1 files changed, 210 insertions, 0 deletions
diff --git a/mobile/android/modules/geckoview/GeckoViewProcessHangMonitor.sys.mjs b/mobile/android/modules/geckoview/GeckoViewProcessHangMonitor.sys.mjs
new file mode 100644
index 0000000000..7f6f14a29e
--- /dev/null
+++ b/mobile/android/modules/geckoview/GeckoViewProcessHangMonitor.sys.mjs
@@ -0,0 +1,210 @@
+/* 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/. */
+
+import { GeckoViewModule } from "resource://gre/modules/GeckoViewModule.sys.mjs";
+
+export class GeckoViewProcessHangMonitor extends GeckoViewModule {
+  constructor(aModuleInfo) {
+    super(aModuleInfo);
+
+    /**
+     * Collection of hang reports that haven't expired or been dismissed
+     * by the user. These are nsIHangReports.
+     */
+    this._activeReports = new Set();
+
+    /**
+     * Collection of hang reports that have been suppressed for a short
+     * period of time. Keys are nsIHangReports. Values are timeouts for
+     * when the wait time expires.
+     */
+    this._pausedReports = new Map();
+
+    /**
+     * Simple index used for report identification
+     */
+    this._nextIndex = 0;
+
+    /**
+     * Map of report IDs to report objects.
+     * Keys are numbers. Values are nsIHangReports.
+     */
+    this._reportIndex = new Map();
+
+    /**
+     * Map of report objects to report IDs.
+     * Keys are nsIHangReports. Values are numbers.
+     */
+    this._reportLookupIndex = new Map();
+  }
+
+  onInit() {
+    debug`onInit`;
+    Services.obs.addObserver(this, "process-hang-report");
+    Services.obs.addObserver(this, "clear-hang-report");
+  }
+
+  onDestroy() {
+    debug`onDestroy`;
+    Services.obs.removeObserver(this, "process-hang-report");
+    Services.obs.removeObserver(this, "clear-hang-report");
+  }
+
+  onEnable() {
+    debug`onEnable`;
+    this.registerListener([
+      "GeckoView:HangReportStop",
+      "GeckoView:HangReportWait",
+    ]);
+  }
+
+  onDisable() {
+    debug`onDisable`;
+    this.unregisterListener();
+  }
+
+  // Bundle event handler.
+  onEvent(aEvent, aData, aCallback) {
+    debug`onEvent: event=${aEvent}, data=${aData}`;
+
+    if (this._reportIndex.has(aData.hangId)) {
+      const report = this._reportIndex.get(aData.hangId);
+      switch (aEvent) {
+        case "GeckoView:HangReportStop":
+          this.stopHang(report);
+          break;
+        case "GeckoView:HangReportWait":
+          this.pauseHang(report);
+          break;
+      }
+    } else {
+      debug`Report not found: reportIndex=${this._reportIndex}`;
+    }
+  }
+
+  // nsIObserver event handler
+  observe(aSubject, aTopic, aData) {
+    debug`observe(aTopic=${aTopic})`;
+    aSubject.QueryInterface(Ci.nsIHangReport);
+    if (!aSubject.isReportForBrowserOrChildren(this.browser.frameLoader)) {
+      return;
+    }
+
+    switch (aTopic) {
+      case "process-hang-report": {
+        this.reportHang(aSubject);
+        break;
+      }
+      case "clear-hang-report": {
+        this.clearHang(aSubject);
+        break;
+      }
+    }
+  }
+
+  /**
+   * 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;
+    }
+  }
+
+  /**
+   * Terminate whatever is causing this report, be it an add-on or page script.
+   * This is done without updating any report notifications.
+   */
+  stopHang(report) {
+    report.terminateScript();
+  }
+
+  /**
+   *
+   */
+  pauseHang(report) {
+    this._activeReports.delete(report);
+
+    // Create a new timeout with notify callback
+    const timer = this.window.setTimeout(() => {
+      for (const [stashedReport, otherTimer] of this._pausedReports) {
+        if (otherTimer === timer) {
+          this._pausedReports.delete(stashedReport);
+
+          // We're still hung, so move the report back to the active
+          // list.
+          this._activeReports.add(report);
+          break;
+        }
+      }
+    }, this.WAIT_EXPIRATION_TIME);
+
+    this._pausedReports.set(report, timer);
+  }
+
+  /**
+   * construct an information bundle
+   */
+  notifyReport(report) {
+    this.eventDispatcher.sendRequest({
+      type: "GeckoView:HangReport",
+      hangId: this._reportLookupIndex.get(report),
+      scriptFileName: report.scriptFileName,
+    });
+  }
+
+  /**
+   * Handle a potentially new hang report.
+   */
+  reportHang(report) {
+    // if we aren't enabled then default to stopping the script
+    if (!this.enabled) {
+      this.stopHang(report);
+      return;
+    }
+
+    // if we have already notified, remind
+    if (this._activeReports.has(report)) {
+      this.notifyReport(report);
+      return;
+    }
+
+    // If this hang was already reported and paused by the user then ignore it.
+    if (this._pausedReports.has(report)) {
+      return;
+    }
+
+    const index = this._nextIndex++;
+    this._reportLookupIndex.set(report, index);
+    this._reportIndex.set(index, report);
+    this._activeReports.add(report);
+
+    // Actually notify the new report
+    this.notifyReport(report);
+  }
+
+  clearHang(report) {
+    this._activeReports.delete(report);
+
+    const timer = this._pausedReports.get(report);
+    if (timer) {
+      this.window.clearTimeout(timer);
+    }
+    this._pausedReports.delete(report);
+
+    if (this._reportLookupIndex.has(report)) {
+      const index = this._reportLookupIndex.get(report);
+      this._reportIndex.delete(index);
+    }
+    this._reportLookupIndex.delete(report);
+    report.userCanceled();
+  }
+}
+
+const { debug, warn } = GeckoViewProcessHangMonitor.initLogging(
+  "GeckoViewProcessHangMonitor"
+);