[WIP]Oilpan: checking for nearly-dead observers.

Source/core/dom/ContextLifecycleNotifier.cpp

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  * Copyright (C) 2013 Google Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 21 matching lines @@
 #include "wtf/TemporaryChange.h"
 
 namespace blink {
 
 void ContextLifecycleNotifier::notifyResumingActiveDOMObjects()
 {
     TemporaryChange<IterationType> scope(m_iterating, IteratingOverAll);
     Vector<ContextLifecycleObserver*> snapshotOfObservers;
     copyToVector(m_observers, snapshotOfObservers);
     for (ContextLifecycleObserver* observer : snapshotOfObservers) {
+#if !ENABLE(OILPAN)
+        if (!isObserverAlive(observer))
+            continue;
+#endif
         // FIXME: Oilpan: At the moment, it's possible that a ActiveDOMObject

[haraken, 2015/05/09 14:50:33]

Not related to this CL, I think this FIXME is valid only in non-oilpan. In
oilpan, the observers are guaranteed to be kept alive during the iteration.

         // observer is destructed while iterating. Once we enable Oilpan by default
         // for all LifecycleObserver<T>s, we can remove the hack by making m_observers
         // a HeapHashSet<WeakMember<LifecycleObserver<T>>>.
         // (i.e., we can just iterate m_observers without taking a snapshot).
         // For more details, see https://codereview.chromium.org/247253002/.
         if (m_observers.contains(observer)) {
             if (observer->observerType() != ContextLifecycleObserver::ActiveDOMObjectType)
                 continue;
             ActiveDOMObject* activeDOMObject = static_cast<ActiveDOMObject*>(observer);
             ASSERT(activeDOMObject->executionContext() == context());
             ASSERT(activeDOMObject->suspendIfNeededCalled());
             activeDOMObject->resume();
         }
     }
 }
 
 void ContextLifecycleNotifier::notifySuspendingActiveDOMObjects()
 {
     TemporaryChange<IterationType> scope(m_iterating, IteratingOverAll);
     Vector<ContextLifecycleObserver*> snapshotOfObservers;
     copyToVector(m_observers, snapshotOfObservers);
     for (ContextLifecycleObserver* observer : snapshotOfObservers) {
+#if !ENABLE(OILPAN)
+        if (!isObserverAlive(observer))
+            continue;
+#endif
         // It's possible that the ActiveDOMObject is already destructed.
         // See a FIXME above.
         if (m_observers.contains(observer)) {
             if (observer->observerType() != ContextLifecycleObserver::ActiveDOMObjectType)
                 continue;
             ActiveDOMObject* activeDOMObject = static_cast<ActiveDOMObject*>(observer);
             ASSERT(activeDOMObject->executionContext() == context());
             ASSERT(activeDOMObject->suspendIfNeededCalled());
             activeDOMObject->suspend();
         }
     }
 }
 
 void ContextLifecycleNotifier::notifyStoppingActiveDOMObjects()
 {
     TemporaryChange<IterationType> scope(m_iterating, IteratingOverAll);
     Vector<ContextLifecycleObserver*> snapshotOfObservers;
     copyToVector(m_observers, snapshotOfObservers);
     for (ContextLifecycleObserver* observer : snapshotOfObservers) {
+#if !ENABLE(OILPAN)
+        if (!isObserverAlive(observer))
+            continue;
+#endif
         // It's possible that the ActiveDOMObject is already destructed.
         // See a FIXME above.
         if (m_observers.contains(observer)) {
             if (observer->observerType() != ContextLifecycleObserver::ActiveDOMObjectType)
                 continue;
             ActiveDOMObject* activeDOMObject = static_cast<ActiveDOMObject*>(observer);
             ASSERT(activeDOMObject->executionContext() == context());
             ASSERT(activeDOMObject->suspendIfNeededCalled());
             activeDOMObject->stop();
         }
     }
 }
 
 unsigned ContextLifecycleNotifier::activeDOMObjectCount() const
 {
     unsigned activeDOMObjects = 0;
     for (ContextLifecycleObserver* observer : m_observers) {
+#if !ENABLE(OILPAN)
+        if (!isObserverAlive(observer))
+            continue;
+#endif
         if (observer->observerType() != ContextLifecycleObserver::ActiveDOMObjectType)
             continue;
         activeDOMObjects++;
     }
     return activeDOMObjects;
 }
 
 bool ContextLifecycleNotifier::hasPendingActivity() const
 {
     for (ContextLifecycleObserver* observer : m_observers) {
+#if !ENABLE(OILPAN)
+        if (!isObserverAlive(observer))
+            continue;
+#endif
         if (observer->observerType() != ContextLifecycleObserver::ActiveDOMObjectType)
             continue;
         ActiveDOMObject* activeDOMObject = static_cast<ActiveDOMObject*>(observer);
         if (activeDOMObject->hasPendingActivity())
             return true;
     }
     return false;
 }
 
 #if ENABLE(ASSERT)
 bool ContextLifecycleNotifier::contains(ActiveDOMObject* object) const
 {
     for (ContextLifecycleObserver* observer : m_observers) {
+#if !ENABLE(OILPAN)
+        if (!isObserverAlive(observer))
+            continue;
+#endif
         if (observer->observerType() != ContextLifecycleObserver::ActiveDOMObjectType)
             continue;
         ActiveDOMObject* activeDOMObject = static_cast<ActiveDOMObject*>(observer);
         if (activeDOMObject == object)
             return true;
     }
     return false;
 }
 #endif
 
 } // namespace blink