Oilpan: Prepare moving AXObject to heap

Source/modules/accessibility/AXObjectCacheImpl.h

 /*
  * Copyright (C) 2014, Google 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 37 matching lines @@
 
 struct TextMarkerData {
     AXID axID;
     Node* node;
     int offset;
     EAffinity affinity;
 };
 
 // This class should only be used from inside the accessibility directory.
 class MODULES_EXPORT AXObjectCacheImpl : public AXObjectCache {
-    WTF_MAKE_NONCOPYABLE(AXObjectCacheImpl); WTF_MAKE_FAST_ALLOCATED(AXObjectCacheImpl);
+    WTF_MAKE_NONCOPYABLE(AXObjectCacheImpl);
+    WTF_MAKE_FAST_ALLOCATED_WILL_BE_REMOVED(AXObjectCacheImpl);
 public:
-    static AXObjectCache* create(Document&);
+    static PassOwnPtrWillBeRawPtr<AXObjectCache> create(Document&);
 
     explicit AXObjectCacheImpl(Document&);
     ~AXObjectCacheImpl();
+    DECLARE_VIRTUAL_TRACE();
 
     AXObject* focusedUIElementForPage(const Page*);
 
+    virtual void dispose() override;
+
     virtual void selectionChanged(Node*) override;
     virtual void childrenChanged(Node*) override;
     virtual void childrenChanged(LayoutObject*) override;
     virtual void checkedStateChanged(Node*) override;
     virtual void listboxOptionStateChanged(HTMLOptionElement*);
     virtual void listboxSelectedChildrenChanged(HTMLSelectElement*);
     virtual void listboxActiveIndexChanged(HTMLSelectElement*);
 
     virtual void remove(LayoutObject*) override;
     virtual void remove(Node*) override;
@@ skipping 50 matching lines @@
     AXObject* getOrCreate(AbstractInlineTextBox*);
 
     // will only return the AXObject if it already exists
     AXObject* get(Node*);
     AXObject* get(LayoutObject*);
     AXObject* get(Widget*);
     AXObject* get(AbstractInlineTextBox*);
 
     AXObject* firstAccessibleObjectFromNode(const Node*);
 
+#if ENABLE(OILPAN)
+    void remove(AXObject*);

[dmazzoni, 2015/04/28 06:53:25]

Can we make this change for the non-oilpan compile just so there aren't two code
paths?

[keishi, 2015/05/28 06:49:19]

Done.

+#else
     void remove(AXID);
+#endif
     void remove(AbstractInlineTextBox*);
 
     void childrenChanged(AXObject*);
 
     void handleActiveDescendantChanged(Node*);
     void handleAriaRoleChanged(Node*);
     void handleAriaExpandedChange(Node*);
     void handleAriaSelectedChanged(Node*);
 
     void recomputeIsIgnored(LayoutObject*);
 
     bool accessibilityEnabled();
     bool inlineTextBoxAccessibilityEnabled();
 
+#if !ENABLE(OILPAN)
     void removeAXID(AXObject*);
+#endif
     bool isIDinUse(AXID id) const { return m_idsInUse.contains(id); }
 
     AXID platformGenerateAXID() const;
 
     // Counts the number of times the document has been modified. Some attribute values are cached
     // as long as the modification count hasn't changed.
     int modificationCount() const { return m_modificationCount; }
 
     void postNotification(LayoutObject*, AXNotification);
     void postNotification(Node*, AXNotification);
     void postNotification(AXObject*, AXNotification);
 
 protected:
     void postPlatformNotification(AXObject*, AXNotification);
     void textChanged(AXObject*);
     void labelChanged(Element*);
 
     // This is a weak reference cache for knowing if Nodes used by TextMarkers are valid.
     void setNodeInUse(Node* n) { m_textMarkerNodes.add(n); }
     void removeNodeForUse(Node* n) { m_textMarkerNodes.remove(n); }
     bool isNodeInUse(Node* n) { return m_textMarkerNodes.contains(n); }
 
-    PassRefPtr<AXObject> createFromRenderer(LayoutObject*);
-    PassRefPtr<AXObject> createFromNode(Node*);
-    PassRefPtr<AXObject> createFromInlineTextBox(AbstractInlineTextBox*);
+    PassRefPtrWillBeRawPtr<AXObject> createFromRenderer(LayoutObject*);
+    PassRefPtrWillBeRawPtr<AXObject> createFromNode(Node*);
+    PassRefPtrWillBeRawPtr<AXObject> createFromInlineTextBox(AbstractInlineTextBox*);
 
 private:
+    void removeAXID(AXID);
+
     Document& m_document;
+
+#if ENABLE(OILPAN)
+    HeapHashMap<AXID, WeakMember<AXObject>> m_objects;
+    HeapHashMap<LayoutObject*, Member<AXObject>> m_layoutObjectMapping;
+    HeapHashMap<WeakMember<Widget>, Member<AXObject>> m_widgetObjectMapping;
+    HeapHashMap<WeakMember<Node>, Member<AXObject>> m_nodeObjectMapping;

[dmazzoni, 2015/04/28 06:53:25]

I'm worried about WeakMember<Node> here. We rely on getting a call to
AXObjectCache::remove(Node*) from Node::willBeDeletedFromDocument currently.
With this change, it looks like that call won't happen, so we'll end up with an
entry in the HashMap with a null key and the AXObject won't detach itself.

[keishi, 2015/05/28 06:49:19]

HeapHashMap with WeakMember entries will automatically be removed by weak
processing.
However, in this case we need to call AXNodeObject::detach for the removed nodes
so I am doing custom weak processing.
I've registered AXObjectCacheImpl::clearWeakMembers as a weak processing
callback using registerWeakMembers.
AXObjectCacheImpl::clearWeakMembers scans the map for unmarked Nodes, and calls
remove(Node*) so they are removed from the map and so AXNodeObject::detach is
called.

+    HeapHashMap<AbstractInlineTextBox*, Member<AXObject>> m_inlineTextBoxObjectMapping;
+#else
     HashMap<AXID, RefPtr<AXObject>> m_objects;
     HashMap<LayoutObject*, AXID> m_layoutObjectMapping;
     HashMap<Widget*, AXID> m_widgetObjectMapping;
     HashMap<Node*, AXID> m_nodeObjectMapping;
     HashMap<AbstractInlineTextBox*, AXID> m_inlineTextBoxObjectMapping;
-    HashSet<Node*> m_textMarkerNodes;
+#endif
+    WillBeHeapHashSet<RawPtrWillBeWeakMember<Node>> m_textMarkerNodes;
     int m_modificationCount;
 
     HashSet<AXID> m_idsInUse;
 
     Timer<AXObjectCacheImpl> m_notificationPostTimer;
-    Vector<pair<RefPtr<AXObject>, AXNotification>> m_notificationsToPost;
+    WillBeHeapVector<pair<RefPtrWillBeMember<AXObject>, AXNotification>> m_notificationsToPost;
     void notificationPostTimerFired(Timer<AXObjectCacheImpl>*);
 
     AXObject* focusedImageMapUIElement(HTMLAreaElement*);
 
     AXID getAXID(AXObject*);
 
     void textChanged(Node*);
     bool nodeIsTextControl(const Node*);
 
     Settings* settings();
 };
 
 // This is the only subclass of AXObjectCache.
 DEFINE_TYPE_CASTS(AXObjectCacheImpl, AXObjectCache, cache, true, true);
 
 bool nodeHasRole(Node*, const String& role);
 // This will let you know if aria-hidden was explicitly set to false.
 bool isNodeAriaVisible(Node*);
 
 }
 
 #endif