/* -*- 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(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