Bug 1569077 - Part 3: Add --capture-profile argument to the layout debugger. r=dbaron

Differential Revision: https://phabricator.services.mozilla.com/D39469

--HG--
extra : moz-landing-system : lando

layout/tools/layout-debug/src/nsLayoutDebugCLH.cpp

@@ -99,10 +99,12 @@ nsLayoutDebugCLH::Handle(nsICommandLine* aCmdLine) {
   nsString url;
   bool autoclose = false;
   double delay = 0.0;
+  bool captureProfile = false;
+  nsString profileFilename;
 
-  rv =
-      HandleFlagWithOptionalArgument(aCmdLine, NS_LITERAL_STRING("layoutdebug"),
-                                     EmptyString(), url, flagPresent);
+  rv = HandleFlagWithOptionalArgument(
+      aCmdLine, NS_LITERAL_STRING("layoutdebug"),
+      NS_LITERAL_STRING("about:blank"), url, flagPresent);
   NS_ENSURE_SUCCESS(rv, rv);
 
   if (!flagPresent) {
@@ -113,21 +115,24 @@ nsLayoutDebugCLH::Handle(nsICommandLine* aCmdLine) {
                                       0.0, delay, autoclose);
   NS_ENSURE_SUCCESS(rv, rv);
 
+  rv = HandleFlagWithOptionalArgument(
+      aCmdLine, NS_LITERAL_STRING("capture-profile"),
+      NS_LITERAL_STRING("profile.json"), profileFilename, captureProfile);
+  NS_ENSURE_SUCCESS(rv, rv);
+
   nsCOMPtr<nsIMutableArray> argsArray = nsArray::Create();
 
-  if (!url.IsEmpty()) {
-    nsCOMPtr<nsIURI> uri;
-    nsAutoCString resolvedSpec;
+  nsCOMPtr<nsIURI> uri;
+  nsAutoCString resolvedSpec;
 
-    rv = aCmdLine->ResolveURI(url, getter_AddRefs(uri));
-    NS_ENSURE_SUCCESS(rv, rv);
+  rv = aCmdLine->ResolveURI(url, getter_AddRefs(uri));
+  NS_ENSURE_SUCCESS(rv, rv);
 
-    rv = uri->GetSpec(resolvedSpec);
-    NS_ENSURE_SUCCESS(rv, rv);
+  rv = uri->GetSpec(resolvedSpec);
+  NS_ENSURE_SUCCESS(rv, rv);
 
-    rv = AppendArg(argsArray, NS_ConvertUTF8toUTF16(resolvedSpec));
-    NS_ENSURE_SUCCESS(rv, rv);
-  }
+  rv = AppendArg(argsArray, NS_ConvertUTF8toUTF16(resolvedSpec));
+  NS_ENSURE_SUCCESS(rv, rv);
 
   if (autoclose) {
     nsString arg;
@@ -137,6 +142,15 @@ nsLayoutDebugCLH::Handle(nsICommandLine* aCmdLine) {
     NS_ENSURE_SUCCESS(rv, rv);
   }
 
+  if (captureProfile) {
+    nsString arg;
+    arg.AppendLiteral("profile=");
+    arg.Append(profileFilename);
+
+    rv = AppendArg(argsArray, arg);
+    NS_ENSURE_SUCCESS(rv, rv);
+  }
+
   nsCOMPtr<nsIWindowWatcher> wwatch =
       do_GetService(NS_WINDOWWATCHER_CONTRACTID);
   NS_ENSURE_TRUE(wwatch, NS_ERROR_FAILURE);
@@ -154,6 +168,10 @@ nsLayoutDebugCLH::GetHelpInfo(nsACString& aResult) {
       "  --layoutdebug [<url>] Start with Layout Debugger\n"
       "  --autoclose [<seconds>] Automatically close the Layout Debugger once\n"
       "                     the page has loaded, after delaying the specified\n"
-      "                     number of seconds (which defaults to 0).\n");
+      "                     number of seconds (which defaults to 0).\n"
+      "  --capture-profile [<filename>] Capture a profile of the Layout\n"
+      "                     Debugger using the Gecko Profiler, and save the\n"
+      "                     profile to the specified file (which defaults to\n"
+      "                     profile.json).\n");
   return NS_OK;
 }

layout/tools/layout-debug/ui/content/layoutdebug.js

@@ -10,10 +10,13 @@ var gMultiProcessBrowser = window.docShell.QueryInterface(Ci.nsILoadContext)
   .useRemoteTabs;
 var gFissionBrowser = window.docShell.QueryInterface(Ci.nsILoadContext)
   .useRemoteSubframes;
+var gWritingProfile = false;
+var gWrittenProfile = false;
 
 const { E10SUtils } = ChromeUtils.import(
   "resource://gre/modules/E10SUtils.jsm"
 );
+const { OS } = ChromeUtils.import("resource://gre/modules/osfile.jsm");
 const { Preferences } = ChromeUtils.import(
   "resource://gre/modules/Preferences.jsm"
 );
@@ -177,10 +180,13 @@ nsLDBBrowserContentListener.prototype = {
         // This does mean that --autoclose doesn't work when the URL on
         // the command line is about:blank (or not specified), but that's
         // not a big deal.
-        setTimeout(
-          () => Services.startup.quit(Ci.nsIAppStartup.eAttemptQuit),
-          gArgs.delay * 1000
-        );
+        setTimeout(function() {
+          if (gArgs.profile && Services.profiler) {
+            dumpProfile();
+          } else {
+            Services.startup.quit(Ci.nsIAppStartup.eAttemptQuit);
+          }
+        }, gArgs.delay * 1000);
       }
     }
   },
@@ -234,11 +240,15 @@ function parseArguments() {
   if (window.arguments) {
     args.url = window.arguments[0];
     for (let i = 1; i < window.arguments.length; ++i) {
-      if (/^autoclose=(.*)$/.test(window.arguments[i])) {
+      let arg = window.arguments[i];
+      if (/^autoclose=(.*)$/.test(arg)) {
         args.autoclose = true;
         args.delay = +RegExp.$1;
+      } else if (/^profile=(.*)$/.test(arg)) {
+        args.profile = true;
+        args.profileFilename = RegExp.$1;
       } else {
-        throw `Unknown option ${window.arguments[i]}`;
+        throw `Unknown option ${arg}`;
       }
     }
   }
@@ -262,6 +272,29 @@ function OnLDBLoad() {
   };
 
   gArgs = parseArguments();
+
+  if (gArgs.profile) {
+    if (Services.profiler) {
+      let env = Cc["@mozilla.org/process/environment;1"].getService(
+        Ci.nsIEnvironment
+      );
+      if (!env.exists("MOZ_PROFILER_SYMBOLICATE")) {
+        dump(
+          "Warning: MOZ_PROFILER_SYMBOLICATE environment variable not set; " +
+            "profile will not be symbolicated.\n"
+        );
+      }
+      Services.profiler.StartProfiler(
+        1 << 20,
+        1,
+        ["default"],
+        ["GeckoMain", "Compositor", "Renderer", "RenderBackend", "StyleThread"]
+      );
+    } else {
+      dump("Cannot profile Layout Debugger; profiler was not compiled in.\n");
+    }
+  }
+
   if (gArgs.url) {
     loadURI(gArgs.url);
   }
@@ -283,6 +316,43 @@ function checkPersistentMenus() {
   checkPersistentMenu("reflowCounts");
 }
 
+function dumpProfile() {
+  gWritingProfile = true;
+
+  let cwd = Services.dirsvc.get("CurWorkD", Ci.nsIFile).path;
+  let filename = OS.Path.join(cwd, gArgs.profileFilename);
+
+  dump(`Writing profile to ${filename}...\n`);
+
+  Services.profiler.dumpProfileToFileAsync(filename).then(function() {
+    gWritingProfile = false;
+    gWrittenProfile = true;
+    dump(`done\n`);
+    Services.startup.quit(Ci.nsIAppStartup.eAttemptQuit);
+  });
+}
+
+function OnLDBBeforeUnload(event) {
+  if (gArgs.profile && Services.profiler) {
+    if (gWrittenProfile) {
+      // We've finished writing the profile.  Allow the window to close.
+      return;
+    }
+
+    event.preventDefault();
+
+    if (gWritingProfile) {
+      // Wait for the profile to finish being written out.
+      return;
+    }
+
+    // The dumpProfileToFileAsync call can block for a while, so run it off a
+    // timeout to avoid annoying the window manager if we're doing this in
+    // response to clicking the window's close button.
+    setTimeout(dumpProfile, 0);
+  }
+}
+
 function OnLDBUnload() {
   gDebugger.detachBrowser();
 }

layout/tools/layout-debug/ui/content/layoutdebug.xul

@@ -28,6 +28,7 @@
         titlemenuseparator=" - "
         windowtype="mozapp:layoutdebug"
         onload="OnLDBLoad();"
+        onclose="OnLDBBeforeUnload(event);"
         onunload="OnLDBUnload();"
         width="1024" height="768"
         screenX="4" screenY="4"