Introduce infrastructure for tracing ScriptWrappables.

third_party/WebKit/Source/bindings/core/v8/ScriptWrappableVisitor.cpp

Index: third_party/WebKit/Source/bindings/core/v8/ScriptWrappableVisitor.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/ScriptWrappableVisitor.cpp b/third_party/WebKit/Source/bindings/core/v8/ScriptWrappableVisitor.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..7e2307abd6e0ecf98f9d7ad60649cadc3ad252ac
--- /dev/null
+++ b/third_party/WebKit/Source/bindings/core/v8/ScriptWrappableVisitor.cpp
@@ -0,0 +1,48 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "bindings/core/v8/ScriptWrappableVisitor.h"
+
+#include "bindings/core/v8/ScriptWrappable.h"
+#include "bindings/core/v8/ScriptWrappableHeapTracer.h"
+#include "core/dom/NodeRareData.h"
+#include "core/events/EventListenerMap.h"
+#include "core/events/EventTarget.h"
+#include "platform/heap/HeapPage.h"
+
+namespace blink {
+
+bool ScriptWrappableVisitor::isHeaderMarked(const void* garbageCollected) const

[haraken, 2016/04/19 04:58:31]

If you think that the tracing performance really matters enough to optimize the
API call overhead, I think you should inline all the methods of
ScriptWrappableVisitor.

[Marcel Hlopko, 2016/04/19 12:40:29]

Done for private methods. I'll measure the impact of both api call optimization
and inlining after we're correctly tracing all and refactor code to inline
traceWrappers too if neccessary.

[haraken, 2016/04/19 12:51:05]

Sounds like a plan :)

+{
+    return HeapObjectHeader::fromPayload(garbageCollected)->isWrapperMarked();
+}
+
+void ScriptWrappableVisitor::markHeader(const ScriptWrappable* scriptWrappable) const
+{
+    markHeader(static_cast<const void*>(scriptWrappable));
+
+    ScriptWrappableHeapTracer::markWrappersInAllWorlds(scriptWrappable, m_isolate);
+}
+
+void ScriptWrappableVisitor::markHeader(const void* garbageCollected) const
+{
+    HeapObjectHeader* header = HeapObjectHeader::fromPayload(garbageCollected);
+    header->markWrapper();

[haraken, 2016/04/19 04:58:31]

It looks a bit confusing that markHeader calls markWrapper. I'd suggest renaming
all the methods to markWrapperHeader consistently.

[Marcel Hlopko, 2016/04/19 12:40:29]

Done.

+    m_tracer->AddHeaderToUnmark(header);
+}
+
+void ScriptWrappableVisitor::traceWrappers(const ScriptWrappable* wrappable) const
+{
+    if (wrappable && !isHeaderMarked(wrappable)) {
+        markHeader(wrappable);
+        wrappable->traceWrappers(this);
+    }
+}
+
+void ScriptWrappableVisitor::traceWrappers(const ScriptWrappable& wrappable) const
+{
+    traceWrappers(&wrappable);
+}
+
+} // namespace blink