/*********************                                                        */
/*! \file stats_timer.h
 ** \verbatim
 ** Top contributors (to current version):
 **   Gereon Kremer
 ** This file is part of the CVC4 project.
 ** Copyright (c) 2009-2021 by the authors listed in the file AUTHORS
 ** in the top-level source directory and their institutional affiliations.
 ** All rights reserved.  See the file COPYING in the top-level source
 ** directory for licensing information.\endverbatim
 **
 ** \brief Timer statistics
 **
 ** Stat classes that hold timers
 **/

#include "cvc4_private_library.h"

#ifndef CVC4__UTIL__STATS_TIMER_H
#define CVC4__UTIL__STATS_TIMER_H

#include <chrono>

#include "cvc4_export.h"
#include "util/stats_base.h"

namespace cvc5 {
namespace timer_stat_detail {
using clock = std::chrono::steady_clock;
using time_point = clock::time_point;
struct duration : public std::chrono::nanoseconds
{
};
}  // namespace timer_stat_detail

template <>
void CVC4_EXPORT safe_print(int fd, const timer_stat_detail::duration& t);

class CodeTimer;

/**
 * A timer statistic.  The timer can be started and stopped
 * arbitrarily, like a stopwatch; the value of the statistic at the
 * end is the accumulated time over all (start,stop) pairs.
 */
class CVC4_EXPORT TimerStat : public BackedStat<timer_stat_detail::duration>
{
 public:
  typedef cvc5::CodeTimer CodeTimer;

  /**
   * Construct a timer statistic with the given name.  Newly-constructed
   * timers have a 0.0 value and are not running.
   */
  TimerStat(const std::string& name)
      : BackedStat<timer_stat_detail::duration>(name,
                                                timer_stat_detail::duration()),
        d_start(),
        d_running(false)
  {
  }

  /** Start the timer. */
  void start();

  /**
   * Stop the timer and update the statistic value with the
   * accumulated time.
   */
  void stop();

  /** If the timer is currently running */
  bool running() const;

  timer_stat_detail::duration get() const;

  void flushInformation(std::ostream& out) const override;
  void safeFlushInformation(int fd) const override;

  SExpr getValue() const override;

 private:
  /** The last start time of this timer */
  timer_stat_detail::time_point d_start;

  /** Whether this timer is currently running */
  bool d_running;
}; /* class TimerStat */

/**
 * Utility class to make it easier to call stop() at the end of a
 * code block.  When constructed, it starts the timer.  When
 * destructed, it stops the timer.
 */
class CodeTimer
{
 public:
  CodeTimer(TimerStat& timer, bool allow_reentrant = false);
  ~CodeTimer();

private:
  TimerStat& d_timer;
  bool d_reentrant;

  /** Private copy constructor undefined (no copy permitted). */
  CodeTimer(const CodeTimer& timer) = delete;
  /** Private assignment operator undefined (no copy permitted). */
  CodeTimer& operator=(const CodeTimer& timer) = delete;
}; /* class CodeTimer */

}  // namespace cvc5

#endif