Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright 1997-2008 Sun Microsystems, Inc.  All Rights Reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

  * CA 95054 USA or visit www.sun.com if you need additional information or

  * have any questions.

  *

  */

 class ReferenceProcessor;

 // MarkSweep takes care of global mark-compact garbage collection for a

 // GenCollectedHeap using a four-phase pointer forwarding algorithm.  All

 // generations are assumed to support marking; those that can also support

 // compaction.

 //

 // Class unloading will only occur when a full gc is invoked.

 // If VALIDATE_MARK_SWEEP is defined, the -XX:+ValidateMarkSweep flag will

 // be operational, and will provide slow but comprehensive self-checks within

 // the GC.  This is not enabled by default in product or release builds,

 // since the extra call to track_adjusted_pointer() in _adjust_pointer()

 // would be too much overhead, and would disturb performance measurement.

 // However, debug builds are sometimes way too slow to run GC tests!

 #ifdef ASSERT

 #define VALIDATE_MARK_SWEEP 1

 #endif

 #ifdef VALIDATE_MARK_SWEEP

 #define VALIDATE_MARK_SWEEP_ONLY(code) code

 #else

 #define VALIDATE_MARK_SWEEP_ONLY(code)

 #endif

 // declared at end

 class PreservedMark;

 class MarkSweep : AllStatic {

   //

   // Inline closure decls

   //

   class FollowRootClosure: public OopsInGenClosure {

    public:

     virtual void do_oop(oop* p);

     virtual void do_oop(narrowOop* p);

     virtual const bool do_nmethods() const { return true; }

   };

   class MarkAndPushClosure: public OopClosure {

    public:

     virtual void do_oop(oop* p);

     virtual void do_oop(narrowOop* p);

     virtual const bool do_nmethods() const { return true; }

   };

   class FollowStackClosure: public VoidClosure {

    public:

     virtual void do_void();

   };

   class AdjustPointerClosure: public OopsInGenClosure {

    private:

     bool _is_root;

    public:

     AdjustPointerClosure(bool is_root) : _is_root(is_root) {}

     virtual void do_oop(oop* p);

     virtual void do_oop(narrowOop* p);

   };

   // Used for java/lang/ref handling

   class IsAliveClosure: public BoolObjectClosure {

    public:

     virtual void do_object(oop p);

     virtual bool do_object_b(oop p);

   };

   class KeepAliveClosure: public OopClosure {

    protected:

     template <class T> void do_oop_work(T* p);

    public:

     virtual void do_oop(oop* p);

     virtual void do_oop(narrowOop* p);

   };

   //

   // Friend decls

   //

   friend class AdjustPointerClosure;

   friend class KeepAliveClosure;

   friend class VM_MarkSweep;

   friend void marksweep_init();

   //

   // Vars

   //

  protected:

   // Traversal stack used during phase1

   static GrowableArray<oop>*             _marking_stack;

   // Stack for live klasses to revisit at end of marking phase

   static GrowableArray<Klass*>*          _revisit_klass_stack;

   // Space for storing/restoring mark word

   static GrowableArray<markOop>*         _preserved_mark_stack;

   static GrowableArray<oop>*             _preserved_oop_stack;

   static size_t                          _preserved_count;

   static size_t                          _preserved_count_max;

   static PreservedMark*                  _preserved_marks;

   // Reference processing (used in ...follow_contents)

   static ReferenceProcessor*             _ref_processor;

 #ifdef VALIDATE_MARK_SWEEP

   static GrowableArray<void*>*           _root_refs_stack;

   static GrowableArray<oop> *            _live_oops;

   static GrowableArray<oop> *            _live_oops_moved_to;

   static GrowableArray<size_t>*          _live_oops_size;

   static size_t                          _live_oops_index;

   static size_t                          _live_oops_index_at_perm;

   static GrowableArray<void*>*           _other_refs_stack;

   static GrowableArray<void*>*           _adjusted_pointers;

   static bool                            _pointer_tracking;

   static bool                            _root_tracking;

   // The following arrays are saved since the time of the last GC and

   // assist in tracking down problems where someone has done an errant

   // store into the heap, usually to an oop that wasn't properly

   // handleized across a GC. If we crash or otherwise fail before the

   // next GC, we can query these arrays to find out the object we had

   // intended to do the store to (assuming it is still alive) and the

   // offset within that object. Covered under RecordMarkSweepCompaction.

   static GrowableArray<HeapWord*> *      _cur_gc_live_oops;

   static GrowableArray<HeapWord*> *      _cur_gc_live_oops_moved_to;

   static GrowableArray<size_t>*          _cur_gc_live_oops_size;

   static GrowableArray<HeapWord*> *      _last_gc_live_oops;

   static GrowableArray<HeapWord*> *      _last_gc_live_oops_moved_to;

   static GrowableArray<size_t>*          _last_gc_live_oops_size;

 #endif

   // Non public closures

   static IsAliveClosure   is_alive;

   static KeepAliveClosure keep_alive;

   // Class unloading. Update subklass/sibling/implementor links at end of marking phase.

   static void follow_weak_klass_links();

   // Debugging

   static void trace(const char* msg) PRODUCT_RETURN;

  public:

   // Public closures

   static FollowRootClosure    follow_root_closure;

   static MarkAndPushClosure   mark_and_push_closure;

   static FollowStackClosure   follow_stack_closure;

   static AdjustPointerClosure adjust_root_pointer_closure;

   static AdjustPointerClosure adjust_pointer_closure;

   // Reference Processing

   static ReferenceProcessor* const ref_processor() { return _ref_processor; }

   // Call backs for marking

   static void mark_object(oop obj);

   // Mark pointer and follow contents.  Empty marking stack afterwards.

   template <class T> static inline void follow_root(T* p);

   // Mark pointer and follow contents.

   template <class T> static inline void mark_and_follow(T* p);

   // Check mark and maybe push on marking stack

   template <class T> static inline void mark_and_push(T* p);

   static void follow_stack();   // Empty marking stack.

   static void preserve_mark(oop p, markOop mark);

                                 // Save the mark word so it can be restored later

   static void adjust_marks();   // Adjust the pointers in the preserved marks table

   static void restore_marks();  // Restore the marks that we saved in preserve_mark

   template <class T> static inline void adjust_pointer(T* p, bool isroot);

   static void adjust_root_pointer(oop* p)  { adjust_pointer(p, true); }

   static void adjust_pointer(oop* p)       { adjust_pointer(p, false); }

   static void adjust_pointer(narrowOop* p) { adjust_pointer(p, false); }

 #ifdef VALIDATE_MARK_SWEEP

   static void track_adjusted_pointer(void* p, bool isroot);

   static void check_adjust_pointer(void* p);

   static void track_interior_pointers(oop obj);

   static void check_interior_pointers();

   static void reset_live_oop_tracking(bool at_perm);

   static void register_live_oop(oop p, size_t size);

   static void validate_live_oop(oop p, size_t size);

   static void live_oop_moved_to(HeapWord* q, size_t size, HeapWord* compaction_top);

   static void compaction_complete();

   // Querying operation of RecordMarkSweepCompaction results.

   // Finds and prints the current base oop and offset for a word

   // within an oop that was live during the last GC. Helpful for

   // tracking down heap stomps.

   static void print_new_location_of_heap_address(HeapWord* q);

 #endif

   // Call backs for class unloading

   static void revisit_weak_klass_link(Klass* k);  // Update subklass/sibling/implementor links at end of marking.

 };

 class PreservedMark VALUE_OBJ_CLASS_SPEC {

 private:

   oop _obj;

   markOop _mark;

 public:

   void init(oop obj, markOop mark) {

     _obj = obj;

     _mark = mark;

   }

   void adjust_pointer() {

     MarkSweep::adjust_pointer(&_obj);

   }

   void restore() {

     _obj->set_mark(_mark);

   }

 };