--- a/src/share/vm/memory/sharedHeap.hpp	Wed Jun 04 13:51:09 2008 -0700
+++ b/src/share/vm/memory/sharedHeap.hpp	Thu Jun 05 15:57:56 2008 -0700
@@ -44,6 +44,9 @@
 class SharedHeap : public CollectedHeap {
   friend class VMStructs;
 
+  friend class VM_GC_Operation;
+  friend class VM_CGC_Operation;
+
 private:
   // For claiming strong_roots tasks.
   SubTasksDone* _process_strong_tasks;
@@ -82,6 +85,14 @@
   // function.
   SharedHeap(CollectorPolicy* policy_);
 
+  // Returns true if the calling thread holds the heap lock,
+  // or the calling thread is a par gc thread and the heap_lock is held
+  // by the vm thread doing a gc operation.
+  bool heap_lock_held_for_gc();
+  // True if the heap_lock is held by the a non-gc thread invoking a gc
+  // operation.
+  bool _thread_holds_heap_lock_for_gc;
+
 public:
   static SharedHeap* heap() { return _sh; }
 
@@ -97,8 +108,8 @@
 
   void set_perm(PermGen* perm_gen) { _perm_gen = perm_gen; }
 
-  // A helper function that fills an allocated-but-not-yet-initialized
-  // region with a garbage object.
+  // A helper function that fills a region of the heap with
+  // with a single object.
   static void fill_region_with_object(MemRegion mr);
 
   // Minimum garbage fill object size
@@ -214,13 +225,12 @@
   // "SharedHeap" can use in the implementation of its virtual
   // functions.
 
-protected:
+public:
 
   // Do anything common to GC's.
   virtual void gc_prologue(bool full) = 0;
   virtual void gc_epilogue(bool full) = 0;
 
-public:
   //
   // New methods from CollectedHeap
   //
@@ -266,7 +276,8 @@
   }
 
   // Some utilities.
-  void print_size_transition(size_t bytes_before,
+  void print_size_transition(outputStream* out,
+                             size_t bytes_before,
                              size_t bytes_after,
                              size_t capacity);
 };