Oilpan: DOM wrappers don't need to keep persistent handles

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 0f9ad60c7a86af4e5bbdbb5d69f936234ae0bcf6..0b9fc38ef4610ca7c3bd1544e5056499b11e0673 100644
--- a/Source/platform/heap/ThreadState.cpp
+++ b/Source/platform/heap/ThreadState.cpp
@@ -110,10 +110,6 @@ static void* getStackStart()
 #endif
 }
 
-// The maximum number of WrapperPersistentRegions to keep around in the
-// m_pooledWrapperPersistentRegions pool.
-static const size_t MaxPooledWrapperPersistentRegionCount = 2;
-
 WTF::ThreadSpecific<ThreadState*>* ThreadState::s_threadSpecific = 0;
 uint8_t ThreadState::s_mainThreadStateStorage[sizeof(ThreadState)];
 SafePointBarrier* ThreadState::s_safePointBarrier = 0;
@@ -299,9 +295,6 @@ template<> struct InitializeHeaps<0> {
 
 ThreadState::ThreadState()
     : m_thread(currentThread())
-    , m_liveWrapperPersistents(new WrapperPersistentRegion())
-    , m_pooledWrapperPersistents(0)
-    , m_pooledWrapperPersistentRegionCount(0)
     , m_persistents(adoptPtr(new PersistentAnchor()))
     , m_startOfStack(reinterpret_cast<intptr_t*>(getStackStart()))
     , m_endOfStack(reinterpret_cast<intptr_t*>(getStackStart()))
@@ -318,6 +311,7 @@ ThreadState::ThreadState()
     , m_shouldFlushHeapDoesNotContainCache(false)
     , m_lowCollectionRate(false)
     , m_numberOfSweeperTasks(0)
+    , m_traceDOMWrappers(0)

[tkent, 2014/10/15 03:48:35]

nit: We can use |nullptr|.

 #if defined(ADDRESS_SANITIZER)
     , m_asanFakeStack(__asan_get_current_fake_stack())
 #endif
@@ -341,14 +335,6 @@ ThreadState::~ThreadState()
     for (int i = 0; i < NumberOfHeaps; i++)
         delete m_heaps[i];
     deleteAllValues(m_interruptors);
-    while (m_liveWrapperPersistents) {
-        WrapperPersistentRegion* region = WrapperPersistentRegion::removeHead(&m_liveWrapperPersistents);
-        delete region;
-    }
-    while (m_pooledWrapperPersistents) {
-        WrapperPersistentRegion* region = WrapperPersistentRegion::removeHead(&m_pooledWrapperPersistents);
-        delete region;
-    }
     **s_threadSpecific = 0;
 }
 
@@ -584,9 +570,9 @@ void ThreadState::visitStack(Visitor* visitor)
 void ThreadState::visitPersistents(Visitor* visitor)
 {
     m_persistents->trace(visitor);
-    {
-        TRACE_EVENT0("blink_gc", "WrapperPersistentRegion::trace");
-        WrapperPersistentRegion::trace(m_liveWrapperPersistents, visitor);
+    if (m_traceDOMWrappers) {
+        TRACE_EVENT0("blink_gc", "V8GCController::traceDOMWrappers");

[sof, 2014/10/12 20:40:43]

Push this down into V8GCController::traceDOMrappers() ?

+        m_traceDOMWrappers(visitor);
     }
 }
 
@@ -695,34 +681,6 @@ bool ThreadState::popAndInvokeWeakPointerCallback(Visitor* visitor)
     return false;
 }
 
-WrapperPersistentRegion* ThreadState::takeWrapperPersistentRegion()
-{
-    WrapperPersistentRegion* region;
-    if (m_pooledWrapperPersistentRegionCount) {
-        region = WrapperPersistentRegion::removeHead(&m_pooledWrapperPersistents);
-        m_pooledWrapperPersistentRegionCount--;
-    } else {
-        region = new WrapperPersistentRegion();
-    }
-    ASSERT(region);
-    WrapperPersistentRegion::insertHead(&m_liveWrapperPersistents, region);
-    return region;
-}
-
-void ThreadState::freeWrapperPersistentRegion(WrapperPersistentRegion* region)
-{
-    if (!region->removeIfNotLast(&m_liveWrapperPersistents))
-        return;
-
-    // Region was removed, ie. it was not the last region in the list.
-    if (m_pooledWrapperPersistentRegionCount < MaxPooledWrapperPersistentRegionCount) {
-        WrapperPersistentRegion::insertHead(&m_pooledWrapperPersistents, region);
-        m_pooledWrapperPersistentRegionCount++;
-    } else {
-        delete region;
-    }
-}
-
 PersistentNode* ThreadState::globalRoots()
 {
     AtomicallyInitializedStatic(PersistentNode*, anchor = new PersistentAnchor);