Make GlobalHandle::NodeBlock deletable

src/global-handles.h

Index: src/global-handles.h
diff --git a/src/global-handles.h b/src/global-handles.h
index cd75133a24367092ec07e87bd9fc451a8a9e9d64..deb04e7c3e94813c2db7a20c724e18b894f4665a 100644
--- a/src/global-handles.h
+++ b/src/global-handles.h
@@ -156,6 +156,8 @@ class GlobalHandles {
     return number_of_global_handles_;
   }
 
+  int block_count() const { return number_of_blocks_; }

[Michael Starzinger, 2013/08/01 12:29:02]

nit: Let's add a short one-liner comment to the accessor as well.

+
   // Clear the weakness of a global handle.
   static void ClearWeakness(Object** location);
 
@@ -275,11 +277,14 @@ class GlobalHandles {
 #ifdef DEBUG
   void PrintStats();
   void Print();
+  void VerifyBlockInvariants();
 #endif
 
  private:
   explicit GlobalHandles(Isolate* isolate);
 
+  void SortBlocks(bool shouldPrune);
+
   // Migrates data from the internal representation (object_group_connections_,
   // retainer_infos_ and implicit_ref_connections_) to the public and more
   // efficient representation (object_groups_ and implicit_ref_groups_).
@@ -296,17 +301,19 @@ class GlobalHandles {
 
   Isolate* isolate_;
 
+  // Field always containing the number of blocks allocated.
+  int number_of_blocks_;
   // Field always containing the number of handles to global objects.
   int number_of_global_handles_;
 
-  // List of all allocated node blocks.
+  // Ends of a doubly-linked list of blocks
+  // which is sorted from fullest to emptiest during GC.
   NodeBlock* first_block_;
+  NodeBlock* last_block_;
 
-  // List of node blocks with used nodes.
-  NodeBlock* first_used_block_;
-
-  // Free list of nodes.
-  Node* first_free_;
+  // All blocks before this one will always be full
+  // and none after this will be full.
+  NodeBlock* first_non_full_block_;
 
   // Contains all nodes holding new space objects. Note: when the list
   // is accessed, some of the objects may have been promoted already.