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1 | /* |
2 | * Distributed under the Boost Software License, Version 1.0. | |
3 | * (See accompanying file LICENSE_1_0.txt or copy at | |
4 | * http://www.boost.org/LICENSE_1_0.txt) | |
5 | * | |
6 | * Copyright (c) 2011 Helge Bahmann | |
7 | * Copyright (c) 2013-2014 Andrey Semashev | |
8 | */ | |
9 | /*! | |
10 | * \file lockpool.cpp | |
11 | * | |
12 | * This file contains implementation of the lockpool used to emulate atomic ops. | |
13 | */ | |
14 | ||
15 | #include <cstddef> | |
16 | #include <boost/config.hpp> | |
17 | #include <boost/assert.hpp> | |
18 | #include <boost/memory_order.hpp> | |
19 | #include <boost/atomic/capabilities.hpp> | |
20 | ||
21 | #if BOOST_ATOMIC_FLAG_LOCK_FREE == 2 | |
22 | #include <boost/atomic/detail/operations_lockfree.hpp> | |
23 | #elif !defined(BOOST_HAS_PTHREADS) | |
24 | #error Boost.Atomic: Unsupported target platform, POSIX threads are required when native atomic operations are not available | |
25 | #else | |
26 | #include <pthread.h> | |
27 | #define BOOST_ATOMIC_USE_PTHREAD | |
28 | #endif | |
29 | ||
30 | #include <boost/atomic/detail/lockpool.hpp> | |
31 | #include <boost/atomic/detail/pause.hpp> | |
32 | ||
33 | namespace boost { | |
34 | namespace atomics { | |
35 | namespace detail { | |
36 | ||
37 | namespace { | |
38 | ||
39 | // This seems to be the maximum across all modern CPUs | |
40 | // NOTE: This constant is made as a macro because some compilers (gcc 4.4 for one) don't allow enums or namespace scope constants in alignment attributes | |
41 | #define BOOST_ATOMIC_CACHE_LINE_SIZE 64 | |
42 | ||
43 | #if defined(BOOST_ATOMIC_USE_PTHREAD) | |
44 | typedef pthread_mutex_t lock_type; | |
45 | #else | |
46 | typedef atomics::detail::operations< 1u, false > lock_operations; | |
47 | typedef lock_operations::storage_type lock_type; | |
48 | #endif | |
49 | ||
50 | enum | |
51 | { | |
52 | padding_size = (sizeof(lock_type) <= BOOST_ATOMIC_CACHE_LINE_SIZE ? | |
53 | (BOOST_ATOMIC_CACHE_LINE_SIZE - sizeof(lock_type)) : | |
54 | (BOOST_ATOMIC_CACHE_LINE_SIZE - sizeof(lock_type) % BOOST_ATOMIC_CACHE_LINE_SIZE)) | |
55 | }; | |
56 | ||
57 | template< unsigned int PaddingSize > | |
58 | struct BOOST_ALIGNMENT(BOOST_ATOMIC_CACHE_LINE_SIZE) padded_lock | |
59 | { | |
60 | lock_type lock; | |
61 | // The additional padding is needed to avoid false sharing between locks | |
62 | char padding[PaddingSize]; | |
63 | }; | |
64 | ||
65 | template< > | |
66 | struct BOOST_ALIGNMENT(BOOST_ATOMIC_CACHE_LINE_SIZE) padded_lock< 0u > | |
67 | { | |
68 | lock_type lock; | |
69 | }; | |
70 | ||
71 | typedef padded_lock< padding_size > padded_lock_t; | |
72 | ||
73 | static padded_lock_t g_lock_pool[41] | |
74 | #if defined(BOOST_ATOMIC_USE_PTHREAD) | |
75 | = | |
76 | { | |
77 | { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, | |
78 | { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, | |
79 | { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, | |
80 | { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, | |
81 | { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, | |
82 | { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, | |
83 | { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, | |
84 | { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, | |
85 | { PTHREAD_MUTEX_INITIALIZER } | |
86 | } | |
87 | #endif | |
88 | ; | |
89 | ||
90 | } // namespace | |
91 | ||
92 | ||
93 | #if !defined(BOOST_ATOMIC_USE_PTHREAD) | |
94 | ||
95 | // NOTE: This function must NOT be inline. Otherwise MSVC 9 will sometimes generate broken code for modulus operation which result in crashes. | |
96 | BOOST_ATOMIC_DECL lockpool::scoped_lock::scoped_lock(const volatile void* addr) BOOST_NOEXCEPT : | |
97 | m_lock(&g_lock_pool[reinterpret_cast< std::size_t >(addr) % (sizeof(g_lock_pool) / sizeof(*g_lock_pool))].lock) | |
98 | { | |
99 | while (lock_operations::test_and_set(*static_cast< lock_type* >(m_lock), memory_order_acquire)) | |
100 | { | |
101 | do | |
102 | { | |
103 | atomics::detail::pause(); | |
104 | } | |
105 | while (!!lock_operations::load(*static_cast< lock_type* >(m_lock), memory_order_relaxed)); | |
106 | } | |
107 | } | |
108 | ||
109 | BOOST_ATOMIC_DECL lockpool::scoped_lock::~scoped_lock() BOOST_NOEXCEPT | |
110 | { | |
111 | lock_operations::clear(*static_cast< lock_type* >(m_lock), memory_order_release); | |
112 | } | |
113 | ||
114 | BOOST_ATOMIC_DECL void signal_fence() BOOST_NOEXCEPT; | |
115 | ||
116 | #else // !defined(BOOST_ATOMIC_USE_PTHREAD) | |
117 | ||
118 | BOOST_ATOMIC_DECL lockpool::scoped_lock::scoped_lock(const volatile void* addr) BOOST_NOEXCEPT : | |
119 | m_lock(&g_lock_pool[reinterpret_cast< std::size_t >(addr) % (sizeof(g_lock_pool) / sizeof(*g_lock_pool))].lock) | |
120 | { | |
121 | BOOST_VERIFY(pthread_mutex_lock(static_cast< pthread_mutex_t* >(m_lock)) == 0); | |
122 | } | |
123 | ||
124 | BOOST_ATOMIC_DECL lockpool::scoped_lock::~scoped_lock() BOOST_NOEXCEPT | |
125 | { | |
126 | BOOST_VERIFY(pthread_mutex_unlock(static_cast< pthread_mutex_t* >(m_lock)) == 0); | |
127 | } | |
128 | ||
129 | #endif // !defined(BOOST_ATOMIC_USE_PTHREAD) | |
130 | ||
131 | BOOST_ATOMIC_DECL void lockpool::thread_fence() BOOST_NOEXCEPT | |
132 | { | |
133 | #if BOOST_ATOMIC_THREAD_FENCE > 0 | |
134 | atomics::detail::thread_fence(memory_order_seq_cst); | |
135 | #else | |
136 | // Emulate full fence by locking/unlocking a mutex | |
137 | scoped_lock lock(0); | |
138 | #endif | |
139 | } | |
140 | ||
141 | BOOST_ATOMIC_DECL void lockpool::signal_fence() BOOST_NOEXCEPT | |
142 | { | |
143 | // This function is intentionally non-inline, even if empty. This forces the compiler to treat its call as a compiler barrier. | |
144 | #if BOOST_ATOMIC_SIGNAL_FENCE > 0 | |
145 | atomics::detail::signal_fence(memory_order_seq_cst); | |
146 | #endif | |
147 | } | |
148 | ||
149 | } // namespace detail | |
150 | } // namespace atomics | |
151 | } // namespace boost |