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 adaptive_mutex.hpp
9 * \author Andrey Semashev
10 * \date 01.08.2010
11 *
12 * \brief This header is the Boost.Log library implementation, see the library documentation
13 * at http://www.boost.org/doc/libs/release/libs/log/doc/html/index.html.
14 */
15
16#ifndef BOOST_LOG_DETAIL_ADAPTIVE_MUTEX_HPP_INCLUDED_
17#define BOOST_LOG_DETAIL_ADAPTIVE_MUTEX_HPP_INCLUDED_
18
19#include <boost/log/detail/config.hpp>
20
21#ifdef BOOST_HAS_PRAGMA_ONCE
22#pragma once
23#endif
24
25#ifndef BOOST_LOG_NO_THREADS
26
27#include <boost/throw_exception.hpp>
28#include <boost/thread/exceptions.hpp>
29#include <boost/assert/source_location.hpp>
30
31#if defined(BOOST_THREAD_POSIX) // This one can be defined by users, so it should go first
32#define BOOST_LOG_ADAPTIVE_MUTEX_USE_PTHREAD
33#elif defined(BOOST_WINDOWS)
34#define BOOST_LOG_ADAPTIVE_MUTEX_USE_WINAPI
35#elif defined(BOOST_HAS_PTHREADS)
36#define BOOST_LOG_ADAPTIVE_MUTEX_USE_PTHREAD
37#endif
38
39#if defined(BOOST_LOG_ADAPTIVE_MUTEX_USE_WINAPI)
40
41#include <boost/log/detail/pause.hpp>
42#include <boost/winapi/thread.hpp>
43#include <boost/detail/interlocked.hpp>
44
45#if defined(__INTEL_COMPILER) || defined(_MSC_VER)
46# if defined(__INTEL_COMPILER)
47# define BOOST_LOG_COMPILER_BARRIER __memory_barrier()
48# elif defined(__clang__) // clang-win also defines _MSC_VER
49# define BOOST_LOG_COMPILER_BARRIER __atomic_signal_fence(__ATOMIC_SEQ_CST)
50# else
51extern "C" void _ReadWriteBarrier(void);
52# if defined(BOOST_MSVC)
53# pragma intrinsic(_ReadWriteBarrier)
54# endif
55# define BOOST_LOG_COMPILER_BARRIER _ReadWriteBarrier()
56# endif
57#elif defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
58# define BOOST_LOG_COMPILER_BARRIER __asm__ __volatile__("" : : : "memory")
59#endif
60
61#include <boost/log/detail/header.hpp>
62
63namespace boost {
64
65BOOST_LOG_OPEN_NAMESPACE
66
67namespace aux {
68
69//! A mutex that performs spinning or thread yielding in case of contention
70class adaptive_mutex
71{
72private:
73 enum state
74 {
75 initial_pause = 2,
76 max_pause = 16
77 };
78
79 long m_State;
80
81public:
82 adaptive_mutex() : m_State(0) {}
83
84 bool try_lock()
85 {
86 return (BOOST_INTERLOCKED_COMPARE_EXCHANGE(&m_State, 1L, 0L) == 0L);
87 }
88
89 void lock()
90 {
91#if defined(BOOST_LOG_AUX_PAUSE)
92 unsigned int pause_count = initial_pause;
93#endif
94 while (!try_lock())
95 {
96#if defined(BOOST_LOG_AUX_PAUSE)
97 if (pause_count < max_pause)
98 {
99 for (unsigned int i = 0; i < pause_count; ++i)
100 {
101 BOOST_LOG_AUX_PAUSE;
102 }
103 pause_count += pause_count;
104 }
105 else
106 {
107 // Restart spinning after waking up this thread
108 pause_count = initial_pause;
109 boost::winapi::SwitchToThread();
110 }
111#else
112 boost::winapi::SwitchToThread();
113#endif
114 }
115 }
116
117 void unlock()
118 {
119#if (defined(_M_IX86) || defined(_M_AMD64)) && defined(BOOST_LOG_COMPILER_BARRIER)
120 BOOST_LOG_COMPILER_BARRIER;
121 m_State = 0L;
122 BOOST_LOG_COMPILER_BARRIER;
123#else
124 BOOST_INTERLOCKED_EXCHANGE(&m_State, 0L);
125#endif
126 }
127
128 // Non-copyable
129 BOOST_DELETED_FUNCTION(adaptive_mutex(adaptive_mutex const&))
130 BOOST_DELETED_FUNCTION(adaptive_mutex& operator= (adaptive_mutex const&))
131};
132
133#undef BOOST_LOG_AUX_PAUSE
134#undef BOOST_LOG_COMPILER_BARRIER
135
136} // namespace aux
137
138BOOST_LOG_CLOSE_NAMESPACE // namespace log
139
140} // namespace boost
141
142#include <boost/log/detail/footer.hpp>
143
144#elif defined(BOOST_LOG_ADAPTIVE_MUTEX_USE_PTHREAD)
145
146#include <pthread.h>
147#include <boost/assert.hpp>
148#include <boost/log/detail/header.hpp>
149
150#if defined(PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP)
151#define BOOST_LOG_ADAPTIVE_MUTEX_USE_PTHREAD_MUTEX_ADAPTIVE_NP
152#endif
153
154namespace boost {
155
156BOOST_LOG_OPEN_NAMESPACE
157
158namespace aux {
159
160//! A mutex that performs spinning or thread yielding in case of contention
161class adaptive_mutex
162{
163private:
164 pthread_mutex_t m_State;
165
166public:
167 adaptive_mutex()
168 {
169#if defined(BOOST_LOG_ADAPTIVE_MUTEX_USE_PTHREAD_MUTEX_ADAPTIVE_NP)
170 pthread_mutexattr_t attrs;
171 pthread_mutexattr_init(attr: &attrs);
172 pthread_mutexattr_settype(attr: &attrs, kind: PTHREAD_MUTEX_ADAPTIVE_NP);
173
174 const int err = pthread_mutex_init(mutex: &m_State, mutexattr: &attrs);
175 pthread_mutexattr_destroy(attr: &attrs);
176#else
177 const int err = pthread_mutex_init(&m_State, NULL);
178#endif
179 if (BOOST_UNLIKELY(err != 0))
180 throw_exception< thread_resource_error >(err, descr: "Failed to initialize an adaptive mutex", func: "adaptive_mutex::adaptive_mutex()", __FILE__, __LINE__);
181 }
182
183 ~adaptive_mutex()
184 {
185 BOOST_VERIFY(pthread_mutex_destroy(&m_State) == 0);
186 }
187
188 bool try_lock()
189 {
190 const int err = pthread_mutex_trylock(mutex: &m_State);
191 if (err == 0)
192 return true;
193 if (BOOST_UNLIKELY(err != EBUSY))
194 throw_exception< lock_error >(err, descr: "Failed to lock an adaptive mutex", func: "adaptive_mutex::try_lock()", __FILE__, __LINE__);
195 return false;
196 }
197
198 void lock()
199 {
200 const int err = pthread_mutex_lock(mutex: &m_State);
201 if (BOOST_UNLIKELY(err != 0))
202 throw_exception< lock_error >(err, descr: "Failed to lock an adaptive mutex", func: "adaptive_mutex::lock()", __FILE__, __LINE__);
203 }
204
205 void unlock()
206 {
207 BOOST_VERIFY(pthread_mutex_unlock(&m_State) == 0);
208 }
209
210 // Non-copyable
211 BOOST_DELETED_FUNCTION(adaptive_mutex(adaptive_mutex const&))
212 BOOST_DELETED_FUNCTION(adaptive_mutex& operator= (adaptive_mutex const&))
213
214private:
215 template< typename ExceptionT >
216 static BOOST_NOINLINE BOOST_LOG_NORETURN void throw_exception(int err, const char* descr, const char* func, const char* file, int line)
217 {
218 boost::throw_exception(ExceptionT(err, descr), boost::source_location(file, line, func));
219 }
220};
221
222} // namespace aux
223
224BOOST_LOG_CLOSE_NAMESPACE // namespace log
225
226} // namespace boost
227
228#include <boost/log/detail/footer.hpp>
229
230#endif
231
232#endif // BOOST_LOG_NO_THREADS
233
234#endif // BOOST_LOG_DETAIL_ADAPTIVE_MUTEX_HPP_INCLUDED_
235

source code of boost/libs/log/include/boost/log/detail/adaptive_mutex.hpp