/*

 * Copyright 2001-2007 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.

 *

 */

// TenuredGeneration models the heap containing old (promoted/tenured) objects.

class ParGCAllocBufferWithBOT;

class TenuredGeneration: public OneContigSpaceCardGeneration {

  friend class VMStructs;

 protected:

  // current shrinking effect: this damps shrinking when the heap gets empty.

  size_t _shrink_factor;

  // Some statistics from before gc started.

  // These are gathered in the gc_prologue (and should_collect)

  // to control growing/shrinking policy in spite of promotions.

  size_t _capacity_at_prologue;

  size_t _used_at_prologue;

#ifndef SERIALGC

  // To support parallel promotion: an array of parallel allocation

  // buffers, one per thread, initially NULL.

  ParGCAllocBufferWithBOT** _alloc_buffers;

#endif // SERIALGC

  // Retire all alloc buffers before a full GC, so that they will be

  // re-allocated at the start of the next young GC.

  void retire_alloc_buffers_before_full_gc();

  GenerationCounters*   _gen_counters;

  CSpaceCounters*       _space_counters;

 public:

  TenuredGeneration(ReservedSpace rs, size_t initial_byte_size, int level,

                    GenRemSet* remset);

  Generation::Name kind() { return Generation::MarkSweepCompact; }

  // Printing

  const char* name() const;

  const char* short_name() const { return "Tenured"; }

  bool must_be_youngest() const { return false; }

  bool must_be_oldest() const { return true; }

  // Does a "full" (forced) collection invoked on this generation collect

  // all younger generations as well? Note that this is a

  // hack to allow the collection of the younger gen first if the flag is

  // set. This is better than using th policy's should_collect_gen0_first()

  // since that causes us to do an extra unnecessary pair of restart-&-stop-world.

  virtual bool full_collects_younger_generations() const {

    return !CollectGen0First;

  }

  // Mark sweep support

  void compute_new_size();

  int allowed_dead_ratio() const;

  virtual void gc_prologue(bool full);

  virtual void gc_epilogue(bool full);

  bool should_collect(bool   full,

                      size_t word_size,

                      bool   is_tlab);

  virtual void collect(bool full,

                       bool clear_all_soft_refs,

                       size_t size,

                       bool is_tlab);

#ifndef SERIALGC

  // Overrides.

  virtual oop par_promote(int thread_num,

                          oop obj, markOop m, size_t word_sz);

  virtual void par_promote_alloc_undo(int thread_num,

                                      HeapWord* obj, size_t word_sz);

  virtual void par_promote_alloc_done(int thread_num);

#endif // SERIALGC

  // Performance Counter support

  void update_counters();

  // Statistics

  virtual void update_gc_stats(int level, bool full);

  virtual bool promotion_attempt_is_safe(size_t max_promoted_in_bytes,

    bool younger_handles_promotion_failure) const;

  void verify_alloc_buffers_clean();

};