Allow collection of DOM objects in minor GC cycles.

include/v8.h

 // Copyright 2012 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
@@ skipping 384 matching lines @@
 
   /**
    * Marks the reference to this object independent. Garbage collector
    * is free to ignore any object groups containing this object.
    * Weak callback for an independent handle should not
    * assume that it will be preceded by a global GC prologue callback
    * or followed by a global GC epilogue callback.
    */
   inline void MarkIndependent();
 
+  /**
+     Marks the reference to this object externally unreachable.
+     Scavenger GC treats this object unreachable if all objects
+     in the object group which this object belongs to are neither
+     strongly reachable nor weakly reachable. This mark is cleared
+     after each scavenger GC.  If this object is not in the new
+     space, this API has no effect.
+   */

[Michael Starzinger, 2012/10/26 14:16:48]

Nit of the day: can we add asterisks to the beginning of each comment line?

[haraken, 2012/10/30 08:51:17]

Done.

+  inline void MarkExternallyUnreachable();
+
   /** Returns true if this handle was previously marked as independent. */
   inline bool IsIndependent() const;
 
   /** Checks if the handle holds the only reference to an object. */
   inline bool IsNearDeath() const;
 
   /** Returns true if the handle's reference is weak.  */
   inline bool IsWeak() const;
 
   /**
@@ skipping 3071 matching lines @@
  private:
   V8();
 
   static internal::Object** GlobalizeReference(internal::Object** handle);
   static void DisposeGlobal(internal::Object** global_handle);
   static void MakeWeak(internal::Object** global_handle,
                        void* data,
                        WeakReferenceCallback);
   static void ClearWeak(internal::Object** global_handle);
   static void MarkIndependent(internal::Object** global_handle);
+  static void MarkExternallyUnreachable(internal::Object** global_handle);
   static bool IsGlobalIndependent(internal::Object** global_handle);
   static bool IsGlobalNearDeath(internal::Object** global_handle);
   static bool IsGlobalWeak(internal::Object** global_handle);
   static void SetWrapperClassId(internal::Object** global_handle,
                                 uint16_t class_id);
   static uint16_t GetWrapperClassId(internal::Object** global_handle);
 
   template <class T> friend class Handle;
   template <class T> friend class Local;
   template <class T> friend class Persistent;
@@ skipping 751 matching lines @@
 void Persistent<T>::ClearWeak() {
   V8::ClearWeak(reinterpret_cast<internal::Object**>(**this));
 }
 
 template <class T>
 void Persistent<T>::MarkIndependent() {
   V8::MarkIndependent(reinterpret_cast<internal::Object**>(**this));
 }
 
 template <class T>
+void Persistent<T>::MarkExternallyUnreachable() {
+  V8::MarkExternallyUnreachable(reinterpret_cast<internal::Object**>(**this));
+}
+
+template <class T>
 void Persistent<T>::SetWrapperClassId(uint16_t class_id) {
   V8::SetWrapperClassId(reinterpret_cast<internal::Object**>(**this), class_id);
 }
 
 template <class T>
 uint16_t Persistent<T>::WrapperClassId() const {
   return V8::GetWrapperClassId(reinterpret_cast<internal::Object**>(**this));
 }
 
 Arguments::Arguments(internal::Object** implicit_args,
@@ skipping 419 matching lines @@
 
 
 }  // namespace v8
 
 
 #undef V8EXPORT
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_