From 6882a04fb36642862b11efe514251d32070c3d65 Mon Sep 17 00:00:00 2001
From: Konstantin Tokarev <annulen@yandex.ru>
Date: Thu, 25 Aug 2016 19:20:41 +0300
Subject: Imported QtWebKit TP3 (git b57bc6801f1876c3220d5a4bfea33d620d477443)

Change-Id: I3b1d8a2808782c9f34d50240000e20cb38d3680f
Reviewed-by: Konstantin Tokarev <annulen@yandex.ru>
---
 Source/WebCore/dom/DocumentSharedObjectPool.cpp | 80 +++++++------------------
 1 file changed, 20 insertions(+), 60 deletions(-)

(limited to 'Source/WebCore/dom/DocumentSharedObjectPool.cpp')

diff --git a/Source/WebCore/dom/DocumentSharedObjectPool.cpp b/Source/WebCore/dom/DocumentSharedObjectPool.cpp
index 997e8668d..b5f721cae 100644
--- a/Source/WebCore/dom/DocumentSharedObjectPool.cpp
+++ b/Source/WebCore/dom/DocumentSharedObjectPool.cpp
@@ -10,10 +10,10 @@
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
- * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
@@ -31,72 +31,32 @@
 
 namespace WebCore {
 
-class ShareableElementDataCacheKey {
-public:
-    ShareableElementDataCacheKey(const Attribute* attributes, unsigned attributeCount)
-        : m_attributes(attributes)
-        , m_attributeCount(attributeCount)
-    { }
-
-    bool operator!=(const ShareableElementDataCacheKey& other) const
-    {
-        if (m_attributeCount != other.m_attributeCount)
-            return true;
-        return memcmp(m_attributes, other.m_attributes, sizeof(Attribute) * m_attributeCount);
-    }
-
-    unsigned hash() const
-    {
-        return StringHasher::hashMemory(m_attributes, m_attributeCount * sizeof(Attribute));
-    }
-
-private:
-    const Attribute* m_attributes;
-    unsigned m_attributeCount;
-};
-
-class ShareableElementDataCacheEntry {
-public:
-    ShareableElementDataCacheEntry(const ShareableElementDataCacheKey& k, PassRefPtr<ShareableElementData> v)
-        : key(k)
-        , value(v)
-    { }
+inline unsigned attributeHash(const Vector<Attribute>& attributes)
+{
+    return StringHasher::hashMemory(attributes.data(), attributes.size() * sizeof(Attribute));
+}
 
-    ShareableElementDataCacheKey key;
-    RefPtr<ShareableElementData> value;
-};
+inline bool hasSameAttributes(const Vector<Attribute>& attributes, ShareableElementData& elementData)
+{
+    if (attributes.size() != elementData.length())
+        return false;
+    return !memcmp(attributes.data(), elementData.m_attributeArray, attributes.size() * sizeof(Attribute));
+}
 
-PassRefPtr<ShareableElementData> DocumentSharedObjectPool::cachedShareableElementDataWithAttributes(const Vector<Attribute>& attributes)
+Ref<ShareableElementData> DocumentSharedObjectPool::cachedShareableElementDataWithAttributes(const Vector<Attribute>& attributes)
 {
     ASSERT(!attributes.isEmpty());
 
-    ShareableElementDataCacheKey cacheKey(attributes.data(), attributes.size());
-    unsigned cacheHash = cacheKey.hash();
+    auto& cachedData = m_shareableElementDataCache.add(attributeHash(attributes), nullptr).iterator->value;
 
-    ShareableElementDataCache::iterator cacheIterator = m_shareableElementDataCache.add(cacheHash, nullptr).iterator;
-    if (cacheIterator->value && cacheIterator->value->key != cacheKey)
-        cacheHash = 0;
+    // FIXME: This prevents sharing when there's a hash collision.
+    if (cachedData && !hasSameAttributes(attributes, *cachedData))
+        return ShareableElementData::createWithAttributes(attributes);
 
-    RefPtr<ShareableElementData> elementData;
-    if (cacheHash && cacheIterator->value)
-        elementData = cacheIterator->value->value;
-    else
-        elementData = ShareableElementData::createWithAttributes(attributes);
+    if (!cachedData)
+        cachedData = ShareableElementData::createWithAttributes(attributes);
 
-    if (!cacheHash || cacheIterator->value)
-        return elementData.release();
-
-    cacheIterator->value = adoptPtr(new ShareableElementDataCacheEntry(ShareableElementDataCacheKey(elementData->m_attributeArray, elementData->length()), elementData));
-
-    return elementData.release();
-}
-
-DocumentSharedObjectPool::DocumentSharedObjectPool()
-{
-}
-
-DocumentSharedObjectPool::~DocumentSharedObjectPool()
-{
+    return *cachedData;
 }
 
 }
-- 
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