/* -*- C++ -*-

 * lemon/time_measure.h - Part of LEMON, a generic C++ optimization library

 *

 * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

 * (Egervary Research Group on Combinatorial Optimization, EGRES).

 *

 * Permission to use, modify and distribute this software is granted

 * provided that this copyright notice appears in all copies. For

 * precise terms see the accompanying LICENSE file.

 *

 * This software is provided "AS IS" with no warranty of any kind,

 * express or implied, and with no claim as to its suitability for any

 * purpose.

 *

 */

#ifndef LEMON_TIME_MEASURE_H

#define LEMON_TIME_MEASURE_H

///\ingroup misc

///\file

///\brief Tools for measuring cpu usage

#include <sys/time.h>

#include <sys/times.h>

#include <fstream>

#include <iostream>

#include <unistd.h>

namespace lemon {

  /// \addtogroup misc

  /// @{

  /// A class to store (cpu)time instances.

  /// This class stores five time values.

  /// - a real time

  /// - a user cpu time

  /// - a system cpu time

  /// - a user cpu time of children

  /// - a system cpu time of children

  ///

  /// TimeStamp's can be added to or substracted from each other and

  /// they can be pushed to a stream.

  ///

  /// In most cases, perhaps \ref Timer class is what you want to use instead.

  ///

  ///\author Alpar Juttner

  class TimeStamp

  {

    struct rtms 

    {

      double tms_utime;

      double tms_stime;

      double tms_cutime;

      double tms_cstime;

      rtms() {}

      rtms(tms ts) : tms_utime(ts.tms_utime), tms_stime(ts.tms_stime),

		     tms_cutime(ts.tms_cutime), tms_cstime(ts.tms_cstime) {}

    };

    rtms ts;

    double real_time;

    rtms &getTms() {return ts;}

    const rtms &getTms() const {return ts;}

    void _reset() 

    { ts.tms_utime=ts.tms_stime=ts.tms_cutime=ts.tms_cstime=0; real_time=0;}

  public:

    ///Read the current time values of the process

    void stamp()

    {

      timeval tv;

      tms _ts;

      times(&_ts);

      gettimeofday(&tv, 0);real_time=tv.tv_sec+double(tv.tv_usec)/1e6;

      ts=_ts;

    }

    /// Constructor initializing with zero

    TimeStamp()

    { _reset(); }

    ///Constructor initializing with the current time values of the process

    TimeStamp(void *) { stamp();}

    ///Set every time value to zero

    TimeStamp &reset() {_reset();return *this;}

    ///\e

    TimeStamp &operator+=(const TimeStamp &b)

    {

      ts.tms_utime+=b.ts.tms_utime;

      ts.tms_stime+=b.ts.tms_stime;

      ts.tms_cutime+=b.ts.tms_cutime;

      ts.tms_cstime+=b.ts.tms_cstime;

      real_time+=b.real_time;

      return *this;

    }

    ///\e

    TimeStamp operator+(const TimeStamp &b) const

    {

      TimeStamp t(*this);

      return t+=b;

    }

    ///\e

    TimeStamp &operator-=(const TimeStamp &b)

    {

      ts.tms_utime-=b.ts.tms_utime;

      ts.tms_stime-=b.ts.tms_stime;

      ts.tms_cutime-=b.ts.tms_cutime;

      ts.tms_cstime-=b.ts.tms_cstime;

      real_time-=b.real_time;

      return *this;

    }

    ///\e

    TimeStamp operator-(const TimeStamp &b) const

    {

      TimeStamp t(*this);

      return t-=b;

    }

    ///\e

    TimeStamp &operator*=(double b)

    {

      ts.tms_utime*=b;

      ts.tms_stime*=b;

      ts.tms_cutime*=b;

      ts.tms_cstime*=b;

      real_time*=b;

      return *this;

    }

    ///\e

    TimeStamp operator*(double b) const

    {

      TimeStamp t(*this);

      return t*=b;

    }

    friend TimeStamp operator*(double b,const TimeStamp &t);

    ///\e

    TimeStamp &operator/=(double b)

    {

      ts.tms_utime/=b;

      ts.tms_stime/=b;

      ts.tms_cutime/=b;

      ts.tms_cstime/=b;

      real_time/=b;

      return *this;

    }

    ///\e

    TimeStamp operator/(double b) const

    {

      TimeStamp t(*this);

      return t/=b;

    }

    ///The time ellapsed since the last call of stamp()

    TimeStamp ellapsed() const

    {

      TimeStamp t(NULL);

      return t-*this;

    }

    friend std::ostream& operator<<(std::ostream& os,const TimeStamp &t);

    ///Gives back the user time of the process

    double userTime() const

    {

      return double(ts.tms_utime)/sysconf(_SC_CLK_TCK);

    }

    ///Gives back the system time of the process

    double systemTime() const

    {

      return double(ts.tms_stime)/sysconf(_SC_CLK_TCK);

    }

    ///Gives back the user time of the process' children

    double cUserTime() const

    {

      return double(ts.tms_cutime)/sysconf(_SC_CLK_TCK);

    }

    ///Gives back the user time of the process' children

    double cSystemTime() const

    {

      return double(ts.tms_cstime)/sysconf(_SC_CLK_TCK);

    }

    ///Gives back the real time

    double realTime() const {return real_time;}

  };

  TimeStamp operator*(double b,const TimeStamp &t) 

  {

    return t*b;

  }

  ///Class for measuring the cpu time and real time usage of the process

  ///Class for measuring the cpu time and real time usage of the process.

  ///It is quite easy-to-use, here is a short example.

  ///\code

  ///#include<lemon/time_measure.h>

  ///#include<iostream>

  ///

  ///int main()

  ///{

  ///

  ///  ...

  ///

  ///  Timer T;

  ///  doSomething();

  ///  std::cout << T << '\n';

  ///  T.reset();

  ///  doSomethingElse();

  ///  std::cout << T << '\n';

  ///

  ///  ...

  ///

  ///}

  ///\endcode

  ///

  ///The \ref Timer can also be \ref stop() "stopped" and

  ///\ref start() "started" again, so it is possible to compute collected

  ///running times.

  ///

  ///\warning Depending on the operation system and its actual configuration

  ///the time counters have a certain (relatively big) granularity.

  ///Therefore this tool is not appropriate to measure very short times.

  ///Also, if you start and stop the timer very frequently, it could lead

  ///distorted results.

  ///

  ///The \ref Timer also counts the number of \ref start()

  ///executions, and is stops only after the same amount (or more)

  ///\ref stop() "stop()"s. This can be useful e.g. to compute the running time

  ///of recursive functions.

  ///

  ///\todo This shouldn't be Unix (Linux) specific.

  ///

  ///\author Alpar Juttner

  class Timer

  {

    int running; //Timer is running iff running>0; (running>=0 always holds)

    TimeStamp start_time; //This is the relativ start-time if the timer

                          //is running, the collected running time otherwise.

    void _reset() {if(running) start_time.stamp(); else start_time.reset();}

  public: 

    ///Constructor.

    ///\param _running indicates whether or not the timer starts immediately.

    ///

    Timer(bool _running=true) :running(_running) {_reset();}

    ///Computes the ellapsed time

    ///This conversion computes the ellapsed time

    ///

    operator TimeStamp () const

    {

      TimeStamp t;

      t.stamp();

      return running?t-start_time:start_time;

    }

    ///Resets the time counters

    ///Resets the time counters

    ///

    void reset()

    {

      _reset();

    }

    ///Start the time counters

    ///This function starts the time counters.

    ///

    ///If the timer is started more than ones, it will remain running

    ///until the same amount of \ref stop() is called.

    ///\sa stop()

    void start() 

    {

      if(running) running++;

      else {

	TimeStamp t;

	t.stamp();

	start_time=t-start_time;

      }

    }

    ///Stop the time counters

    ///This function stops the time counters.

    ///

    ///\sa stop()

    void stop() 

    {

      if(running && !--running) {

	TimeStamp t;

	t.stamp();

	start_time=t-start_time;

      }

    }

    ///Gives back the ellapsed user time of the process

    double userTime() const

    {

      return operator TimeStamp().userTime();

    }

    ///Gives back the ellapsed system time of the process

    double systemTime() const

    {

      return operator TimeStamp().systemTime();

    }

    ///Gives back the ellapsed user time of the process' children

    double cUserTime() const

    {

      return operator TimeStamp().cUserTime();

    }

    ///Gives back the ellapsed user time of the process' children

    double cSystemTime() const

    {

      return operator TimeStamp().cSystemTime();

    }

    ///Gives back the ellapsed real time

    double realTime() const

    {

      return operator TimeStamp().realTime();

    }

  };

  ///Prints the time counters

  ///Prints the time counters in the following form:

  ///

  /// <tt>u: XX.XXs s: XX.XXs cu: XX.XXs cs: XX.XXs real: XX.XXs</tt>

  ///

  /// where the values are the

  /// \li \c u: user cpu time,

  /// \li \c s: system cpu time,

  /// \li \c cu: user cpu time of children,

  /// \li \c cs: system cpu time of children,

  /// \li \c real: real time.

  /// \relates TimeStamp

  inline std::ostream& operator<<(std::ostream& os,const TimeStamp &t)

  {

    long cls = sysconf(_SC_CLK_TCK);

    os << "u: " << double(t.getTms().tms_utime)/cls <<

      "s, s: " << double(t.getTms().tms_stime)/cls <<

      "s, cu: " << double(t.getTms().tms_cutime)/cls <<

      "s, cs: " << double(t.getTms().tms_cstime)/cls <<

      "s, real: " << t.realTime() << "s";

    return os;

  }

  ///Tool to measure the running time more exactly.

  ///This function calls \c f several times and returns the average

  ///running time. The number of the executions will be choosen in such a way

  ///that the full real running time will be roughly between \c min_time

  ///and <tt>2*min_time</tt>.

  ///\param f the function object to be measured.

  ///\param min_time the minimum total running time.

  ///\retval num if it is not \c NULL, then *num will contain the actual

  ///        number of execution of \c f.

  ///\retval full_time if it is not \c NULL, then *full_time

  ///        will contain the actual

  ///        total running time.

  ///\return The average running time of \c f.

  template<class F>

  TimeStamp runningTimeTest(const F &f,double min_time=10,int *num = NULL,

			TimeStamp *full_time=NULL)

  {

    Timer t;

    TimeStamp full;

    int total=0;

    for(int tn=1;tn < 1<<24; tn*=2) {

      for(;total<tn;total++) f();

      full=t;

      if(full.realTime()>min_time) {

	if(num) *num=total;

	if(full_time) *full_time=full;

      return full/total;

      }

    }

    return TimeStamp();

  }

  /// @}  

} //namespace lemon

#endif //LEMON_TIME_MEASURE_H