[857] | 1 | #ifndef BOOST_DETAIL_SP_COUNTED_BASE_W32_HPP_INCLUDED
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| 2 | #define BOOST_DETAIL_SP_COUNTED_BASE_W32_HPP_INCLUDED
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| 3 |
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| 4 | // MS compatible compilers support #pragma once
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| 5 |
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| 6 | #if defined(_MSC_VER) && (_MSC_VER >= 1020)
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| 7 | # pragma once
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| 8 | #endif
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| 9 |
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| 10 | //
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| 11 | // detail/sp_counted_base_w32.hpp
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| 12 | //
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| 13 | // Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
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| 14 | // Copyright 2004-2005 Peter Dimov
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| 15 | //
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| 16 | // Distributed under the Boost Software License, Version 1.0. (See
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| 17 | // accompanying file LICENSE_1_0.txt or copy at
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| 18 | // http://www.boost.org/LICENSE_1_0.txt)
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| 19 | //
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| 20 | //
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| 21 | // Lock-free algorithm by Alexander Terekhov
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| 22 | //
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| 23 | // Thanks to Ben Hitchings for the #weak + (#shared != 0)
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| 24 | // formulation
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| 25 | //
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| 26 |
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| 27 | #include <boost/detail/interlocked.hpp>
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| 28 | #include <typeinfo>
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| 29 |
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| 30 | namespace boost
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| 31 | {
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| 32 |
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| 33 | namespace detail
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| 34 | {
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| 35 |
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| 36 | class sp_counted_base
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| 37 | {
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| 38 | private:
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| 39 |
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| 40 | sp_counted_base( sp_counted_base const & );
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| 41 | sp_counted_base & operator= ( sp_counted_base const & );
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| 42 |
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| 43 | long use_count_; // #shared
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| 44 | long weak_count_; // #weak + (#shared != 0)
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| 45 |
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| 46 | public:
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| 47 |
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| 48 | sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
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| 49 | {
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| 50 | }
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| 51 |
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| 52 | virtual ~sp_counted_base() // nothrow
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| 53 | {
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| 54 | }
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| 55 |
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| 56 | // dispose() is called when use_count_ drops to zero, to release
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| 57 | // the resources managed by *this.
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| 58 |
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| 59 | virtual void dispose() = 0; // nothrow
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| 60 |
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| 61 | // destroy() is called when weak_count_ drops to zero.
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| 62 |
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| 63 | virtual void destroy() // nothrow
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| 64 | {
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| 65 | delete this;
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| 66 | }
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| 67 |
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| 68 | virtual void * get_deleter( std::type_info const & ti ) = 0;
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| 69 |
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| 70 | void add_ref_copy()
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| 71 | {
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| 72 | BOOST_INTERLOCKED_INCREMENT( &use_count_ );
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| 73 | }
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| 74 |
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| 75 | bool add_ref_lock() // true on success
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| 76 | {
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| 77 | for( ;; )
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| 78 | {
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| 79 | long tmp = static_cast< long const volatile& >( use_count_ );
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| 80 | if( tmp == 0 ) return false;
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| 81 | if( BOOST_INTERLOCKED_COMPARE_EXCHANGE( &use_count_, tmp + 1, tmp ) == tmp ) return true;
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| 82 | }
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| 83 | }
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| 84 |
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| 85 | void release() // nothrow
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| 86 | {
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| 87 | if( BOOST_INTERLOCKED_DECREMENT( &use_count_ ) == 0 )
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| 88 | {
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| 89 | dispose();
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| 90 | weak_release();
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| 91 | }
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| 92 | }
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| 93 |
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| 94 | void weak_add_ref() // nothrow
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| 95 | {
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| 96 | BOOST_INTERLOCKED_INCREMENT( &weak_count_ );
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| 97 | }
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| 98 |
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| 99 | void weak_release() // nothrow
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| 100 | {
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| 101 | if( BOOST_INTERLOCKED_DECREMENT( &weak_count_ ) == 0 )
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| 102 | {
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| 103 | destroy();
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| 104 | }
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| 105 | }
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| 106 |
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| 107 | long use_count() const // nothrow
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| 108 | {
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| 109 | return static_cast<long const volatile &>( use_count_ );
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| 110 | }
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| 111 | };
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| 112 |
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| 113 | } // namespace detail
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| 114 |
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| 115 | } // namespace boost
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| 116 |
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| 117 | #endif // #ifndef BOOST_DETAIL_SP_COUNTED_BASE_W32_HPP_INCLUDED
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