1 files changed, 397 insertions, 0 deletions
diff --git a/browser/modules/ProcessHangMonitor.jsm b/browser/modules/ProcessHangMonitor.jsm
new file mode 100644
index 000000000..e048f5b40
--- /dev/null
+++ b/browser/modules/ProcessHangMonitor.jsm
@@ -0,0 +1,397 @@
+/* -*- 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
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+var Cc = Components.classes;
+var Ci = Components.interfaces;
+var Cu = Components.utils;
+
+this.EXPORTED_SYMBOLS = ["ProcessHangMonitor"];
+
+Cu.import("resource://gre/modules/AppConstants.jsm");
+Cu.import("resource://gre/modules/Services.jsm");
+
+/**
+ * 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.
+ */
+
+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;
+    }
+  },
+
+  /**
+   * Collection of hang reports that haven't expired or been dismissed
+   * by the user. These are nsIHangReports.
+   */
+  _activeReports: new Set(),
+
+  /**
+   * Collection of hang reports that have been suppressed for a short
+   * period of time. Value is an nsITimer for when the wait time
+   * expires.
+   */
+  _pausedReports: new Map(),
+
+  /**
+   * Initialize hang reporting. Called once in the parent process.
+   */
+  init: function() {
+    Services.obs.addObserver(this, "process-hang-report", false);
+    Services.obs.addObserver(this, "clear-hang-report", false);
+    Services.obs.addObserver(this, "xpcom-shutdown", false);
+    Services.ww.registerNotification(this);
+  },
+
+  /**
+   * Terminate JavaScript associated with the hang being reported for
+   * the selected browser in |win|.
+   */
+  terminateScript: function(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: function(win) {
+    this.handleUserInput(win, report => {
+      function callback() {
+        report.endStartingDebugger();
+      }
+
+      report.beginStartingDebugger();
+
+      let svc = Cc["@mozilla.org/dom/slow-script-debug;1"].getService(Ci.nsISlowScriptDebug);
+      let handler = svc.remoteActivationHandler;
+      handler.handleSlowScriptDebug(report.scriptBrowser, callback);
+    });
+  },
+
+  /**
+   * Terminate the plugin process associated with a hang being reported
+   * for the selected browser in |win|. Will attempt to generate a combined
+   * crash report for all processes.
+   */
+  terminatePlugin: function(win) {
+    this.handleUserInput(win, report => report.terminatePlugin());
+  },
+
+  /**
+   * Dismiss the browser notification and invoke an appropriate action based on
+   * the hang type.
+   */
+  stopIt: function (win) {
+    let report = this.findActiveReport(win.gBrowser.selectedBrowser);
+    if (!report) {
+      return;
+    }
+
+    switch (report.hangType) {
+      case report.SLOW_SCRIPT:
+        this.terminateScript(win);
+        break;
+      case report.PLUGIN_HANG:
+        this.terminatePlugin(win);
+        break;
+    }
+  },
+
+  /**
+   * 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: function(win) {
+    let report = this.findActiveReport(win.gBrowser.selectedBrowser);
+    if (!report) {
+      return;
+    }
+    // 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, otherTimer] of this._pausedReports) {
+        if (otherTimer === timer) {
+          this.removePausedReport(stashedReport);
+
+          // We're still hung, so move the report back to the active
+          // list and update the UI.
+          this._activeReports.add(report);
+          this.updateWindows();
+          break;
+        }
+      }
+    }, this.WAIT_EXPIRATION_TIME, timer.TYPE_ONE_SHOT);
+
+    this._pausedReports.set(report, timer);
+
+    // 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: function(win, func) {
+    let report = this.findActiveReport(win.gBrowser.selectedBrowser);
+    if (!report) {
+      return null;
+    }
+    this.removeActiveReport(report);
+
+    return func(report);
+  },
+
+  observe: function(subject, topic, data) {
+    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.ww.unregisterNotification(this);
+        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.QueryInterface(Ci.nsIDOMWindow);
+        let listener = (ev) => {
+          win.removeEventListener("load", listener, true);
+          this.updateWindows();
+        };
+        win.addEventListener("load", listener, true);
+        break;
+    }
+  },
+
+  /**
+   * Find a active hang report for the given <browser> element.
+   */
+  findActiveReport: function(browser) {
+    let frameLoader = browser.QueryInterface(Ci.nsIFrameLoaderOwner).frameLoader;
+    for (let report of this._activeReports) {
+      if (report.isReportForBrowser(frameLoader)) {
+        return report;
+      }
+    }
+    return null;
+  },
+
+  /**
+   * Find a paused hang report for the given <browser> element.
+   */
+  findPausedReport: function(browser) {
+    let frameLoader = browser.QueryInterface(Ci.nsIFrameLoaderOwner).frameLoader;
+    for (let [report, ] of this._pausedReports) {
+      if (report.isReportForBrowser(frameLoader)) {
+        return report;
+      }
+    }
+    return null;
+  },
+
+  /**
+   * Remove an active hang report from the active list and cancel the timer
+   * associated with it.
+   */
+  removeActiveReport: function(report) {
+    this._activeReports.delete(report);
+    this.updateWindows();
+  },
+
+  /**
+   * Remove a paused hang report from the paused list and cancel the timer
+   * associated with it.
+   */
+  removePausedReport: function(report) {
+    let timer = this._pausedReports.get(report);
+    if (timer) {
+      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: function() {
+    let e = Services.wm.getEnumerator("navigator:browser");
+    while (e.hasMoreElements()) {
+      let win = e.getNext();
+
+      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: function(win) {
+    let report = this.findActiveReport(win.gBrowser.selectedBrowser);
+
+    if (report) {
+      this.showNotification(win, report);
+    } else {
+      this.hideNotification(win);
+    }
+  },
+
+  /**
+   * Show the notification for a hang.
+   */
+  showNotification: function(win, report) {
+    let nb = win.document.getElementById("high-priority-global-notificationbox");
+    let notification = nb.getNotificationWithValue("process-hang");
+    if (notification) {
+      return;
+    }
+
+    let bundle = win.gNavigatorBundle;
+
+    let buttons = [{
+        label: bundle.getString("processHang.button_stop.label"),
+        accessKey: bundle.getString("processHang.button_stop.accessKey"),
+        callback: function() {
+          ProcessHangMonitor.stopIt(win);
+        }
+      },
+      {
+        label: bundle.getString("processHang.button_wait.label"),
+        accessKey: bundle.getString("processHang.button_wait.accessKey"),
+        callback: function() {
+          ProcessHangMonitor.waitLonger(win);
+        }
+      }];
+
+    if (AppConstants.MOZ_DEV_EDITION && report.hangType == report.SLOW_SCRIPT) {
+      buttons.push({
+        label: bundle.getString("processHang.button_debug.label"),
+        accessKey: bundle.getString("processHang.button_debug.accessKey"),
+        callback: function() {
+          ProcessHangMonitor.debugScript(win);
+        }
+      });
+    }
+
+    nb.appendNotification(bundle.getString("processHang.label"),
+                          "process-hang",
+                          "chrome://browser/content/aboutRobots-icon.png",
+                          nb.PRIORITY_WARNING_HIGH, buttons);
+  },
+
+  /**
+   * Ensure that no hang notifications are visible in |win|.
+   */
+  hideNotification: function(win) {
+    let nb = win.document.getElementById("high-priority-global-notificationbox");
+    let notification = nb.getNotificationWithValue("process-hang");
+    if (notification) {
+      nb.removeNotification(notification);
+    }
+  },
+
+  /**
+   * Install event handlers on |win| to watch for events that would
+   * cause a different hang report to be displayed.
+   */
+  trackWindow: function(win) {
+    win.gBrowser.tabContainer.addEventListener("TabSelect", this, true);
+    win.gBrowser.tabContainer.addEventListener("TabRemotenessChange", this, true);
+  },
+
+  untrackWindow: function(win) {
+    win.gBrowser.tabContainer.removeEventListener("TabSelect", this, true);
+    win.gBrowser.tabContainer.removeEventListener("TabRemotenessChange", this, true);
+  },
+
+  handleEvent: function(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") {
+      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: function(report) {
+    // If this hang was already reported reset the timer for it.
+    if (this._activeReports.has(report)) {
+      // 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)) {
+      return;
+    }
+
+    // On e10s this counts slow-script/hanged-plugin notice only once.
+    // This code is not reached on non-e10s.
+    if (report.hangType == report.SLOW_SCRIPT) {
+      // On non-e10s, SLOW_SCRIPT_NOTICE_COUNT is probed at nsGlobalWindow.cpp
+      Services.telemetry.getHistogramById("SLOW_SCRIPT_NOTICE_COUNT").add();
+    } else if (report.hangType == report.PLUGIN_HANG) {
+      // On non-e10s we have sufficient plugin telemetry probes,
+      // so PLUGIN_HANG_NOTICE_COUNT is only probed on e10s.
+      Services.telemetry.getHistogramById("PLUGIN_HANG_NOTICE_COUNT").add();
+    }
+
+    this._activeReports.add(report);
+    this.updateWindows();
+  },
+
+  clearHang: function(report) {
+    this.removeActiveReport(report);
+    this.removePausedReport(report);
+    report.userCanceled();
+  },
+};