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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 block_on_overflow.hpp | |
9 | * \author Andrey Semashev | |
10 | * \date 04.01.2012 | |
11 | * | |
12 | * The header contains implementation of \c block_on_overflow strategy for handling | |
13 | * queue overflows in bounded queues for the asynchronous sink frontend. | |
14 | */ | |
15 | ||
16 | #ifndef BOOST_LOG_SINKS_BLOCK_ON_OVERFLOW_HPP_INCLUDED_ | |
17 | #define BOOST_LOG_SINKS_BLOCK_ON_OVERFLOW_HPP_INCLUDED_ | |
18 | ||
19 | #include <boost/log/detail/config.hpp> | |
20 | ||
21 | #ifdef BOOST_HAS_PRAGMA_ONCE | |
22 | #pragma once | |
23 | #endif | |
24 | ||
25 | #if defined(BOOST_LOG_NO_THREADS) | |
26 | #error Boost.Log: This header content is only supported in multithreaded environment | |
27 | #endif | |
28 | ||
29 | #include <boost/intrusive/options.hpp> | |
30 | #include <boost/intrusive/list.hpp> | |
31 | #include <boost/intrusive/list_hook.hpp> | |
32 | #include <boost/thread/condition_variable.hpp> | |
33 | #include <boost/log/core/record_view.hpp> | |
34 | #include <boost/log/detail/header.hpp> | |
35 | ||
36 | namespace boost { | |
37 | ||
38 | BOOST_LOG_OPEN_NAMESPACE | |
39 | ||
40 | namespace sinks { | |
41 | ||
42 | /*! | |
43 | * \brief Blocking strategy for handling log record queue overflows | |
44 | * | |
45 | * This strategy will cause enqueueing threads to block when the | |
46 | * log record queue overflows. The blocked threads will be woken as | |
47 | * soon as there appears free space in the queue, in the same order | |
48 | * they attempted to enqueue records. | |
49 | */ | |
50 | class block_on_overflow | |
51 | { | |
52 | #ifndef BOOST_LOG_DOXYGEN_PASS | |
53 | private: | |
54 | typedef intrusive::list_base_hook< | |
55 | intrusive::link_mode< intrusive::auto_unlink > | |
56 | > thread_context_hook_t; | |
57 | ||
58 | struct thread_context : | |
59 | public thread_context_hook_t | |
60 | { | |
61 | condition_variable cond; | |
62 | bool result; | |
63 | ||
64 | thread_context() : result(true) {} | |
65 | }; | |
66 | ||
67 | typedef intrusive::list< | |
68 | thread_context, | |
69 | intrusive::base_hook< thread_context_hook_t >, | |
70 | intrusive::constant_time_size< false > | |
71 | > thread_contexts; | |
72 | ||
73 | private: | |
74 | //! Blocked threads | |
75 | thread_contexts m_thread_contexts; | |
76 | ||
77 | public: | |
78 | /*! | |
79 | * Default constructor. | |
80 | */ | |
81 | BOOST_DEFAULTED_FUNCTION(block_on_overflow(), {}) | |
82 | ||
83 | /*! | |
84 | * This method is called by the queue when overflow is detected. | |
85 | * | |
86 | * \param lock An internal lock that protects the queue | |
87 | * | |
88 | * \retval true Attempt to enqueue the record again. | |
89 | * \retval false Discard the record. | |
90 | */ | |
91 | template< typename LockT > | |
92 | bool on_overflow(record_view const&, LockT& lock) | |
93 | { | |
94 | thread_context context; | |
95 | m_thread_contexts.push_back(context); | |
96 | do | |
97 | { | |
98 | context.cond.wait(lock); | |
99 | } | |
100 | while (context.is_linked()); | |
101 | ||
102 | return context.result; | |
103 | } | |
104 | ||
105 | /*! | |
106 | * This method is called by the queue when there appears a free space. | |
107 | * The internal lock protecting the queue is locked when calling this method. | |
108 | */ | |
109 | void on_queue_space_available() | |
110 | { | |
111 | if (!m_thread_contexts.empty()) | |
112 | { | |
113 | m_thread_contexts.front().cond.notify_one(); | |
114 | m_thread_contexts.pop_front(); | |
115 | } | |
116 | } | |
117 | ||
118 | /*! | |
119 | * This method is called by the queue to interrupt any possible waits in \c on_overflow. | |
120 | * The internal lock protecting the queue is locked when calling this method. | |
121 | */ | |
122 | void interrupt() | |
123 | { | |
124 | while (!m_thread_contexts.empty()) | |
125 | { | |
126 | thread_context& context = m_thread_contexts.front(); | |
127 | context.result = false; | |
128 | context.cond.notify_one(); | |
129 | m_thread_contexts.pop_front(); | |
130 | } | |
131 | } | |
132 | ||
133 | // Copying prohibited | |
134 | BOOST_DELETED_FUNCTION(block_on_overflow(block_on_overflow const&)) | |
135 | BOOST_DELETED_FUNCTION(block_on_overflow& operator= (block_on_overflow const&)) | |
136 | #endif // BOOST_LOG_DOXYGEN_PASS | |
137 | }; | |
138 | ||
139 | } // namespace sinks | |
140 | ||
141 | BOOST_LOG_CLOSE_NAMESPACE // namespace log | |
142 | ||
143 | } // namespace boost | |
144 | ||
145 | #include <boost/log/detail/footer.hpp> | |
146 | ||
147 | #endif // BOOST_LOG_SINKS_BLOCK_ON_OVERFLOW_HPP_INCLUDED_ |