126 lines
4.0 KiB
C++
126 lines
4.0 KiB
C++
#ifndef BOOST_THREAD_PTHREAD_ONCE_HPP
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#define BOOST_THREAD_PTHREAD_ONCE_HPP
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// once.hpp
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//
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// (C) Copyright 2007-8 Anthony Williams
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// (C) Copyright 2011-2012 Vicente J. Botet Escriba
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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#include <boost/thread/detail/config.hpp>
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#include <boost/thread/pthread/pthread_mutex_scoped_lock.hpp>
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#include <boost/thread/detail/delete.hpp>
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#include <boost/detail/no_exceptions_support.hpp>
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#include <boost/assert.hpp>
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#include <boost/config/abi_prefix.hpp>
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#include <boost/cstdint.hpp>
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#include <pthread.h>
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#include <csignal>
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namespace boost
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{
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#define BOOST_ONCE_INITIAL_FLAG_VALUE 0
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namespace thread_detail
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{
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//#ifdef SIG_ATOMIC_MAX
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// typedef sig_atomic_t uintmax_atomic_t;
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// #define BOOST_THREAD_DETAIL_UINTMAX_ATOMIC_MAX_C SIG_ATOMIC_MAX
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//#else
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typedef unsigned long uintmax_atomic_t;
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#define BOOST_THREAD_DETAIL_UINTMAX_ATOMIC_C2(value) value##ul
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#define BOOST_THREAD_DETAIL_UINTMAX_ATOMIC_MAX_C BOOST_THREAD_DETAIL_UINTMAX_ATOMIC_C2(~0)
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//#endif
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}
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#ifdef BOOST_THREAD_PROVIDES_ONCE_CXX11
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struct once_flag
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{
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BOOST_THREAD_NO_COPYABLE(once_flag)
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BOOST_CONSTEXPR once_flag() BOOST_NOEXCEPT
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: epoch(BOOST_ONCE_INITIAL_FLAG_VALUE)
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{}
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private:
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volatile thread_detail::uintmax_atomic_t epoch;
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template<typename Function>
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friend
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void call_once(once_flag& flag,Function f);
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};
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#else // BOOST_THREAD_PROVIDES_ONCE_CXX11
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struct once_flag
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{
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volatile thread_detail::uintmax_atomic_t epoch;
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};
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#define BOOST_ONCE_INIT {BOOST_ONCE_INITIAL_FLAG_VALUE}
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#endif // BOOST_THREAD_PROVIDES_ONCE_CXX11
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namespace detail
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{
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BOOST_THREAD_DECL thread_detail::uintmax_atomic_t& get_once_per_thread_epoch();
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BOOST_THREAD_DECL extern thread_detail::uintmax_atomic_t once_global_epoch;
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BOOST_THREAD_DECL extern pthread_mutex_t once_epoch_mutex;
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BOOST_THREAD_DECL extern pthread_cond_t once_epoch_cv;
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}
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// Based on Mike Burrows fast_pthread_once algorithm as described in
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// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2444.html
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template<typename Function>
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void call_once(once_flag& flag,Function f)
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{
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static thread_detail::uintmax_atomic_t const uninitialized_flag=BOOST_ONCE_INITIAL_FLAG_VALUE;
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static thread_detail::uintmax_atomic_t const being_initialized=uninitialized_flag+1;
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thread_detail::uintmax_atomic_t const epoch=flag.epoch;
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thread_detail::uintmax_atomic_t& this_thread_epoch=detail::get_once_per_thread_epoch();
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if(epoch<this_thread_epoch)
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{
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pthread::pthread_mutex_scoped_lock lk(&detail::once_epoch_mutex);
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while(flag.epoch<=being_initialized)
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{
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if(flag.epoch==uninitialized_flag)
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{
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flag.epoch=being_initialized;
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BOOST_TRY
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{
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pthread::pthread_mutex_scoped_unlock relocker(&detail::once_epoch_mutex);
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f();
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}
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BOOST_CATCH (...)
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{
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flag.epoch=uninitialized_flag;
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BOOST_VERIFY(!pthread_cond_broadcast(&detail::once_epoch_cv));
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BOOST_RETHROW
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}
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BOOST_CATCH_END
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flag.epoch=--detail::once_global_epoch;
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BOOST_VERIFY(!pthread_cond_broadcast(&detail::once_epoch_cv));
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}
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else
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{
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while(flag.epoch==being_initialized)
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{
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BOOST_VERIFY(!pthread_cond_wait(&detail::once_epoch_cv,&detail::once_epoch_mutex));
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}
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}
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}
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this_thread_epoch=detail::once_global_epoch;
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}
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}
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}
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#include <boost/config/abi_suffix.hpp>
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#endif
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