* associated with it.
*/
removePausedReport(report) {
let info = this._pausedReports.get(report);
info?.timer?.cancel();
this._pausedReports.delete(report);
},
/**
* Iterate over all XUL windows and ensure that the proper hang
* reports are shown for each one. Also install event handlers in
* each window to watch for events that would cause a different hang
* report to be displayed.
*/
updateWindows() {
let e = Services.wm.getEnumerator("navigator:browser");
// If it turns out we have no windows (this can happen on macOS),
// we have no opportunity to ask the user whether or not they want
// to stop the hang or wait, so we'll opt for stopping the hang.
if (!e.hasMoreElements()) {
this.stopAllHangs("no-windows-left");
return;
}
for (let win of e) {
this.updateWindow(win);
// Only listen for these events if there are active hang reports.
if (this._activeReports.size) {
this.trackWindow(win);
} else {
this.untrackWindow(win);
}
}
},
/**
* If there is a hang report for the current tab in |win|, display it.
*/
updateWindow(win) {
let report = this.findActiveReport(win.gBrowser.selectedBrowser);
if (report) {
let info = this._activeReports.get(report);
if (info && !info.notificationTime) {
info.notificationTime = Cu.now();
}
this.showNotification(win, report);
} else {
this.hideNotification(win);
}
},
/**
* Show the notification for a hang.
*/
async showNotification(win, report) {
let bundle = win.gNavigatorBundle;
let buttons = [
{
label: bundle.getString("processHang.button_stop2.label"),
accessKey: bundle.getString("processHang.button_stop2.accessKey"),
callback() {
ProcessHangMonitor.stopIt(win);
},
},
];
let message;
let doc = win.document;
let brandShortName = doc
.getElementById("bundle_brand")
.getString("brandShortName");
let notificationTag;
if (report.addonId) {
notificationTag = report.addonId;
let aps = Cc["@mozilla.org/addons/policy-service;1"].getService(
Ci.nsIAddonPolicyService
);
let addonName = aps.getExtensionName(report.addonId);
message = bundle.getFormattedString("processHang.add-on.label2", [
addonName,
brandShortName,
]);
buttons.unshift({
label: bundle.getString("processHang.add-on.learn-more.text"),
});
} else {
let scriptBrowser = report.scriptBrowser;
if (scriptBrowser == win.gBrowser?.selectedBrowser) {
notificationTag = "selected-tab";
message = bundle.getFormattedString("processHang.selected_tab.label", [
brandShortName,
]);
} else {
let tab =
scriptBrowser?.ownerGlobal.gBrowser?.getTabForBrowser(scriptBrowser);
if (!tab) {
notificationTag = "nonspecific_tab";
message = bundle.getFormattedString(
"processHang.nonspecific_tab.label",
[brandShortName]
);
} else {
notificationTag = scriptBrowser.browserId.toString();
let title = tab.getAttribute("label");
title = elideMiddleOfString(title, 60);
message = bundle.getFormattedString(
"processHang.specific_tab.label",
[title, brandShortName]
);
}
}
}
let notification =
win.gNotificationBox.getNotificationWithValue("process-hang");
if (notificationTag == notification?.getAttribute("notification-tag")) {
return;
}
if (notification) {
notification.label = message;
notification.setAttribute("notification-tag", notificationTag);
return;
}
// Show the "debug script" button unconditionally if we are in Developer or Nightly
// editions, or if DevTools are opened on the slow tab.
if (
AppConstants.MOZ_DEV_EDITION ||
AppConstants.NIGHTLY_BUILD ||
report.scriptBrowser.browsingContext.watchedByDevTools
) {
buttons.push({
label: bundle.getString("processHang.button_debug.label"),
accessKey: bundle.getString("processHang.button_debug.accessKey"),
callback() {
ProcessHangMonitor.debugScript(win);
},
});
}
// Sometimes the window may have closed already, in which case we won't
// be able to create a message bar so we need to handle any related errors.
try {
let hangNotification = await win.gNotificationBox.appendNotification(
"process-hang",
{
label: message,
image: "chrome://browser/content/aboutRobots-icon.png",
priority: win.gNotificationBox.PRIORITY_INFO_HIGH,
eventCallback: event => {
if (event == "dismissed") {
ProcessHangMonitor.waitLonger(win);
}
},
},
buttons
);
hangNotification.setAttribute("notification-tag", notificationTag);
} catch (err) {
console.warn(err);
}
},
/**
* Ensure that no hang notifications are visible in |win|.
*/
hideNotification(win) {
let notification =
win.gNotificationBox.getNotificationWithValue("process-hang");
if (notification) {
win.gNotificationBox.removeNotification(notification);
}
},
/**
* Install event handlers on |win| to watch for events that would
* cause a different hang report to be displayed.
*/
trackWindow(win) {
win.gBrowser.tabContainer.addEventListener("TabSelect", this, true);
win.gBrowser.tabContainer.addEventListener(
"TabRemotenessChange",
this,
true
);
},
untrackWindow(win) {
win.gBrowser.tabContainer.removeEventListener("TabSelect", this, true);
win.gBrowser.tabContainer.removeEventListener(
"TabRemotenessChange",
this,
true
);
},
handleEvent(event) {
let win = event.target.ownerGlobal;
// If a new tab is selected or if a tab changes remoteness, then
// we may need to show or hide a hang notification.
if (event.type == "TabSelect" || event.type == "TabRemotenessChange") {
if (event.type == "TabSelect" && event.detail.previousTab) {
// If we've got a notification, check the previous tab's report and
// indicate the user switched tabs while the notification was up.
let r =
this.findActiveReport(event.detail.previousTab.linkedBrowser) ||
this.findPausedReport(event.detail.previousTab.linkedBrowser);
if (r) {
let info = this._activeReports.get(r) || this._pausedReports.get(r);
info.deselectCount++;
}
}
this.updateWindow(win);
}
},
/**
* Handle a potentially new hang report. If it hasn't been seen
* before, show a notification for it in all open XUL windows.
*/
reportHang(report) {
let now = Cu.now();
if (this._shuttingDown) {
this.stopHang(report, "shutdown-in-progress", {
lastReportFromChild: now,
waitCount: 0,
deselectCount: 0,
});
return;
}
// If this hang was already reported reset the timer for it.
if (this._activeReports.has(report)) {
this._activeReports.get(report).lastReportFromChild = now;
// if this report is in active but doesn't have a notification associated
// with it, display a notification.
this.updateWindows();
return;
}
// If this hang was already reported and paused by the user ignore it.
if (this._pausedReports.has(report)) {
this._pausedReports.get(report).lastReportFromChild = now;
return;
}
// On e10s this counts slow-script notice only once.
// This code is not reached on non-e10s.
Services.telemetry.getHistogramById("SLOW_SCRIPT_NOTICE_COUNT").add();
this._activeReports.set(report, {
deselectCount: 0,
lastReportFromChild: now,
waitCount: 0,
});
this.updateWindows();
},
clearHang(report) {
this._recordTelemetryForReport(report, "cleared");
this.removeActiveReport(report);
this.removePausedReport(report);
report.userCanceled();
},
};