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f16081c2 JW |
1 | // std::mutex implementation -*- C++ -*- |
2 | ||
a945c346 | 3 | // Copyright (C) 2003-2024 Free Software Foundation, Inc. |
f16081c2 JW |
4 | // |
5 | // This file is part of the GNU ISO C++ Library. This library is free | |
6 | // software; you can redistribute it and/or modify it under the | |
7 | // terms of the GNU General Public License as published by the | |
8 | // Free Software Foundation; either version 3, or (at your option) | |
9 | // any later version. | |
10 | ||
11 | // This library is distributed in the hope that it will be useful, | |
12 | // but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | // GNU General Public License for more details. | |
15 | ||
16 | // Under Section 7 of GPL version 3, you are granted additional | |
17 | // permissions described in the GCC Runtime Library Exception, version | |
18 | // 3.1, as published by the Free Software Foundation. | |
19 | ||
20 | // You should have received a copy of the GNU General Public License and | |
21 | // a copy of the GCC Runtime Library Exception along with this program; | |
22 | // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see | |
23 | // <http://www.gnu.org/licenses/>. | |
24 | ||
3b07547d | 25 | /** @file bits/std_mutex.h |
f16081c2 JW |
26 | * This is an internal header file, included by other library headers. |
27 | * Do not attempt to use it directly. @headername{mutex} | |
28 | */ | |
29 | ||
30 | #ifndef _GLIBCXX_MUTEX_H | |
31 | #define _GLIBCXX_MUTEX_H 1 | |
32 | ||
33 | #pragma GCC system_header | |
34 | ||
35 | #if __cplusplus < 201103L | |
36 | # include <bits/c++0x_warning.h> | |
37 | #else | |
38 | ||
b4b1c6aa | 39 | #include <errno.h> // EBUSY |
f16081c2 JW |
40 | #include <bits/functexcept.h> |
41 | #include <bits/gthr.h> | |
f16081c2 JW |
42 | |
43 | namespace std _GLIBCXX_VISIBILITY(default) | |
44 | { | |
45 | _GLIBCXX_BEGIN_NAMESPACE_VERSION | |
46 | ||
47 | /** | |
48 | * @defgroup mutexes Mutexes | |
49 | * @ingroup concurrency | |
50 | * | |
51 | * Classes for mutex support. | |
52 | * @{ | |
53 | */ | |
54 | ||
55 | #ifdef _GLIBCXX_HAS_GTHREADS | |
b584cbdb JW |
56 | /// @cond undocumented |
57 | ||
f16081c2 JW |
58 | // Common base class for std::mutex and std::timed_mutex |
59 | class __mutex_base | |
60 | { | |
61 | protected: | |
62 | typedef __gthread_mutex_t __native_type; | |
63 | ||
64 | #ifdef __GTHREAD_MUTEX_INIT | |
65 | __native_type _M_mutex = __GTHREAD_MUTEX_INIT; | |
66 | ||
67 | constexpr __mutex_base() noexcept = default; | |
68 | #else | |
69 | __native_type _M_mutex; | |
70 | ||
71 | __mutex_base() noexcept | |
72 | { | |
73 | // XXX EAGAIN, ENOMEM, EPERM, EBUSY(may), EINVAL(may) | |
74 | __GTHREAD_MUTEX_INIT_FUNCTION(&_M_mutex); | |
75 | } | |
76 | ||
77 | ~__mutex_base() noexcept { __gthread_mutex_destroy(&_M_mutex); } | |
78 | #endif | |
79 | ||
80 | __mutex_base(const __mutex_base&) = delete; | |
81 | __mutex_base& operator=(const __mutex_base&) = delete; | |
82 | }; | |
b584cbdb | 83 | /// @endcond |
f16081c2 | 84 | |
b584cbdb JW |
85 | /** The standard mutex type. |
86 | * | |
87 | * A simple, non-recursive, non-timed mutex. | |
88 | * | |
89 | * Do not call `lock()` and `unlock()` directly, use a scoped lock type | |
90 | * such as `std::unique_lock`, `std::lock_guard`, or (since C++17) | |
91 | * `std::scoped_lock`. | |
92 | * | |
93 | * @headerfile mutex | |
94 | * @since C++11 | |
95 | */ | |
f16081c2 JW |
96 | class mutex : private __mutex_base |
97 | { | |
98 | public: | |
99 | typedef __native_type* native_handle_type; | |
100 | ||
101 | #ifdef __GTHREAD_MUTEX_INIT | |
102 | constexpr | |
103 | #endif | |
104 | mutex() noexcept = default; | |
105 | ~mutex() = default; | |
106 | ||
107 | mutex(const mutex&) = delete; | |
108 | mutex& operator=(const mutex&) = delete; | |
109 | ||
110 | void | |
111 | lock() | |
112 | { | |
113 | int __e = __gthread_mutex_lock(&_M_mutex); | |
114 | ||
115 | // EINVAL, EAGAIN, EBUSY, EINVAL, EDEADLK(may) | |
116 | if (__e) | |
117 | __throw_system_error(__e); | |
118 | } | |
119 | ||
af177d72 | 120 | _GLIBCXX_NODISCARD |
f16081c2 JW |
121 | bool |
122 | try_lock() noexcept | |
123 | { | |
124 | // XXX EINVAL, EAGAIN, EBUSY | |
125 | return !__gthread_mutex_trylock(&_M_mutex); | |
126 | } | |
127 | ||
128 | void | |
129 | unlock() | |
130 | { | |
131 | // XXX EINVAL, EAGAIN, EPERM | |
132 | __gthread_mutex_unlock(&_M_mutex); | |
133 | } | |
134 | ||
135 | native_handle_type | |
2c15eace | 136 | native_handle() noexcept |
f16081c2 JW |
137 | { return &_M_mutex; } |
138 | }; | |
139 | ||
b584cbdb JW |
140 | /// @cond undocumented |
141 | ||
7d2a98a7 JW |
142 | // Implementation details for std::condition_variable |
143 | class __condvar | |
144 | { | |
145 | using timespec = __gthread_time_t; | |
146 | ||
147 | public: | |
148 | __condvar() noexcept | |
149 | { | |
150 | #ifndef __GTHREAD_COND_INIT | |
151 | __GTHREAD_COND_INIT_FUNCTION(&_M_cond); | |
152 | #endif | |
153 | } | |
154 | ||
155 | ~__condvar() | |
156 | { | |
157 | int __e __attribute__((__unused__)) = __gthread_cond_destroy(&_M_cond); | |
158 | __glibcxx_assert(__e != EBUSY); // threads are still blocked | |
159 | } | |
160 | ||
161 | __condvar(const __condvar&) = delete; | |
162 | __condvar& operator=(const __condvar&) = delete; | |
163 | ||
164 | __gthread_cond_t* native_handle() noexcept { return &_M_cond; } | |
165 | ||
166 | // Expects: Calling thread has locked __m. | |
167 | void | |
9e18a253 | 168 | wait(mutex& __m) |
7d2a98a7 JW |
169 | { |
170 | int __e __attribute__((__unused__)) | |
171 | = __gthread_cond_wait(&_M_cond, __m.native_handle()); | |
172 | __glibcxx_assert(__e == 0); | |
173 | } | |
174 | ||
175 | void | |
9e18a253 | 176 | wait_until(mutex& __m, timespec& __abs_time) |
7d2a98a7 JW |
177 | { |
178 | __gthread_cond_timedwait(&_M_cond, __m.native_handle(), &__abs_time); | |
179 | } | |
180 | ||
181 | #ifdef _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT | |
182 | void | |
9e18a253 | 183 | wait_until(mutex& __m, clockid_t __clock, timespec& __abs_time) |
7d2a98a7 JW |
184 | { |
185 | pthread_cond_clockwait(&_M_cond, __m.native_handle(), __clock, | |
186 | &__abs_time); | |
187 | } | |
188 | #endif | |
189 | ||
190 | void | |
191 | notify_one() noexcept | |
192 | { | |
193 | int __e __attribute__((__unused__)) = __gthread_cond_signal(&_M_cond); | |
194 | __glibcxx_assert(__e == 0); | |
195 | } | |
196 | ||
197 | void | |
198 | notify_all() noexcept | |
199 | { | |
200 | int __e __attribute__((__unused__)) = __gthread_cond_broadcast(&_M_cond); | |
201 | __glibcxx_assert(__e == 0); | |
202 | } | |
203 | ||
204 | protected: | |
205 | #ifdef __GTHREAD_COND_INIT | |
206 | __gthread_cond_t _M_cond = __GTHREAD_COND_INIT; | |
207 | #else | |
208 | __gthread_cond_t _M_cond; | |
209 | #endif | |
210 | }; | |
b584cbdb | 211 | /// @endcond |
7d2a98a7 | 212 | |
f16081c2 JW |
213 | #endif // _GLIBCXX_HAS_GTHREADS |
214 | ||
215 | /// Do not acquire ownership of the mutex. | |
269fa2a9 | 216 | struct defer_lock_t { explicit defer_lock_t() = default; }; |
f16081c2 JW |
217 | |
218 | /// Try to acquire ownership of the mutex without blocking. | |
269fa2a9 | 219 | struct try_to_lock_t { explicit try_to_lock_t() = default; }; |
f16081c2 JW |
220 | |
221 | /// Assume the calling thread has already obtained mutex ownership | |
222 | /// and manage it. | |
269fa2a9 | 223 | struct adopt_lock_t { explicit adopt_lock_t() = default; }; |
f16081c2 | 224 | |
6b4f8906 | 225 | /// Tag used to prevent a scoped lock from acquiring ownership of a mutex. |
288695f7 | 226 | _GLIBCXX17_INLINE constexpr defer_lock_t defer_lock { }; |
6b4f8906 JW |
227 | |
228 | /// Tag used to prevent a scoped lock from blocking if a mutex is locked. | |
288695f7 | 229 | _GLIBCXX17_INLINE constexpr try_to_lock_t try_to_lock { }; |
6b4f8906 JW |
230 | |
231 | /// Tag used to make a scoped lock take ownership of a locked mutex. | |
288695f7 | 232 | _GLIBCXX17_INLINE constexpr adopt_lock_t adopt_lock { }; |
f16081c2 | 233 | |
6b4f8906 JW |
234 | /** @brief A simple scoped lock type. |
235 | * | |
236 | * A lock_guard controls mutex ownership within a scope, releasing | |
237 | * ownership in the destructor. | |
b584cbdb JW |
238 | * |
239 | * @headerfile mutex | |
240 | * @since C++11 | |
6b4f8906 | 241 | */ |
f16081c2 JW |
242 | template<typename _Mutex> |
243 | class lock_guard | |
244 | { | |
245 | public: | |
246 | typedef _Mutex mutex_type; | |
247 | ||
64bcf3f0 | 248 | [[__nodiscard__]] |
f16081c2 JW |
249 | explicit lock_guard(mutex_type& __m) : _M_device(__m) |
250 | { _M_device.lock(); } | |
251 | ||
64bcf3f0 | 252 | [[__nodiscard__]] |
2c15eace | 253 | lock_guard(mutex_type& __m, adopt_lock_t) noexcept : _M_device(__m) |
f16081c2 JW |
254 | { } // calling thread owns mutex |
255 | ||
256 | ~lock_guard() | |
257 | { _M_device.unlock(); } | |
258 | ||
259 | lock_guard(const lock_guard&) = delete; | |
260 | lock_guard& operator=(const lock_guard&) = delete; | |
261 | ||
262 | private: | |
263 | mutex_type& _M_device; | |
264 | }; | |
265 | ||
f0b88346 | 266 | /// @} group mutexes |
f16081c2 JW |
267 | _GLIBCXX_END_NAMESPACE_VERSION |
268 | } // namespace | |
f16081c2 | 269 | #endif // C++11 |
f16081c2 | 270 | #endif // _GLIBCXX_MUTEX_H |