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1 | #ifndef BOOST_SMART_PTR_DETAIL_SPINLOCK_STD_ATOMIC_HPP_INCLUDED |
2 | #define BOOST_SMART_PTR_DETAIL_SPINLOCK_STD_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 | // | |
11 | // Copyright (c) 2014 Peter Dimov | |
12 | // | |
13 | // Distributed under the Boost Software License, Version 1.0. | |
14 | // See accompanying file LICENSE_1_0.txt or copy at | |
15 | // http://www.boost.org/LICENSE_1_0.txt) | |
16 | // | |
17 | ||
18 | #include <boost/smart_ptr/detail/yield_k.hpp> | |
19 | #include <atomic> | |
20 | ||
21 | namespace boost | |
22 | { | |
23 | ||
24 | namespace detail | |
25 | { | |
26 | ||
27 | class spinlock | |
28 | { | |
29 | public: | |
30 | ||
31 | std::atomic_flag v_; | |
32 | ||
33 | public: | |
34 | ||
35 | bool try_lock() | |
36 | { | |
37 | return !v_.test_and_set( std::memory_order_acquire ); | |
38 | } | |
39 | ||
40 | void lock() | |
41 | { | |
42 | for( unsigned k = 0; !try_lock(); ++k ) | |
43 | { | |
44 | boost::detail::yield( k ); | |
45 | } | |
46 | } | |
47 | ||
48 | void unlock() | |
49 | { | |
50 | v_ .clear( std::memory_order_release ); | |
51 | } | |
52 | ||
53 | public: | |
54 | ||
55 | class scoped_lock | |
56 | { | |
57 | private: | |
58 | ||
59 | spinlock & sp_; | |
60 | ||
61 | scoped_lock( scoped_lock const & ); | |
62 | scoped_lock & operator=( scoped_lock const & ); | |
63 | ||
64 | public: | |
65 | ||
66 | explicit scoped_lock( spinlock & sp ): sp_( sp ) | |
67 | { | |
68 | sp.lock(); | |
69 | } | |
70 | ||
71 | ~scoped_lock() | |
72 | { | |
73 | sp_.unlock(); | |
74 | } | |
75 | }; | |
76 | }; | |
77 | ||
78 | } // namespace detail | |
79 | } // namespace boost | |
80 | ||
81 | #define BOOST_DETAIL_SPINLOCK_INIT { ATOMIC_FLAG_INIT } | |
82 | ||
83 | #endif // #ifndef BOOST_SMART_PTR_DETAIL_SPINLOCK_STD_ATOMIC_HPP_INCLUDED |