#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 |