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1 | #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_SYNC_HPP_INCLUDED |
2 | #define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_SYNC_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 | // detail/sp_counted_base_sync.hpp - g++ 4.1+ __sync intrinsics | |
11 | // | |
12 | // Copyright (c) 2007 Peter Dimov | |
13 | // | |
14 | // Distributed under the Boost Software License, Version 1.0. | |
15 | // See accompanying file LICENSE_1_0.txt or copy at | |
16 | // http://www.boost.org/LICENSE_1_0.txt | |
17 | ||
18 | #include <boost/detail/sp_typeinfo.hpp> | |
19 | #include <limits.h> | |
20 | ||
21 | #if defined( __ia64__ ) && defined( __INTEL_COMPILER ) | |
22 | # include <ia64intrin.h> | |
23 | #endif | |
24 | ||
25 | namespace boost | |
26 | { | |
27 | ||
28 | namespace detail | |
29 | { | |
30 | ||
31 | #if INT_MAX >= 2147483647 | |
32 | ||
33 | typedef int sp_int32_t; | |
34 | ||
35 | #else | |
36 | ||
37 | typedef long sp_int32_t; | |
38 | ||
39 | #endif | |
40 | ||
41 | inline void atomic_increment( sp_int32_t * pw ) | |
42 | { | |
43 | __sync_fetch_and_add( pw, 1 ); | |
44 | } | |
45 | ||
46 | inline sp_int32_t atomic_decrement( sp_int32_t * pw ) | |
47 | { | |
48 | return __sync_fetch_and_add( pw, -1 ); | |
49 | } | |
50 | ||
51 | inline sp_int32_t atomic_conditional_increment( sp_int32_t * pw ) | |
52 | { | |
53 | // long r = *pw; | |
54 | // if( r != 0 ) ++*pw; | |
55 | // return r; | |
56 | ||
57 | sp_int32_t r = *pw; | |
58 | ||
59 | for( ;; ) | |
60 | { | |
61 | if( r == 0 ) | |
62 | { | |
63 | return r; | |
64 | } | |
65 | ||
66 | sp_int32_t r2 = __sync_val_compare_and_swap( pw, r, r + 1 ); | |
67 | ||
68 | if( r2 == r ) | |
69 | { | |
70 | return r; | |
71 | } | |
72 | else | |
73 | { | |
74 | r = r2; | |
75 | } | |
76 | } | |
77 | } | |
78 | ||
79 | class sp_counted_base | |
80 | { | |
81 | private: | |
82 | ||
83 | sp_counted_base( sp_counted_base const & ); | |
84 | sp_counted_base & operator= ( sp_counted_base const & ); | |
85 | ||
86 | sp_int32_t use_count_; // #shared | |
87 | sp_int32_t weak_count_; // #weak + (#shared != 0) | |
88 | ||
89 | public: | |
90 | ||
91 | sp_counted_base(): use_count_( 1 ), weak_count_( 1 ) | |
92 | { | |
93 | } | |
94 | ||
95 | virtual ~sp_counted_base() // nothrow | |
96 | { | |
97 | } | |
98 | ||
99 | // dispose() is called when use_count_ drops to zero, to release | |
100 | // the resources managed by *this. | |
101 | ||
102 | virtual void dispose() = 0; // nothrow | |
103 | ||
104 | // destroy() is called when weak_count_ drops to zero. | |
105 | ||
106 | virtual void destroy() // nothrow | |
107 | { | |
108 | delete this; | |
109 | } | |
110 | ||
111 | virtual void * get_deleter( sp_typeinfo const & ti ) = 0; | |
112 | virtual void * get_untyped_deleter() = 0; | |
113 | ||
114 | void add_ref_copy() | |
115 | { | |
116 | atomic_increment( &use_count_ ); | |
117 | } | |
118 | ||
119 | bool add_ref_lock() // true on success | |
120 | { | |
121 | return atomic_conditional_increment( &use_count_ ) != 0; | |
122 | } | |
123 | ||
124 | void release() // nothrow | |
125 | { | |
126 | if( atomic_decrement( &use_count_ ) == 1 ) | |
127 | { | |
128 | dispose(); | |
129 | weak_release(); | |
130 | } | |
131 | } | |
132 | ||
133 | void weak_add_ref() // nothrow | |
134 | { | |
135 | atomic_increment( &weak_count_ ); | |
136 | } | |
137 | ||
138 | void weak_release() // nothrow | |
139 | { | |
140 | if( atomic_decrement( &weak_count_ ) == 1 ) | |
141 | { | |
142 | destroy(); | |
143 | } | |
144 | } | |
145 | ||
146 | long use_count() const // nothrow | |
147 | { | |
148 | return const_cast< sp_int32_t const volatile & >( use_count_ ); | |
149 | } | |
150 | }; | |
151 | ||
152 | } // namespace detail | |
153 | ||
154 | } // namespace boost | |
155 | ||
156 | #endif // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_SYNC_HPP_INCLUDED |