1// -*- C++ -*-
2
3// Copyright (C) 2005-2015 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 3, 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 COPYING3.  If not see
18// <http://www.gnu.org/licenses/>.
19
20
21// Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
22
23// Permission to use, copy, modify, sell, and distribute this software
24// is hereby granted without fee, provided that the above copyright
25// notice appears in all copies, and that both that copyright notice
26// and this permission notice appear in supporting documentation. None
27// of the above authors, nor IBM Haifa Research Laboratories, make any
28// representation about the suitability of this software for any
29// purpose. It is provided "as is" without express or implied
30// warranty.
31
32/**
33 * @file timing_test_base.hpp
34 * Contains a base class for timing tests.
35 */
36
37#ifndef PB_DS_TIMING_TEST_BASE_HPP
38#define PB_DS_TIMING_TEST_BASE_HPP
39
40#include <performance/time/elapsed_timer.hpp>
41#include <statistic/result_recorder.hpp>
42
43namespace __gnu_pbds
44{
45  namespace test
46  {
47    namespace detail
48    {
49      class timing_test_base
50      {
51      protected:
52	template<typename Functor>
53	double
54	operator()(Functor& fn);
55
56	static double
57        min_time_res();
58
59      private:
60	template<typename Functor>
61	std::size_t
62	get_min_resolution(Functor&);
63
64	template<typename Functor>
65	double
66	run_at_resolution(Functor&, std::size_t);
67      };
68
69      template<typename Functor>
70      double
71      timing_test_base::operator()(Functor& fn)
72      {
73	const std::size_t resolution = get_min_resolution(fn);
74	__gnu_pbds::test::detail::result_recorder<double> rec;
75	double res;
76	do
77	  res = run_at_resolution(fn, resolution);
78	while (rec.add_result(res) == false);
79	res = rec.get_sample_mean() / resolution;
80	return res;
81      }
82
83      double
84      timing_test_base::min_time_res()
85      { return 1e-7; }
86
87      template<typename Functor>
88      std::size_t
89      timing_test_base::get_min_resolution(Functor& fn)
90      {
91	std::size_t guess = 0;
92	const double epsilon_val = min_time_res();
93	double res;
94	do
95	  {
96	    guess = guess * 2 + 1;
97	    res = run_at_resolution(fn, guess);
98	  }
99	while (res < epsilon_val);
100	return guess;
101      }
102
103      template<typename Functor>
104      double
105      timing_test_base::run_at_resolution(Functor& fn, std::size_t resolution)
106      {
107	elapsed_timer res;
108	fn(resolution);
109	return res;
110      }
111
112    } // namespace detail
113  } // namespace test
114} // namespace __gnu_pbds
115
116#endif
117
118