Timer.h

00001 /*
00002  * Tiny Vector Matrix Library
00003  * Dense Vector Matrix Libary of Tiny size using Expression Templates
00004  *
00005  * Copyright (C) 2001 - 2007 Olaf Petzold <opetzold@users.sourceforge.net>
00006  *
00007  * This library is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * This library is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with this library; if not, write to the Free Software
00019  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
00020  *
00021  * $Id: Timer.h,v 1.9 2007-06-23 15:58:59 opetzold Exp $
00022  */
00023 
00024 #ifndef TVMET_UTIL_TIMER_H
00025 #define TVMET_UTIL_TIMER_H
00026 
00027 #if defined(TVMET_HAVE_SYS_TIME_H) && defined(TVMET_HAVE_UNISTD_H)
00028 #  include <sys/time.h>
00029 #  include <sys/resource.h>
00030 #  include <unistd.h>
00031 #else
00032 #  include <ctime>
00033 #endif
00034 
00035 namespace tvmet {
00036 
00037 namespace util {
00038 
00039 /**
00040    \class Timer Timer.h "tvmet/util/Timer.h"
00041    \brief A quick& dirty portable timer, measures elapsed time.
00042 
00043    It is recommended that implementations measure wall clock rather than CPU
00044    time since the intended use is performance measurement on systems where
00045    total elapsed time is more important than just process or CPU time.
00046 
00047    The accuracy of timings depends on the accuracy of timing information
00048    provided by the underlying platform, and this varies from platform to
00049    platform.
00050 */
00051 
00052 class Timer
00053 {
00054   Timer(const Timer&);
00055   Timer& operator=(const Timer&);
00056 
00057 public: // types
00058   typedef double                    time_t;
00059 
00060 public:
00061   /** starts the timer immediatly. */
00062   Timer() { m_start_time = getTime(); }
00063 
00064   /** restarts the timer */
00065   void restart() { m_start_time = getTime(); }
00066 
00067   /** return elapsed time in seconds */
00068   time_t elapsed() const { return (getTime() - m_start_time); }
00069 
00070 private:
00071   time_t getTime() const {
00072 #if defined(TVMET_HAVE_SYS_TIME_H) && defined(TVMET_HAVE_UNISTD_H)
00073     getrusage(RUSAGE_SELF, &m_rusage);
00074     time_t sec = m_rusage.ru_utime.tv_sec; // user, no system time
00075     time_t usec  = m_rusage.ru_utime.tv_usec; // user, no system time
00076     return sec + usec/1e6;
00077 #else
00078     return static_cast<time_t>(std::clock()) / static_cast<time_t>(CLOCKS_PER_SEC);
00079 #endif
00080   }
00081 
00082 private:
00083 #if defined(TVMET_HAVE_SYS_TIME_H) && defined(TVMET_HAVE_UNISTD_H)
00084   mutable struct rusage                 m_rusage;
00085 #endif
00086   time_t                         m_start_time;
00087 };
00088 
00089 } // namespace util
00090 
00091 } // namespace tvmet
00092 
00093 #endif // TVMET_UTIL_TIMER_H
00094 
00095 // Local Variables:
00096 // mode:C++
00097 // tab-width:8
00098 // End: