1 | #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_GCC_ATOMIC_HPP_INCLUDED |
2 | #define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_GCC_ATOMIC_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_gcc_atomic.hpp - g++ 4.7+ __atomic intrinsics |
11 | // |
12 | // Copyright 2007, 2020 Peter Dimov |
13 | // Distributed under the Boost Software License, Version 1.0. |
14 | // https://www.boost.org/LICENSE_1_0.txt |
15 | |
16 | #include <boost/smart_ptr/detail/sp_typeinfo_.hpp> |
17 | #include <boost/config.hpp> |
18 | #include <boost/cstdint.hpp> |
19 | |
20 | #if defined(BOOST_SP_REPORT_IMPLEMENTATION) |
21 | |
22 | #include <boost/config/pragma_message.hpp> |
23 | BOOST_PRAGMA_MESSAGE("Using __atomic sp_counted_base" ) |
24 | |
25 | #endif |
26 | |
27 | namespace boost |
28 | { |
29 | |
30 | namespace detail |
31 | { |
32 | |
33 | inline void atomic_increment( boost::uint_least32_t * pw ) |
34 | { |
35 | __atomic_fetch_add( pw, 1, __ATOMIC_RELAXED ); |
36 | } |
37 | |
38 | inline boost::uint_least32_t atomic_decrement( boost::uint_least32_t * pw ) |
39 | { |
40 | return __atomic_fetch_sub( pw, 1, __ATOMIC_ACQ_REL ); |
41 | } |
42 | |
43 | inline boost::uint_least32_t atomic_conditional_increment( boost::uint_least32_t * pw ) |
44 | { |
45 | // long r = *pw; |
46 | // if( r != 0 ) ++*pw; |
47 | // return r; |
48 | |
49 | boost::uint_least32_t r = __atomic_load_n( pw, __ATOMIC_RELAXED ); |
50 | |
51 | for( ;; ) |
52 | { |
53 | if( r == 0 ) |
54 | { |
55 | return r; |
56 | } |
57 | |
58 | if( __atomic_compare_exchange_n( pw, &r, r + 1, true, __ATOMIC_RELAXED, __ATOMIC_RELAXED ) ) |
59 | { |
60 | return r; |
61 | } |
62 | } |
63 | } |
64 | |
65 | inline boost::uint_least32_t atomic_load( boost::uint_least32_t const * pw ) |
66 | { |
67 | return __atomic_load_n( pw, __ATOMIC_ACQUIRE ); |
68 | } |
69 | |
70 | class BOOST_SYMBOL_VISIBLE sp_counted_base |
71 | { |
72 | private: |
73 | |
74 | sp_counted_base( sp_counted_base const & ); |
75 | sp_counted_base & operator= ( sp_counted_base const & ); |
76 | |
77 | boost::uint_least32_t use_count_; // #shared |
78 | boost::uint_least32_t weak_count_; // #weak + (#shared != 0) |
79 | |
80 | public: |
81 | |
82 | sp_counted_base(): use_count_( 1 ), weak_count_( 1 ) |
83 | { |
84 | } |
85 | |
86 | virtual ~sp_counted_base() // nothrow |
87 | { |
88 | } |
89 | |
90 | // dispose() is called when use_count_ drops to zero, to release |
91 | // the resources managed by *this. |
92 | |
93 | virtual void dispose() = 0; // nothrow |
94 | |
95 | // destroy() is called when weak_count_ drops to zero. |
96 | |
97 | virtual void destroy() // nothrow |
98 | { |
99 | delete this; |
100 | } |
101 | |
102 | virtual void * get_deleter( sp_typeinfo_ const & ti ) = 0; |
103 | virtual void * get_local_deleter( sp_typeinfo_ const & ti ) = 0; |
104 | virtual void * get_untyped_deleter() = 0; |
105 | |
106 | void add_ref_copy() |
107 | { |
108 | atomic_increment( pw: &use_count_ ); |
109 | } |
110 | |
111 | bool add_ref_lock() // true on success |
112 | { |
113 | return atomic_conditional_increment( pw: &use_count_ ) != 0; |
114 | } |
115 | |
116 | void release() // nothrow |
117 | { |
118 | if( atomic_decrement( pw: &use_count_ ) == 1 ) |
119 | { |
120 | dispose(); |
121 | weak_release(); |
122 | } |
123 | } |
124 | |
125 | void weak_add_ref() // nothrow |
126 | { |
127 | atomic_increment( pw: &weak_count_ ); |
128 | } |
129 | |
130 | void weak_release() // nothrow |
131 | { |
132 | if( atomic_decrement( pw: &weak_count_ ) == 1 ) |
133 | { |
134 | destroy(); |
135 | } |
136 | } |
137 | |
138 | long use_count() const // nothrow |
139 | { |
140 | return atomic_load( pw: &use_count_ ); |
141 | } |
142 | }; |
143 | |
144 | } // namespace detail |
145 | |
146 | } // namespace boost |
147 | |
148 | #endif // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_SYNC_HPP_INCLUDED |
149 | |