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#ifndef SHARE_VM_GC_G1_G1IHOPCONTROL_HPP

#define SHARE_VM_GC_G1_G1IHOPCONTROL_HPP

#include "memory/allocation.hpp"

#include "utilities/numberSeq.hpp"

class G1Predictions;

class G1NewTracer;

// Base class for algorithms that calculate the heap occupancy at which

// concurrent marking should start. This heap usage threshold should be relative

// to old gen size.

class G1IHOPControl : public CHeapObj<mtGC> {

 protected:

  // 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;

  // Most recent complete mutator allocation period in seconds.

  double _last_allocation_time_s;

  // Amount of bytes allocated during _last_allocation_time_s.

  size_t _last_allocated_bytes;

  // Initialize an instance with the initial IHOP value in percent. The target

  // occupancy will be updated at the first heap expansion.

  G1IHOPControl(double initial_ihop_percent);

  // Most recent time from the end of the initial mark to the start of the first

  // mixed gc.

  virtual double last_marking_length_s() const = 0;

 public:

  virtual ~G1IHOPControl() { }

  // Get the current non-young occupancy at which concurrent marking should start.

  virtual size_t get_conc_mark_start_threshold() = 0;

  // Adjust target occupancy.

  virtual 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.

  virtual void update_allocation_info(double allocation_time_s, size_t allocated_bytes, size_t additional_buffer_size);

  // Update the time spent in the mutator beginning from the end of initial mark to

  // the first mixed gc.

  virtual void update_marking_length(double marking_length_s) = 0;

  virtual void print();

  virtual void send_trace_event(G1NewTracer* tracer);

};

// The returned concurrent mark starting occupancy threshold is a fixed value

// relative to the maximum heap size.

class G1StaticIHOPControl : public G1IHOPControl {

  // Most recent mutator time between the end of initial mark to the start of the

  // first mixed gc.

  double _last_marking_length_s;

 protected:

  double last_marking_length_s() const { return _last_marking_length_s; }

 public:

  G1StaticIHOPControl(double ihop_percent);

  size_t get_conc_mark_start_threshold() {

    guarantee(_target_occupancy > 0, "Target occupancy must have been initialized.");

    return (size_t) (_initial_ihop_percent * _target_occupancy / 100.0);

  }

  virtual void update_marking_length(double marking_length_s) {

   assert(marking_length_s > 0.0, "Marking length must be larger than zero but is %.3f", marking_length_s);

    _last_marking_length_s = marking_length_s;

  }

};

// This algorithm tries to return a concurrent mark starting occupancy value that

// makes sure that during marking the given target occupancy is never exceeded,

// based on predictions of current allocation rate and time periods between

// initial mark and the first mixed gc.

class G1AdaptiveIHOPControl : public G1IHOPControl {

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

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

  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;

  bool have_enough_data_for_prediction() 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;

 protected:

  virtual double last_marking_length_s() const { return _marking_times_s.last(); }

 public:

  G1AdaptiveIHOPControl(double ihop_percent,

                        G1Predictions const* predictor,

                        size_t heap_reserve_percent, // The percentage of total heap capacity that should not be tapped into.

                        size_t heap_waste_percent);  // The percentage of the free space in the heap that we think is not usable for allocation.

  virtual size_t get_conc_mark_start_threshold();

  virtual void update_allocation_info(double allocation_time_s, size_t allocated_bytes, size_t additional_buffer_size);

  virtual void update_marking_length(double marking_length_s);

  virtual void print();

  virtual void send_trace_event(G1NewTracer* tracer);

};

#endif // SHARE_VM_GC_G1_G1IHOPCONTROL_HPP