Better handling of DocumentOrderedMap same-ID lookups during tree removals

third_party/WebKit/Source/core/dom/DocumentOrderedMap.h

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 44 matching lines @@
     bool containsMultiple(const AtomicString&) const;
     // concrete instantiations of the get<>() method template
     Element* getElementById(const AtomicString&, const TreeScope*) const;
     const WillBeHeapVector<RawPtrWillBeMember<Element>>& getAllElementsById(const AtomicString&, const TreeScope*) const;
     Element* getElementByMapName(const AtomicString&, const TreeScope*) const;
     Element* getElementByLowercasedMapName(const AtomicString&, const TreeScope*) const;
     Element* getElementByLabelForAttribute(const AtomicString&, const TreeScope*) const;
 
     DECLARE_TRACE();
 
+#if ENABLE(ASSERT)
+    void willBeRemovingId(const AtomicString*);

[esprehn, 2015/12/18 00:42:26]

willRemoveId()

no "Be"

[sof, 2015/12/18 07:31:53]

Renamed to willRemoveId().

+#endif
+
 private:
+    DocumentOrderedMap();

[esprehn, 2015/12/18 00:42:26]

we should declare the destructor too

[sof, 2015/12/18 07:31:53]

Done, but see below.

+
     template<bool keyMatches(const AtomicString&, const Element&)>
     Element* get(const AtomicString&, const TreeScope*) const;
 
     class MapEntry : public NoBaseWillBeGarbageCollected<MapEntry> {
     public:
         explicit MapEntry(Element* firstElement)
             : element(firstElement)
             , count(1)
         {
         }
 
         DECLARE_TRACE();
 
         RawPtrWillBeMember<Element> element;
         unsigned count;
         WillBeHeapVector<RawPtrWillBeMember<Element>> orderedList;
     };
 
     using Map = WillBeHeapHashMap<AtomicString, OwnPtrWillBeMember<MapEntry>>;
 
     mutable Map m_map;
+#if ENABLE(ASSERT)
+    const AtomicString* m_removingId;

[tkent, 2015/12/18 00:30:57]

Can you make this |AtomicString| and check AtomicString::isNull() instead of
nullptr?

[esprehn, 2015/12/18 00:42:26]

+1

[sof, 2015/12/18 07:31:53]

Done that; slight downside with such a design is it leaves you with a
non-trivial finalizer on the Oilpan side.

+#endif
 };
 
 inline bool DocumentOrderedMap::contains(const AtomicString& id) const
 {
     return m_map.contains(id);
 }
 
 inline bool DocumentOrderedMap::containsMultiple(const AtomicString& id) const
 {
     Map::const_iterator it = m_map.find(id);
     return it != m_map.end() && it->value->count > 1;
 }
 
 } // namespace blink
 
 #endif // DocumentOrderedMap_h