119 lines
3.1 KiB
C++
119 lines
3.1 KiB
C++
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/*
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* Copyright Andrey Semashev 2007 - 2015.
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* Distributed under the Boost Software License, Version 1.0.
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* (See accompanying file LICENSE_1_0.txt or copy at
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* http://www.boost.org/LICENSE_1_0.txt)
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*/
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/*!
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* \file counter.hpp
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* \author Andrey Semashev
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* \date 01.05.2007
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*
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* The header contains implementation of the counter attribute.
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*/
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#ifndef BOOST_LOG_ATTRIBUTES_COUNTER_HPP_INCLUDED_
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#define BOOST_LOG_ATTRIBUTES_COUNTER_HPP_INCLUDED_
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#include <boost/static_assert.hpp>
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#include <boost/type_traits/is_integral.hpp>
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#include <boost/log/detail/config.hpp>
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#include <boost/log/attributes/attribute.hpp>
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#include <boost/log/attributes/attribute_cast.hpp>
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#include <boost/log/attributes/attribute_value_impl.hpp>
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#ifndef BOOST_LOG_NO_THREADS
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#include <boost/memory_order.hpp>
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#include <boost/atomic/atomic.hpp>
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#endif // BOOST_LOG_NO_THREADS
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#include <boost/log/detail/header.hpp>
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#ifdef BOOST_HAS_PRAGMA_ONCE
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#pragma once
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#endif
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namespace boost {
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BOOST_LOG_OPEN_NAMESPACE
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namespace attributes {
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/*!
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* \brief A class of an attribute that counts an integral value
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*
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* This attribute acts as a counter - it returns a monotonously
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* changing value each time requested. The attribute value type can be specified
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* as a template parameter. The type must be an integral type.
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*/
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template< typename T >
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class counter :
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public attribute
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{
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BOOST_STATIC_ASSERT_MSG(is_integral< T >::value, "Boost.Log: Only integral types are supported by the counter attribute");
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public:
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//! A counter value type
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typedef T value_type;
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protected:
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//! Factory implementation
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class BOOST_SYMBOL_VISIBLE impl :
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public attribute::impl
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{
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private:
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#ifndef BOOST_LOG_NO_THREADS
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boost::atomic< value_type > m_counter;
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#else
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value_type m_counter;
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#endif
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const value_type m_step;
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public:
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impl(value_type initial, value_type step) BOOST_NOEXCEPT :
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m_counter(initial), m_step(step)
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{
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}
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attribute_value get_value()
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{
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#ifndef BOOST_LOG_NO_THREADS
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value_type value = m_counter.fetch_add(m_step, boost::memory_order_relaxed);
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#else
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value_type value = m_counter;
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m_counter += m_step;
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#endif
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return make_attribute_value(value);
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}
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};
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public:
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/*!
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* Constructor
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*
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* \param initial Initial value of the counter
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* \param step Changing step of the counter. Each value acquired from the attribute
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* will be greater than the previous one by this amount.
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*/
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explicit counter(value_type initial = (value_type)0, value_type step = (value_type)1) :
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attribute(new impl(initial, step))
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{
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}
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/*!
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* Constructor for casting support
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*/
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explicit counter(cast_source const& source) :
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attribute(source.as< impl >())
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{
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}
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};
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} // namespace attributes
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BOOST_LOG_CLOSE_NAMESPACE // namespace log
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} // namespace boost
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#include <boost/log/detail/footer.hpp>
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#endif // BOOST_LOG_ATTRIBUTES_COUNTER_HPP_INCLUDED_
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