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/*
* Copyright Andrey Semashev 2007 - 2015.
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying file LICENSE_1_0.txt or copy at
* http://www.boost.org/LICENSE_1_0.txt)
*/
/*!
* \file adaptive_mutex.hpp
* \author Andrey Semashev
* \date 01.08.2010
*
* \brief This header is the Boost.Log library implementation, see the library documentation
* at http://www.boost.org/doc/libs/release/libs/log/doc/html/index.html.
*/
#ifndef BOOST_LOG_DETAIL_ADAPTIVE_MUTEX_HPP_INCLUDED_
#define BOOST_LOG_DETAIL_ADAPTIVE_MUTEX_HPP_INCLUDED_
#include <boost/log/detail/config.hpp>
#ifdef BOOST_HAS_PRAGMA_ONCE
#pragma once
#endif
#ifndef BOOST_LOG_NO_THREADS
#include <boost/throw_exception.hpp>
#include <boost/thread/exceptions.hpp>
#if defined(BOOST_THREAD_POSIX) // This one can be defined by users, so it should go first
#define BOOST_LOG_ADAPTIVE_MUTEX_USE_PTHREAD
#elif defined(BOOST_WINDOWS)
#define BOOST_LOG_ADAPTIVE_MUTEX_USE_WINAPI
#elif defined(BOOST_HAS_PTHREADS)
#define BOOST_LOG_ADAPTIVE_MUTEX_USE_PTHREAD
#endif
#if defined(BOOST_LOG_ADAPTIVE_MUTEX_USE_WINAPI)
#include <boost/log/detail/pause.hpp>
#include <boost/winapi/thread.hpp>
#include <boost/detail/interlocked.hpp>
#if defined(__INTEL_COMPILER) || defined(_MSC_VER)
# if defined(__INTEL_COMPILER)
# define BOOST_LOG_COMPILER_BARRIER __memory_barrier()
# else
extern "C" void _ReadWriteBarrier(void);
# if defined(BOOST_MSVC)
# pragma intrinsic(_ReadWriteBarrier)
# endif
# define BOOST_LOG_COMPILER_BARRIER _ReadWriteBarrier()
# endif
#elif defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
# define BOOST_LOG_COMPILER_BARRIER __asm__ __volatile__("" : : : "memory")
#endif
#include <boost/log/detail/header.hpp>
namespace boost {
BOOST_LOG_OPEN_NAMESPACE
namespace aux {
//! A mutex that performs spinning or thread yielding in case of contention
class adaptive_mutex
{
private:
enum state
{
initial_pause = 2,
max_pause = 16
};
long m_State;
public:
adaptive_mutex() : m_State(0) {}
bool try_lock()
{
return (BOOST_INTERLOCKED_COMPARE_EXCHANGE(&m_State, 1L, 0L) == 0L);
}
void lock()
{
#if defined(BOOST_LOG_AUX_PAUSE)
unsigned int pause_count = initial_pause;
#endif
while (!try_lock())
{
#if defined(BOOST_LOG_AUX_PAUSE)
if (pause_count < max_pause)
{
for (unsigned int i = 0; i < pause_count; ++i)
{
BOOST_LOG_AUX_PAUSE;
}
pause_count += pause_count;
}
else
{
// Restart spinning after waking up this thread
pause_count = initial_pause;
boost::winapi::SwitchToThread();
}
#else
boost::winapi::SwitchToThread();
#endif
}
}
void unlock()
{
#if (defined(_M_IX86) || defined(_M_AMD64)) && defined(BOOST_LOG_COMPILER_BARRIER)
BOOST_LOG_COMPILER_BARRIER;
m_State = 0L;
BOOST_LOG_COMPILER_BARRIER;
#else
BOOST_INTERLOCKED_EXCHANGE(&m_State, 0L);
#endif
}
// Non-copyable
BOOST_DELETED_FUNCTION(adaptive_mutex(adaptive_mutex const&))
BOOST_DELETED_FUNCTION(adaptive_mutex& operator= (adaptive_mutex const&))
};
#undef BOOST_LOG_AUX_PAUSE
#undef BOOST_LOG_COMPILER_BARRIER
} // namespace aux
BOOST_LOG_CLOSE_NAMESPACE // namespace log
} // namespace boost
#include <boost/log/detail/footer.hpp>
#elif defined(BOOST_LOG_ADAPTIVE_MUTEX_USE_PTHREAD)
#include <pthread.h>
#include <boost/assert.hpp>
#include <boost/log/detail/header.hpp>
#if defined(PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP)
#define BOOST_LOG_ADAPTIVE_MUTEX_USE_PTHREAD_MUTEX_ADAPTIVE_NP
#endif
namespace boost {
BOOST_LOG_OPEN_NAMESPACE
namespace aux {
//! A mutex that performs spinning or thread yielding in case of contention
class adaptive_mutex
{
private:
pthread_mutex_t m_State;
public:
adaptive_mutex()
{
#if defined(BOOST_LOG_ADAPTIVE_MUTEX_USE_PTHREAD_MUTEX_ADAPTIVE_NP)
pthread_mutexattr_t attrs;
pthread_mutexattr_init(&attrs);
pthread_mutexattr_settype(&attrs, PTHREAD_MUTEX_ADAPTIVE_NP);
const int err = pthread_mutex_init(&m_State, &attrs);
pthread_mutexattr_destroy(&attrs);
#else
const int err = pthread_mutex_init(&m_State, NULL);
#endif
if (BOOST_UNLIKELY(err != 0))
throw_exception< thread_resource_error >(err, "Failed to initialize an adaptive mutex", "adaptive_mutex::adaptive_mutex()", __FILE__, __LINE__);
}
~adaptive_mutex()
{
BOOST_VERIFY(pthread_mutex_destroy(&m_State) == 0);
}
bool try_lock()
{
const int err = pthread_mutex_trylock(&m_State);
if (err == 0)
return true;
if (BOOST_UNLIKELY(err != EBUSY))
throw_exception< lock_error >(err, "Failed to lock an adaptive mutex", "adaptive_mutex::try_lock()", __FILE__, __LINE__);
return false;
}
void lock()
{
const int err = pthread_mutex_lock(&m_State);
if (BOOST_UNLIKELY(err != 0))
throw_exception< lock_error >(err, "Failed to lock an adaptive mutex", "adaptive_mutex::lock()", __FILE__, __LINE__);
}
void unlock()
{
BOOST_VERIFY(pthread_mutex_unlock(&m_State) == 0);
}
// Non-copyable
BOOST_DELETED_FUNCTION(adaptive_mutex(adaptive_mutex const&))
BOOST_DELETED_FUNCTION(adaptive_mutex& operator= (adaptive_mutex const&))
private:
template< typename ExceptionT >
static BOOST_NOINLINE BOOST_LOG_NORETURN void throw_exception(int err, const char* descr, const char* func, const char* file, int line)
{
#if !defined(BOOST_EXCEPTION_DISABLE)
boost::exception_detail::throw_exception_(ExceptionT(err, descr), func, file, line);
#else
boost::throw_exception(ExceptionT(err, descr));
#endif
}
};
} // namespace aux
BOOST_LOG_CLOSE_NAMESPACE // namespace log
} // namespace boost
#include <boost/log/detail/footer.hpp>
#endif
#endif // BOOST_LOG_NO_THREADS
#endif // BOOST_LOG_DETAIL_ADAPTIVE_MUTEX_HPP_INCLUDED_
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