forked from boostorg/smart_ptr
131 lines
2.8 KiB
C++
131 lines
2.8 KiB
C++
#ifndef BOOST_DETAIL_SP_COUNTED_BASE_W32_HPP_INCLUDED
|
|
#define BOOST_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 <typeinfo>
|
|
|
|
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( std::type_info 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_DETAIL_SP_COUNTED_BASE_W32_HPP_INCLUDED
|