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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 *

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 * 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.

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#ifndef SHARE_VM_GC_G1_G1COLLECTORPOLICY_HPP

#define SHARE_VM_GC_G1_G1COLLECTORPOLICY_HPP

#include "gc/g1/g1CollectorState.hpp"

#include "gc/g1/g1GCPhaseTimes.hpp"

#include "gc/g1/g1InCSetState.hpp"

#include "gc/g1/g1InitialMarkToMixedTimeTracker.hpp"

#include "gc/g1/g1MMUTracker.hpp"

#include "gc/g1/g1Predictions.hpp"

#include "gc/shared/collectorPolicy.hpp"

#include "utilities/pair.hpp"

// A G1CollectorPolicy makes policy decisions that determine the

// characteristics of the collector.  Examples include:

//   * choice of collection set.

//   * when to collect.

class HeapRegion;

class G1CollectionSet;

class CollectionSetChooser;

class G1IHOPControl;

class G1Analytics;

class G1YoungGenSizer;

class G1CollectorPolicy: public CollectorPolicy {

 private:

  G1IHOPControl* _ihop_control;

  G1IHOPControl* create_ihop_control() const;

  // Update the IHOP control with necessary statistics.

  void update_ihop_prediction(double mutator_time_s,

                              size_t mutator_alloc_bytes,

                              size_t young_gen_size);

  void report_ihop_statistics();

  G1Predictions _predictor;

  G1Analytics* _analytics;

  G1MMUTracker* _mmu_tracker;

  void initialize_alignments();

  void initialize_flags();

  double _full_collection_start_sec;

  // Ratio check data for determining if heap growth is necessary.

  uint _ratio_over_threshold_count;

  double _ratio_over_threshold_sum;

  uint _pauses_since_start;

  uint _young_list_target_length;

  uint _young_list_fixed_length;

  // The max number of regions we can extend the eden by while the GC

  // locker is active. This should be >= _young_list_target_length;

  uint _young_list_max_length;

  SurvRateGroup* _short_lived_surv_rate_group;

  SurvRateGroup* _survivor_surv_rate_group;

  double _gc_overhead_perc;

  double _reserve_factor;

  uint   _reserve_regions;

  enum PredictionConstants {

    NumPrevPausesForHeuristics = 10,

    // MinOverThresholdForGrowth must be less than NumPrevPausesForHeuristics,

    // representing the minimum number of pause time ratios that exceed

    // GCTimeRatio before a heap expansion will be triggered.

    MinOverThresholdForGrowth = 4

  };

  G1YoungGenSizer* _young_gen_sizer;

  uint _free_regions_at_end_of_collection;

  size_t _max_rs_lengths;

  size_t _rs_lengths_prediction;

#ifndef PRODUCT

  bool verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group);

#endif // PRODUCT

  void adjust_concurrent_refinement(double update_rs_time,

                                    double update_rs_processed_buffers,

                                    double goal_ms);

  double _pause_time_target_ms;

  size_t _pending_cards;

  // The amount of allocated bytes in old gen during the last mutator and the following

  // young GC phase.

  size_t _bytes_allocated_in_old_since_last_gc;

  G1InitialMarkToMixedTimeTracker _initial_mark_to_mixed;

public:

  const G1Predictions& predictor() const { return _predictor; }

  const G1Analytics* analytics()   const { return const_cast<const G1Analytics*>(_analytics); }

  // Add the given number of bytes to the total number of allocated bytes in the old gen.

  void add_bytes_allocated_in_old_since_last_gc(size_t bytes) { _bytes_allocated_in_old_since_last_gc += bytes; }

  // Accessors

  void set_region_eden(HeapRegion* hr, int young_index_in_cset) {

    hr->set_eden();

    hr->install_surv_rate_group(_short_lived_surv_rate_group);

    hr->set_young_index_in_cset(young_index_in_cset);

  }

  void set_region_survivor(HeapRegion* hr, int young_index_in_cset) {

    assert(hr->is_survivor(), "pre-condition");

    hr->install_surv_rate_group(_survivor_surv_rate_group);

    hr->set_young_index_in_cset(young_index_in_cset);

  }

#ifndef PRODUCT

  bool verify_young_ages();

#endif // PRODUCT

  void record_max_rs_lengths(size_t rs_lengths) {

    _max_rs_lengths = rs_lengths;

  }

  double predict_base_elapsed_time_ms(size_t pending_cards) const;

  double predict_base_elapsed_time_ms(size_t pending_cards,

                                      size_t scanned_cards) const;

  size_t predict_bytes_to_copy(HeapRegion* hr) const;

  double predict_region_elapsed_time_ms(HeapRegion* hr, bool for_young_gc) const;

  double predict_survivor_regions_evac_time() const;

  bool should_update_surv_rate_group_predictors() {

    return collector_state()->last_gc_was_young() && !collector_state()->in_marking_window();

  }

  void cset_regions_freed() {

    bool update = should_update_surv_rate_group_predictors();

    _short_lived_surv_rate_group->all_surviving_words_recorded(update);

    _survivor_surv_rate_group->all_surviving_words_recorded(update);

  }

  G1MMUTracker* mmu_tracker() {

    return _mmu_tracker;

  }

  const G1MMUTracker* mmu_tracker() const {

    return _mmu_tracker;

  }

  double max_pause_time_ms() const {

    return _mmu_tracker->max_gc_time() * 1000.0;

  }

  // Returns an estimate of the survival rate of the region at yg-age

  // "yg_age".

  double predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) const;

  double predict_yg_surv_rate(int age) const;

  double accum_yg_surv_rate_pred(int age) const;

protected:

  G1CollectionSet* _collection_set;

  virtual double average_time_ms(G1GCPhaseTimes::GCParPhases phase) const;

  virtual double other_time_ms(double pause_time_ms) const;

  double young_other_time_ms() const;

  double non_young_other_time_ms() const;

  double constant_other_time_ms(double pause_time_ms) const;

  CollectionSetChooser* cset_chooser() const;

private:

  // The number of bytes copied during the GC.

  size_t _bytes_copied_during_gc;

  // Stash a pointer to the g1 heap.

  G1CollectedHeap* _g1;

  G1GCPhaseTimes* _phase_times;

  // This set of variables tracks the collector efficiency, in order to

  // determine whether we should initiate a new marking.

  double _mark_remark_start_sec;

  double _mark_cleanup_start_sec;

  // Updates the internal young list maximum and target lengths. Returns the

  // unbounded young list target length.

  uint update_young_list_max_and_target_length();

  uint update_young_list_max_and_target_length(size_t rs_lengths);

  // Update the young list target length either by setting it to the

  // desired fixed value or by calculating it using G1's pause

  // prediction model. If no rs_lengths parameter is passed, predict

  // the RS lengths using the prediction model, otherwise use the

  // given rs_lengths as the prediction.

  // Returns the unbounded young list target length.

  uint update_young_list_target_length(size_t rs_lengths);

  // Calculate and return the minimum desired young list target

  // length. This is the minimum desired young list length according

  // to the user's inputs.

  uint calculate_young_list_desired_min_length(uint base_min_length) const;

  // Calculate and return the maximum desired young list target

  // length. This is the maximum desired young list length according

  // to the user's inputs.

  uint calculate_young_list_desired_max_length() const;

  // Calculate and return the maximum young list target length that

  // can fit into the pause time goal. The parameters are: rs_lengths

  // represent the prediction of how large the young RSet lengths will

  // be, base_min_length is the already existing number of regions in

  // the young list, min_length and max_length are the desired min and

  // max young list length according to the user's inputs.

  uint calculate_young_list_target_length(size_t rs_lengths,

                                          uint base_min_length,

                                          uint desired_min_length,

                                          uint desired_max_length) const;

  // Result of the bounded_young_list_target_length() method, containing both the

  // bounded as well as the unbounded young list target lengths in this order.

  typedef Pair<uint, uint, StackObj> YoungTargetLengths;

  YoungTargetLengths young_list_target_lengths(size_t rs_lengths) const;

  void update_rs_lengths_prediction();

  void update_rs_lengths_prediction(size_t prediction);

  // Check whether a given young length (young_length) fits into the

  // given target pause time and whether the prediction for the amount

  // of objects to be copied for the given length will fit into the

  // given free space (expressed by base_free_regions).  It is used by

  // calculate_young_list_target_length().

  bool predict_will_fit(uint young_length, double base_time_ms,

                        uint base_free_regions, double target_pause_time_ms) const;

public:

  size_t pending_cards() const { return _pending_cards; }

  // Calculate the minimum number of old regions we'll add to the CSet

  // during a mixed GC.

  uint calc_min_old_cset_length() const;

  // Calculate the maximum number of old regions we'll add to the CSet

  // during a mixed GC.

  uint calc_max_old_cset_length() const;

  // Returns the given amount of uncollected reclaimable space

  // as a percentage of the current heap capacity.

  double reclaimable_bytes_perc(size_t reclaimable_bytes) const;

private:

  // Sets up marking if proper conditions are met.

  void maybe_start_marking();

  // The kind of STW pause.

  enum PauseKind {

    FullGC,

    YoungOnlyGC,

    MixedGC,

    LastYoungGC,

    InitialMarkGC,

    Cleanup,

    Remark

  };

  // Calculate PauseKind from internal state.

  PauseKind young_gc_pause_kind() const;

  // Record the given STW pause with the given start and end times (in s).

  void record_pause(PauseKind kind, double start, double end);

  // Indicate that we aborted marking before doing any mixed GCs.

  void abort_time_to_mixed_tracking();

public:

  G1CollectorPolicy();

  virtual ~G1CollectorPolicy();

  virtual G1CollectorPolicy* as_g1_policy() { return this; }

  G1CollectorState* collector_state() const;

  G1GCPhaseTimes* phase_times() const { return _phase_times; }

  // Check the current value of the young list RSet lengths and

  // compare it against the last prediction. If the current value is

  // higher, recalculate the young list target length prediction.

  void revise_young_list_target_length_if_necessary(size_t rs_lengths);

  // This should be called after the heap is resized.

  void record_new_heap_size(uint new_number_of_regions);

  void init();

  virtual void note_gc_start(uint num_active_workers);

  // Create jstat counters for the policy.

  virtual void initialize_gc_policy_counters();

  bool need_to_start_conc_mark(const char* source, size_t alloc_word_size = 0);

  bool about_to_start_mixed_phase() const;

  // Record the start and end of an evacuation pause.

  void record_collection_pause_start(double start_time_sec);

  void record_collection_pause_end(double pause_time_ms, size_t cards_scanned, size_t heap_used_bytes_before_gc);

  // Record the start and end of a full collection.

  void record_full_collection_start();

  void record_full_collection_end();

  // Must currently be called while the world is stopped.

  void record_concurrent_mark_init_end(double mark_init_elapsed_time_ms);

  // Record start and end of remark.

  void record_concurrent_mark_remark_start();

  void record_concurrent_mark_remark_end();

  // Record start, end, and completion of cleanup.

  void record_concurrent_mark_cleanup_start();

  void record_concurrent_mark_cleanup_end();

  void record_concurrent_mark_cleanup_completed();

  virtual void print_phases();

  // Record how much space we copied during a GC. This is typically

  // called when a GC alloc region is being retired.

  void record_bytes_copied_during_gc(size_t bytes) {

    _bytes_copied_during_gc += bytes;

  }

  // The amount of space we copied during a GC.

  size_t bytes_copied_during_gc() const {

    return _bytes_copied_during_gc;

  }

  // Determine whether there are candidate regions so that the

  // next GC should be mixed. The two action strings are used

  // in the ergo output when the method returns true or false.

  bool next_gc_should_be_mixed(const char* true_action_str,

                               const char* false_action_str) const;

  virtual void finalize_collection_set(double target_pause_time_ms);

private:

  // Set the state to start a concurrent marking cycle and clear

  // _initiate_conc_mark_if_possible because it has now been

  // acted on.

  void initiate_conc_mark();

public:

  // This sets the initiate_conc_mark_if_possible() flag to start a

  // new cycle, as long as we are not already in one. It's best if it

  // is called during a safepoint when the test whether a cycle is in

  // progress or not is stable.

  bool force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause);

  // This is called at the very beginning of an evacuation pause (it

  // has to be the first thing that the pause does). If

  // initiate_conc_mark_if_possible() is true, and the concurrent

  // marking thread has completed its work during the previous cycle,

  // it will set during_initial_mark_pause() to so that the pause does

  // the initial-mark work and start a marking cycle.

  void decide_on_conc_mark_initiation();

  // If an expansion would be appropriate, because recent GC overhead had

  // exceeded the desired limit, return an amount to expand by.

  virtual size_t expansion_amount();

  // Clear ratio tracking data used by expansion_amount().

  void clear_ratio_check_data();

  // Print stats on young survival ratio

  void print_yg_surv_rate_info() const;

  void finished_recalculating_age_indexes(bool is_survivors) {

    if (is_survivors) {

      _survivor_surv_rate_group->finished_recalculating_age_indexes();

    } else {

      _short_lived_surv_rate_group->finished_recalculating_age_indexes();

    }

  }

  size_t young_list_target_length() const { return _young_list_target_length; }

  bool is_young_list_full() const;

  bool can_expand_young_list() const;

  uint young_list_max_length() const {

    return _young_list_max_length;

  }

  bool adaptive_young_list_length() const;

  virtual bool should_process_references() const {

    return true;

  }

private:

  //

  // Survivor regions policy.

  //

  // Current tenuring threshold, set to 0 if the collector reaches the

  // maximum amount of survivors regions.

  uint _tenuring_threshold;

  // The limit on the number of regions allocated for survivors.

  uint _max_survivor_regions;

  AgeTable _survivors_age_table;

public:

  uint tenuring_threshold() const { return _tenuring_threshold; }

  uint max_survivor_regions() {

    return _max_survivor_regions;

  }

  static const uint REGIONS_UNLIMITED = (uint) -1;

  uint max_regions(InCSetState dest) const {

    switch (dest.value()) {

      case InCSetState::Young:

        return _max_survivor_regions;

      case InCSetState::Old:

        return REGIONS_UNLIMITED;

      default:

        assert(false, "Unknown dest state: " CSETSTATE_FORMAT, dest.value());

        break;

    }

    // keep some compilers happy

    return 0;

  }

  void note_start_adding_survivor_regions() {

    _survivor_surv_rate_group->start_adding_regions();

  }

  void note_stop_adding_survivor_regions() {

    _survivor_surv_rate_group->stop_adding_regions();

  }

  void record_age_table(AgeTable* age_table) {

    _survivors_age_table.merge(age_table);

  }

  void update_max_gc_locker_expansion();

  // Calculates survivor space parameters.

  void update_survivors_policy();

  virtual void post_heap_initialize();

};

#endif // SHARE_VM_GC_G1_G1COLLECTORPOLICY_HPP