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//////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Ion Gaztanaga 2005-2011. 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)
//
// See http://www.boost.org/libs/interprocess for documentation.
//
//////////////////////////////////////////////////////////////////////////////
#ifndef BOOST_INTERPROCESS_DETAIL_SPIN_SEMAPHORE_HPP
#define BOOST_INTERPROCESS_DETAIL_SPIN_SEMAPHORE_HPP
#if (defined _MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif
#include <boost/interprocess/detail/config_begin.hpp>
#include <boost/interprocess/detail/workaround.hpp>
#include <boost/interprocess/detail/atomic.hpp>
#include <boost/interprocess/detail/os_thread_functions.hpp>
#include <boost/interprocess/detail/posix_time_types_wrk.hpp>
#include <boost/cstdint.hpp>
namespace boost {
namespace interprocess {
namespace ipcdetail {
class spin_semaphore
{
spin_semaphore(const spin_semaphore &);
spin_semaphore &operator=(const spin_semaphore &);
public:
spin_semaphore(unsigned int initialCount);
~spin_semaphore();
void post();
void wait();
bool try_wait();
bool timed_wait(const boost::posix_time::ptime &abs_time);
// int get_count() const;
private:
volatile boost::uint32_t m_count;
};
inline spin_semaphore::~spin_semaphore()
{}
inline spin_semaphore::spin_semaphore(unsigned int initialCount)
{ ipcdetail::atomic_write32(&this->m_count, boost::uint32_t(initialCount)); }
inline void spin_semaphore::post()
{
ipcdetail::atomic_inc32(&m_count);
}
inline void spin_semaphore::wait()
{
while(!ipcdetail::atomic_add_unless32(&m_count, boost::uint32_t(-1), boost::uint32_t(0))){
while(ipcdetail::atomic_read32(&m_count) == 0){
ipcdetail::thread_yield();
}
}
}
inline bool spin_semaphore::try_wait()
{
return ipcdetail::atomic_add_unless32(&m_count, boost::uint32_t(-1), boost::uint32_t(0));
}
inline bool spin_semaphore::timed_wait(const boost::posix_time::ptime &abs_time)
{
if(abs_time == boost::posix_time::pos_infin){
this->wait();
return true;
}
//Obtain current count and target time
boost::posix_time::ptime now(microsec_clock::universal_time());
do{
if(this->try_wait()){
break;
}
now = microsec_clock::universal_time();
if(now >= abs_time){
return this->try_wait();
}
// relinquish current time slice
ipcdetail::thread_yield();
}while (true);
return true;
}
//inline int spin_semaphore::get_count() const
//{
//return (int)ipcdetail::atomic_read32(&m_count);
//}
} //namespace ipcdetail {
} //namespace interprocess {
} //namespace boost {
#include <boost/interprocess/detail/config_end.hpp>
#endif //BOOST_INTERPROCESS_DETAIL_SPIN_SEMAPHORE_HPP
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