1 files changed, 60 insertions, 0 deletions
diff --git a/devtools/server/actors/eventlooplag.js b/devtools/server/actors/eventlooplag.js
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+++ b/devtools/server/actors/eventlooplag.js
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+/* 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";
+
+/**
+ * The eventLoopLag actor emits "event-loop-lag" events when the event
+ * loop gets unresponsive. The event comes with a "time" property (the
+ * duration of the lag in milliseconds).
+ */
+
+const {Ci} = require("chrome");
+const Services = require("Services");
+const {XPCOMUtils} = require("resource://gre/modules/XPCOMUtils.jsm");
+const {Actor, ActorClassWithSpec} = require("devtools/shared/protocol");
+const events = require("sdk/event/core");
+const {eventLoopLagSpec} = require("devtools/shared/specs/eventlooplag");
+
+var EventLoopLagActor = exports.EventLoopLagActor = ActorClassWithSpec(eventLoopLagSpec, {
+  _observerAdded: false,
+
+  /**
+   * Start tracking the event loop lags.
+   */
+  start: function () {
+    if (!this._observerAdded) {
+      Services.obs.addObserver(this, "event-loop-lag", false);
+      this._observerAdded = true;
+    }
+    return Services.appShell.startEventLoopLagTracking();
+  },
+
+  /**
+   * Stop tracking the event loop lags.
+   */
+  stop: function () {
+    if (this._observerAdded) {
+      Services.obs.removeObserver(this, "event-loop-lag");
+      this._observerAdded = false;
+    }
+    Services.appShell.stopEventLoopLagTracking();
+  },
+
+  destroy: function () {
+    this.stop();
+    Actor.prototype.destroy.call(this);
+  },
+
+  // nsIObserver
+
+  observe: function (subject, topic, data) {
+    if (topic == "event-loop-lag") {
+      // Forward event loop lag event
+      events.emit(this, "event-loop-lag", data);
+    }
+  },
+
+  QueryInterface: XPCOMUtils.generateQI([Ci.nsIObserver]),
+});