Do not cause unnecessary node lists invalidation on id/name attribute change

Source/core/dom/Document.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
@@ skipping 632 matching lines @@
 
     // Updates for :target (CSS3 selector).
     void setCSSTarget(Element*);
     Element* cssTarget() const { return m_cssTarget; }
 
     void scheduleStyleRecalc();
     bool hasPendingForcedStyleRecalc() const;
 
     void registerNodeList(LiveNodeListBase*);
     void unregisterNodeList(LiveNodeListBase*);
+    void incrementNodeListWithIdNameCacheCount();
+    void decrementNodeListWithIdNameCacheCount();
     bool shouldInvalidateNodeListCaches(const QualifiedName* attrName = 0) const;
     void invalidateNodeListCaches(const QualifiedName* attrName);
 
     void attachNodeIterator(NodeIterator*);
     void detachNodeIterator(NodeIterator*);
     void moveNodeIteratorsToNewDocument(Node&, Document&);
 
     void attachRange(Range*);
     void detachRange(Range*);
 
@@ skipping 707 matching lines @@
 }
 
 inline bool Document::shouldOverrideLegacyDescription(ViewportDescription::Type origin)
 {
     // The different (legacy) meta tags have different priorities based on the type
     // regardless of which order they appear in the DOM. The priority is given by the
     // ViewportDescription::Type enum.
     return origin >= m_legacyViewportDescription.type;
 }
 
+inline void Document::incrementNodeListWithIdNameCacheCount()
+{
+    m_nodeListCounts[InvalidateOnIdNameAttrChange]++;

[eseidel, 2014/02/12 01:55:24]

This seems about the same size as just keeping a list of the pointers.  I wonder
what the tradeoff would be there.

[Inactive, 2014/02/12 02:21:41]

You mean an array of linked lists (whose items would be LiveNodeListBase
pointers) instead of an array of integers? My worry is that this could grow to
use quite a bit more memory if we have more than one LiveNodeListBase per
invalidation type.

+}
+
+inline void Document::decrementNodeListWithIdNameCacheCount()
+{
+    ASSERT(m_nodeListCounts[InvalidateOnIdNameAttrChange] > 0);

[Inactive, 2014/02/12 02:21:41]

You mentioned having good assertions an IRC. There is this one to make sure we
don't decrement more than we should.

And there is a pre-existing assertion in the Document destructor to make sure we
decrement enough (i.e. No list is still registered when the document is
destroyed):
for (unsigned i = 0; i < WTF_ARRAY_LENGTH(m_nodeListCounts); i++)
        ASSERT(!m_nodeListCounts[i]);

+    m_nodeListCounts[InvalidateOnIdNameAttrChange]--;
+}
+
 DEFINE_TYPE_CASTS(Document, ExecutionContextClient, client, client->isDocument(), client.isDocument());
 DEFINE_TYPE_CASTS(Document, ExecutionContext, context, context->isDocument(), context.isDocument());
 DEFINE_NODE_TYPE_CASTS(Document, isDocumentNode());
 
 #define DEFINE_DOCUMENT_TYPE_CASTS(thisType) \
     DEFINE_TYPE_CASTS(thisType, Document, document, document->is##thisType(), document.is##thisType())
 
 // All these varations are needed to avoid ambiguous overloads with the Node and TreeScope versions.
 inline bool operator==(const Document& a, const Document& b) { return &a == &b; }
 inline bool operator==(const Document& a, const Document* b) { return &a == b; }
 inline bool operator==(const Document* a, const Document& b) { return a == &b; }
 inline bool operator!=(const Document& a, const Document& b) { return !(a == b); }
 inline bool operator!=(const Document& a, const Document* b) { return !(a == b); }
 inline bool operator!=(const Document* a, const Document& b) { return !(a == b); }
 
 // Put these methods here, because they require the Document definition, but we really want to inline them.
 
 inline bool Node::isDocumentNode() const
 {
     return this == document();
 }
 
 Node* eventTargetNodeForDocument(Document*);
 
 } // namespace WebCore
 
 #endif // Document_h