1 files changed, 228 insertions, 0 deletions
diff --git a/browser/components/StartupRecorder.sys.mjs b/browser/components/StartupRecorder.sys.mjs
new file mode 100644
index 0000000000..7b69b52690
--- /dev/null
+++ b/browser/components/StartupRecorder.sys.mjs
@@ -0,0 +1,228 @@
+/* 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/. */
+
+const Cm = Components.manager;
+Cm.QueryInterface(Ci.nsIServiceManager);
+
+import { AppConstants } from "resource://gre/modules/AppConstants.sys.mjs";
+
+let firstPaintNotification = "widget-first-paint";
+// widget-first-paint fires much later than expected on Linux.
+if (
+  AppConstants.platform == "linux" ||
+  Services.prefs.getBoolPref("browser.startup.preXulSkeletonUI", false)
+) {
+  firstPaintNotification = "xul-window-visible";
+}
+
+let win, canvas;
+let paints = [];
+let afterPaintListener = () => {
+  let width, height;
+  canvas.width = width = win.innerWidth;
+  canvas.height = height = win.innerHeight;
+  if (width < 1 || height < 1) {
+    return;
+  }
+  let ctx = canvas.getContext("2d", { alpha: false, willReadFrequently: true });
+
+  ctx.drawWindow(
+    win,
+    0,
+    0,
+    width,
+    height,
+    "white",
+    ctx.DRAWWINDOW_DO_NOT_FLUSH |
+      ctx.DRAWWINDOW_DRAW_VIEW |
+      ctx.DRAWWINDOW_ASYNC_DECODE_IMAGES |
+      ctx.DRAWWINDOW_USE_WIDGET_LAYERS
+  );
+  paints.push({
+    data: ctx.getImageData(0, 0, width, height).data,
+    width,
+    height,
+  });
+};
+
+/**
+ * The StartupRecorder component observes notifications at various stages of
+ * startup and records the set of JS modules that were already loaded at
+ * each of these points.
+ * The records are meant to be used by startup tests in
+ * browser/base/content/test/performance
+ * This component only exists in nightly and debug builds, it doesn't ship in
+ * our release builds.
+ */
+export function StartupRecorder() {
+  this.wrappedJSObject = this;
+  this.data = {
+    images: {
+      "image-drawing": new Set(),
+      "image-loading": new Set(),
+    },
+    code: {},
+    extras: {},
+    prefStats: {},
+  };
+  this.done = new Promise(resolve => {
+    this._resolve = resolve;
+  });
+}
+
+StartupRecorder.prototype = {
+  QueryInterface: ChromeUtils.generateQI(["nsIObserver"]),
+
+  record(name) {
+    ChromeUtils.addProfilerMarker("startupRecorder:" + name);
+    this.data.code[name] = {
+      modules: Cu.loadedJSModules.concat(Cu.loadedESModules),
+      services: Object.keys(Cc).filter(c => {
+        try {
+          return Cm.isServiceInstantiatedByContractID(c, Ci.nsISupports);
+        } catch (e) {
+          return false;
+        }
+      }),
+    };
+    this.data.extras[name] = {
+      hiddenWindowLoaded: Services.appShell.hasHiddenWindow,
+    };
+  },
+
+  observe(subject, topic, data) {
+    if (topic == "app-startup" || topic == "content-process-ready-for-script") {
+      // Don't do anything in xpcshell.
+      if (Services.appinfo.ID != "{ec8030f7-c20a-464f-9b0e-13a3a9e97384}") {
+        return;
+      }
+
+      if (
+        !Services.prefs.getBoolPref("browser.startup.record", false) &&
+        !Services.prefs.getBoolPref("browser.startup.recordImages", false)
+      ) {
+        this._resolve();
+        this._resolve = null;
+        return;
+      }
+
+      // We can't ensure our observer will be called first or last, so the list of
+      // topics we observe here should avoid the topics used to trigger things
+      // during startup (eg. the topics observed by BrowserGlue.sys.mjs).
+      let topics = [
+        "profile-do-change", // This catches stuff loaded during app-startup
+        "toplevel-window-ready", // Catches stuff from final-ui-startup
+        firstPaintNotification,
+        "sessionstore-windows-restored",
+        "browser-startup-idle-tasks-finished",
+      ];
+
+      if (Services.prefs.getBoolPref("browser.startup.recordImages", false)) {
+        // For code simplicify, recording images excludes the other startup
+        // recorder behaviors, so we can observe only the image topics.
+        topics = [
+          "image-loading",
+          "image-drawing",
+          "browser-startup-idle-tasks-finished",
+        ];
+      }
+      for (let t of topics) {
+        Services.obs.addObserver(this, t);
+      }
+      return;
+    }
+
+    // We only care about the first paint notification for browser windows, and
+    // not other types (for example, the gfx sanity test window)
+    if (topic == firstPaintNotification) {
+      // In the case we're handling xul-window-visible, we'll have been handed
+      // an nsIAppWindow instead of an nsIDOMWindow.
+      if (subject instanceof Ci.nsIAppWindow) {
+        subject = subject
+          .QueryInterface(Ci.nsIInterfaceRequestor)
+          .getInterface(Ci.nsIDOMWindow);
+      }
+
+      if (
+        subject.document.documentElement.getAttribute("windowtype") !=
+        "navigator:browser"
+      ) {
+        return;
+      }
+    }
+
+    if (topic == "image-drawing" || topic == "image-loading") {
+      this.data.images[topic].add(data);
+      return;
+    }
+
+    Services.obs.removeObserver(this, topic);
+
+    if (topic == firstPaintNotification) {
+      // Because of the check for navigator:browser we made earlier, we know
+      // that if we got here, then the subject must be the first browser window.
+      win = subject;
+      canvas = win.document.createElementNS(
+        "http://www.w3.org/1999/xhtml",
+        "canvas"
+      );
+      canvas.mozOpaque = true;
+      afterPaintListener();
+      win.addEventListener("MozAfterPaint", afterPaintListener);
+    }
+
+    if (topic == "sessionstore-windows-restored") {
+      // We use idleDispatchToMainThread here to record the set of
+      // loaded scripts after we are fully done with startup and ready
+      // to react to user events.
+      Services.tm.dispatchToMainThread(
+        this.record.bind(this, "before handling user events")
+      );
+    } else if (topic == "browser-startup-idle-tasks-finished") {
+      if (Services.prefs.getBoolPref("browser.startup.recordImages", false)) {
+        Services.obs.removeObserver(this, "image-drawing");
+        Services.obs.removeObserver(this, "image-loading");
+        this._resolve();
+        this._resolve = null;
+        return;
+      }
+
+      this.record("before becoming idle");
+      win.removeEventListener("MozAfterPaint", afterPaintListener);
+      win = null;
+      this.data.frames = paints;
+      this.data.prefStats = {};
+      if (AppConstants.DEBUG) {
+        Services.prefs.readStats(
+          (key, value) => (this.data.prefStats[key] = value)
+        );
+      }
+      paints = null;
+
+      if (!Services.env.exists("MOZ_PROFILER_STARTUP_PERFORMANCE_TEST")) {
+        this._resolve();
+        this._resolve = null;
+        return;
+      }
+
+      Services.profiler.getProfileDataAsync().then(profileData => {
+        this.data.profile = profileData;
+        // There's no equivalent StartProfiler call in this file because the
+        // profiler is started using the MOZ_PROFILER_STARTUP environment
+        // variable in browser/base/content/test/performance/browser.ini
+        Services.profiler.StopProfiler();
+
+        this._resolve();
+        this._resolve = null;
+      });
+    } else {
+      const topicsToNames = {
+        "profile-do-change": "before profile selection",
+        "toplevel-window-ready": "before opening first browser window",
+      };
+      topicsToNames[firstPaintNotification] = "before first paint";
+      this.record(topicsToNames[topic]);
+    }
+  },
+};