/Users/dlarimer/dev/libs/cmt/include/boost/cmt/mutex.hpp

#ifndef _BOOST_CMT_MUTEX_HPP_
#define _BOOST_CMT_MUTEX_HPP_
#include <boost/atomic.hpp>
#include <boost/memory_order.hpp>

namespace boost{ namespace cmt {
    void yield();

    class mutex {
        public:
            mutex():m_state(unlocked){}

            inline bool try_lock() {
                return m_state.exchange(locked, boost::memory_order_acquire)!=locked;
            }

            template<typename DurationType>
            bool timed_lock( const DurationType& rel_time ) {
                return timed_lock( boost::get_system_time() + rel_time );
            }

            bool timed_lock( const boost::system_time& abs_time) {
                while( abs_time > boost::get_system_time() ) {
                   if( try_lock() )
                     return true;
                   yield(); 
                }
                return false;
            }
            void lock() {
                while( m_state.exchange(locked, boost::memory_order_acquire)==locked) {
                   yield(); 
                }
            }
            void unlock() {
                m_state.store(unlocked, boost::memory_order_release);
            }
            
        private:
            enum lock_state {locked,unlocked};
            boost::atomic<lock_state> m_state;
    };

} } // namespace boost::cmt

#endif // _BOOST_CMT_MUTEX_HPP_