/*

 * Copyright (c) 2002, 2015, Oracle and/or its affiliates. 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 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_VM_GC_PARALLEL_PSADAPTIVESIZEPOLICY_HPP

#define SHARE_VM_GC_PARALLEL_PSADAPTIVESIZEPOLICY_HPP

#include "gc/shared/adaptiveSizePolicy.hpp"

#include "gc/shared/gcCause.hpp"

#include "gc/shared/gcStats.hpp"

#include "gc/shared/gcUtil.hpp"

// This class keeps statistical information and computes the

// optimal free space for both the young and old generation

// based on current application characteristics (based on gc cost

// and application footprint).

//

// It also computes an optimal tenuring threshold between the young

// and old generations, so as to equalize the cost of collections

// of those generations, as well as optimal survivor space sizes

// for the young generation.

//

// While this class is specifically intended for a generational system

// consisting of a young gen (containing an Eden and two semi-spaces)

// and a tenured gen, as well as a perm gen for reflective data, it

// makes NO references to specific generations.

//

// 05/02/2003 Update

// The 1.5 policy makes use of data gathered for the costs of GC on

// specific generations.  That data does reference specific

// generation.  Also diagnostics specific to generations have

// been added.

// Forward decls

class elapsedTimer;

class PSAdaptiveSizePolicy : public AdaptiveSizePolicy {

 friend class PSGCAdaptivePolicyCounters;

 private:

  // These values are used to record decisions made during the

  // policy.  For example, if the young generation was decreased

  // to decrease the GC cost of minor collections the value

  // decrease_young_gen_for_throughput_true is used.

  // Last calculated sizes, in bytes, and aligned

  // NEEDS_CLEANUP should use sizes.hpp,  but it works in ints, not size_t's

  // Time statistics

  AdaptivePaddedAverage* _avg_major_pause;

  // Footprint statistics

  AdaptiveWeightedAverage* _avg_base_footprint;

  // Statistical data gathered for GC

  GCStats _gc_stats;

  size_t _survivor_size_limit;   // Limit in bytes of survivor size

  const double _collection_cost_margin_fraction;

  // Variable for estimating the major and minor pause times.

  // These variables represent linear least-squares fits of

  // the data.

  //   major pause time vs. old gen size

  LinearLeastSquareFit* _major_pause_old_estimator;

  //   major pause time vs. young gen size

  LinearLeastSquareFit* _major_pause_young_estimator;

  // These record the most recent collection times.  They

  // are available as an alternative to using the averages

  // for making ergonomic decisions.

  double _latest_major_mutator_interval_seconds;

  const size_t _space_alignment; // alignment for eden, survivors

  const double _gc_minor_pause_goal_sec;    // goal for maximum minor gc pause

  // The amount of live data in the heap at the last full GC, used

  // as a baseline to help us determine when we need to perform the

  // next full GC.

  size_t _live_at_last_full_gc;

  // decrease/increase the old generation for minor pause time

  int _change_old_gen_for_min_pauses;

  // increase/decrease the young generation for major pause time

  int _change_young_gen_for_maj_pauses;

  // Flag indicating that the adaptive policy is ready to use

  bool _old_gen_policy_is_ready;

  // Changing the generation sizing depends on the data that is

  // gathered about the effects of changes on the pause times and

  // throughput.  These variable count the number of data points

  // gathered.  The policy may use these counters as a threshold

  // for reliable data.

  julong _young_gen_change_for_major_pause_count;

  // To facilitate faster growth at start up, supplement the normal

  // growth percentage for the young gen eden and the

  // old gen space for promotion with these value which decay

  // with increasing collections.

  uint _young_gen_size_increment_supplement;

  uint _old_gen_size_increment_supplement;

  // The number of bytes absorbed from eden into the old gen by moving the

  // boundary over live data.

  size_t _bytes_absorbed_from_eden;

 private:

  // Accessors

  AdaptivePaddedAverage* avg_major_pause() const { return _avg_major_pause; }

  double gc_minor_pause_goal_sec() const { return _gc_minor_pause_goal_sec; }

  void adjust_eden_for_minor_pause_time(bool is_full_gc,

                                   size_t* desired_eden_size_ptr);

  // Change the generation sizes to achieve a GC pause time goal

  // Returned sizes are not necessarily aligned.

  void adjust_promo_for_pause_time(bool is_full_gc,

                         size_t* desired_promo_size_ptr,

                         size_t* desired_eden_size_ptr);

  void adjust_eden_for_pause_time(bool is_full_gc,

                         size_t* desired_promo_size_ptr,

                         size_t* desired_eden_size_ptr);

  // Change the generation sizes to achieve an application throughput goal

  // Returned sizes are not necessarily aligned.

  void adjust_promo_for_throughput(bool is_full_gc,

                             size_t* desired_promo_size_ptr);

  void adjust_eden_for_throughput(bool is_full_gc,

                             size_t* desired_eden_size_ptr);

  // Change the generation sizes to achieve minimum footprint

  // Returned sizes are not aligned.

  size_t adjust_promo_for_footprint(size_t desired_promo_size,

                                    size_t desired_total);

  size_t adjust_eden_for_footprint(size_t desired_promo_size,

                                   size_t desired_total);

  // Size in bytes for an increment or decrement of eden.

  virtual size_t eden_increment(size_t cur_eden, uint percent_change);

  virtual size_t eden_decrement(size_t cur_eden);

  size_t eden_decrement_aligned_down(size_t cur_eden);

  size_t eden_increment_with_supplement_aligned_up(size_t cur_eden);

  // Size in bytes for an increment or decrement of the promotion area

  virtual size_t promo_increment(size_t cur_promo, uint percent_change);

  virtual size_t promo_decrement(size_t cur_promo);

  size_t promo_decrement_aligned_down(size_t cur_promo);

  size_t promo_increment_with_supplement_aligned_up(size_t cur_promo);

  // Returns a change that has been scaled down.  Result

  // is not aligned.  (If useful, move to some shared

  // location.)

  size_t scale_down(size_t change, double part, double total);

 protected:

  // Time accessors

  // Footprint accessors

  size_t live_space() const {

    return (size_t)(avg_base_footprint()->average() +

                    avg_young_live()->average() +

                    avg_old_live()->average());

  }

  size_t free_space() const {

    return _eden_size + _promo_size;

  }

  void set_promo_size(size_t new_size) {

    _promo_size = new_size;

  }

  void set_survivor_size(size_t new_size) {

    _survivor_size = new_size;

  }

  // Update estimators

  void update_minor_pause_old_estimator(double minor_pause_in_ms);

  virtual GCPolicyKind kind() const { return _gc_ps_adaptive_size_policy; }

 public:

  // Use by ASPSYoungGen and ASPSOldGen to limit boundary moving.

  size_t eden_increment_aligned_up(size_t cur_eden);

  size_t eden_increment_aligned_down(size_t cur_eden);

  size_t promo_increment_aligned_up(size_t cur_promo);

  size_t promo_increment_aligned_down(size_t cur_promo);

  virtual size_t eden_increment(size_t cur_eden);

  virtual size_t promo_increment(size_t cur_promo);

  // Accessors for use by performance counters

  AdaptivePaddedNoZeroDevAverage*  avg_promoted() const {

    return _gc_stats.avg_promoted();

  }

  AdaptiveWeightedAverage* avg_base_footprint() const {

    return _avg_base_footprint;

  }

  // Input arguments are initial free space sizes for young and old

  // generations, the initial survivor space size, the

  // alignment values and the pause & throughput goals.

  //

  // NEEDS_CLEANUP this is a singleton object

  PSAdaptiveSizePolicy(size_t init_eden_size,

                       size_t init_promo_size,

                       size_t init_survivor_size,

                       size_t space_alignment,

                       double gc_pause_goal_sec,

                       double gc_minor_pause_goal_sec,

                       uint gc_time_ratio);

  // Methods indicating events of interest to the adaptive size policy,

  // called by GC algorithms. It is the responsibility of users of this

  // policy to call these methods at the correct times!

  void major_collection_begin();

  void major_collection_end(size_t amount_live, GCCause::Cause gc_cause);

  void tenured_allocation(size_t size) {

    _avg_pretenured->sample(size);

  }

  // Accessors

  // NEEDS_CLEANUP   should use sizes.hpp

  static size_t calculate_free_based_on_live(size_t live, uintx ratio_as_percentage);

  size_t calculated_old_free_size_in_bytes() const;

  size_t average_old_live_in_bytes() const {

    return (size_t) avg_old_live()->average();

  }

  size_t average_promoted_in_bytes() const {

    return (size_t)avg_promoted()->average();

  }

  size_t padded_average_promoted_in_bytes() const {

    return (size_t)avg_promoted()->padded_average();

  }

  int change_young_gen_for_maj_pauses() {

    return _change_young_gen_for_maj_pauses;

  }

  void set_change_young_gen_for_maj_pauses(int v) {

    _change_young_gen_for_maj_pauses = v;

  }

  int change_old_gen_for_min_pauses() {

    return _change_old_gen_for_min_pauses;

  }

  void set_change_old_gen_for_min_pauses(int v) {

    _change_old_gen_for_min_pauses = v;

  }

  // Return true if the old generation size was changed

  // to try to reach a pause time goal.

  bool old_gen_changed_for_pauses() {

    bool result = _change_old_gen_for_maj_pauses != 0 ||

                  _change_old_gen_for_min_pauses != 0;

    return result;

  }

  // Return true if the young generation size was changed

  // to try to reach a pause time goal.

  bool young_gen_changed_for_pauses() {

    bool result = _change_young_gen_for_min_pauses != 0 ||

                  _change_young_gen_for_maj_pauses != 0;

    return result;

  }

  // end flags for pause goal

  // Return true if the old generation size was changed

  // to try to reach a throughput goal.

  bool old_gen_changed_for_throughput() {

    bool result = _change_old_gen_for_throughput != 0;

    return result;

  }

  // Return true if the young generation size was changed

  // to try to reach a throughput goal.

  bool young_gen_changed_for_throughput() {

    bool result = _change_young_gen_for_throughput != 0;

    return result;

  }

  int decrease_for_footprint() { return _decrease_for_footprint; }

  // Accessors for estimators.  The slope of the linear fit is

  // currently all that is used for making decisions.

  LinearLeastSquareFit* major_pause_old_estimator() {

    return _major_pause_old_estimator;

  }

  LinearLeastSquareFit* major_pause_young_estimator() {

    return _major_pause_young_estimator;

  }

  virtual void clear_generation_free_space_flags();

  float major_pause_old_slope() { return _major_pause_old_estimator->slope(); }

  float major_pause_young_slope() {

    return _major_pause_young_estimator->slope();

  }

  float major_collection_slope() { return _major_collection_estimator->slope();}

  bool old_gen_policy_is_ready() { return _old_gen_policy_is_ready; }

  // Given the amount of live data in the heap, should we

  // perform a Full GC?

  bool should_full_GC(size_t live_in_old_gen);

  // Calculates optimal (free) space sizes for both the young and old

  // generations.  Stores results in _eden_size and _promo_size.

  // Takes current used space in all generations as input, as well

  // as an indication if a full gc has just been performed, for use

  // in deciding if an OOM error should be thrown.

  void compute_generations_free_space(size_t young_live,

                                      size_t eden_live,

                                      size_t old_live,

                                      size_t cur_eden,  // current eden in bytes

                                      size_t max_old_gen_size,

                                      size_t max_eden_size,

                                      bool   is_full_gc);

  void compute_eden_space_size(size_t young_live,

                               size_t eden_live,

                               size_t cur_eden,  // current eden in bytes

                               size_t max_eden_size,

                               bool   is_full_gc);

  void compute_old_gen_free_space(size_t old_live,

                                             size_t cur_eden,  // current eden in bytes

                                             size_t max_old_gen_size,

                                             bool   is_full_gc);

  // Calculates new survivor space size;  returns a new tenuring threshold

  // value. Stores new survivor size in _survivor_size.

  uint compute_survivor_space_size_and_threshold(bool   is_survivor_overflow,

                                                 uint    tenuring_threshold,

                                                 size_t survivor_limit);

  // Return the maximum size of a survivor space if the young generation were of

  // size gen_size.

  size_t max_survivor_size(size_t gen_size) {

    // Never allow the target survivor size to grow more than MinSurvivorRatio

    // of the young generation size.  We cannot grow into a two semi-space

    // system, with Eden zero sized.  Even if the survivor space grows, from()

    // might grow by moving the bottom boundary "down" -- so from space will

    // remain almost full anyway (top() will be near end(), but there will be a

    // large filler object at the bottom).

    const size_t sz = gen_size / MinSurvivorRatio;

    const size_t alignment = _space_alignment;

    return sz > alignment ? align_size_down(sz, alignment) : alignment;

  }

  size_t live_at_last_full_gc() {

    return _live_at_last_full_gc;

  }

  size_t bytes_absorbed_from_eden() const { return _bytes_absorbed_from_eden; }

  void   reset_bytes_absorbed_from_eden() { _bytes_absorbed_from_eden = 0; }

  void set_bytes_absorbed_from_eden(size_t val) {

    _bytes_absorbed_from_eden = val;

  }

  // Update averages that are always used (even

  // if adaptive sizing is turned off).

  void update_averages(bool is_survivor_overflow,

                       size_t survived,

                       size_t promoted);

  // Printing support

  virtual bool print() const;

  // Decay the supplemental growth additive.

  void decay_supplemental_growth(bool is_full_gc);

};

#endif // SHARE_VM_GC_PARALLEL_PSADAPTIVESIZEPOLICY_HPP