[Webkit-unassigned] [Bug 37722] Allow to construct HashTraits<WebCore::QualifiedName>::constructDeletedValue

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=37722


Maciej Stachowiak <mjs at apple.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #53549|review?                     |review-
               Flag|                            |




--- Comment #4 from Maciej Stachowiak <mjs at apple.com>  2010-04-16 16:03:46 PST ---
(From update of attachment 53549)
The ChangeLog needs to explain the purpose of this change. I can't tell if this
is fixing a bug, changing performance, or just a refactoring change.

> Index: WebCore/dom/QualifiedName.cpp
> ===================================================================
> --- WebCore/dom/QualifiedName.cpp	(revision 57720)
> +++ WebCore/dom/QualifiedName.cpp	(working copy)
> @@ -78,6 +78,7 @@ void QualifiedName::deref()
>      if (!m_impl)
>          return;
>  #endif
> +    ASSERT(m_impl); // HashTableDeletedValue values must be never destructed.

Hash table deleted values are generally are generally -1 cast to a pointer
rather than 0 cast to a pointer by convention.

>  
>      if (m_impl->hasOneRef())
>          gNameCache->remove(m_impl);
> Index: WebCore/dom/QualifiedName.h
> ===================================================================
> --- WebCore/dom/QualifiedName.h	(revision 57720)
> +++ WebCore/dom/QualifiedName.h	(working copy)
> @@ -58,6 +58,8 @@ public:
>  
>      QualifiedName(const AtomicString& prefix, const AtomicString& localName, const AtomicString& namespaceURI);
>      QualifiedName(const AtomicString& prefix, const char* localName, const AtomicString& namespaceURI);
> +    QualifiedName(WTF::HashTableDeletedValueType) : m_impl(0) { }
> +    bool isHashTableDeletedValue() const { return !m_impl; }
>      ~QualifiedName() { deref(); }
>  #ifdef QNAME_DEFAULT_CONSTRUCTOR
>      QualifiedName() : m_impl(0) { }
> @@ -167,7 +169,7 @@ namespace WTF {
>      template<> struct HashTraits<WebCore::QualifiedName> : GenericHashTraits<WebCore::QualifiedName> {
>          static const bool emptyValueIsZero = false;
>          static WebCore::QualifiedName emptyValue() { return WebCore::QualifiedName(WebCore::nullAtom, WebCore::nullAtom, WebCore::nullAtom); }
> -        static void constructDeletedValue(WebCore::QualifiedName& slot) { new (&slot) WebCore::QualifiedName(WebCore::nullAtom, WebCore::AtomicString(HashTableDeletedValue), WebCore::nullAtom); }
> +        static void constructDeletedValue(WebCore::QualifiedName& slot) { new (&slot) WebCore::QualifiedName(WTF::HashTableDeletedValue); }
>          static bool isDeletedValue(const WebCore::QualifiedName& slot) { return slot.localName().isHashTableDeletedValue(); }
>      };
>  }

r- for not explaining the purpose of the patch. Please resubmit with an
explanation of what bug is being fixed (if any) and a test case of there is a
behavior change.

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