// -*- c++ -*-

#ifndef HUGO_TIME_MEASURE_H

#define HUGO_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 hugo {

  /// \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

  {

    tms ts;

    double real_time;

  public:

    tms &getTms() {return ts;}

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

    ///Read the current time values of the process

    void stamp()

    {

      timeval tv;

      times(&ts);

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

    }

    /// Constructor initializing with zero

    TimeStamp()

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

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

    TimeStamp(void *) { stamp();}

    ///

    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;

    }

    ///

    TimeStamp operator+(const TimeStamp &b) const

    {

      TimeStamp t(*this);

      return t+=b;

    }

    ///

    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;

    }

    ///

    TimeStamp operator-(const TimeStamp &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 getUserTime() const

    {

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

    }

    ///Gives back the system time of the process

    double getSystemTime() const

    {

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

    }

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

    double getCUserTime() const

    {

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

    }

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

    double getCSystemTime() const

    {

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

    }

    ///Gives back the real time of the process

    double getRealTime() const {return real_time;}

  };

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

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

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

  ///\code

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

  ///#include<iostream>

  ///int main()

  ///{

  ///

  ///  ...

  ///

  ///  Timer T;

  ///  doSomething();

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

  ///  T.reset();

  ///  doSomethingElse();

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

  ///

  ///  ...

  ///

  ///}

  ///\endcode

  ///

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

  ///

  ///\author Alpar Juttner

  class Timer

  {

    TimeStamp start_time;

    void _reset() {start_time.stamp();}

  public: 

    ///Constructor. It starts with zero time counters

    Timer() {_reset();}

    ///Computes the ellapsed time

    ///This conversion computes the ellapsed time

    ///since the construction of \c t or since

    ///the last \c t.reset().

    operator TimeStamp ()

    {

      TimeStamp t;

      t.stamp();

      return t-start_time;

    }

    ///Resets the time counters

    TimeStamp reset()

    {

      TimeStamp t(start_time);

      _reset();

      return start_time-t;

    }

  };

  ///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.

  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.getRealTime() << "s";

    return os;

  }

  /// @}  

} //namespace hugo

#endif //HUGO_TIME_MEASURE_H