/* -*- C++ -*-

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

  *

  * Copyright (C) 2004 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

  * (Egervary Combinatorial Optimization Research Group, 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

   {

     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<lemon/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.

   /// \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.getRealTime() << "s";

     return os;

   }

   /// @}  

 } //namespace lemon

 #endif //LEMON_TIME_MEASURE_H