boost/smart_ptr/detail/spinlock_sync.hpp

#ifndef BOOST_SMART_PTR_DETAIL_SPINLOCK_SYNC_HPP_INCLUDED
#define BOOST_SMART_PTR_DETAIL_SPINLOCK_SYNC_HPP_INCLUDED
// MS compatible compilers support #pragma once
#if defined(_MSC_VER) && (_MSC_VER >= 1020)
# pragma once
#endif
//
//  Copyright (c) 2008 Peter Dimov
//
//  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/smart_ptr/detail/yield_k.hpp>
#if defined( __ia64__ ) && defined( __INTEL_COMPILER )
# include <ia64intrin.h>
#endif
namespace boost
{
namespace detail
{
class spinlock
{
public:
    int v_;
public:
    bool try_lock()
    {
        int r = __sync_lock_test_and_set( &v_, 1 );
        return r == 0;
    }
    void lock()
    {
        for( unsigned k = 0; !try_lock(); ++k )
        {
            boost::detail::yield( k );
        }
    }
    void unlock()
    {
        __sync_lock_release( &v_ );
    }
public:
    class scoped_lock
    {
    private:
        spinlock & sp_;
        scoped_lock( scoped_lock const & );
        scoped_lock & operator=( scoped_lock const & );
    public:
        explicit scoped_lock( spinlock & sp ): sp_( sp )
        {
            sp.lock();
        }
        ~scoped_lock()
        {
            sp_.unlock();
        }
    };
};
} // namespace detail
} // namespace boost
#define BOOST_DETAIL_SPINLOCK_INIT {0}
#endif // #ifndef BOOST_SMART_PTR_DETAIL_SPINLOCK_SYNC_HPP_INCLUDED