1/*
2 * Copyright Andrey Semashev 2007 - 2015.
3 * Distributed under the Boost Software License, Version 1.0.
4 * (See accompanying file LICENSE_1_0.txt or copy at
5 * http://www.boost.org/LICENSE_1_0.txt)
6 */
7/*!
8 * \file timer.hpp
9 * \author Andrey Semashev
10 * \date 02.12.2007
11 *
12 * The header contains implementation of a stop watch attribute.
13 */
14
15#ifndef BOOST_LOG_ATTRIBUTES_TIMER_HPP_INCLUDED_
16#define BOOST_LOG_ATTRIBUTES_TIMER_HPP_INCLUDED_
17
18#include <boost/log/detail/config.hpp>
19#include <boost/log/attributes/attribute.hpp>
20#include <boost/log/attributes/attribute_cast.hpp>
21#include <boost/log/attributes/time_traits.hpp>
22#include <boost/log/detail/header.hpp>
23
24#ifdef BOOST_HAS_PRAGMA_ONCE
25#pragma once
26#endif
27
28namespace boost {
29
30BOOST_LOG_OPEN_NAMESPACE
31
32namespace attributes {
33
34/*!
35 * \brief A class of an attribute that makes an attribute value of the time interval since construction
36 *
37 * The timer attribute calculates the time passed since its construction and returns it on value acquisition.
38 * The attribute value type is <tt>boost::posix_time::time_duration</tt>.
39 *
40 * On Windows platform there are two implementations of the attribute. The default one is more precise but
41 * a bit slower. This version uses <tt>QueryPerformanceFrequence</tt>/<tt>QueryPerformanceCounter</tt> API
42 * to calculate elapsed time.
43 *
44 * There are known problems with these functions when used with some CPUs, notably AMD Athlon with
45 * Cool'n'Quiet technology enabled. See the following links for more information and possible resolutions:
46 *
47 * http://support.microsoft.com/?scid=kb;en-us;895980
48 * http://support.microsoft.com/?id=896256
49 *
50 * In case if none of these solutions apply, you are free to define <tt>BOOST_LOG_NO_QUERY_PERFORMANCE_COUNTER</tt> macro to
51 * fall back to another implementation based on Boost.DateTime.
52 */
53class BOOST_LOG_API timer :
54 public attribute
55{
56public:
57 //! Attribute value type
58 typedef utc_time_traits::time_type::time_duration_type value_type;
59
60private:
61 //! Factory implementation
62 class BOOST_SYMBOL_VISIBLE impl;
63
64public:
65 /*!
66 * Constructor. Starts time counting.
67 */
68 timer();
69 /*!
70 * Constructor for casting support
71 */
72 explicit timer(cast_source const& source);
73};
74
75} // namespace attributes
76
77BOOST_LOG_CLOSE_NAMESPACE // namespace log
78
79} // namespace boost
80
81#include <boost/log/detail/footer.hpp>
82
83#endif // BOOST_LOG_ATTRIBUTES_TIMER_HPP_INCLUDED_
84

source code of boost/libs/log/include/boost/log/attributes/timer.hpp