diff --git a/src/global-handles.h b/src/global-handles.h
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+// Copyright 2007-2008 the V8 project authors. 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
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef V8_GLOBAL_HANDLES_H_
+#define V8_GLOBAL_HANDLES_H_
+
+#include "list-inl.h"
+
+namespace v8 {
+namespace internal {
+
+// Structure for tracking global handles.
+// A single list keeps all the allocated global handles.
+// Destroyed handles stay in the list but is added to the free list.
+// At GC the destroyed global handles are removed from the free list
+// and deallocated.
+
+// Callback function on handling weak global handles.
+// typedef bool (*WeakSlotCallback)(Object** pointer);
+
+// An object group is treated like a single JS object: if one of object in
+// the group is alive, all objects in the same group are considered alive.
+// An object group is used to simulate object relationship in a DOM tree.
+class ObjectGroup : public Malloced {
+ public:
+  ObjectGroup() : objects_(4) {}
+  explicit ObjectGroup(size_t capacity) : objects_(capacity) {}
+
+  List<Object**> objects_;
+};
+
+
+class GlobalHandles : public AllStatic {
+ public:
+  // Creates a new global handle that is alive until Destroy is called.
+  static Handle<Object> Create(Object* value);
+
+  // Destroy a global handle.
+  static void Destroy(Object** location);
+
+  // Make the global handle weak and set the callback parameter for the
+  // handle.  When the garbage collector recognizes that only weak global
+  // handles point to an object the handles are cleared and the callback
+  // function is invoked (for each handle) with the handle and corresponding
+  // parameter as arguments.  Note: cleared means set to Smi::FromInt(0). The
+  // reason is that Smi::FromInt(0) does not change during garage collection.
+  static void MakeWeak(Object** location,
+                       void* parameter,
+                       WeakReferenceCallback callback);
+
+  // Returns the current number of weak handles.
+  static int NumberOfWeakHandles() { return number_of_weak_handles_; }
+
+  // Returns the current number of weak handles to global objects.
+  // These handles are also included in NumberOfWeakHandles().
+  static int NumberOfGlobalObjectWeakHandles() {
+    return number_of_global_object_weak_handles_;
+  }
+
+  // Clear the weakness of a global handle.
+  static void ClearWeakness(Object** location);
+
+  // Tells whether global handle is near death.
+  static bool IsNearDeath(Object** location);
+
+  // Tells whether global handle is weak.
+  static bool IsWeak(Object** location);
+
+  // Process pending weak handles.
+  static void PostGarbageCollectionProcessing();
+
+  // Iterates over all handles.
+  static void IterateRoots(ObjectVisitor* v);
+
+  // Iterates over all weak roots in heap.
+  static void IterateWeakRoots(ObjectVisitor* v);
+
+  // Find all weak handles satisfying the callback predicate, mark
+  // them as pending.
+  static void IdentifyWeakHandles(WeakSlotCallback f);
+
+  // Add an object group.
+  // Should only used in GC callback function before a collection.
+  // All groups are destroyed after a mark-compact collection.
+  static void AddGroup(Object*** handles, size_t length);
+
+  // Returns the object groups.
+  static List<ObjectGroup*>* ObjectGroups();
+
+  // Remove bags, this should only happen after GC.
+  static void RemoveObjectGroups();
+
+  // Tear down the global handle structure.
+  static void TearDown();
+
+#ifdef DEBUG
+  static void PrintStats();
+  static void Print();
+#endif
+ private:
+  // Internal node structure, one for each global handle.
+  class Node;
+
+  // Field always containing the number of weak and near-death handles.
+  static int number_of_weak_handles_;
+
+  // Field always containing the number of weak and near-death handles
+  // to global objects.  These objects are also included in
+  // number_of_weak_handles_.
+  static int number_of_global_object_weak_handles_;
+
+  // Global handles are kept in a single linked list pointed to by head_.
+  static Node* head_;
+  static Node* head() { return head_; }
+  static void set_head(Node* value) { head_ = value; }
+
+  // Free list for DESTROYED global handles not yet deallocated.
+  static Node* first_free_;
+  static Node* first_free() { return first_free_; }
+  static void set_first_free(Node* value) { first_free_ = value; }
+};
+
+
+} }  // namespace v8::internal
+
+#endif  // V8_GLOBAL_HANDLES_H_