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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