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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 counter.hpp | |
9 | * \author Andrey Semashev | |
10 | * \date 01.05.2007 | |
11 | * | |
12 | * The header contains implementation of the counter attribute. | |
13 | */ | |
14 | ||
15 | #ifndef BOOST_LOG_ATTRIBUTES_COUNTER_HPP_INCLUDED_ | |
16 | #define BOOST_LOG_ATTRIBUTES_COUNTER_HPP_INCLUDED_ | |
17 | ||
18 | #include <boost/static_assert.hpp> | |
19 | #include <boost/type_traits/is_integral.hpp> | |
20 | #include <boost/log/detail/config.hpp> | |
21 | #include <boost/log/attributes/attribute.hpp> | |
22 | #include <boost/log/attributes/attribute_cast.hpp> | |
23 | #include <boost/log/attributes/attribute_value_impl.hpp> | |
24 | #ifndef BOOST_LOG_NO_THREADS | |
25 | #include <boost/memory_order.hpp> | |
26 | #include <boost/atomic/atomic.hpp> | |
27 | #endif // BOOST_LOG_NO_THREADS | |
28 | #include <boost/log/detail/header.hpp> | |
29 | ||
30 | #ifdef BOOST_HAS_PRAGMA_ONCE | |
31 | #pragma once | |
32 | #endif | |
33 | ||
34 | namespace boost { | |
35 | ||
36 | BOOST_LOG_OPEN_NAMESPACE | |
37 | ||
38 | namespace attributes { | |
39 | ||
40 | /*! | |
41 | * \brief A class of an attribute that counts an integral value | |
42 | * | |
43 | * This attribute acts as a counter - it returns a monotonously | |
44 | * changing value each time requested. The attribute value type can be specified | |
45 | * as a template parameter. The type must be an integral type. | |
46 | */ | |
47 | template< typename T > | |
48 | class counter : | |
49 | public attribute | |
50 | { | |
51 | BOOST_STATIC_ASSERT_MSG(is_integral< T >::value, "Boost.Log: Only integral types are supported by the counter attribute"); | |
52 | ||
53 | public: | |
54 | //! A counter value type | |
55 | typedef T value_type; | |
56 | ||
57 | protected: | |
58 | //! Factory implementation | |
59 | class BOOST_SYMBOL_VISIBLE impl : | |
60 | public attribute::impl | |
61 | { | |
62 | private: | |
63 | #ifndef BOOST_LOG_NO_THREADS | |
64 | boost::atomic< value_type > m_counter; | |
65 | #else | |
66 | value_type m_counter; | |
67 | #endif | |
68 | const value_type m_step; | |
69 | ||
70 | public: | |
71 | impl(value_type initial, value_type step) BOOST_NOEXCEPT : | |
72 | m_counter(initial), m_step(step) | |
73 | { | |
74 | } | |
75 | ||
76 | attribute_value get_value() | |
77 | { | |
78 | #ifndef BOOST_LOG_NO_THREADS | |
79 | value_type value = m_counter.fetch_add(m_step, boost::memory_order_relaxed); | |
80 | #else | |
81 | value_type value = m_counter; | |
82 | m_counter += m_step; | |
83 | #endif | |
84 | return make_attribute_value(value); | |
85 | } | |
86 | }; | |
87 | ||
88 | public: | |
89 | /*! | |
90 | * Constructor | |
91 | * | |
92 | * \param initial Initial value of the counter | |
93 | * \param step Changing step of the counter. Each value acquired from the attribute | |
94 | * will be greater than the previous one by this amount. | |
95 | */ | |
96 | explicit counter(value_type initial = (value_type)0, value_type step = (value_type)1) : | |
97 | attribute(new impl(initial, step)) | |
98 | { | |
99 | } | |
100 | ||
101 | /*! | |
102 | * Constructor for casting support | |
103 | */ | |
104 | explicit counter(cast_source const& source) : | |
105 | attribute(source.as< impl >()) | |
106 | { | |
107 | } | |
108 | }; | |
109 | ||
110 | } // namespace attributes | |
111 | ||
112 | BOOST_LOG_CLOSE_NAMESPACE // namespace log | |
113 | ||
114 | } // namespace boost | |
115 | ||
116 | #include <boost/log/detail/footer.hpp> | |
117 | ||
118 | #endif // BOOST_LOG_ATTRIBUTES_COUNTER_HPP_INCLUDED_ |