[Oilpan]: Make StylePropertySet fully garbage collected.

Source/core/dom/ElementData.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  * Copyright (C) 2014 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 16 matching lines @@
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef ElementData_h
 #define ElementData_h
 
 #include "core/dom/Attribute.h"
 #include "core/dom/SpaceSplitString.h"
+#include "platform/heap/Handle.h"
 #include "wtf/text/AtomicString.h"
 
 namespace WebCore {
 
 class Attr;
 class ShareableElementData;
 class StylePropertySet;
 class UniqueElementData;
 
 class AttributeCollection {
@@ skipping 10 matching lines @@
 
     unsigned size() const { return m_size; }
 
 private:
     const Attribute* m_array;
     unsigned m_size;
 };
 
 // ElementData represents very common, but not necessarily unique to an element,
 // data such as attributes, inline style, and parsed class names and ids.
-class ElementData : public RefCounted<ElementData> {
-    WTF_MAKE_FAST_ALLOCATED;
+class ElementData : public RefCountedWillBeGarbageCollectedFinalized<ElementData> {
+    WTF_MAKE_FAST_ALLOCATED_WILL_BE_REMOVED;
 public:
+#if ENABLE(OILPAN)
+    // Override GarbageCollectedFinalized's finalizeGarbageCollectedObject to
+    // dispatch to the correct subclass' destructor.

[Mads Ager (chromium), 2014/06/25 09:18:33]

Nit: subclass's destructor or subclass destructor

[wibling-chromium, 2014/06/25 09:30:47]

I tend not to add an extra s when the word is ending in s. I have heard some
people have heated debates about this, so if you feel strongly I will add a s:)

+    void finalizeGarbageCollectedObject();
+#else
     // Override RefCounted's deref() to ensure operator delete is called on
     // the appropriate subclass type.
     void deref();
+#endif
 
     void clearClass() const { m_classNames.clear(); }
     void setClass(const AtomicString& className, bool shouldFoldCase) const { m_classNames.set(className, shouldFoldCase); }
     const SpaceSplitString& classNames() const { return m_classNames; }
 
     const AtomicString& idForStyleResolution() const { return m_idForStyleResolution; }
     void setIdForStyleResolution(const AtomicString& newId) const { m_idForStyleResolution = newId; }
 
     const StylePropertySet* inlineStyle() const { return m_inlineStyle.get(); }
 
@@ skipping 11 matching lines @@
     size_t findAttributeIndexByName(const AtomicString& name, bool shouldIgnoreAttributeCase) const;
     size_t findAttrNodeIndex(Attr*) const;
 
     bool hasID() const { return !m_idForStyleResolution.isNull(); }
     bool hasClass() const { return !m_classNames.isNull(); }
 
     bool isEquivalent(const ElementData* other) const;
 
     bool isUnique() const { return m_isUnique; }
 
+    void traceAfterDispatch(Visitor*);
+    void trace(Visitor*);
+
 protected:
     ElementData();
     explicit ElementData(unsigned arraySize);
     ElementData(const ElementData&, bool isUnique);
 
     // Keep the type in a bitfield instead of using virtual destructors to avoid adding a vtable.
     unsigned m_isUnique : 1;
     unsigned m_arraySize : 28;
     mutable unsigned m_presentationAttributeStyleIsDirty : 1;
     mutable unsigned m_styleAttributeIsDirty : 1;
     mutable unsigned m_animatedSVGAttributesAreDirty : 1;
 
-    mutable RefPtr<StylePropertySet> m_inlineStyle;
+    mutable RefPtrWillBeMember<StylePropertySet> m_inlineStyle;
     mutable SpaceSplitString m_classNames;
     mutable AtomicString m_idForStyleResolution;
 
 private:
     friend class Element;
     friend class ShareableElementData;
     friend class UniqueElementData;
     friend class SVGElement;
 
+#if !ENABLE(OILPAN)
     void destroy();
+#endif
 
     const Attribute* attributeBase() const;
     const Attribute* findAttributeByName(const AtomicString& name, bool shouldIgnoreAttributeCase) const;
     size_t findAttributeIndexByNameSlowCase(const AtomicString& name, bool shouldIgnoreAttributeCase) const;
 
-    PassRefPtr<UniqueElementData> makeUniqueCopy() const;
+    PassRefPtrWillBeRawPtr<UniqueElementData> makeUniqueCopy() const;
 };
 
 #if COMPILER(MSVC)
 #pragma warning(push)
 #pragma warning(disable: 4200) // Disable "zero-sized array in struct/union" warning
 #endif
 
 // SharableElementData is managed by ElementDataCache and is produced by
 // the parser during page load for elements that have identical attributes. This
 // is a memory optimization since it's very common for many elements to have
 // duplicate sets of attributes (ex. the same classes).
 class ShareableElementData FINAL : public ElementData {
 public:
-    static PassRefPtr<ShareableElementData> createWithAttributes(const Vector<Attribute>&);
+    static PassRefPtrWillBeRawPtr<ShareableElementData> createWithAttributes(const Vector<Attribute>&);
 
     explicit ShareableElementData(const Vector<Attribute>&);
     explicit ShareableElementData(const UniqueElementData&);
     ~ShareableElementData();
 
+    void traceAfterDispatch(Visitor* visitor) { ElementData::traceAfterDispatch(visitor); }
+
+    // Add support for placement new as ShareableElementData is not allocated
+    // with a fixed size. Instead the allocated memory size is computed based on
+    // the number of attributes. This requires us to use Heap::allocate directly
+    // with the computed size and subsequently call placement new with the
+    // allocated memory address.
+    void* operator new(std::size_t, void* location)
+    {
+        return location;
+    }
+
     Attribute m_attributeArray[0];
 };
 
 #if COMPILER(MSVC)
 #pragma warning(pop)
 #endif
 
 // UniqueElementData is created when an element needs to mutate its attributes
 // or gains presentation attribute style (ex. width="10"). It does not need to
 // be created to fill in values in the ElementData that are derived from
 // attributes. For example populating the m_inlineStyle from the style attribute
 // doesn't require a UniqueElementData as all elements with the same style
 // attribute will have the same inline style.
 class UniqueElementData FINAL : public ElementData {
 public:
-    static PassRefPtr<UniqueElementData> create();
-    PassRefPtr<ShareableElementData> makeShareableCopy() const;
+    static PassRefPtrWillBeRawPtr<UniqueElementData> create();
+    PassRefPtrWillBeRawPtr<ShareableElementData> makeShareableCopy() const;
 
     // These functions do no error/duplicate checking.
     void appendAttribute(const QualifiedName&, const AtomicString&);
     void removeAttributeAt(size_t index);
 
     Attribute& attributeAt(unsigned index);
     Attribute* findAttributeByName(const QualifiedName&);
 
     UniqueElementData();
     explicit UniqueElementData(const ShareableElementData&);
     explicit UniqueElementData(const UniqueElementData&);
 
+    void traceAfterDispatch(Visitor*);
+
     // FIXME: We might want to support sharing element data for elements with
     // presentation attribute style. Lots of table cells likely have the same
     // attributes. Most modern pages don't use presentation attributes though
     // so this might not make sense.
-    mutable RefPtr<StylePropertySet> m_presentationAttributeStyle;
+    mutable RefPtrWillBeMember<StylePropertySet> m_presentationAttributeStyle;
     Vector<Attribute, 4> m_attributeVector;
 };
 
+#if !ENABLE(OILPAN)
 inline void ElementData::deref()
 {
     if (!derefBase())
         return;
     destroy();
 }
+#endif
 
 inline size_t ElementData::attributeCount() const
 {
     if (isUnique())
         return static_cast<const UniqueElementData*>(this)->m_attributeVector.size();
     return m_arraySize;
 }
 
 inline const StylePropertySet* ElementData::presentationAttributeStyle() const
 {
@@ skipping 93 matching lines @@
 }
 
 inline Attribute& UniqueElementData::attributeAt(unsigned index)
 {
     return m_attributeVector.at(index);
 }
 
 } // namespace WebCore
 
 #endif // ElementData_h