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Jeff Thompsonf7d49942013-08-01 16:47:40 -07001#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
Jeff Thompson2277ce52013-08-01 17:34:11 -070027#include <ndnboost/detail/interlocked.hpp>
28#include <ndnboost/detail/workaround.hpp>
29#include <ndnboost/detail/sp_typeinfo.hpp>
Jeff Thompsonf7d49942013-08-01 16:47:40 -070030
31namespace ndnboost
32{
33
34namespace detail
35{
36
37class sp_counted_base
38{
39private:
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
47public:
48
49 sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
50 {
51 }
52
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
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_untyped_deleter() = 0;
71
72 void add_ref_copy()
73 {
74 BOOST_INTERLOCKED_INCREMENT( &use_count_ );
75 }
76
77 bool add_ref_lock() // true on success
78 {
79 for( ;; )
80 {
81 long tmp = static_cast< long const volatile& >( use_count_ );
82 if( tmp == 0 ) return false;
83
84#if defined( BOOST_MSVC ) && BOOST_WORKAROUND( BOOST_MSVC, == 1200 )
85
86 // work around a code generation bug
87
88 long tmp2 = tmp + 1;
89 if( BOOST_INTERLOCKED_COMPARE_EXCHANGE( &use_count_, tmp2, tmp ) == tmp2 - 1 ) return true;
90
91#else
92
93 if( BOOST_INTERLOCKED_COMPARE_EXCHANGE( &use_count_, tmp + 1, tmp ) == tmp ) return true;
94
95#endif
96 }
97 }
98
99 void release() // nothrow
100 {
101 if( BOOST_INTERLOCKED_DECREMENT( &use_count_ ) == 0 )
102 {
103 dispose();
104 weak_release();
105 }
106 }
107
108 void weak_add_ref() // nothrow
109 {
110 BOOST_INTERLOCKED_INCREMENT( &weak_count_ );
111 }
112
113 void weak_release() // nothrow
114 {
115 if( BOOST_INTERLOCKED_DECREMENT( &weak_count_ ) == 0 )
116 {
117 destroy();
118 }
119 }
120
121 long use_count() const // nothrow
122 {
123 return static_cast<long const volatile &>( use_count_ );
124 }
125};
126
127} // namespace detail
128
129} // namespace ndnboost
130
131#endif // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_W32_HPP_INCLUDED