/*

 * Copyright 2002-2007 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 GCTaskManager;

class GCTaskQueue;

class OopStack;

class ReferenceProcessor;

class ParallelScavengeHeap;

class PSIsAliveClosure;

class PSRefProcTaskExecutor;

class PSScavenge: AllStatic {

  friend class PSIsAliveClosure;

  friend class PSKeepAliveClosure;

  friend class PSPromotionManager;

 enum ScavengeSkippedCause {

   not_skipped = 0,

   to_space_not_empty,

   promoted_too_large,

   full_follows_scavenge

 };

  // Saved value of to_space->top(), used to prevent objects in to_space from

  // being rescanned.

  static HeapWord* _to_space_top_before_gc;

  // Number of consecutive attempts to scavenge that were skipped

  static int                _consecutive_skipped_scavenges;

 protected:

  // Flags/counters

  static ReferenceProcessor* _ref_processor;        // Reference processor for scavenging.

  static PSIsAliveClosure    _is_alive_closure;     // Closure used for reference processing

  static CardTableExtension* _card_table;           // We cache the card table for fast access.

  static bool                _survivor_overflow;    // Overflow this collection

  static int                 _tenuring_threshold;   // tenuring threshold for next scavenge

  static elapsedTimer        _accumulated_time;     // total time spent on scavenge

  static HeapWord*           _young_generation_boundary; // The lowest address possible for the young_gen.

                                                         // This is used to decide if an oop should be scavenged,

                                                         // cards should be marked, etc.

  static GrowableArray<markOop>* _preserved_mark_stack; // List of marks to be restored after failed promotion

  static GrowableArray<oop>*     _preserved_oop_stack;  // List of oops that need their mark restored.

  static CollectorCounters*      _counters;         // collector performance counters

  static void clean_up_failed_promotion();

  static bool should_attempt_scavenge();

  static HeapWord* to_space_top_before_gc() { return _to_space_top_before_gc; }

  static inline void save_to_space_top_before_gc();

  // Private accessors

  static CardTableExtension* const card_table()       { assert(_card_table != NULL, "Sanity"); return _card_table; }

 public:

  // Accessors

  static int              tenuring_threshold()  { return _tenuring_threshold; }

  static elapsedTimer*    accumulated_time()    { return &_accumulated_time; }

  static bool             promotion_failed()

    { return _preserved_mark_stack != NULL; }

  static int              consecutive_skipped_scavenges()

    { return _consecutive_skipped_scavenges; }

  // Performance Counters

  static CollectorCounters* counters()           { return _counters; }

  // Used by scavenge_contents && psMarkSweep

  static ReferenceProcessor* const reference_processor() {

    assert(_ref_processor != NULL, "Sanity");

    return _ref_processor;

  }

  // Used to add tasks

  static GCTaskManager* const gc_task_manager();

  // The promotion managers tell us if they encountered overflow

  static void set_survivor_overflow(bool state) {

    _survivor_overflow = state;

  }

  // Adaptive size policy support.  When the young generation/old generation

  // boundary moves, _young_generation_boundary must be reset

  static void set_young_generation_boundary(HeapWord* v) {

    _young_generation_boundary = v;

  }

  // Called by parallelScavengeHeap to init the tenuring threshold

  static void initialize();

  // Scavenge entry point

  static void invoke();

  // Return true is a collection was done.  Return

  // false if the collection was skipped.

  static bool invoke_no_policy();

  // If an attempt to promote fails, this method is invoked

  static void oop_promotion_failed(oop obj, markOop obj_mark);

  static inline bool should_scavenge(oop p);

  // These call should_scavenge() above and, if it returns true, also check that

  // the object was not newly copied into to_space.  The version with the bool

  // argument is a convenience wrapper that fetches the to_space pointer from

  // the heap and calls the other version (if the arg is true).

  static inline bool should_scavenge(oop p, MutableSpace* to_space);

  static inline bool should_scavenge(oop p, bool check_to_space);

  inline static void copy_and_push_safe_barrier(PSPromotionManager* pm, oop* p);

  // Is an object in the young generation

  // This assumes that the HeapWord argument is in the heap,

  // so it only checks one side of the complete predicate.

  inline static bool is_obj_in_young(HeapWord* o) {

    const bool result = (o >= _young_generation_boundary);

    return result;

  }

};