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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 unbounded_fifo_queue.hpp | |
9 | * \author Andrey Semashev | |
10 | * \date 24.07.2011 | |
11 | * | |
12 | * The header contains implementation of unbounded FIFO queueing strategy for | |
13 | * the asynchronous sink frontend. | |
14 | */ | |
15 | ||
16 | #ifndef BOOST_LOG_SINKS_UNBOUNDED_FIFO_QUEUE_HPP_INCLUDED_ | |
17 | #define BOOST_LOG_SINKS_UNBOUNDED_FIFO_QUEUE_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/memory_order.hpp> | |
30 | #include <boost/atomic/atomic.hpp> | |
31 | #include <boost/log/detail/event.hpp> | |
32 | #include <boost/log/detail/threadsafe_queue.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 Unbounded FIFO log record queueing strategy | |
44 | * | |
45 | * The \c unbounded_fifo_queue class is intended to be used with | |
46 | * the \c asynchronous_sink frontend as a log record queueing strategy. | |
47 | * | |
48 | * This strategy implements the simplest logic of log record buffering between | |
49 | * threads: the queue has no limits and imposes no ordering over the queued | |
50 | * elements aside from the order in which they are enqueued. | |
51 | * Because of this the queue provides decent performance and scalability, | |
52 | * however if sink backends can't consume log records fast enough the queue | |
53 | * may grow uncontrollably. When this is an issue, it is recommended to | |
54 | * use one of the bounded strategies. | |
55 | */ | |
56 | class unbounded_fifo_queue | |
57 | { | |
58 | private: | |
59 | typedef boost::log::aux::threadsafe_queue< record_view > queue_type; | |
60 | ||
61 | private: | |
62 | //! Thread-safe queue | |
63 | queue_type m_queue; | |
64 | //! Event object to block on | |
65 | boost::log::aux::event m_event; | |
66 | //! Interruption flag | |
67 | boost::atomic< bool > m_interruption_requested; | |
68 | ||
69 | protected: | |
70 | //! Default constructor | |
71 | unbounded_fifo_queue() : m_interruption_requested(false) | |
72 | { | |
73 | } | |
74 | //! Initializing constructor | |
75 | template< typename ArgsT > | |
76 | explicit unbounded_fifo_queue(ArgsT const&) : m_interruption_requested(false) | |
77 | { | |
78 | } | |
79 | ||
80 | //! Enqueues log record to the queue | |
81 | void enqueue(record_view const& rec) | |
82 | { | |
83 | m_queue.push(rec); | |
84 | m_event.set_signalled(); | |
85 | } | |
86 | ||
87 | //! Attempts to enqueue log record to the queue | |
88 | bool try_enqueue(record_view const& rec) | |
89 | { | |
90 | // Assume the call never blocks | |
91 | enqueue(rec); | |
92 | return true; | |
93 | } | |
94 | ||
95 | //! Attempts to dequeue a log record ready for processing from the queue, does not block if the queue is empty | |
96 | bool try_dequeue_ready(record_view& rec) | |
97 | { | |
98 | return m_queue.try_pop(rec); | |
99 | } | |
100 | ||
101 | //! Attempts to dequeue log record from the queue, does not block if the queue is empty | |
102 | bool try_dequeue(record_view& rec) | |
103 | { | |
104 | return m_queue.try_pop(rec); | |
105 | } | |
106 | ||
107 | //! Dequeues log record from the queue, blocks if the queue is empty | |
108 | bool dequeue_ready(record_view& rec) | |
109 | { | |
110 | // Try the fast way first | |
111 | if (m_queue.try_pop(rec)) | |
112 | return true; | |
113 | ||
114 | // Ok, we probably have to wait for new records | |
115 | while (true) | |
116 | { | |
117 | m_event.wait(); | |
118 | if (m_interruption_requested.exchange(false, boost::memory_order_acquire)) | |
119 | return false; | |
120 | if (m_queue.try_pop(rec)) | |
121 | return true; | |
122 | } | |
123 | } | |
124 | ||
125 | //! Wakes a thread possibly blocked in the \c dequeue method | |
126 | void interrupt_dequeue() | |
127 | { | |
128 | m_interruption_requested.store(true, boost::memory_order_release); | |
129 | m_event.set_signalled(); | |
130 | } | |
131 | }; | |
132 | ||
133 | } // namespace sinks | |
134 | ||
135 | BOOST_LOG_CLOSE_NAMESPACE // namespace log | |
136 | ||
137 | } // namespace boost | |
138 | ||
139 | #include <boost/log/detail/footer.hpp> | |
140 | ||
141 | #endif // BOOST_LOG_SINKS_UNBOUNDED_FIFO_QUEUE_HPP_INCLUDED_ |