src/share/vm/gc_implementation/g1/satbQueue.hpp

rev 7327 : 8075215: SATB buffer processing found reclaimed humongous object
Summary: Don't assume SATB buffer entries are valid objects
Reviewed-by: brutisso, ecaspole

*** 23,55 ****
   */
  
  #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_SATBQUEUE_HPP
  #define SHARE_VM_GC_IMPLEMENTATION_G1_SATBQUEUE_HPP
  
  #include "gc_implementation/g1/ptrQueue.hpp"
  
- class ObjectClosure;
  class JavaThread;
  class SATBMarkQueueSet;
  
  // A ptrQueue whose elements are "oops", pointers to object heads.
  class ObjPtrQueue: public PtrQueue {
-   friend class Threads;
    friend class SATBMarkQueueSet;
-   friend class G1RemarkThreadsClosure;
  
  private:
    // Filter out unwanted entries from the buffer.
    void filter();
  
-   // Apply the closure to all elements and empty the buffer;
-   void apply_closure_and_empty(ObjectClosure* cl);
- 
-   // Apply the closure to all elements of "buf", down to "index" (inclusive.)
-   static void apply_closure_to_buffer(ObjectClosure* cl,
-                                       void** buf, size_t index, size_t sz);
- 
  public:
    ObjPtrQueue(PtrQueueSet* qset, bool perm = false) :
      // SATB queues are only active during marking cycles. We create
      // them with their active field set to false. If a thread is
      // created during a cycle and its SATB queue needs to be activated
--- 23,56 ----
   */
  
  #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_SATBQUEUE_HPP
  #define SHARE_VM_GC_IMPLEMENTATION_G1_SATBQUEUE_HPP
  
+ #include "memory/allocation.hpp"
  #include "gc_implementation/g1/ptrQueue.hpp"
  
  class JavaThread;
  class SATBMarkQueueSet;
  
+ // Base class for processing the contents of a SATB buffer.
+ class SATBBufferClosure : public StackObj {
+ protected:
+   ~SATBBufferClosure() { }
+ 
+ public:
+   // Process the SATB entries in the designated buffer range.
+   virtual void do_buffer(void** buffer, size_t size) = 0;
+ };
+ 
  // A ptrQueue whose elements are "oops", pointers to object heads.
  class ObjPtrQueue: public PtrQueue {
    friend class SATBMarkQueueSet;
  
  private:
    // Filter out unwanted entries from the buffer.
    void filter();
  
  public:
    ObjPtrQueue(PtrQueueSet* qset, bool perm = false) :
      // SATB queues are only active during marking cycles. We create
      // them with their active field set to false. If a thread is
      // created during a cycle and its SATB queue needs to be activated
*** 58,67 ****
--- 59,72 ----
      PtrQueue(qset, perm, false /* active */) { }
  
    // Process queue entries and free resources.
    void flush();
  
+   // Apply cl to the active part of the buffer.
+   // Prerequisite: Must be at a safepoint.
+   void apply_closure_and_empty(SATBBufferClosure* cl);
+ 
    // Overrides PtrQueue::should_enqueue_buffer(). See the method's
    // definition for more information.
    virtual bool should_enqueue_buffer();
  
  #ifndef PRODUCT
*** 95,108 ****
    void set_active_all_threads(bool active, bool expected_active);
  
    // Filter all the currently-active SATB buffers.
    void filter_thread_buffers();
  
!   // If there exists some completed buffer, pop it, then apply the
!   // closure to all its elements, and return true.  If no
!   // completed buffers exist, return false.
!   bool apply_closure_to_completed_buffer(ObjectClosure* closure);
  
  #ifndef PRODUCT
    // Helpful for debugging
    void print_all(const char* msg);
  #endif // PRODUCT
--- 100,115 ----
    void set_active_all_threads(bool active, bool expected_active);
  
    // Filter all the currently-active SATB buffers.
    void filter_thread_buffers();
  
!   // If there exists some completed buffer, pop and process it, and
!   // return true.  Otherwise return false.  Processing a buffer
!   // consists of applying the closure to the buffer range starting
!   // with the first non-NULL entry to the end of the buffer; the
!   // leading entries may be NULL due to filtering.
!   bool apply_closure_to_completed_buffer(SATBBufferClosure* cl);
  
  #ifndef PRODUCT
    // Helpful for debugging
    void print_all(const char* msg);
  #endif // PRODUCT