#ifndef BOOST_DETAIL_LWM_LINUX_HPP_INCLUDED#define BOOST_DETAIL_LWM_LINUX_HPP_INCLUDED////  boost/detail/lwm_linux.hpp////  Copyright (c) 2002 Peter Dimov and Multi Media Ltd.//// 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)//////  This implementation uses <asm/atomic.h>. This is a kernel header;//  using kernel headers in a user program may cause a number of problems,//  and not all flavors of Linux provide the atomic instructions.////  This file is only provided because the performance of this implementation//  is about 3.5 times higher than the pthreads version. Use at your own risk//  (by defining BOOST_USE_ASM_ATOMIC_H.)//#include <asm/atomic.h>#include <sched.h>namespace boost{namespace detail{class lightweight_mutex{private:    atomic_t a_;    lightweight_mutex(lightweight_mutex const &);    lightweight_mutex & operator=(lightweight_mutex const &);public:    lightweight_mutex()    {        atomic_t a = ATOMIC_INIT(1);        a_ = a;    }    class scoped_lock;    friend class scoped_lock;    class scoped_lock    {    private:        lightweight_mutex & m_;        scoped_lock(scoped_lock const &);        scoped_lock & operator=(scoped_lock const &);    public:        explicit scoped_lock(lightweight_mutex & m): m_(m)        {            while( !atomic_dec_and_test(&m_.a_) )            {                atomic_inc(&m_.a_);                sched_yield();            }        }        ~scoped_lock()        {            atomic_inc(&m_.a_);        }    };};} // namespace detail} // namespace boost#endif // #ifndef BOOST_DETAIL_LWM_LINUX_HPP_INCLUDED