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The C and C++ Include Header Files
/usr/include/c++/13/bits/std_mutex.h
$ cat -n /usr/include/c++/13/bits/std_mutex.h 1 // std::mutex implementation -*- C++ -*- 2 3 // Copyright (C) 2003-2023 Free Software Foundation, Inc. 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 25 /** @file bits/std_mutex.h 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 39 #include <errno.h> // EBUSY 40 #include <bits/functexcept.h> 41 #include <bits/gthr.h> 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 56 /// @cond undocumented 57 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 }; 83 /// @endcond 84 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 */ 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 } 119 120 _GLIBCXX_NODISCARD 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 136 native_handle() noexcept 137 { return &_M_mutex; } 138 }; 139 140 /// @cond undocumented 141 142 // 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 168 wait(mutex& __m) 169 { 170 int __e __attribute__((__unused__)) 171 = __gthread_cond_wait(&_M_cond, __m.native_handle()); 172 __glibcxx_assert(__e == 0); 173 } 174 175 void 176 wait_until(mutex& __m, timespec& __abs_time) 177 { 178 __gthread_cond_timedwait(&_M_cond, __m.native_handle(), &__abs_time); 179 } 180 181 #ifdef _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT 182 void 183 wait_until(mutex& __m, clockid_t __clock, timespec& __abs_time) 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 }; 211 /// @endcond 212 213 #endif // _GLIBCXX_HAS_GTHREADS 214 215 /// Do not acquire ownership of the mutex. 216 struct defer_lock_t { explicit defer_lock_t() = default; }; 217 218 /// Try to acquire ownership of the mutex without blocking. 219 struct try_to_lock_t { explicit try_to_lock_t() = default; }; 220 221 /// Assume the calling thread has already obtained mutex ownership 222 /// and manage it. 223 struct adopt_lock_t { explicit adopt_lock_t() = default; }; 224 225 /// Tag used to prevent a scoped lock from acquiring ownership of a mutex. 226 _GLIBCXX17_INLINE constexpr defer_lock_t defer_lock { }; 227 228 /// Tag used to prevent a scoped lock from blocking if a mutex is locked. 229 _GLIBCXX17_INLINE constexpr try_to_lock_t try_to_lock { }; 230 231 /// Tag used to make a scoped lock take ownership of a locked mutex. 232 _GLIBCXX17_INLINE constexpr adopt_lock_t adopt_lock { }; 233 234 /** @brief A simple scoped lock type. 235 * 236 * A lock_guard controls mutex ownership within a scope, releasing 237 * ownership in the destructor. 238 * 239 * @headerfile mutex 240 * @since C++11 241 */ 242 template<typename _Mutex> 243 class lock_guard 244 { 245 public: 246 typedef _Mutex mutex_type; 247 248 explicit lock_guard(mutex_type& __m) : _M_device(__m) 249 { _M_device.lock(); } 250 251 lock_guard(mutex_type& __m, adopt_lock_t) noexcept : _M_device(__m) 252 { } // calling thread owns mutex 253 254 ~lock_guard() 255 { _M_device.unlock(); } 256 257 lock_guard(const lock_guard&) = delete; 258 lock_guard& operator=(const lock_guard&) = delete; 259 260 private: 261 mutex_type& _M_device; 262 }; 263 264 /// @} group mutexes 265 _GLIBCXX_END_NAMESPACE_VERSION 266 } // namespace 267 #endif // C++11 268 #endif // _GLIBCXX_MUTEX_H
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