[oilpan]: optimize the way we allocate persistent handles in wrappers.

Source/platform/heap/ThreadState.h

 /*
  * 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 38 matching lines @@
 namespace blink {
 
 class BaseHeap;
 class BaseHeapPage;
 class FinalizedHeapObjectHeader;
 struct GCInfo;
 class HeapContainsCache;
 class HeapObjectHeader;
 class PageMemory;
 class PersistentNode;
+class WrapperPersistentRegion;
 class Visitor;
 class SafePointBarrier;
 class SafePointAwareMutexLocker;
 template<typename Header> class ThreadHeap;
 class CallbackStack;
 
 typedef uint8_t* Address;
 
 typedef void (*FinalizationCallback)(void*);
 typedef void (*VisitorCallback)(Visitor*, void* self);
@@ skipping 452 matching lines @@
     BaseHeap* heap(int index) const { return m_heaps[index]; }
 
     // Infrastructure to determine if an address is within one of the
     // address ranges for the Blink heap. If the address is in the Blink
     // heap the containing heap page is returned.
     HeapContainsCache* heapContainsCache() { return m_heapContainsCache.get(); }
     BaseHeapPage* contains(Address address) { return heapPageFromAddress(address); }
     BaseHeapPage* contains(void* pointer) { return contains(reinterpret_cast<Address>(pointer)); }
     BaseHeapPage* contains(const void* pointer) { return contains(const_cast<void*>(pointer)); }
 
+    WrapperPersistentRegion* wrapperRoots() const
+    {
+        ASSERT(m_wrapperPersistents);
+        return m_wrapperPersistents;
+    }
+    WrapperPersistentRegion* addWrapperPersistentRegion();
+    void removeWrapperPersistentRegion(WrapperPersistentRegion*);
+
     // List of persistent roots allocated on the given thread.
     PersistentNode* roots() const { return m_persistents.get(); }
 
     // List of global persistent roots not owned by any particular thread.
     // globalRootsMutex must be acquired before any modifications.
     static PersistentNode* globalRoots();
     static Mutex& globalRootsMutex();
 
     // Visit local thread stack and trace all pointers conservatively.
     void visitStack(Visitor*);
@@ skipping 104 matching lines @@
     // We can't create a static member of type ThreadState here
     // because it will introduce global constructor and destructor.
     // We would like to manage lifetime of the ThreadState attached
     // to the main thread explicitly instead and still use normal
     // constructor and destructor for the ThreadState class.
     // For this we reserve static storage for the main ThreadState
     // and lazily construct ThreadState in it using placement new.
     static uint8_t s_mainThreadStateStorage[];
 
     ThreadIdentifier m_thread;
+    WrapperPersistentRegion* m_wrapperPersistents;

[haraken, 2014/09/02 05:22:06]

m_wrapperPersistents => m_usedWrapperPersistents
m_wrapperPersistentRegionPool => m_pooledWrapperPersistents

?

[wibling-chromium, 2014/09/02 11:19:38]

Done. Changed them to

m_liveWrapperPersistents
m_pooledWrapperPersistents

+    WrapperPersistentRegion* m_wrapperPersistentRegionPool;

[haraken, 2014/09/02 05:22:06]

WrapperPersistentRegion is owned by either m_wrapperPersistents or
m_wrapperPersistentRegionPool. Can we use Deque<OwnPtr<WrapperPersistentRegion>>
and avoid implementing insertHead, removeHead etc?

[wibling-chromium, 2014/09/02 11:19:38]

I would prefer to keep it a double-linked list to make internal removal fast.
Ie. there is a good chance for a region to be removed while in the middle of the
list via the removeIfNotLast method.

+    size_t m_wrapperPersistentRegionPoolSize;
     OwnPtr<PersistentNode> m_persistents;
     StackState m_stackState;
     intptr_t* m_startOfStack;
     intptr_t* m_endOfStack;
     void* m_safePointScopeMarker;
     Vector<Address> m_safePointStackCopy;
     bool m_atSafePoint;
     Vector<Interruptor*> m_interruptors;
     bool m_gcRequested;
     bool m_forcePreciseGCForTesting;
@@ skipping 142 matching lines @@
     // HeapPage header. We use some of the bits to determine
     // whether the page is part of a terminting thread or
     // if the page is traced after being terminated (orphaned).
     uintptr_t m_terminating : 1;
     uintptr_t m_tracedAfterOrphaned : 1;
 };
 
 }
 
 #endif // ThreadState_h