Bug 1444296 part 1 - Have servo report traversal statistics to gecko. r=bholley

MozReview-Commit-ID: 52YO9mzvneR

--HG--
extra : rebase_source : 873f58bd4ef8e426c350090e4132a8714f4667f4
extra : source : a9d9dc35b9e85eb483aa984977606883680a16c5

layout/style/ServoBindings.cpp

@@ -68,6 +68,7 @@
 #include "mozilla/StyleAnimationValue.h"
 #include "mozilla/SystemGroup.h"
 #include "mozilla/ServoMediaList.h"
+#include "mozilla/ServoTraversalStatistics.h"
 #include "mozilla/Telemetry.h"
 #include "mozilla/RWLock.h"
 #include "mozilla/dom/Element.h"
@@ -97,6 +98,10 @@ using namespace mozilla::dom;
 SERVO_ARC_TYPE(StyleContext, ServoStyleContext)
 #undef SERVO_ARC_TYPE
 
+// Definitions of the global traversal stats.
+bool ServoTraversalStatistics::sActive = false;
+ServoTraversalStatistics ServoTraversalStatistics::sSingleton;
+
 static RWLock* sServoFFILock = nullptr;
 
 static

layout/style/ServoBindings.toml

@@ -76,6 +76,7 @@ headers = [
     "mozilla/ServoMediaList.h",
     "mozilla/ServoStyleContext.h",
     "mozilla/ServoDeclarationBlock.h",
+    "mozilla/ServoTraversalStatistics.h",
     "mozilla/SizeOfState.h",
     "nsCSSCounterStyleRule.h",
     "nsCSSFontFaceRule.h",
@@ -230,6 +231,7 @@ whitelist-types = [
     "mozilla::ServoStyleSheet",
     "mozilla::ServoStyleSheetInner",
     "mozilla::ServoStyleSetSizes",
+    "mozilla::ServoTraversalStatistics",
     "mozilla::CSSPseudoClassType",
     "mozilla::css::ErrorReporter",
     "mozilla::css::LoaderReusableStyleSheets",

layout/style/ServoTraversalStatistics.h

@@ -0,0 +1,32 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#ifndef mozilla_ServoTraversalStatistics_h
+#define mozilla_ServoTraversalStatistics_h
+
+#include <inttypes.h>
+
+namespace mozilla {
+
+// Traversal statistics for Servo traversal.
+//
+// See style::context::PerThreadTraversalStatistics for
+// meaning of these fields.
+struct ServoTraversalStatistics
+{
+  uint32_t mElementsTraversed = 0;
+  uint32_t mElementsStyled = 0;
+  uint32_t mElementsMatched = 0;
+  uint32_t mStylesShared = 0;
+  uint32_t mStylesReused = 0;
+
+  static bool sActive;
+  static ServoTraversalStatistics sSingleton;
+};
+
+} // namespace mozilla
+
+#endif // mozilla_ServoTraversalStatistics_h

layout/style/moz.build

@@ -123,6 +123,7 @@ EXPORTS.mozilla += [
     'ServoStyleSet.h',
     'ServoStyleSheet.h',
     'ServoSupportsRule.h',
+    'ServoTraversalStatistics.h',
     'ServoTypes.h',
     'ServoUtils.h',
     'SheetType.h',