/*

 * Copyright (c) 2018, Red Hat, Inc. All rights reserved.

 *

 * 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#ifndef SHARE_GC_SHENANDOAH_SHENANDOAHHEURISTICS_HPP

#define SHARE_GC_SHENANDOAH_SHENANDOAHHEURISTICS_HPP

#include "gc/shenandoah/shenandoahHeap.hpp"

#include "gc/shenandoah/shenandoahPhaseTimings.hpp"

#include "gc/shenandoah/shenandoahSharedVariables.hpp"

#include "memory/allocation.hpp"

#include "runtime/globals_extension.hpp"

#define SHENANDOAH_ERGO_DISABLE_FLAG(name)                                  \

  do {                                                                      \

    if (FLAG_IS_DEFAULT(name) && (name)) {                                  \

      log_info(gc)("Heuristics ergonomically sets -XX:-" #name);            \

      FLAG_SET_DEFAULT(name, false);                                        \

    }                                                                       \

  } while (0)

#define SHENANDOAH_ERGO_ENABLE_FLAG(name)                                   \

  do {                                                                      \

    if (FLAG_IS_DEFAULT(name) && !(name)) {                                 \

      log_info(gc)("Heuristics ergonomically sets -XX:+" #name);            \

      FLAG_SET_DEFAULT(name, true);                                         \

    }                                                                       \

  } while (0)

#define SHENANDOAH_ERGO_OVERRIDE_DEFAULT(name, value)                       \

  do {                                                                      \

    if (FLAG_IS_DEFAULT(name)) {                                            \

      log_info(gc)("Heuristics ergonomically sets -XX:" #name "=" #value);  \

      FLAG_SET_DEFAULT(name, value);                                        \

    }                                                                       \

  } while (0)

#define SHENANDOAH_CHECK_FLAG_SET(name)                                     \

  do {                                                                      \

    if (!name) {                                                            \

      err_msg message("Heuristics needs -XX:+" #name " to work correctly"); \

      vm_exit_during_initialization("Error", message);                      \

    }                                                                       \

  } while (0)

class ShenandoahCollectionSet;

class ShenandoahHeapRegion;

class ShenandoahHeuristics : public CHeapObj<mtGC> {

  static const intx Concurrent_Adjust   =  1; // recover from penalties

  static const intx Degenerated_Penalty = 10; // how much to penalize average GC duration history on Degenerated GC

  static const intx Full_Penalty        = 20; // how much to penalize average GC duration history on Full GC

protected:

  typedef struct {

    ShenandoahHeapRegion* _region;

    size_t _garbage;

    uint64_t _seqnum_last_alloc;

  } RegionData;

  bool _update_refs_early;

  bool _update_refs_adaptive;

  RegionData* _region_data;

  size_t _region_data_size;

  uint _degenerated_cycles_in_a_row;

  uint _successful_cycles_in_a_row;

  size_t _bytes_in_cset;

  double _cycle_start;

  double _last_cycle_end;

  size_t _gc_times_learned;

  size_t _gc_time_penalties;

  TruncatedSeq* _gc_time_history;

  // There may be many threads that contend to set this flag

  ShenandoahSharedFlag _metaspace_oom;

  static int compare_by_garbage(RegionData a, RegionData b);

  static int compare_by_garbage_then_alloc_seq_ascending(RegionData a, RegionData b);

  static int compare_by_alloc_seq_ascending(RegionData a, RegionData b);

  static int compare_by_alloc_seq_descending(RegionData a, RegionData b);

  RegionData* get_region_data_cache(size_t num);

  virtual void choose_collection_set_from_regiondata(ShenandoahCollectionSet* set,

                                                     RegionData* data, size_t data_size,

                                                     size_t free) = 0;

public:

  ShenandoahHeuristics();

  virtual ~ShenandoahHeuristics();

  void record_gc_start();

  void record_gc_end();

  void record_metaspace_oom()     { _metaspace_oom.set(); }

  void clear_metaspace_oom()      { _metaspace_oom.unset(); }

  bool has_metaspace_oom() const  { return _metaspace_oom.is_set(); }

  virtual void record_cycle_start();

  virtual void record_cycle_end();

  virtual void record_phase_time(ShenandoahPhaseTimings::Phase phase, double secs);

  virtual bool should_start_gc() const;

  virtual bool should_start_update_refs();

  virtual bool should_degenerate_cycle();

  virtual void record_success_concurrent();

  virtual void record_success_degenerated();

  virtual void record_success_full();

  virtual void record_allocation_failure_gc();

  virtual void record_requested_gc();

  virtual void choose_collection_set(ShenandoahCollectionSet* collection_set);

  virtual bool can_process_references();

  virtual bool should_process_references();

  virtual bool can_unload_classes();

  virtual bool can_unload_classes_normal();

  virtual bool should_unload_classes();

  virtual const char* name() = 0;

  virtual bool is_diagnostic() = 0;

  virtual bool is_experimental() = 0;

  virtual void initialize();

  double time_since_last_gc() const;

};

#endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEURISTICS_HPP