131 lines
3.0 KiB
C++
131 lines
3.0 KiB
C++
#ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_W32_HPP_INCLUDED
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#define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_W32_HPP_INCLUDED
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// MS compatible compilers support #pragma once
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#if defined(_MSC_VER) && (_MSC_VER >= 1020)
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# pragma once
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#endif
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//
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// detail/sp_counted_base_w32.hpp
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//
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// Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
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// Copyright 2004-2005 Peter Dimov
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//
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//
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// Lock-free algorithm by Alexander Terekhov
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//
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// Thanks to Ben Hitchings for the #weak + (#shared != 0)
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// formulation
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//
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#include <boost/detail/interlocked.hpp>
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#include <boost/detail/workaround.hpp>
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#include <boost/detail/sp_typeinfo.hpp>
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namespace boost
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{
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namespace detail
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{
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class sp_counted_base
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{
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private:
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sp_counted_base( sp_counted_base const & );
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sp_counted_base & operator= ( sp_counted_base const & );
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long use_count_; // #shared
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long weak_count_; // #weak + (#shared != 0)
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public:
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sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
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{
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}
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virtual ~sp_counted_base() // nothrow
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{
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}
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// dispose() is called when use_count_ drops to zero, to release
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// the resources managed by *this.
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virtual void dispose() = 0; // nothrow
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// destroy() is called when weak_count_ drops to zero.
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virtual void destroy() // nothrow
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{
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delete this;
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}
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virtual void * get_deleter( sp_typeinfo const & ti ) = 0;
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void add_ref_copy()
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{
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BOOST_INTERLOCKED_INCREMENT( &use_count_ );
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}
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bool add_ref_lock() // true on success
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{
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for( ;; )
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{
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long tmp = static_cast< long const volatile& >( use_count_ );
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if( tmp == 0 ) return false;
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#if defined( BOOST_MSVC ) && BOOST_WORKAROUND( BOOST_MSVC, == 1200 )
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// work around a code generation bug
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long tmp2 = tmp + 1;
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if( BOOST_INTERLOCKED_COMPARE_EXCHANGE( &use_count_, tmp2, tmp ) == tmp2 - 1 ) return true;
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#else
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if( BOOST_INTERLOCKED_COMPARE_EXCHANGE( &use_count_, tmp + 1, tmp ) == tmp ) return true;
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#endif
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}
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}
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void release() // nothrow
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{
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if( BOOST_INTERLOCKED_DECREMENT( &use_count_ ) == 0 )
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{
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dispose();
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weak_release();
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}
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}
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void weak_add_ref() // nothrow
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{
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BOOST_INTERLOCKED_INCREMENT( &weak_count_ );
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}
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void weak_release() // nothrow
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{
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if( BOOST_INTERLOCKED_DECREMENT( &weak_count_ ) == 0 )
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{
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destroy();
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}
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}
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long use_count() const // nothrow
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{
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return static_cast<long const volatile &>( use_count_ );
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}
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};
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} // namespace detail
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} // namespace boost
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#endif // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_W32_HPP_INCLUDED
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