introduce eternal handles

src/global-handles.h

Index: src/global-handles.h
diff --git a/src/global-handles.h b/src/global-handles.h
index cd75133a24367092ec07e87bd9fc451a8a9e9d64..cff6f933577a54de807c7676d7981f1d4536741e 100644
--- a/src/global-handles.h
+++ b/src/global-handles.h
@@ -331,6 +331,55 @@ class GlobalHandles {
 };
 
 
+class EternalHandles {
+ public:
+  static const int kInvalidIndex = -1;

[Michael Starzinger, 2013/08/01 13:26:11]

Instead of exposing the kInvalidIndex constant, can we have an additional
Exists(SingletonHandle) method instead? Then make this constant private.

+  enum IndexedHandle {

[Michael Starzinger, 2013/08/01 13:26:11]

There is a slight name collision going on here I think. IIUC, every eternal
handle will get an "index" when being created. This enum here describes
well-known eternal handles, and for each enum constant you can have exactly one
eternal handle that has some arbitrary index. So I would suggest the following
renaming to make things easier to understand:

s/IndexedHandle/SingletonHandle/
s/indexed_handles_/singleton_handles/
s/CreateIndexed/CreateSingleton/

The GetIndex() method would rename unchanged as it gives back the "index" of a
singleton-handle.

+    I18N_TEMPLATE_ONE,
+    I18N_TEMPLATE_TWO,
+
+    LAST_INDEX = I18N_TEMPLATE_TWO

[Michael Starzinger, 2013/08/01 13:26:11]

nit: Let's call this NUMBER_OF_SINGLETON_HANDLES instead and drop the explicit
assignment.

+  };
+
+  EternalHandles();
+  ~EternalHandles();
+
+  int NumberOfHandles() { return size_; }
+
+  int Create(Isolate* isolate, Object* object);
+
+  inline Object** Get(int index) {

[Michael Starzinger, 2013/08/01 13:26:11]

The publicly visible Get() method should return Handle<Object> instead. Of
course there can be a private GetSlot() that returns the handle location.

+    ASSERT(index >= 0 && index < size_);
+    return &blocks_[index >> kShift][index & kMask];
+  }
+
+  inline int GetIndex(IndexedHandle i) {
+    return indexed_handles_[i];
+  }
+
+  int CreateIndexed(Isolate* isolate, Object* object, IndexedHandle i) {
+    ASSERT(GetIndex(i) == kInvalidIndex);
+    indexed_handles_[i] = Create(isolate, object);
+    return indexed_handles_[i];
+  }
+
+  void IterateAllRoots(ObjectVisitor* visitor);
+  void IterateNewSpaceRoots(ObjectVisitor* visitor);
+  void PostGarbageCollectionProcessing(Heap* heap);
+
+ private:
+  static const int kShift = 8;
+  static const int kSize = 1 << kShift;
+  static const int kMask = 0xff;
+  int size_;

[Michael Starzinger, 2013/08/01 13:26:11]

nit: Let's add an empty newline after the constants.

+  List<Object**> blocks_;
+  List<int> new_space_indices_;
+  int indexed_handles_[LAST_INDEX+1];
+
+  DISALLOW_COPY_AND_ASSIGN(EternalHandles);
+};
+
+
 } }  // namespace v8::internal
 
 #endif  // V8_GLOBAL_HANDLES_H_