[Oilpan]: Make StylePropertySet fully garbage collected.

Source/core/css/resolver/MatchedPropertiesCache.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 17 matching lines @@
 
 #include "config.h"
 #include "core/css/resolver/MatchedPropertiesCache.h"
 
 #include "core/css/StylePropertySet.h"
 #include "core/css/resolver/StyleResolverState.h"
 #include "core/rendering/style/RenderStyle.h"
 
 namespace WebCore {
 
+#if ENABLE(OILPAN)
+bool CachedMatchedPropertiesHashTraits::traceInCollection(Visitor* visitor, Member<CachedMatchedProperties>& cachedProperties, WTF::ShouldWeakPointersBeMarkedStrongly strongify)
+{
+    // Only honor the cache's weakness semantics if the collection is traced
+    // with WeakPointersActWeak. Otherwise just trace the cachedProperties
+    // strongly, ie. call trace on it.
+    if (strongify == WTF::WeakPointersActWeak) {
+        // A given cache entry is only kept alive if none of the MatchedProperties
+        // in the CachedMatchedProperties value contain a dead "properties" field.
+        // If there is a dead field the entire cache entry is removed.
+        HeapVector<MatchedProperties>::iterator it = cachedProperties->matchedProperties.begin();
+        HeapVector<MatchedProperties>::iterator end = cachedProperties->matchedProperties.end();
+        for (; it != end; ++it) {
+            if (!visitor->isAlive(it->properties)) {
+                // For now report the cache entry as dead. This might not
+                // be the final result if in a subsequent call for this entry,
+                // the "properties" field has been marked via another path.
+                return true;
+            }
+        }
+    }
+    // At this point none of the entries in the matchedProperties vector
+    // had a dead "properties" field so trace CachedMatchedProperties strongly.
+    visitor->trace(cachedProperties);
+    return false;
+}
+#endif
+
 void CachedMatchedProperties::set(const RenderStyle* style, const RenderStyle* parentStyle, const MatchResult& matchResult)
 {
     matchedProperties.appendVector(matchResult.matchedProperties);
     ranges = matchResult.ranges;
 
     // Note that we don't cache the original RenderStyle instance. It may be further modified.
     // The RenderStyle in the cache is really just a holder for the substructures and never used as-is.
     this->renderStyle = RenderStyle::clone(style);
     this->parentRenderStyle = RenderStyle::clone(parentStyle);
 }
 
 void CachedMatchedProperties::clear()
 {
     matchedProperties.clear();
     renderStyle = nullptr;
     parentRenderStyle = nullptr;
 }
 
 MatchedPropertiesCache::MatchedPropertiesCache()
+#if !ENABLE(OILPAN)
     : m_additionsSinceLastSweep(0)
     , m_sweepTimer(this, &MatchedPropertiesCache::sweep)
+#endif
 {
 }
 
 const CachedMatchedProperties* MatchedPropertiesCache::find(unsigned hash, const StyleResolverState& styleResolverState, const MatchResult& matchResult)
 {
     ASSERT(hash);
 
     Cache::iterator it = m_cache.find(hash);
     if (it == m_cache.end())
         return 0;
     CachedMatchedProperties* cacheItem = it->value.get();
     ASSERT(cacheItem);
 
     size_t size = matchResult.matchedProperties.size();
     if (size != cacheItem->matchedProperties.size())
         return 0;
     if (cacheItem->renderStyle->insideLink() != styleResolverState.style()->insideLink())
         return 0;
     for (size_t i = 0; i < size; ++i) {
         if (matchResult.matchedProperties[i] != cacheItem->matchedProperties[i])
             return 0;
     }
     if (cacheItem->ranges != matchResult.ranges)
         return 0;
     return cacheItem;
 }
 
 void MatchedPropertiesCache::add(const RenderStyle* style, const RenderStyle* parentStyle, unsigned hash, const MatchResult& matchResult)
 {
+#if !ENABLE(OILPAN)
     static const unsigned maxAdditionsBetweenSweeps = 100;
     if (++m_additionsSinceLastSweep >= maxAdditionsBetweenSweeps
         && !m_sweepTimer.isActive()) {
         static const unsigned sweepTimeInSeconds = 60;
         m_sweepTimer.startOneShot(sweepTimeInSeconds, FROM_HERE);
     }
+#endif
 
     ASSERT(hash);
     Cache::AddResult addResult = m_cache.add(hash, nullptr);
     if (addResult.isNewEntry)
-        addResult.storedValue->value = adoptPtr(new CachedMatchedProperties);
+        addResult.storedValue->value = adoptPtrWillBeNoop(new CachedMatchedProperties);
 
     CachedMatchedProperties* cacheItem = addResult.storedValue->value.get();
     if (!addResult.isNewEntry)
         cacheItem->clear();
 
     cacheItem->set(style, parentStyle, matchResult);
 }
 
 void MatchedPropertiesCache::clear()
 {
     m_cache.clear();
 }
 
 void MatchedPropertiesCache::clearViewportDependent()
 {
     Vector<unsigned, 16> toRemove;
     for (Cache::iterator it = m_cache.begin(); it != m_cache.end(); ++it) {
         CachedMatchedProperties* cacheItem = it->value.get();
         if (cacheItem->renderStyle->hasViewportUnits())
             toRemove.append(it->key);
     }
     m_cache.removeAll(toRemove);
 }
 
+#if !ENABLE(OILPAN)
 void MatchedPropertiesCache::sweep(Timer<MatchedPropertiesCache>*)
 {
     // Look for cache entries containing a style declaration with a single ref and remove them.
     // This may happen when an element attribute mutation causes it to generate a new inlineStyle()
     // or presentationAttributeStyle(), potentially leaving this cache with the last ref on the old one.
     Vector<unsigned, 16> toRemove;
     Cache::iterator it = m_cache.begin();
     Cache::iterator end = m_cache.end();
     for (; it != end; ++it) {
         CachedMatchedProperties* cacheItem = it->value.get();
         Vector<MatchedProperties>& matchedProperties = cacheItem->matchedProperties;
         for (size_t i = 0; i < matchedProperties.size(); ++i) {
             if (matchedProperties[i].properties->hasOneRef()) {
                 toRemove.append(it->key);
                 break;
             }
         }
     }
     m_cache.removeAll(toRemove);
     m_additionsSinceLastSweep = 0;
 }
+#endif
 
 bool MatchedPropertiesCache::isCacheable(const Element* element, const RenderStyle* style, const RenderStyle* parentStyle)
 {
     // FIXME: CSSPropertyWebkitWritingMode modifies state when applying to document element. We can't skip the applying by caching.
     if (element == element->document().documentElement() && element->document().writingModeSetOnDocumentElement())
         return false;
     if (style->unique() || (style->styleType() != NOPSEUDO && parentStyle->unique()))
         return false;
     if (style->hasAppearance())
         return false;
     if (style->zoom() != RenderStyle::initialZoom())
         return false;
     if (style->writingMode() != RenderStyle::initialWritingMode())
         return false;
     if (style->hasCurrentColor())
         return false;
     // CSSPropertyInternalCallback sets the rule's selector name into the RenderStyle, and that's not recalculated if the RenderStyle is loaded from the cache, so don't cache it.
     if (!style->callbackSelectors().isEmpty())
         return false;
     // The cache assumes static knowledge about which properties are inherited.
     if (parentStyle->hasExplicitlyInheritedProperties())
         return false;
     return true;
 }
 
+void MatchedPropertiesCache::trace(Visitor* visitor)
+{
+    visitor->trace(m_cache);
 }
+
+}