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The C and C++ Include Header Files
cat -n /usr/include/c++/15/bits/std_mutex.h
1 // std::mutex implementation -*- C++ -*- 2 3 // Copyright (C) 2003-2025 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 #ifdef _GLIBCXX_SYSHDR 34 #pragma GCC system_header 35 #endif 36 37 #if __cplusplus < 201103L 38 # include <bits/c++0x_warning.h> 39 #else 40 41 #include <errno.h> // EBUSY 42 #include <bits/functexcept.h> 43 #include <bits/gthr.h> 44 45 namespace std _GLIBCXX_VISIBILITY(default) 46 { 47 _GLIBCXX_BEGIN_NAMESPACE_VERSION 48 49 /** 50 * @defgroup mutexes Mutexes 51 * @ingroup concurrency 52 * 53 * Classes for mutex support. 54 * @{ 55 */ 56 57 #ifdef _GLIBCXX_HAS_GTHREADS 58 /// @cond undocumented 59 60 // Common base class for std::mutex and std::timed_mutex 61 class __mutex_base 62 { 63 protected: 64 typedef __gthread_mutex_t __native_type; 65 66 #ifdef __GTHREAD_MUTEX_INIT 67 __native_type _M_mutex = __GTHREAD_MUTEX_INIT; 68 69 constexpr __mutex_base() noexcept = default; 70 #else 71 __native_type _M_mutex; 72 73 __mutex_base() noexcept 74 { 75 // XXX EAGAIN, ENOMEM, EPERM, EBUSY(may), EINVAL(may) 76 __GTHREAD_MUTEX_INIT_FUNCTION(&_M_mutex); 77 } 78 79 ~__mutex_base() noexcept { __gthread_mutex_destroy(&_M_mutex); } 80 #endif 81 82 __mutex_base(const __mutex_base&) = delete; 83 __mutex_base& operator=(const __mutex_base&) = delete; 84 }; 85 /// @endcond 86 87 /** The standard mutex type. 88 * 89 * A simple, non-recursive, non-timed mutex. 90 * 91 * Do not call `lock()` and `unlock()` directly, use a scoped lock type 92 * such as `std::unique_lock`, `std::lock_guard`, or (since C++17) 93 * `std::scoped_lock`. 94 * 95 * @headerfile mutex 96 * @since C++11 97 */ 98 class mutex : private __mutex_base 99 { 100 public: 101 typedef __native_type* native_handle_type; 102 103 #ifdef __GTHREAD_MUTEX_INIT 104 constexpr 105 #endif 106 mutex() noexcept = default; 107 ~mutex() = default; 108 109 mutex(const mutex&) = delete; 110 mutex& operator=(const mutex&) = delete; 111 112 void 113 lock() 114 { 115 int __e = __gthread_mutex_lock(&_M_mutex); 116 117 // EINVAL, EAGAIN, EBUSY, EINVAL, EDEADLK(may) 118 if (__e) 119 __throw_system_error(__e); 120 } 121 122 _GLIBCXX_NODISCARD 123 bool 124 try_lock() noexcept 125 { 126 // XXX EINVAL, EAGAIN, EBUSY 127 return !__gthread_mutex_trylock(&_M_mutex); 128 } 129 130 void 131 unlock() 132 { 133 // XXX EINVAL, EAGAIN, EPERM 134 __gthread_mutex_unlock(&_M_mutex); 135 } 136 137 native_handle_type 138 native_handle() noexcept 139 { return &_M_mutex; } 140 }; 141 142 /// @cond undocumented 143 144 // Implementation details for std::condition_variable 145 class __condvar 146 { 147 using timespec = __gthread_time_t; 148 149 public: 150 __condvar() noexcept 151 { 152 #ifndef __GTHREAD_COND_INIT 153 __GTHREAD_COND_INIT_FUNCTION(&_M_cond); 154 #endif 155 } 156 157 ~__condvar() 158 { 159 int __e __attribute__((__unused__)) = __gthread_cond_destroy(&_M_cond); 160 __glibcxx_assert(__e != EBUSY); // threads are still blocked 161 } 162 163 __condvar(const __condvar&) = delete; 164 __condvar& operator=(const __condvar&) = delete; 165 166 __gthread_cond_t* native_handle() noexcept { return &_M_cond; } 167 168 // Expects: Calling thread has locked __m. 169 void 170 wait(mutex& __m) 171 { 172 int __e __attribute__((__unused__)) 173 = __gthread_cond_wait(&_M_cond, __m.native_handle()); 174 __glibcxx_assert(__e == 0); 175 } 176 177 void 178 wait_until(mutex& __m, timespec& __abs_time) 179 { 180 __gthread_cond_timedwait(&_M_cond, __m.native_handle(), &__abs_time); 181 } 182 183 #ifdef _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT 184 void 185 wait_until(mutex& __m, clockid_t __clock, timespec& __abs_time) 186 { 187 pthread_cond_clockwait(&_M_cond, __m.native_handle(), __clock, 188 &__abs_time); 189 } 190 #endif 191 192 void 193 notify_one() noexcept 194 { 195 int __e __attribute__((__unused__)) = __gthread_cond_signal(&_M_cond); 196 __glibcxx_assert(__e == 0); 197 } 198 199 void 200 notify_all() noexcept 201 { 202 int __e __attribute__((__unused__)) = __gthread_cond_broadcast(&_M_cond); 203 __glibcxx_assert(__e == 0); 204 } 205 206 protected: 207 #ifdef __GTHREAD_COND_INIT 208 __gthread_cond_t _M_cond = __GTHREAD_COND_INIT; 209 #else 210 __gthread_cond_t _M_cond; 211 #endif 212 }; 213 /// @endcond 214 215 #endif // _GLIBCXX_HAS_GTHREADS 216 217 /// Do not acquire ownership of the mutex. 218 struct defer_lock_t { explicit defer_lock_t() = default; }; 219 220 /// Try to acquire ownership of the mutex without blocking. 221 struct try_to_lock_t { explicit try_to_lock_t() = default; }; 222 223 /// Assume the calling thread has already obtained mutex ownership 224 /// and manage it. 225 struct adopt_lock_t { explicit adopt_lock_t() = default; }; 226 227 /// Tag used to prevent a scoped lock from acquiring ownership of a mutex. 228 _GLIBCXX17_INLINE constexpr defer_lock_t defer_lock { }; 229 230 /// Tag used to prevent a scoped lock from blocking if a mutex is locked. 231 _GLIBCXX17_INLINE constexpr try_to_lock_t try_to_lock { }; 232 233 /// Tag used to make a scoped lock take ownership of a locked mutex. 234 _GLIBCXX17_INLINE constexpr adopt_lock_t adopt_lock { }; 235 236 /** @brief A simple scoped lock type. 237 * 238 * A lock_guard controls mutex ownership within a scope, releasing 239 * ownership in the destructor. 240 * 241 * @headerfile mutex 242 * @since C++11 243 */ 244 template<typename _Mutex> 245 class lock_guard 246 { 247 public: 248 typedef _Mutex mutex_type; 249 250 [[__nodiscard__]] 251 explicit lock_guard(mutex_type& __m) : _M_device(__m) 252 { _M_device.lock(); } 253 254 [[__nodiscard__]] 255 lock_guard(mutex_type& __m, adopt_lock_t) noexcept : _M_device(__m) 256 { } // calling thread owns mutex 257 258 ~lock_guard() 259 { _M_device.unlock(); } 260 261 lock_guard(const lock_guard&) = delete; 262 lock_guard& operator=(const lock_guard&) = delete; 263 264 private: 265 mutex_type& _M_device; 266 }; 267 268 /// @} group mutexes 269 _GLIBCXX_END_NAMESPACE_VERSION 270 } // namespace 271 #endif // C++11 272 #endif // _GLIBCXX_MUTEX_H
