Oilpan: clear out AsyncCallChainMaps in an orderly manner.

Source/core/inspector/AsyncCallStackTracker.cpp

Index: Source/core/inspector/AsyncCallStackTracker.cpp
diff --git a/Source/core/inspector/AsyncCallStackTracker.cpp b/Source/core/inspector/AsyncCallStackTracker.cpp
index f899e041ec14d62c1432c7bfbab0c78c3a105b8c..34c9129487a2c2b94ad2970528aeb2bf2369295d 100644
--- a/Source/core/inspector/AsyncCallStackTracker.cpp
+++ b/Source/core/inspector/AsyncCallStackTracker.cpp
@@ -63,22 +63,29 @@ class AsyncCallStackTracker::AsyncCallChainMap final {
     ALLOW_ONLY_INLINE_ALLOCATION();
 public:
     using MapType = WillBeHeapHashMap<K, RefPtrWillBeMember<AsyncCallStackTracker::AsyncCallChain>>;
-    explicit AsyncCallChainMap(AsyncCallStackTracker* tracker) : m_tracker(tracker) { }
+    explicit AsyncCallChainMap(AsyncCallStackTracker* tracker)
+        : m_tracker(tracker)
+    {
+    }
 
     ~AsyncCallChainMap()
     {
-        clear();
+        // Verify that this object has been explicitly cleared already.
+        ASSERT(!m_tracker);
     }
 
     void clear()

[aandrey, 2014/12/12 08:40:52]

nit: clear -> dispose

[sof, 2014/12/12 09:16:33]

done.

     {
-        for (auto it : m_asyncCallChains) {
-            if (AsyncCallStackTracker::Listener* listener = m_tracker->m_listener)
+        if (!m_tracker)

[aandrey, 2014/12/12 08:40:52]

once a clear() is called, the object is unusable. so clear() should not be
called twice.

[sof, 2014/12/12 09:16:33]

Done.

+            return;
+
+        if (AsyncCallStackTracker::Listener* listener = m_tracker->m_listener) {
+            for (auto it : m_asyncCallChains) {
                 listener->didRemoveAsyncCallChain(it.value.get());

[aandrey, 2014/12/12 08:40:52]

please revert, as a didRemoveAsyncCallChain() may destruct a
m_tracker->m_listener object

[sof, 2014/12/12 09:16:33]

Done.

-            else
-                break;
+            }
         }
         m_asyncCallChains.clear();
+        m_tracker = nullptr;
     }
 
     void set(typename MapType::KeyPeekInType key, PassRefPtrWillBeRawPtr<AsyncCallChain> chain)
@@ -98,6 +105,7 @@ public:
 
     void remove(typename MapType::KeyPeekInType key)
     {
+        ASSERT(m_tracker);
         RefPtrWillBeRawPtr<AsyncCallStackTracker::AsyncCallChain> chain = m_asyncCallChains.take(key);
         if (chain && m_tracker->m_listener)
             m_tracker->m_listener->didRemoveAsyncCallChain(chain.get());
@@ -105,11 +113,12 @@ public:
 
     void trace(Visitor* visitor)
     {
+        visitor->trace(m_tracker);
         visitor->trace(m_asyncCallChains);
     }
 
 private:
-    AsyncCallStackTracker* m_tracker;
+    RawPtrWillBeMember<AsyncCallStackTracker> m_tracker;
     MapType m_asyncCallChains;
 };
 
@@ -137,6 +146,7 @@ public:
         OwnPtrWillBeRawPtr<ExecutionContextData> self = m_tracker->m_executionContextDataMap.take(executionContext());
         ASSERT_UNUSED(self, self == this);
         ContextLifecycleObserver::contextDestroyed();
+        dispose();
     }
 
     int nextAsyncOperationUniqueId()
@@ -164,6 +174,18 @@ public:
 #endif
     }
 
+    void dispose()
+    {
+        m_timerCallChains.clear();
+        m_animationFrameCallChains.clear();
+        m_eventCallChains.clear();
+        m_xhrCallChains.clear();
+        m_mutationObserverCallChains.clear();
+        m_executionContextTaskCallChains.clear();
+        m_v8AsyncTaskCallChains.clear();
+        m_asyncOperationCallChains.clear();
+    }
+
     RawPtrWillBeMember<AsyncCallStackTracker> m_tracker;
     HashSet<int> m_intervalTimerIds;
     AsyncCallChainMap<int> m_timerCallChains;
@@ -598,6 +620,9 @@ void AsyncCallStackTracker::clear()
 {
     m_currentAsyncCallChain.clear();
     m_nestedAsyncCallCount = 0;
+    for (auto& it : m_executionContextDataMap) {

[aandrey, 2014/12/12 08:40:52]

nit: no need for {  }

[sof, 2014/12/12 09:16:33]

done.

+        it.value->dispose();
+    }
     m_executionContextDataMap.clear();
 }