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/*
* 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)
*
* Copyright (c) 2011 Helge Bahmann
* Copyright (c) 2013-2014 Andrey Semashev
*/
/*!
* \file lockpool.cpp
*
* This file contains implementation of the lockpool used to emulate atomic ops.
*/
#include <cstddef>
#include <boost/config.hpp>
#include <boost/assert.hpp>
#include <boost/memory_order.hpp>
#include <boost/atomic/capabilities.hpp>
#if BOOST_ATOMIC_FLAG_LOCK_FREE == 2
#include <boost/atomic/detail/operations_lockfree.hpp>
#elif !defined(BOOST_HAS_PTHREADS)
#error Boost.Atomic: Unsupported target platform, POSIX threads are required when native atomic operations are not available
#else
#include <pthread.h>
#define BOOST_ATOMIC_USE_PTHREAD
#endif
#include <boost/atomic/detail/lockpool.hpp>
#include <boost/atomic/detail/pause.hpp>
namespace boost {
namespace atomics {
namespace detail {
namespace {
// This seems to be the maximum across all modern CPUs
// NOTE: This constant is made as a macro because some compilers (gcc 4.4 for one) don't allow enums or namespace scope constants in alignment attributes
#define BOOST_ATOMIC_CACHE_LINE_SIZE 64
template< unsigned int N >
struct padding
{
char data[N];
};
template< >
struct padding< 0 >
{
};
struct BOOST_ALIGNMENT(BOOST_ATOMIC_CACHE_LINE_SIZE) padded_lock
{
#if defined(BOOST_ATOMIC_USE_PTHREAD)
typedef pthread_mutex_t lock_type;
#else
typedef atomics::detail::operations< 1u, false > operations;
typedef operations::storage_type lock_type;
#endif
lock_type lock;
// The additional padding is needed to avoid false sharing between locks
enum { padding_size = (sizeof(lock_type) <= BOOST_ATOMIC_CACHE_LINE_SIZE ?
(BOOST_ATOMIC_CACHE_LINE_SIZE - sizeof(lock_type)) :
(BOOST_ATOMIC_CACHE_LINE_SIZE - sizeof(lock_type) % BOOST_ATOMIC_CACHE_LINE_SIZE)) };
padding< padding_size > pad;
};
static padded_lock g_lock_pool[41]
#if defined(BOOST_ATOMIC_USE_PTHREAD)
=
{
PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
PTHREAD_MUTEX_INITIALIZER
}
#endif
;
} // namespace
#if !defined(BOOST_ATOMIC_USE_PTHREAD)
// NOTE: This function must NOT be inline. Otherwise MSVC 9 will sometimes generate broken code for modulus operation which result in crashes.
BOOST_ATOMIC_DECL lockpool::scoped_lock::scoped_lock(const volatile void* addr) BOOST_NOEXCEPT :
m_lock(&g_lock_pool[reinterpret_cast< std::size_t >(addr) % (sizeof(g_lock_pool) / sizeof(*g_lock_pool))].lock)
{
while (padded_lock::operations::test_and_set(*static_cast< padded_lock::lock_type* >(m_lock), memory_order_acquire))
{
atomics::detail::pause();
}
}
BOOST_ATOMIC_DECL lockpool::scoped_lock::~scoped_lock() BOOST_NOEXCEPT
{
padded_lock::operations::clear(*static_cast< padded_lock::lock_type* >(m_lock), memory_order_release);
}
BOOST_ATOMIC_DECL void signal_fence() BOOST_NOEXCEPT;
#else // !defined(BOOST_ATOMIC_USE_PTHREAD)
BOOST_ATOMIC_DECL lockpool::scoped_lock::scoped_lock(const volatile void* addr) BOOST_NOEXCEPT :
m_lock(&g_lock_pool[reinterpret_cast< std::size_t >(addr) % (sizeof(g_lock_pool) / sizeof(*g_lock_pool))].lock)
{
BOOST_VERIFY(pthread_mutex_lock(static_cast< pthread_mutex_t* >(m_lock)) == 0);
}
BOOST_ATOMIC_DECL lockpool::scoped_lock::~scoped_lock() BOOST_NOEXCEPT
{
BOOST_VERIFY(pthread_mutex_unlock(static_cast< pthread_mutex_t* >(m_lock)) == 0);
}
#endif // !defined(BOOST_ATOMIC_USE_PTHREAD)
BOOST_ATOMIC_DECL void lockpool::thread_fence() BOOST_NOEXCEPT
{
#if BOOST_ATOMIC_THREAD_FENCE > 0
atomics::detail::thread_fence(memory_order_seq_cst);
#else
// Emulate full fence by locking/unlocking a mutex
scoped_lock lock(0);
#endif
}
BOOST_ATOMIC_DECL void lockpool::signal_fence() BOOST_NOEXCEPT
{
// This function is intentionally non-inline, even if empty. This forces the compiler to treat its call as a compiler barrier.
#if BOOST_ATOMIC_SIGNAL_FENCE > 0
atomics::detail::signal_fence(memory_order_seq_cst);
#endif
}
} // namespace detail
} // namespace atomics
} // namespace boost
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