#ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_W32_HPP_INCLUDED | |
#define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_W32_HPP_INCLUDED | |
// MS compatible compilers support #pragma once | |
#if defined(_MSC_VER) && (_MSC_VER >= 1020) | |
# pragma once | |
#endif | |
// | |
// detail/sp_counted_base_w32.hpp | |
// | |
// Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd. | |
// Copyright 2004-2005 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) | |
// | |
// | |
// Lock-free algorithm by Alexander Terekhov | |
// | |
// Thanks to Ben Hitchings for the #weak + (#shared != 0) | |
// formulation | |
// | |
#include <boost/detail/interlocked.hpp> | |
#include <boost/detail/workaround.hpp> | |
#include <boost/detail/sp_typeinfo.hpp> | |
namespace boost | |
{ | |
namespace detail | |
{ | |
class sp_counted_base | |
{ | |
private: | |
sp_counted_base( sp_counted_base const & ); | |
sp_counted_base & operator= ( sp_counted_base const & ); | |
long use_count_; // #shared | |
long weak_count_; // #weak + (#shared != 0) | |
public: | |
sp_counted_base(): use_count_( 1 ), weak_count_( 1 ) | |
{ | |
} | |
virtual ~sp_counted_base() // nothrow | |
{ | |
} | |
// dispose() is called when use_count_ drops to zero, to release | |
// the resources managed by *this. | |
virtual void dispose() = 0; // nothrow | |
// destroy() is called when weak_count_ drops to zero. | |
virtual void destroy() // nothrow | |
{ | |
delete this; | |
} | |
virtual void * get_deleter( sp_typeinfo const & ti ) = 0; | |
void add_ref_copy() | |
{ | |
BOOST_INTERLOCKED_INCREMENT( &use_count_ ); | |
} | |
bool add_ref_lock() // true on success | |
{ | |
for( ;; ) | |
{ | |
long tmp = static_cast< long const volatile& >( use_count_ ); | |
if( tmp == 0 ) return false; | |
#if defined( BOOST_MSVC ) && BOOST_WORKAROUND( BOOST_MSVC, == 1200 ) | |
// work around a code generation bug | |
long tmp2 = tmp + 1; | |
if( BOOST_INTERLOCKED_COMPARE_EXCHANGE( &use_count_, tmp2, tmp ) == tmp2 - 1 ) return true; | |
#else | |
if( BOOST_INTERLOCKED_COMPARE_EXCHANGE( &use_count_, tmp + 1, tmp ) == tmp ) return true; | |
#endif | |
} | |
} | |
void release() // nothrow | |
{ | |
if( BOOST_INTERLOCKED_DECREMENT( &use_count_ ) == 0 ) | |
{ | |
dispose(); | |
weak_release(); | |
} | |
} | |
void weak_add_ref() // nothrow | |
{ | |
BOOST_INTERLOCKED_INCREMENT( &weak_count_ ); | |
} | |
void weak_release() // nothrow | |
{ | |
if( BOOST_INTERLOCKED_DECREMENT( &weak_count_ ) == 0 ) | |
{ | |
destroy(); | |
} | |
} | |
long use_count() const // nothrow | |
{ | |
return static_cast<long const volatile &>( use_count_ ); | |
} | |
}; | |
} // namespace detail | |
} // namespace boost | |
#endif // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_W32_HPP_INCLUDED |