Oilpan: Remove guardRef and guardDeref from TreeScope.

Source/core/dom/Document.cpp

Index: Source/core/dom/Document.cpp
diff --git a/Source/core/dom/Document.cpp b/Source/core/dom/Document.cpp
index eabfa0cdc08e437d17625bca4eb61938e1ce847d..abb7bfdd92be9cd1e27587f2df81f5f25a0f7ea6 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -71,6 +71,7 @@
 #include "core/dom/Element.h"
 #include "core/dom/ElementDataCache.h"
 #include "core/dom/ElementTraversal.h"
+#include "core/dom/EventHandlerRegistry.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/dom/ExecutionContextTask.h"
 #include "core/dom/MainThreadTaskRunner.h"
@@ -378,7 +379,9 @@ DocumentVisibilityObserver::DocumentVisibilityObserver(Document& document)
 
 DocumentVisibilityObserver::~DocumentVisibilityObserver()
 {
+#if !ENABLE(OILPAN)
     unregisterObserver();
+#endif
 }
 
 void DocumentVisibilityObserver::unregisterObserver()
@@ -522,8 +525,14 @@ Document::~Document()
     ASSERT(!renderView());
     ASSERT(m_ranges.isEmpty());
     ASSERT(!parentTreeScope());
+#if !ENABLE(OILPAN)
     ASSERT(!hasGuardRefCount());
+    // With Oilpan, either the document outlives the visibility observers
+    // or the visibility observers and the document die in the same GC round.
+    // When they die in the same GC round, the list of visibility observers
+    // will not be empty on Document destruction.
     ASSERT(m_visibilityObservers.isEmpty());
+#endif
 
     if (m_templateDocument)
         m_templateDocument->m_templateDocumentHost = 0; // balanced in ensureTemplateDocument().
@@ -544,8 +553,10 @@ Document::~Document()
     if (this == topDocument())
         clearAXObjectCache();
 
+#if !ENABLE(OILPAN)
     if (m_styleSheetList)
         m_styleSheetList->detachFromDocument();
+#endif
 
     if (m_importsController) {
         m_importsController->wasDetachedFrom(*this);
@@ -1425,8 +1436,8 @@ void Document::didChangeVisibilityState()
     dispatchEvent(Event::create(EventTypeNames::webkitvisibilitychange));
 
     PageVisibilityState state = pageVisibilityState();
-    HashSet<DocumentVisibilityObserver*>::const_iterator observerEnd = m_visibilityObservers.end();
-    for (HashSet<DocumentVisibilityObserver*>::const_iterator it = m_visibilityObservers.begin(); it != observerEnd; ++it)
+    DocumentVisibilityObserverSet::const_iterator observerEnd = m_visibilityObservers.end();
+    for (DocumentVisibilityObserverSet::const_iterator it = m_visibilityObservers.begin(); it != observerEnd; ++it)
         (*it)->didChangeVisibilityState(state);
 }
 
@@ -4820,7 +4831,7 @@ void Document::detachRange(Range* range)
     m_ranges.remove(range);
 }
 
-void Document::getCSSCanvasContext(const String& type, const String& name, int width, int height, bool& is2d, RefPtr<CanvasRenderingContext2D>& context2d, bool& is3d, RefPtr<WebGLRenderingContext>& context3d)
+void Document::getCSSCanvasContext(const String& type, const String& name, int width, int height, bool& is2d, RefPtrWillBeRawPtr<CanvasRenderingContext2D>& context2d, bool& is3d, RefPtrWillBeRawPtr<WebGLRenderingContext>& context3d)
 {
     HTMLCanvasElement& element = getCSSCanvasElement(name);
     element.setSize(IntSize(width, height));
@@ -5023,10 +5034,33 @@ void Document::decrementLoadEventDelayCount()
     ASSERT(m_loadEventDelayCount);
     --m_loadEventDelayCount;
 
-    if (frame() && !m_loadEventDelayCount && !m_loadEventDelayTimer.isActive())
+    if (!m_loadEventDelayCount)
+        checkLoadEventSoon();
+}
+
+void Document::checkLoadEventSoon()
+{
+    if (frame() && !m_loadEventDelayTimer.isActive())
         m_loadEventDelayTimer.startOneShot(0, FROM_HERE);
 }
 
+bool Document::isDelayingLoadEvent()
+{
+#if ENABLE(OILPAN)
+    // Always delay load events until after garbage collection.
+    // This way we don't have to explicitly delay load events via
+    // incrementLoadEventDelayCount and decrementLoadEventDelayCount in
+    // Node destructors.
+    if (ThreadState::current()->isSweepInProgress()) {
+        if (!m_loadEventDelayCount)
+            checkLoadEventSoon();
+        return true;
+    }
+#endif
+    return m_loadEventDelayCount;
+}
+
+
 void Document::loadEventDelayTimerFired(Timer<Document>*)
 {
     if (frame())
@@ -5580,9 +5614,40 @@ void Document::invalidateNodeListCaches(const QualifiedName* attrName)
         (*it)->invalidateCacheForAttribute(attrName);
 }
 
+void Document::clearWeakMembers(Visitor* visitor)
+{
+    if (m_axObjectCache)
+        m_axObjectCache->clearWeakMembers(visitor);
+
+    if (m_markers)
+        m_markers->clearWeakMembers(visitor);
+
+    // FIXME: Oilpan: Use a weak counted set instead.
+    if (m_touchEventTargets) {
+        Vector<Node*> deadNodes;
+        for (TouchEventTargetSet::iterator it = m_touchEventTargets->begin(); it != m_touchEventTargets->end(); ++it) {
+            if (!visitor->isAlive(it->key))
+                deadNodes.append(it->key);
+        }
+        for (unsigned i = 0; i < deadNodes.size(); ++i)
+            didClearTouchEventHandlers(deadNodes[i]);
+    }
+
+    EventHandlerRegistry* registry = static_cast<EventHandlerRegistry*>(DocumentSupplement::from(this, EventHandlerRegistry::supplementName()));
+    // FIXME: Oilpan: This is pretty funky. The current code disables all modifications of the
+    // EventHandlerRegistry when the document becomes inactive. To keep that behavior we only
+    // perform weak processing of the registry when the document is active.

[haraken, 2014/04/25 14:30:32]

Just to confirm: Even if we don't have the isActive() check, there is no
problem. We just don't need to clear weak members for inactive documents. In
that sense, the isActive() check is a slight performance optimization. Right?

[Mads Ager (chromium), 2014/04/28 09:45:21]

Without the isActive check this will crash for the following reason: the weak
processing uses the existing code which does *not* remove anything if the
document is not active. That means that the weak processing will not remove the
dead element from the set. That will then be a problem on the next round of weak
processing that will access the already dead element to figure out if it is
alive or not. So, for now we keep the same guarding here to keep the same
behavior as before without introducing crashes in weak processing.

+    if (registry && isActive())
+        registry->clearWeakMembers(visitor);

[haraken, 2014/04/25 14:30:32]

EventHandlerRegistry is a supplement object of Document. So instead of
dispatching EventHandlerRegistry::clearWeakMembers() from Document, you can just
register the EventHandlerRegistry::clearWeakMembers() in EventHandlerRegistry.

[Mads Ager (chromium), 2014/04/28 09:45:21]

I can't at this point because the EventHandlerRegistry is not in the oilpan
heap. Ian is working on moving all the supplements to the oilpan heap. Once that
is done this can be moved to the EventHandlerRegistry itself.

+}
+
 void Document::trace(Visitor* visitor)
 {
+    visitor->trace(m_styleSheetList);
+    visitor->trace(m_visibilityObservers);
+    visitor->registerWeakMembers<Document, &Document::clearWeakMembers>(this);
     Supplementable<Document>::trace(visitor);
+    TreeScope::trace(visitor);
     ContainerNode::trace(visitor);
 }