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#ifndef SHARE_GC_G1_G1IHOPCONTROL_HPP
#define SHARE_GC_G1_G1IHOPCONTROL_HPP

#include "gc/g1/g1OldGenAllocationTracker.hpp"
#include "memory/allocation.hpp"
#include "utilities/numberSeq.hpp"

class G1Predictions;
class G1NewTracer;

// Implements two strategies for calculating the concurrent mark starting occupancy threshold:
// - Static mode: Uses a fixed percentage of the target heap occupancy.
// - Adaptive mode: Predicts a threshold based on allocation rates and marking durations
//   to ensure the target occupancy is never exceeded during marking.
class G1IHOPControl : public CHeapObj<mtGC> {
 private:
  const bool _is_adaptive;

  // The initial IHOP value relative to the target occupancy.
  double _initial_ihop_percent;

  // The target maximum occupancy of the heap. The target occupancy is the number
  // of bytes when marking should be finished and reclaim started.
  size_t _target_occupancy;

  // Percentage of maximum heap capacity we should avoid to touch
  const size_t _heap_reserve_percent;

  // Percentage of free heap that should be considered as waste.
  const size_t _heap_waste_percent;

  // Most recent complete mutator allocation period in seconds.
  double _last_allocation_time_s;
  const G1OldGenAllocationTracker* _old_gen_alloc_tracker;

  const G1Predictions* _predictor;
  TruncatedSeq _marking_times_s;
  TruncatedSeq _allocation_rate_s;

  // The most recent unrestrained size of the young gen. This is used as an additional
  // factor in the calculation of the threshold, as the threshold is based on
  // non-young gen occupancy at the end of GC. For the IHOP threshold, we need to
  // consider the young gen size during that time too.
  // Since we cannot know what young gen sizes are used in the future, we will just
  // use the current one. We expect that this one will be one with a fairly large size,
  // as there is no marking or mixed gc that could impact its size too much.
  size_t _last_unrestrained_young_size;

  // Get a new prediction bounded below by zero from the given sequence.
  double predict(const TruncatedSeq* seq) const;

  bool have_enough_data_for_prediction() const;
  double last_marking_length_s() const;

  // The "actual" target threshold the algorithm wants to keep during and at the
  // end of marking. This is typically lower than the requested threshold, as the
  // algorithm needs to consider restrictions by the environment.
  size_t actual_target_threshold() const;

 void print_log(size_t non_young_occupancy);
 void send_trace_event(G1NewTracer* tracer, size_t non_young_occupancy);

 public:
  G1IHOPControl(double ihop_percent,
                const G1OldGenAllocationTracker* old_gen_alloc_tracker,
                bool adaptive,
                const G1Predictions* predictor,
                size_t heap_reserve_percent,
                size_t heap_waste_percent);

  // Adjust target occupancy.
  void update_target_occupancy(size_t new_target_occupancy);

  // Update information about time during which allocations in the Java heap occurred,
  // how large these allocations were in bytes, and an additional buffer.
  // The allocations should contain any amount of space made unusable for further
  // allocation, e.g. any waste caused by TLAB allocation, space at the end of
  // humongous objects that can not be used for allocation, etc.
  // Together with the target occupancy, this additional buffer should contain the
  // difference between old gen size and total heap size at the start of reclamation,
  // and space required for that reclamation.
  void update_allocation_info(double allocation_time_s, size_t additional_buffer_size);

  // Update the time spent in the mutator beginning from the end of concurrent start to
  // the first mixed gc.
  void update_marking_length(double marking_length_s);

  // Get the current non-young occupancy at which concurrent marking should start.
  size_t get_conc_mark_start_threshold();

  void report_statistics(G1NewTracer* tracer, size_t non_young_occupancy);
};

#endif // SHARE_GC_G1_G1IHOPCONTROL_HPP