ceph/src/boost/boost/log/attributes/timer.hpp

   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
  28 namespace boost {
  29
  30 BOOST_LOG_OPEN_NAMESPACE
  31
  32 namespace 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  */
  53 class BOOST_LOG_API timer :
  54     public attribute
  55 {
  56 public:
  57     //! Attribute value type
  58     typedef utc_time_traits::time_type::time_duration_type value_type;
  59
  60 private:
  61     //! Factory implementation
  62     class BOOST_SYMBOL_VISIBLE impl;
  63
  64 public:
  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
  77 BOOST_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_