boost/mpi/timer.hpp

   1 // Copyright (C) 2006 Douglas Gregor <doug.gregor -at- gmail.com>
   2
   3 // Use, modification and distribution is subject to the Boost Software
   4 // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   5 // http://www.boost.org/LICENSE_1_0.txt)
   6
   7 /** @file timer.hpp
   8  *
   9  *  This header provides the @c timer class, which provides access to
  10  *  the MPI timers.
  11  */
  12 #ifndef BOOST_MPI_TIMER_HPP
  13 #define BOOST_MPI_TIMER_HPP
  14
  15 #include <boost/mpi/config.hpp>
  16 #include <boost/limits.hpp>
  17
  18 namespace boost { namespace mpi {
  19
  20 /** @brief A simple timer that provides access to the MPI timing
  21  * facilities.
  22  *
  23  *  The @c timer class is a simple wrapper around the MPI timing
  24  *  facilities that mimics the interface of the Boost Timer library.
  25  */
  26 class BOOST_MPI_DECL timer {
  27 public:
  28   /** Initializes the timer
  29    *
  30    * @post @c elapsed() == 0
  31    */
  32   timer();
  33
  34   /** Restart the timer.
  35    *
  36    * @post @c elapsed() == 0
  37    */
  38   void restart();
  39
  40   /** Return the amount of time that has elapsed since the last
  41    *  construction or reset, in seconds.
  42    */
  43   double elapsed() const;
  44
  45   /** Return an estimate of the maximum possible value of
  46    *  elapsed(). Note that this routine may return too high a value on
  47    *  some systems.
  48    */
  49   double elapsed_max() const;
  50
  51   /** Returns the minimum non-zero value that @c elapsed() may
  52    *  return. This is the resolution of the timer.
  53    */
  54   double elapsed_min() const;
  55
  56   /** Determines whether the elapsed time values are global times or
  57       local processor times. */
  58   static bool time_is_global();
  59
  60 private:
  61   double start_time;
  62 }; // timer
  63
  64 inline timer::timer()
  65 {
  66   restart();
  67 }
  68
  69 inline void timer::restart()
  70 {
  71   start_time = MPI_Wtime();
  72 }
  73
  74 inline double timer::elapsed() const
  75 {
  76   return MPI_Wtime() - start_time;
  77 }
  78
  79 inline double timer::elapsed_max() const
  80 {
  81   return (std::numeric_limits<double>::max)();
  82 }
  83
  84 inline double timer::elapsed_min() const
  85 {
  86   return MPI_Wtick();
  87 }
  88
  89 } } // end namespace boost::mpi
  90
  91 #endif // BOOST_MPI_TIMER_HPP