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#ifndef SHARE_VM_GC_IMPLEMENTATION_SHARED_ALLOCATIONSTATS_HPP

#define SHARE_VM_GC_IMPLEMENTATION_SHARED_ALLOCATIONSTATS_HPP

#include "utilities/macros.hpp"

#include "memory/allocation.hpp"

#include "utilities/globalDefinitions.hpp"

#include "gc_implementation/shared/gcUtil.hpp"

class AllocationStats VALUE_OBJ_CLASS_SPEC {

  // A duration threshold (in ms) used to filter

  // possibly unreliable samples.

  static float _threshold;

  // We measure the demand between the end of the previous sweep and

  // beginning of this sweep:

  //   Count(end_last_sweep) - Count(start_this_sweep)

  //     + split_births(between) - split_deaths(between)

  // The above number divided by the time since the end of the

  // previous sweep gives us a time rate of demand for blocks

  // of this size. We compute a padded average of this rate as

  // our current estimate for the time rate of demand for blocks

  // of this size. Similarly, we keep a padded average for the time

  // between sweeps. Our current estimate for demand for blocks of

  // this size is then simply computed as the product of these two

  // estimates.

  AdaptivePaddedAverage _demand_rate_estimate;

  ssize_t     _desired;          // Demand estimate computed as described above

  ssize_t     _coal_desired;     // desired +/- small-percent for tuning coalescing

  ssize_t     _surplus;          // count - (desired +/- small-percent),

                                 // used to tune splitting in best fit

  ssize_t     _bfr_surp;         // surplus at start of current sweep

  ssize_t     _prev_sweep;       // count from end of previous sweep

  ssize_t     _before_sweep;     // count from before current sweep

  ssize_t     _coal_births;      // additional chunks from coalescing

  ssize_t     _coal_deaths;      // loss from coalescing

  ssize_t     _split_births;     // additional chunks from splitting

  ssize_t     _split_deaths;     // loss from splitting

  size_t      _returned_bytes;   // number of bytes returned to list.

 public:

  void initialize(bool split_birth = false) {

    AdaptivePaddedAverage* dummy =

      new (&_demand_rate_estimate) AdaptivePaddedAverage(CMS_FLSWeight,

                                                         CMS_FLSPadding);

    _desired = 0;

    _coal_desired = 0;

    _surplus = 0;

    _bfr_surp = 0;

    _prev_sweep = 0;

    _before_sweep = 0;

    _coal_births = 0;

    _coal_deaths = 0;

    _split_births = (split_birth ? 1 : 0);

    _split_deaths = 0;

    _returned_bytes = 0;

  }

  AllocationStats() {

    initialize();

  }

  // The rate estimate is in blocks per second.

  void compute_desired(size_t count,

                       float inter_sweep_current,

                       float inter_sweep_estimate,

                       float intra_sweep_estimate) {

    // If the latest inter-sweep time is below our granularity

    // of measurement, we may call in here with

    // inter_sweep_current == 0. However, even for suitably small

    // but non-zero inter-sweep durations, we may not trust the accuracy

    // of accumulated data, since it has not been "integrated"

    // (read "low-pass-filtered") long enough, and would be

    // vulnerable to noisy glitches. In such cases, we

    // ignore the current sample and use currently available

    // historical estimates.

    assert(prev_sweep() + split_births() + coal_births()        // "Total Production Stock"

           >= split_deaths() + coal_deaths() + (ssize_t)count, // "Current stock + depletion"

           "Conservation Principle");

    if (inter_sweep_current > _threshold) {

      ssize_t demand = prev_sweep() - (ssize_t)count + split_births() + coal_births()

                       - split_deaths() - coal_deaths();

      assert(demand >= 0,

             err_msg("Demand (" SSIZE_FORMAT ") should be non-negative for "

                     PTR_FORMAT " (size=" SIZE_FORMAT ")",

      // Defensive: adjust for imprecision in event counting

      if (demand < 0) {

        demand = 0;

      }

      float old_rate = _demand_rate_estimate.padded_average();

      float rate = ((float)demand)/inter_sweep_current;

      _demand_rate_estimate.sample(rate);

      float new_rate = _demand_rate_estimate.padded_average();

      ssize_t old_desired = _desired;

      float delta_ise = (CMSExtrapolateSweep ? intra_sweep_estimate : 0.0);

      _desired = (ssize_t)(new_rate * (inter_sweep_estimate + delta_ise));

      if (PrintFLSStatistics > 1) {

        gclog_or_tty->print_cr("demand: " SSIZE_FORMAT ", old_rate: %f, current_rate: %f, "

                               "new_rate: %f, old_desired: " SSIZE_FORMAT ", new_desired: " SSIZE_FORMAT,

                                demand, old_rate, rate, new_rate, old_desired, _desired);

      }

    }

  }

  ssize_t desired() const { return _desired; }

  void set_desired(ssize_t v) { _desired = v; }

  ssize_t coal_desired() const { return _coal_desired; }

  void set_coal_desired(ssize_t v) { _coal_desired = v; }

  ssize_t surplus() const { return _surplus; }

  void set_surplus(ssize_t v) { _surplus = v; }

  void increment_surplus() { _surplus++; }

  void decrement_surplus() { _surplus--; }

  ssize_t bfr_surp() const { return _bfr_surp; }

  void set_bfr_surp(ssize_t v) { _bfr_surp = v; }

  ssize_t prev_sweep() const { return _prev_sweep; }

  void set_prev_sweep(ssize_t v) { _prev_sweep = v; }

  ssize_t before_sweep() const { return _before_sweep; }

  void set_before_sweep(ssize_t v) { _before_sweep = v; }

  ssize_t coal_births() const { return _coal_births; }

  void set_coal_births(ssize_t v) { _coal_births = v; }

  void increment_coal_births() { _coal_births++; }

  ssize_t coal_deaths() const { return _coal_deaths; }

  void set_coal_deaths(ssize_t v) { _coal_deaths = v; }

  void increment_coal_deaths() { _coal_deaths++; }

  ssize_t split_births() const { return _split_births; }

  void set_split_births(ssize_t v) { _split_births = v; }

  void increment_split_births() { _split_births++; }

  ssize_t split_deaths() const { return _split_deaths; }

  void set_split_deaths(ssize_t v) { _split_deaths = v; }

  void increment_split_deaths() { _split_deaths++; }

  NOT_PRODUCT(

    size_t returned_bytes() const { return _returned_bytes; }

    void set_returned_bytes(size_t v) { _returned_bytes = v; }

  )

};

#endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_ALLOCATIONSTATS_HPP