Lazy peer API.

runtime/vm/heap.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_HEAP_H_
 #define VM_HEAP_H_
 
 #include "platform/assert.h"
 #include "vm/allocation.h"
 #include "vm/flags.h"
 #include "vm/globals.h"
 #include "vm/pages.h"
 #include "vm/scavenger.h"
 
 namespace dart {
 
 // Forward declarations.
 class Isolate;
+class Object;

[siva, 2012/09/14 00:03:46]

Why is this forward declaration needed? I don't see any reference to Object in
thew new code.

[cshapiro, 2012/09/15 01:23:41]

This forward reference for Object is noise.  Removed.

 class ObjectPointerVisitor;
 class ObjectSet;
 class VirtualMemory;
 
 DECLARE_FLAG(bool, verbose_gc);
 DECLARE_FLAG(bool, verify_before_gc);
 DECLARE_FLAG(bool, verify_after_gc);
 DECLARE_FLAG(bool, gc_at_alloc);
 
 class Heap {
@@ skipping 120 matching lines @@
   // Returns the [lowest, highest) addresses in the heap.
   void StartEndAddress(uword* start, uword* end) const;
 
   ObjectSet* CreateAllocatedObjectSet() const;
 
   // Generates a profile of the current and VM isolate heaps.
   void Profile(Dart_HeapProfileWriteCallback callback, void* stream) const;
 
   static const char* GCReasonToString(GCReason gc_reason);
 
+  // Associates a peer with an object.  If an object has a peer, it is
+  // replaced.  A value of NULL disassociate an object from its peer.
+  void SetPeer(RawObject* raw_obj, void* peer);
+
+  // Retrieves the peer associated with an object.  Returns NULL if
+  // there is no association.
+  void* GetPeer(RawObject* raw_obj);
+
+  // Returns the number of objects with a peer.
+  int64_t PeerCount() const;
+
  private:
   Heap();
 
   uword AllocateNew(intptr_t size);
   uword AllocateOld(intptr_t size);
   uword AllocateCode(PageSpace* space, intptr_t size);
 
   // The different spaces used for allocation.
   Scavenger* new_space_;
   PageSpace* old_space_;
@@ skipping 20 matching lines @@
  public:
   NoGCScope() {}
  private:
   DISALLOW_COPY_AND_ASSIGN(NoGCScope);
 };
 #endif  // defined(DEBUG)
 
 }  // namespace dart
 
 #endif  // VM_HEAP_H_