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1 | // (C) Copyright 2013 Andrey Semashev |
2 | // (C) Copyright 2013 Vicente J. Botet Escriba | |
3 | // | |
4 | // Distributed under the Boost Software License, Version 1.0. (See accompanying | |
5 | // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
6 | ||
7 | //#define __STDC_CONSTANT_MACROS | |
8 | #include <boost/thread/detail/config.hpp> | |
9 | #include <boost/thread/once.hpp> | |
92f5a8d4 | 10 | #include <boost/thread/pthread/pthread_helpers.hpp> |
7c673cae FG |
11 | #include <boost/thread/pthread/pthread_mutex_scoped_lock.hpp> |
12 | #include <boost/assert.hpp> | |
13 | #include <boost/static_assert.hpp> | |
14 | #include <boost/atomic.hpp> | |
15 | #include <boost/memory_order.hpp> | |
16 | #include <pthread.h> | |
17 | ||
18 | namespace boost | |
19 | { | |
20 | namespace thread_detail | |
21 | { | |
22 | ||
23 | enum flag_states | |
24 | { | |
25 | uninitialized, in_progress, initialized | |
26 | }; | |
27 | ||
28 | ||
29 | #ifndef BOOST_THREAD_PROVIDES_ONCE_CXX11 | |
30 | BOOST_STATIC_ASSERT_MSG(sizeof(atomic_int_type) == sizeof(atomic_type), "Boost.Thread: unsupported platform"); | |
31 | #endif | |
32 | ||
33 | static pthread_mutex_t once_mutex = PTHREAD_MUTEX_INITIALIZER; | |
34 | static pthread_cond_t once_cv = PTHREAD_COND_INITIALIZER; | |
35 | ||
36 | BOOST_THREAD_DECL bool enter_once_region(once_flag& flag) BOOST_NOEXCEPT | |
37 | { | |
38 | atomic_type& f = get_atomic_storage(flag); | |
39 | if (f.load(memory_order_acquire) != initialized) | |
40 | { | |
41 | pthread::pthread_mutex_scoped_lock lk(&once_mutex); | |
42 | if (f.load(memory_order_acquire) != initialized) | |
43 | { | |
b32b8144 | 44 | for (;;) |
7c673cae FG |
45 | { |
46 | atomic_int_type expected = uninitialized; | |
47 | if (f.compare_exchange_strong(expected, in_progress, memory_order_acq_rel, memory_order_acquire)) | |
48 | { | |
49 | // We have set the flag to in_progress | |
50 | return true; | |
51 | } | |
52 | else if (expected == initialized) | |
53 | { | |
54 | // Another thread managed to complete the initialization | |
55 | return false; | |
56 | } | |
57 | else | |
58 | { | |
59 | // Wait until the initialization is complete | |
60 | //pthread::pthread_mutex_scoped_lock lk(&once_mutex); | |
92f5a8d4 | 61 | BOOST_VERIFY(!posix::pthread_cond_wait(&once_cv, &once_mutex)); |
7c673cae FG |
62 | } |
63 | } | |
64 | } | |
65 | } | |
66 | return false; | |
67 | } | |
68 | ||
69 | BOOST_THREAD_DECL void commit_once_region(once_flag& flag) BOOST_NOEXCEPT | |
70 | { | |
71 | atomic_type& f = get_atomic_storage(flag); | |
72 | { | |
73 | pthread::pthread_mutex_scoped_lock lk(&once_mutex); | |
74 | f.store(initialized, memory_order_release); | |
75 | } | |
92f5a8d4 | 76 | BOOST_VERIFY(!posix::pthread_cond_broadcast(&once_cv)); |
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77 | } |
78 | ||
79 | BOOST_THREAD_DECL void rollback_once_region(once_flag& flag) BOOST_NOEXCEPT | |
80 | { | |
81 | atomic_type& f = get_atomic_storage(flag); | |
82 | { | |
83 | pthread::pthread_mutex_scoped_lock lk(&once_mutex); | |
84 | f.store(uninitialized, memory_order_release); | |
85 | } | |
92f5a8d4 | 86 | BOOST_VERIFY(!posix::pthread_cond_broadcast(&once_cv)); |
7c673cae FG |
87 | } |
88 | ||
89 | } // namespace thread_detail | |
90 | ||
91 | } // namespace boost |