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