libstdc++-v3/testsuite/util/performance/time/timing_test_base.hpp

   1 // -*- C++ -*-
   2
   3 // Copyright (C) 2005, 2006 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the terms
   7 // of the GNU General Public License as published by the Free Software
   8 // Foundation; either version 2, or (at your option) any later
   9 // version.
  10
  11 // This library is distributed in the hope that it will be useful, but
  12 // WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 // General Public License for more details.
  15
  16 // You should have received a copy of the GNU General Public License
  17 // along with this library; see the file COPYING.  If not, write to
  18 // the Free Software Foundation, 59 Temple Place - Suite 330, Boston,
  19 // MA 02111-1307, USA.
  20
  21 // As a special exception, you may use this file as part of a free
  22 // software library without restriction.  Specifically, if other files
  23 // instantiate templates or use macros or inline functions from this
  24 // file, or you compile this file and link it with other files to
  25 // produce an executable, this file does not by itself cause the
  26 // resulting executable to be covered by the GNU General Public
  27 // License.  This exception does not however invalidate any other
  28 // reasons why the executable file might be covered by the GNU General
  29 // Public License.
  30
  31 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
  32
  33 // Permission to use, copy, modify, sell, and distribute this software
  34 // is hereby granted without fee, provided that the above copyright
  35 // notice appears in all copies, and that both that copyright notice
  36 // and this permission notice appear in supporting documentation. None
  37 // of the above authors, nor IBM Haifa Research Laboratories, make any
  38 // representation about the suitability of this software for any
  39 // purpose. It is provided "as is" without express or implied
  40 // warranty.
  41
  42 /**
  43  * @file timing_test_base.hpp
  44  * Contains a base class for timing tests.
  45  */
  46
  47 #ifndef PB_DS_TIMING_TEST_BASE_HPP
  48 #define PB_DS_TIMING_TEST_BASE_HPP
  49
  50 #include <performance/time/elapsed_timer.hpp>
  51 #include <statistic/result_recorder.hpp>
  52
  53 namespace __gnu_pbds
  54 {
  55   namespace test
  56   {
  57     namespace detail
  58     {
  59       class timing_test_base
  60       {
  61       protected:
  62         template<typename Functor>
  63         double
  64         operator()(Functor& fn);
  65
  66         static double
  67         min_time_res();
  68
  69       private:
  70         template<typename Functor>
  71         std::size_t
  72         get_min_resolution(Functor&);
  73
  74         template<typename Functor>
  75         double
  76         run_at_resolution(Functor&, std::size_t);
  77       };
  78
  79       template<typename Functor>
  80       double
  81       timing_test_base::operator()(Functor& fn)
  82       {
  83         const std::size_t resolution = get_min_resolution(fn);
  84         __gnu_pbds::test::detail::result_recorder<double> rec;
  85         double res;
  86         do
  87           res = run_at_resolution(fn, resolution);
  88         while (rec.add_result(res) == false);
  89         res = rec.get_sample_mean() / resolution;
  90         return res;
  91       }
  92
  93       double
  94       timing_test_base::min_time_res()
  95       { return 1e-7; }
  96
  97       template<typename Functor>
  98       std::size_t
  99       timing_test_base::get_min_resolution(Functor& fn)
 100       {
 101         std::size_t guess = 0;
 102         const double epsilon_val = min_time_res();
 103         double res;
 104         do
 105           {
 106             guess = guess * 2 + 1;
 107             res = run_at_resolution(fn, guess);
 108           }
 109         while (res < epsilon_val);
 110         return guess;
 111       }
 112
 113       template<typename Functor>
 114       double
 115       timing_test_base::run_at_resolution(Functor& fn, std::size_t resolution)
 116       {
 117         elapsed_timer res;
 118         fn(resolution);
 119         return res;
 120       }
 121
 122     } // namespace detail
 123   } // namespace test
 124 } // namespace __gnu_pbds
 125
 126 #endif
 127