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 #if defined(BOOST_MSVC)
34 #pragma warning(push)
35 // 'struct_name' : structure was padded due to __declspec(align())
36 #pragma warning(disable: 4324)
37 #endif
38
39 namespace boost {
40 namespace atomics {
41 namespace detail {
42
43 namespace {
44
45 // Cache line size, in bytes
46 // 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
47 #if defined(__s390__) || defined(__s390x__)
48 #define BOOST_ATOMIC_CACHE_LINE_SIZE 256
49 #elif defined(powerpc) || defined(__powerpc__) || defined(__ppc__)
50 #define BOOST_ATOMIC_CACHE_LINE_SIZE 128
51 #else
52 #define BOOST_ATOMIC_CACHE_LINE_SIZE 64
53 #endif
54
55 #if defined(BOOST_ATOMIC_USE_PTHREAD)
56 typedef pthread_mutex_t lock_type;
57 #else
58 typedef atomics::detail::operations< 1u, false > lock_operations;
59 typedef lock_operations::storage_type lock_type;
60 #endif
61
62 enum
63 {
64 padding_size = (sizeof(lock_type) <= BOOST_ATOMIC_CACHE_LINE_SIZE ?
65 (BOOST_ATOMIC_CACHE_LINE_SIZE - sizeof(lock_type)) :
66 (BOOST_ATOMIC_CACHE_LINE_SIZE - sizeof(lock_type) % BOOST_ATOMIC_CACHE_LINE_SIZE))
67 };
68
69 template< unsigned int PaddingSize >
BOOST_ALIGNMENT(BOOST_ATOMIC_CACHE_LINE_SIZE)70 struct BOOST_ALIGNMENT(BOOST_ATOMIC_CACHE_LINE_SIZE) padded_lock
71 {
72 lock_type lock;
73 // The additional padding is needed to avoid false sharing between locks
74 char padding[PaddingSize];
75 };
76
77 template< >
BOOST_ALIGNMENT(BOOST_ATOMIC_CACHE_LINE_SIZE)78 struct BOOST_ALIGNMENT(BOOST_ATOMIC_CACHE_LINE_SIZE) padded_lock< 0u >
79 {
80 lock_type lock;
81 };
82
83 typedef padded_lock< padding_size > padded_lock_t;
84
85 static padded_lock_t g_lock_pool[41]
86 #if defined(BOOST_ATOMIC_USE_PTHREAD)
87 =
88 {
89 { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER },
90 { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER },
91 { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER },
92 { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER },
93 { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER },
94 { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER },
95 { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER },
96 { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER },
97 { PTHREAD_MUTEX_INITIALIZER }
98 }
99 #endif
100 ;
101
102 } // namespace
103
104
105 #if !defined(BOOST_ATOMIC_USE_PTHREAD)
106
107 // NOTE: This function must NOT be inline. Otherwise MSVC 9 will sometimes generate broken code for modulus operation which result in crashes.
scoped_lock(const volatile void * addr)108 BOOST_ATOMIC_DECL lockpool::scoped_lock::scoped_lock(const volatile void* addr) BOOST_NOEXCEPT :
109 m_lock(&g_lock_pool[reinterpret_cast< std::size_t >(addr) % (sizeof(g_lock_pool) / sizeof(*g_lock_pool))].lock)
110 {
111 while (lock_operations::test_and_set(*static_cast< lock_type* >(m_lock), memory_order_acquire))
112 {
113 do
114 {
115 atomics::detail::pause();
116 }
117 while (!!lock_operations::load(*static_cast< lock_type* >(m_lock), memory_order_relaxed));
118 }
119 }
120
~scoped_lock()121 BOOST_ATOMIC_DECL lockpool::scoped_lock::~scoped_lock() BOOST_NOEXCEPT
122 {
123 lock_operations::clear(*static_cast< lock_type* >(m_lock), memory_order_release);
124 }
125
126 BOOST_ATOMIC_DECL void signal_fence() BOOST_NOEXCEPT;
127
128 #else // !defined(BOOST_ATOMIC_USE_PTHREAD)
129
scoped_lock(const volatile void * addr)130 BOOST_ATOMIC_DECL lockpool::scoped_lock::scoped_lock(const volatile void* addr) BOOST_NOEXCEPT :
131 m_lock(&g_lock_pool[reinterpret_cast< std::size_t >(addr) % (sizeof(g_lock_pool) / sizeof(*g_lock_pool))].lock)
132 {
133 BOOST_VERIFY(pthread_mutex_lock(static_cast< pthread_mutex_t* >(m_lock)) == 0);
134 }
135
~scoped_lock()136 BOOST_ATOMIC_DECL lockpool::scoped_lock::~scoped_lock() BOOST_NOEXCEPT
137 {
138 BOOST_VERIFY(pthread_mutex_unlock(static_cast< pthread_mutex_t* >(m_lock)) == 0);
139 }
140
141 #endif // !defined(BOOST_ATOMIC_USE_PTHREAD)
142
thread_fence()143 BOOST_ATOMIC_DECL void lockpool::thread_fence() BOOST_NOEXCEPT
144 {
145 #if BOOST_ATOMIC_THREAD_FENCE > 0
146 atomics::detail::thread_fence(memory_order_seq_cst);
147 #else
148 // Emulate full fence by locking/unlocking a mutex
149 scoped_lock lock(0);
150 #endif
151 }
152
signal_fence()153 BOOST_ATOMIC_DECL void lockpool::signal_fence() BOOST_NOEXCEPT
154 {
155 // This function is intentionally non-inline, even if empty. This forces the compiler to treat its call as a compiler barrier.
156 #if BOOST_ATOMIC_SIGNAL_FENCE > 0
157 atomics::detail::signal_fence(memory_order_seq_cst);
158 #endif
159 }
160
161 } // namespace detail
162 } // namespace atomics
163 } // namespace boost
164
165 #if defined(BOOST_MSVC)
166 #pragma warning(pop)
167 #endif
168