1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
|
/*
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying file LICENSE_1_0.txt or copy at
* http://www.boost.org/LICENSE_1_0.txt)
*
* Copyright (c) 2011 Helge Bahmann
* Copyright (c) 2013-2014 Andrey Semashev
*/
/*!
* \file lockpool.cpp
*
* This file contains implementation of the lockpool used to emulate atomic ops.
*/
#include <cstddef>
#include <boost/config.hpp>
#include <boost/assert.hpp>
#include <boost/memory_order.hpp>
#include <boost/atomic/capabilities.hpp>
#if BOOST_ATOMIC_FLAG_LOCK_FREE == 2
#include <boost/atomic/detail/operations_lockfree.hpp>
#elif !defined(BOOST_HAS_PTHREADS)
#error Boost.Atomic: Unsupported target platform, POSIX threads are required when native atomic operations are not available
#else
#include <pthread.h>
#define BOOST_ATOMIC_USE_PTHREAD
#endif
#include <boost/atomic/detail/lockpool.hpp>
#include <boost/atomic/detail/pause.hpp>
#if defined(BOOST_MSVC)
#pragma warning(push)
// 'struct_name' : structure was padded due to __declspec(align())
#pragma warning(disable: 4324)
#endif
namespace boost {
namespace atomics {
namespace detail {
namespace {
// This seems to be the maximum across all modern CPUs
// 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
#define BOOST_ATOMIC_CACHE_LINE_SIZE 64
#if defined(BOOST_ATOMIC_USE_PTHREAD)
typedef pthread_mutex_t lock_type;
#else
typedef atomics::detail::operations< 1u, false > lock_operations;
typedef lock_operations::storage_type lock_type;
#endif
enum
{
padding_size = (sizeof(lock_type) <= BOOST_ATOMIC_CACHE_LINE_SIZE ?
(BOOST_ATOMIC_CACHE_LINE_SIZE - sizeof(lock_type)) :
(BOOST_ATOMIC_CACHE_LINE_SIZE - sizeof(lock_type) % BOOST_ATOMIC_CACHE_LINE_SIZE))
};
template< unsigned int PaddingSize >
struct BOOST_ALIGNMENT(BOOST_ATOMIC_CACHE_LINE_SIZE) padded_lock
{
lock_type lock;
// The additional padding is needed to avoid false sharing between locks
char padding[PaddingSize];
};
template< >
struct BOOST_ALIGNMENT(BOOST_ATOMIC_CACHE_LINE_SIZE) padded_lock< 0u >
{
lock_type lock;
};
typedef padded_lock< padding_size > padded_lock_t;
static padded_lock_t g_lock_pool[41]
#if defined(BOOST_ATOMIC_USE_PTHREAD)
=
{
{ PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER },
{ PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER },
{ PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER },
{ PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER },
{ PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER },
{ PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER },
{ PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER },
{ PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER }, { PTHREAD_MUTEX_INITIALIZER },
{ PTHREAD_MUTEX_INITIALIZER }
}
#endif
;
} // namespace
#if !defined(BOOST_ATOMIC_USE_PTHREAD)
// NOTE: This function must NOT be inline. Otherwise MSVC 9 will sometimes generate broken code for modulus operation which result in crashes.
BOOST_ATOMIC_DECL lockpool::scoped_lock::scoped_lock(const volatile void* addr) BOOST_NOEXCEPT :
m_lock(&g_lock_pool[reinterpret_cast< std::size_t >(addr) % (sizeof(g_lock_pool) / sizeof(*g_lock_pool))].lock)
{
while (lock_operations::test_and_set(*static_cast< lock_type* >(m_lock), memory_order_acquire))
{
do
{
atomics::detail::pause();
}
while (!!lock_operations::load(*static_cast< lock_type* >(m_lock), memory_order_relaxed));
}
}
BOOST_ATOMIC_DECL lockpool::scoped_lock::~scoped_lock() BOOST_NOEXCEPT
{
lock_operations::clear(*static_cast< lock_type* >(m_lock), memory_order_release);
}
BOOST_ATOMIC_DECL void signal_fence() BOOST_NOEXCEPT;
#else // !defined(BOOST_ATOMIC_USE_PTHREAD)
BOOST_ATOMIC_DECL lockpool::scoped_lock::scoped_lock(const volatile void* addr) BOOST_NOEXCEPT :
m_lock(&g_lock_pool[reinterpret_cast< std::size_t >(addr) % (sizeof(g_lock_pool) / sizeof(*g_lock_pool))].lock)
{
BOOST_VERIFY(pthread_mutex_lock(static_cast< pthread_mutex_t* >(m_lock)) == 0);
}
BOOST_ATOMIC_DECL lockpool::scoped_lock::~scoped_lock() BOOST_NOEXCEPT
{
BOOST_VERIFY(pthread_mutex_unlock(static_cast< pthread_mutex_t* >(m_lock)) == 0);
}
#endif // !defined(BOOST_ATOMIC_USE_PTHREAD)
BOOST_ATOMIC_DECL void lockpool::thread_fence() BOOST_NOEXCEPT
{
#if BOOST_ATOMIC_THREAD_FENCE > 0
atomics::detail::thread_fence(memory_order_seq_cst);
#else
// Emulate full fence by locking/unlocking a mutex
scoped_lock lock(0);
#endif
}
BOOST_ATOMIC_DECL void lockpool::signal_fence() BOOST_NOEXCEPT
{
// This function is intentionally non-inline, even if empty. This forces the compiler to treat its call as a compiler barrier.
#if BOOST_ATOMIC_SIGNAL_FENCE > 0
atomics::detail::signal_fence(memory_order_seq_cst);
#endif
}
} // namespace detail
} // namespace atomics
} // namespace boost
#if defined(BOOST_MSVC)
#pragma warning(pop)
#endif
|
