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1 | #ifndef BOOST_INTERPROCESS_DETAIL_SP_COUNTED_BASE_ATOMIC_HPP_INCLUDED |
2 | #define BOOST_INTERPROCESS_DETAIL_SP_COUNTED_BASE_ATOMIC_HPP_INCLUDED | |
3 | ||
4 | #ifndef BOOST_CONFIG_HPP | |
5 | # include <boost/config.hpp> | |
6 | #endif | |
7 | # | |
8 | #if defined(BOOST_HAS_PRAGMA_ONCE) | |
9 | # pragma once | |
10 | #endif | |
11 | ||
12 | // Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd. | |
13 | // Copyright 2004-2005 Peter Dimov | |
14 | // Copyright 2007-2012 Ion Gaztanaga | |
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/interprocess/detail/config_begin.hpp> | |
28 | #include <boost/interprocess/detail/workaround.hpp> | |
29 | ||
30 | #include <boost/interprocess/detail/atomic.hpp> | |
31 | #include <typeinfo> | |
32 | ||
33 | namespace boost { | |
34 | ||
35 | namespace interprocess { | |
36 | ||
37 | namespace ipcdetail { | |
38 | ||
39 | class sp_counted_base | |
40 | { | |
41 | private: | |
42 | ||
43 | sp_counted_base( sp_counted_base const & ); | |
44 | sp_counted_base & operator= ( sp_counted_base const & ); | |
45 | ||
46 | boost::uint32_t use_count_; // #shared | |
47 | boost::uint32_t weak_count_; // #weak + (#shared != 0) | |
48 | ||
49 | public: | |
50 | ||
51 | sp_counted_base(): use_count_( 1 ), weak_count_( 1 ) | |
52 | {} | |
53 | ||
54 | ~sp_counted_base() // nothrow | |
55 | {} | |
56 | ||
57 | void add_ref_copy() | |
58 | { | |
59 | ipcdetail::atomic_inc32( &use_count_ ); | |
60 | } | |
61 | ||
62 | bool add_ref_lock() // true on success | |
63 | { | |
64 | for( ;; ) | |
65 | { | |
66 | boost::uint32_t tmp = static_cast< boost::uint32_t const volatile& >( use_count_ ); | |
67 | if( tmp == 0 ) return false; | |
68 | if( ipcdetail::atomic_cas32( &use_count_, tmp + 1, tmp ) == tmp ) | |
69 | return true; | |
70 | } | |
71 | } | |
72 | ||
73 | bool ref_release() // nothrow | |
74 | { return 1 == ipcdetail::atomic_dec32( &use_count_ ); } | |
75 | ||
76 | void weak_add_ref() // nothrow | |
77 | { ipcdetail::atomic_inc32( &weak_count_ ); } | |
78 | ||
79 | bool weak_release() // nothrow | |
80 | { return 1 == ipcdetail::atomic_dec32( &weak_count_ ); } | |
81 | ||
82 | long use_count() const // nothrow | |
83 | { return (long)static_cast<boost::uint32_t const volatile &>( use_count_ ); } | |
84 | }; | |
85 | ||
86 | } // namespace ipcdetail | |
87 | ||
88 | } // namespace interprocess | |
89 | ||
90 | } // namespace boost | |
91 | ||
92 | #include <boost/interprocess/detail/config_end.hpp> | |
93 | ||
94 | #endif // #ifndef BOOST_INTERPROCESS_DETAIL_SP_COUNTED_BASE_ATOMIC_HPP_INCLUDED |