[WebKit] Fix for the memory leak

Memory leak was introduced by "DOM traversal optimizations DOM
Core optimizations Prefetch optimization for DOM Tree Traversal"
Cachelist was being mismanaged. Removing it.

Change-Id: I8abb2b6b30b1fbeb931a19be3567c78c3f697d77

5 files changed, 11 insertions, 42 deletions

diff --git a/Source/WebCore/dom/ChildNodeList.cpp b/Source/WebCore/dom/ChildNodeList.cpp
index 253537c..3328c7c 100644
--- a/Source/WebCore/dom/ChildNodeList.cpp
+++ b/Source/WebCore/dom/ChildNodeList.cpp
@@ -27,27 +27,19 @@
 
 namespace WebCore {
 
-ChildNodeList::ChildNodeList(PassRefPtr<Node> rootNode)
-    : DynamicNodeList(rootNode)
+ChildNodeList::ChildNodeList(PassRefPtr<Node> rootNode, DynamicNodeList::Caches* info)
+    : DynamicNodeList(rootNode, info)
 {
 }
 
-ChildNodeList::~ChildNodeList()
-{
-    m_rootNode->removeCachedChildNodeList(this);
-}
-
 unsigned ChildNodeList::length() const
 {
     if (m_caches->isLengthCacheValid)
         return m_caches->cachedLength;
 
     unsigned len = 0;
-    Vector<Node* >& cachedNodes = m_caches->cachedNodes;
-    for (Node* n = m_rootNode->firstChild(); n; n = n->nextSibling()) {
-        cachedNodes.append(n);
+    for (Node* n = m_rootNode->firstChild(); n; n = n->nextSibling())
         len++;
-    }
 
     m_caches->cachedLength = len;
     m_caches->isLengthCacheValid = true;
@@ -57,9 +49,6 @@ unsigned ChildNodeList::length() const
 
 Node* ChildNodeList::item(unsigned index) const
 {
-    if (m_caches->isLengthCacheValid && index < m_caches->cachedLength)
-        return m_caches->cachedNodes[index];
-
     unsigned int pos = 0;
     Node* n = m_rootNode->firstChild();
 
diff --git a/Source/WebCore/dom/ChildNodeList.h b/Source/WebCore/dom/ChildNodeList.h
index df3d67b..f38106d 100644
--- a/Source/WebCore/dom/ChildNodeList.h
+++ b/Source/WebCore/dom/ChildNodeList.h
@@ -31,18 +31,16 @@ namespace WebCore {
 
     class ChildNodeList : public DynamicNodeList {
     public:
-        static PassRefPtr<ChildNodeList> create(PassRefPtr<Node> rootNode)
+        static PassRefPtr<ChildNodeList> create(PassRefPtr<Node> rootNode, Caches* caches)
         {
-            return adoptRef(new ChildNodeList(rootNode));
+            return adoptRef(new ChildNodeList(rootNode, caches));
         }
 
-        virtual ~ChildNodeList();
-
         virtual unsigned length() const;
         virtual Node* item(unsigned index) const;
 
     protected:
-        ChildNodeList(PassRefPtr<Node> rootNode);
+        ChildNodeList(PassRefPtr<Node> rootNode, Caches*);
 
         virtual bool nodeMatches(Element*) const;
     };
diff --git a/Source/WebCore/dom/Node.cpp b/Source/WebCore/dom/Node.cpp
index 5b173bf..facb694 100644
--- a/Source/WebCore/dom/Node.cpp
+++ b/Source/WebCore/dom/Node.cpp
@@ -628,12 +628,8 @@ void Node::setNodeValue(const String& /*nodeValue*/, ExceptionCode& ec)
 PassRefPtr<NodeList> Node::childNodes()
 {
     NodeListsNodeData* data = ensureRareData()->ensureNodeLists(this);
-    if (data->m_childNodeListCache)
-        return PassRefPtr<ChildNodeList>(data->m_childNodeListCache);
 
-    RefPtr<ChildNodeList> childNodeList = ChildNodeList::create(this);
-    data->m_childNodeListCache = childNodeList.get();
-    return childNodeList.release();
+    return ChildNodeList::create(this, data->m_childNodeListCaches.get());
 }
 
 Node *Node::lastDescendant() const
@@ -1149,16 +1145,6 @@ void Node::removeCachedLabelsNodeList(DynamicNodeList* list)
     data->m_labelsNodeListCache = 0;
 }
 
-void Node::removeCachedChildNodeList(DynamicNodeList* list)
-{
-    ASSERT(rareData());
-    ASSERT(rareData()->nodeLists());
-    ASSERT_UNUSED(list, list->hasOwnCaches());
-
-    NodeListsNodeData* data = rareData()->nodeLists();
-    data->m_childNodeListCache = 0;
-}
-
 Node* Node::traverseNextNode(const Node* stayWithin) const
 {
     prefetchTarget();
@@ -2504,8 +2490,7 @@ void Node::formatForDebugger(char* buffer, unsigned length) const
 
 void NodeListsNodeData::invalidateCaches()
 {
-    if (m_childNodeListCache)
-        m_childNodeListCache->invalidateCache();
+    m_childNodeListCaches->reset();
 
     if (m_labelsNodeListCache)
         m_labelsNodeListCache->invalidateCache();
@@ -2536,7 +2521,7 @@ bool NodeListsNodeData::isEmpty() const
     if (!m_listsWithCaches.isEmpty())
         return false;
 
-    if (m_childNodeListCache)
+    if (m_childNodeListCaches->refCount())
         return false;
     
     TagNodeListCacheNS::const_iterator tagCacheEndNS = m_tagNodeListCacheNS.end();
diff --git a/Source/WebCore/dom/Node.h b/Source/WebCore/dom/Node.h
index ad5ee9d..d75d064 100644
--- a/Source/WebCore/dom/Node.h
+++ b/Source/WebCore/dom/Node.h
@@ -563,7 +563,6 @@ public:
     void removeCachedTagNodeList(TagNodeList*, const AtomicString&);
     void removeCachedTagNodeListNS(TagNodeListNS*, const QualifiedName&);
     void removeCachedLabelsNodeList(DynamicNodeList*);
-    void removeCachedChildNodeList(DynamicNodeList*);
 
     PassRefPtr<NodeList> getElementsByTagName(const AtomicString&);
     PassRefPtr<NodeList> getElementsByTagNameNS(const AtomicString& namespaceURI, const AtomicString& localName);
diff --git a/Source/WebCore/dom/NodeRareData.h b/Source/WebCore/dom/NodeRareData.h
index b81dd3f..7bbd0c1 100644
--- a/Source/WebCore/dom/NodeRareData.h
+++ b/Source/WebCore/dom/NodeRareData.h
@@ -22,7 +22,6 @@
 #ifndef NodeRareData_h
 #define NodeRareData_h
 
-#include "ChildNodeList.h"
 #include "ClassNodeList.h"
 #include "DynamicNodeList.h"
 #include "NameNodeList.h"
@@ -43,7 +42,7 @@ public:
     typedef HashSet<DynamicNodeList*> NodeListSet;
     NodeListSet m_listsWithCaches;
     
-    RefPtr<ChildNodeList> m_childNodeListCache;
+    RefPtr<DynamicNodeList::Caches> m_childNodeListCaches;
     
     typedef HashMap<String, ClassNodeList*> ClassNodeListCache;
     ClassNodeListCache m_classNodeListCache;
@@ -70,8 +69,7 @@ public:
 
 private:
     NodeListsNodeData()
-        : m_childNodeListCache(0)
-        , m_labelsNodeListCache(0)
+        : m_childNodeListCaches(DynamicNodeList::Caches::create()), m_labelsNodeListCache(0)
     {
     }
 };