/*

 * Copyright 1997-2007 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 {

  //

  // In line closure decls

  //

  class FollowRootClosure: public OopsInGenClosure{

   public:

    void do_oop(oop* p) { follow_root(p); }

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

  };

  class MarkAndPushClosure: public OopClosure {

   public:

    void do_oop(oop* p) { mark_and_push(p); }

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

  };

  class FollowStackClosure: public VoidClosure {

   public:

    void do_void() { follow_stack(); }

  };

  class AdjustPointerClosure: public OopsInGenClosure {

    bool _is_root;

   public:

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

    void do_oop(oop* p) { _adjust_pointer(p, _is_root); }

  };

  // Used for java/lang/ref handling

  class IsAliveClosure: public BoolObjectClosure {

   public:

    void do_object(oop p) { assert(false, "don't call"); }

    bool do_object_b(oop p) { return p->is_gc_marked(); }

  };

  class KeepAliveClosure: public OopClosure {

   public:

    void do_oop(oop* 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<oop*>*            _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<oop*>*            _other_refs_stack;

  static GrowableArray<oop*>*            _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);

  static void follow_root(oop* p);        // Mark pointer and follow contents. Empty marking

                                          // stack afterwards.

  static void mark_and_follow(oop* p);    // Mark pointer and follow contents.

  static void _mark_and_push(oop* p);     // Mark pointer and push obj on

                                          // marking stack.

  static void mark_and_push(oop* p) {     // Check mark and maybe push on

                                          // marking stack

    // assert(Universe::is_reserved_heap((oop)p), "we should only be traversing objects here");

    oop m = *p;

    if (m != NULL && !m->mark()->is_marked()) {

      _mark_and_push(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

  static void _adjust_pointer(oop* p, bool isroot);

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

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

#ifdef VALIDATE_MARK_SWEEP

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

  static void check_adjust_pointer(oop* p);     // Adjust this pointer

  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);

  }

};