1 #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_W32_HPP_INCLUDED
2 #define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_W32_HPP_INCLUDED
3 
4 // MS compatible compilers support #pragma once
5 
6 #if defined(_MSC_VER) && (_MSC_VER >= 1020)
7 # pragma once
8 #endif
9 
10 //
11 //  detail/sp_counted_base_w32.hpp
12 //
13 //  Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
14 //  Copyright 2004-2005 Peter Dimov
15 //
16 //  Distributed under the Boost Software License, Version 1.0. (See
17 //  accompanying file LICENSE_1_0.txt or copy at
18 //  http://www.boost.org/LICENSE_1_0.txt)
19 //
20 //
21 //  Lock-free algorithm by Alexander Terekhov
22 //
23 //  Thanks to Ben Hitchings for the #weak + (#shared != 0)
24 //  formulation
25 //
26 
27 #include <boost/smart_ptr/detail/sp_interlocked.hpp>
28 #include <boost/detail/workaround.hpp>
29 #include <boost/detail/sp_typeinfo.hpp>
30 
31 namespace boost
32 {
33 
34 namespace detail
35 {
36 
37 class sp_counted_base
38 {
39 private:
40 
41     sp_counted_base( sp_counted_base const & );
42     sp_counted_base & operator= ( sp_counted_base const & );
43 
44     long use_count_;        // #shared
45     long weak_count_;       // #weak + (#shared != 0)
46 
47 public:
48 
sp_counted_base()49     sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
50     {
51     }
52 
~sp_counted_base()53     virtual ~sp_counted_base() // nothrow
54     {
55     }
56 
57     // dispose() is called when use_count_ drops to zero, to release
58     // the resources managed by *this.
59 
60     virtual void dispose() = 0; // nothrow
61 
62     // destroy() is called when weak_count_ drops to zero.
63 
destroy()64     virtual void destroy() // nothrow
65     {
66         delete this;
67     }
68 
69     virtual void * get_deleter( sp_typeinfo const & ti ) = 0;
70     virtual void * get_local_deleter( sp_typeinfo const & ti ) = 0;
71     virtual void * get_untyped_deleter() = 0;
72 
add_ref_copy()73     void add_ref_copy()
74     {
75         BOOST_SP_INTERLOCKED_INCREMENT( &use_count_ );
76     }
77 
add_ref_lock()78     bool add_ref_lock() // true on success
79     {
80         for( ;; )
81         {
82             long tmp = static_cast< long const volatile& >( use_count_ );
83             if( tmp == 0 ) return false;
84 
85 #if defined( BOOST_MSVC ) && BOOST_WORKAROUND( BOOST_MSVC, == 1200 )
86 
87             // work around a code generation bug
88 
89             long tmp2 = tmp + 1;
90             if( BOOST_SP_INTERLOCKED_COMPARE_EXCHANGE( &use_count_, tmp2, tmp ) == tmp2 - 1 ) return true;
91 
92 #else
93 
94             if( BOOST_SP_INTERLOCKED_COMPARE_EXCHANGE( &use_count_, tmp + 1, tmp ) == tmp ) return true;
95 
96 #endif
97         }
98     }
99 
release()100     void release() // nothrow
101     {
102         if( BOOST_SP_INTERLOCKED_DECREMENT( &use_count_ ) == 0 )
103         {
104             dispose();
105             weak_release();
106         }
107     }
108 
weak_add_ref()109     void weak_add_ref() // nothrow
110     {
111         BOOST_SP_INTERLOCKED_INCREMENT( &weak_count_ );
112     }
113 
weak_release()114     void weak_release() // nothrow
115     {
116         if( BOOST_SP_INTERLOCKED_DECREMENT( &weak_count_ ) == 0 )
117         {
118             destroy();
119         }
120     }
121 
use_count() const122     long use_count() const // nothrow
123     {
124         return static_cast<long const volatile &>( use_count_ );
125     }
126 };
127 
128 } // namespace detail
129 
130 } // namespace boost
131 
132 #endif  // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_W32_HPP_INCLUDED
133