Oilpan: catch some self-referential leaks (main thread.)

Source/platform/heap/ThreadState.cpp

Index: Source/platform/heap/ThreadState.cpp
diff --git a/Source/platform/heap/ThreadState.cpp b/Source/platform/heap/ThreadState.cpp
index b7756d3418cab62cb43047a1743b329f49086dc6..78bb414ad1345c5730bf4c97b0b79f7e319d1fa1 100644
--- a/Source/platform/heap/ThreadState.cpp
+++ b/Source/platform/heap/ThreadState.cpp
@@ -76,6 +76,9 @@ uintptr_t ThreadState::s_mainThreadStackStart = 0;
 uintptr_t ThreadState::s_mainThreadUnderestimatedStackSize = 0;
 uint8_t ThreadState::s_mainThreadStateStorage[sizeof(ThreadState)];
 SafePointBarrier* ThreadState::s_safePointBarrier = nullptr;
+#if ENABLE(ASSERT)
+int ThreadState::s_selfKeepAliveAllocationsOnMainThread = 0;
+#endif
 
 RecursiveMutex& ThreadState::threadAttachMutex()
 {
@@ -166,6 +169,9 @@ void ThreadState::attachMainThread()
     MutexLocker locker(threadAttachMutex());
     ThreadState* state = new(s_mainThreadStateStorage) ThreadState();
     attachedThreads().add(state);
+#if ENABLE(ASSERT)
+    s_selfKeepAliveAllocationsOnMainThread = 0;
+#endif
 }
 
 void ThreadState::detachMainThread()
@@ -189,6 +195,8 @@ void ThreadState::detachMainThread()
         attachedThreads().remove(state);
         state->~ThreadState();
     }
+    // Catch out any self-referential leaks created by the main thread.
+    ASSERT(s_selfKeepAliveAllocationsOnMainThread == 0);
     shutdownHeapIfNecessary();
 }
 
@@ -257,7 +265,10 @@ void ThreadState::cleanup()
         }
         // We should not have any persistents left when getting to this point,
         // if we have it is probably a bug so adding a debug ASSERT to catch this.
-        ASSERT(!currentCount);
+        // (debug tip: use persistentRegion()->dumpLivePersistents() to get a list of
+        // the remaining live Persistent<>s. In gdb, performing "info symbol" on the
+        // trace callback addresses printed should tell you what Persistent<T>s are leaking.)
+        ASSERT(!currentCount && "Persistent<>s leak on thread heap shutdown");
         // All of pre-finalizers should be consumed.
         ASSERT(m_orderedPreFinalizers.isEmpty());
         RELEASE_ASSERT(gcState() == NoGCScheduled);
@@ -1542,4 +1553,23 @@ void ThreadState::reportMarkSweepStats(const char* statsName, const ClassAgeCoun
 }
 #endif
 
+#if ENABLE(ASSERT)
+void ThreadState::incrementSelfKeepAliveAllocations()
+{
+    if (!ThreadState::current()->isMainThread())
+        return;
+
+    s_selfKeepAliveAllocationsOnMainThread++;
+}
+
+void ThreadState::decrementSelfKeepAliveAllocations()
+{
+    if (!ThreadState::current()->isMainThread())
+        return;
+
+    ASSERT(s_selfKeepAliveAllocationsOnMainThread > 0);
+    s_selfKeepAliveAllocationsOnMainThread--;
+}
+#endif
+
 } // namespace blink