/Src/Dependencies/Boost/boost/thread/pthread/once.hpp
http://hadesmem.googlecode.com/ · C++ Header · 95 lines · 72 code · 14 blank · 9 comment · 4 complexity · 45acd5ebda8e0b6a2a92146b2ad5f1c4 MD5 · raw file
- #ifndef BOOST_THREAD_PTHREAD_ONCE_HPP
- #define BOOST_THREAD_PTHREAD_ONCE_HPP
- // once.hpp
- //
- // (C) Copyright 2007-8 Anthony Williams
- //
- // 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/config.hpp>
- #include <pthread.h>
- #include <boost/assert.hpp>
- #include "pthread_mutex_scoped_lock.hpp"
- #include <boost/thread/pthread/pthread_mutex_scoped_lock.hpp>
- #include <boost/cstdint.hpp>
- #include <boost/config/abi_prefix.hpp>
- namespace boost
- {
- struct once_flag
- {
- boost::uintmax_t epoch;
- };
- namespace detail
- {
- BOOST_THREAD_DECL boost::uintmax_t& get_once_per_thread_epoch();
- BOOST_THREAD_DECL extern boost::uintmax_t once_global_epoch;
- BOOST_THREAD_DECL extern pthread_mutex_t once_epoch_mutex;
- BOOST_THREAD_DECL extern pthread_cond_t once_epoch_cv;
- }
-
- #define BOOST_ONCE_INITIAL_FLAG_VALUE 0
- #define BOOST_ONCE_INIT {BOOST_ONCE_INITIAL_FLAG_VALUE}
- // 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 boost::uintmax_t const uninitialized_flag=BOOST_ONCE_INITIAL_FLAG_VALUE;
- static boost::uintmax_t const being_initialized=uninitialized_flag+1;
- boost::uintmax_t const epoch=flag.epoch;
- boost::uintmax_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;
- #ifndef BOOST_NO_EXCEPTIONS
- try
- {
- #endif
- pthread::pthread_mutex_scoped_unlock relocker(&detail::once_epoch_mutex);
- f();
- #ifndef BOOST_NO_EXCEPTIONS
- }
- catch(...)
- {
- flag.epoch=uninitialized_flag;
- BOOST_VERIFY(!pthread_cond_broadcast(&detail::once_epoch_cv));
- throw;
- }
- #endif
- 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