boost/log/attributes/timer.hpp
/*
* Copyright Andrey Semashev 2007 - 2015.
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying file LICENSE_1_0.txt or copy at
* http://www.boost.org/LICENSE_1_0.txt)
*/
/*!
* \file timer.hpp
* \author Andrey Semashev
* \date 02.12.2007
*
* The header contains implementation of a stop watch attribute.
*/
#ifndef BOOST_LOG_ATTRIBUTES_TIMER_HPP_INCLUDED_
#define BOOST_LOG_ATTRIBUTES_TIMER_HPP_INCLUDED_
#include <boost/log/detail/config.hpp>
#include <boost/log/attributes/attribute.hpp>
#include <boost/log/attributes/attribute_cast.hpp>
#include <boost/log/attributes/time_traits.hpp>
#include <boost/log/detail/header.hpp>
#ifdef BOOST_HAS_PRAGMA_ONCE
#pragma once
#endif
namespace boost {
BOOST_LOG_OPEN_NAMESPACE
namespace attributes {
/*!
* \brief A class of an attribute that makes an attribute value of the time interval since construction
*
* The timer attribute calculates the time passed since its construction and returns it on value acquisition.
* The attribute value type is <tt>boost::posix_time::time_duration</tt>.
*
* On Windows platform there are two implementations of the attribute. The default one is more precise but
* a bit slower. This version uses <tt>QueryPerformanceFrequence</tt>/<tt>QueryPerformanceCounter</tt> API
* to calculate elapsed time.
*
* There are known problems with these functions when used with some CPUs, notably AMD Athlon with
* Cool'n'Quiet technology enabled. See the following links for more information and possible resolutions:
*
* http://support.microsoft.com/?scid=kb;en-us;895980
* http://support.microsoft.com/?id=896256
*
* In case if none of these solutions apply, you are free to define <tt>BOOST_LOG_NO_QUERY_PERFORMANCE_COUNTER</tt> macro to
* fall back to another implementation based on Boost.DateTime.
*/
class BOOST_LOG_API timer :
public attribute
{
public:
//! Attribute value type
typedef utc_time_traits::time_type::time_duration_type value_type;
private:
//! Factory implementation
class BOOST_SYMBOL_VISIBLE impl;
public:
/*!
* Constructor. Starts time counting.
*/
timer();
/*!
* Constructor for casting support
*/
explicit timer(cast_source const& source);
};
} // namespace attributes
BOOST_LOG_CLOSE_NAMESPACE // namespace log
} // namespace boost
#include <boost/log/detail/footer.hpp>
#endif // BOOST_LOG_ATTRIBUTES_TIMER_HPP_INCLUDED_