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The C and C++ Include Header Files
/usr/include/c++/11/bits/std_mutex.h
$ cat -n /usr/include/c++/11/bits/std_mutex.h 1 // std::mutex implementation -*- C++ -*- 2 3 // Copyright (C) 2003-2021 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 <system_error> 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 // Common base class for std::mutex and std::timed_mutex 57 class __mutex_base 58 { 59 protected: 60 typedef __gthread_mutex_t __native_type; 61 62 #ifdef __GTHREAD_MUTEX_INIT 63 __native_type _M_mutex = __GTHREAD_MUTEX_INIT; 64 65 constexpr __mutex_base() noexcept = default; 66 #else 67 __native_type _M_mutex; 68 69 __mutex_base() noexcept 70 { 71 // XXX EAGAIN, ENOMEM, EPERM, EBUSY(may), EINVAL(may) 72 __GTHREAD_MUTEX_INIT_FUNCTION(&_M_mutex); 73 } 74 75 ~__mutex_base() noexcept { __gthread_mutex_destroy(&_M_mutex); } 76 #endif 77 78 __mutex_base(const __mutex_base&) = delete; 79 __mutex_base& operator=(const __mutex_base&) = delete; 80 }; 81 82 /// The standard mutex type. 83 class mutex : private __mutex_base 84 { 85 public: 86 typedef __native_type* native_handle_type; 87 88 #ifdef __GTHREAD_MUTEX_INIT 89 constexpr 90 #endif 91 mutex() noexcept = default; 92 ~mutex() = default; 93 94 mutex(const mutex&) = delete; 95 mutex& operator=(const mutex&) = delete; 96 97 void 98 lock() 99 { 100 int __e = __gthread_mutex_lock(&_M_mutex); 101 102 // EINVAL, EAGAIN, EBUSY, EINVAL, EDEADLK(may) 103 if (__e) 104 __throw_system_error(__e); 105 } 106 107 bool 108 try_lock() noexcept 109 { 110 // XXX EINVAL, EAGAIN, EBUSY 111 return !__gthread_mutex_trylock(&_M_mutex); 112 } 113 114 void 115 unlock() 116 { 117 // XXX EINVAL, EAGAIN, EPERM 118 __gthread_mutex_unlock(&_M_mutex); 119 } 120 121 native_handle_type 122 native_handle() noexcept 123 { return &_M_mutex; } 124 }; 125 126 // Implementation details for std::condition_variable 127 class __condvar 128 { 129 using timespec = __gthread_time_t; 130 131 public: 132 __condvar() noexcept 133 { 134 #ifndef __GTHREAD_COND_INIT 135 __GTHREAD_COND_INIT_FUNCTION(&_M_cond); 136 #endif 137 } 138 139 ~__condvar() 140 { 141 int __e __attribute__((__unused__)) = __gthread_cond_destroy(&_M_cond); 142 __glibcxx_assert(__e != EBUSY); // threads are still blocked 143 } 144 145 __condvar(const __condvar&) = delete; 146 __condvar& operator=(const __condvar&) = delete; 147 148 __gthread_cond_t* native_handle() noexcept { return &_M_cond; } 149 150 // Expects: Calling thread has locked __m. 151 void 152 wait(mutex& __m) noexcept 153 { 154 int __e __attribute__((__unused__)) 155 = __gthread_cond_wait(&_M_cond, __m.native_handle()); 156 __glibcxx_assert(__e == 0); 157 } 158 159 void 160 wait_until(mutex& __m, timespec& __abs_time) noexcept 161 { 162 __gthread_cond_timedwait(&_M_cond, __m.native_handle(), &__abs_time); 163 } 164 165 #ifdef _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT 166 void 167 wait_until(mutex& __m, clockid_t __clock, timespec& __abs_time) noexcept 168 { 169 pthread_cond_clockwait(&_M_cond, __m.native_handle(), __clock, 170 &__abs_time); 171 } 172 #endif 173 174 void 175 notify_one() noexcept 176 { 177 int __e __attribute__((__unused__)) = __gthread_cond_signal(&_M_cond); 178 __glibcxx_assert(__e == 0); 179 } 180 181 void 182 notify_all() noexcept 183 { 184 int __e __attribute__((__unused__)) = __gthread_cond_broadcast(&_M_cond); 185 __glibcxx_assert(__e == 0); 186 } 187 188 protected: 189 #ifdef __GTHREAD_COND_INIT 190 __gthread_cond_t _M_cond = __GTHREAD_COND_INIT; 191 #else 192 __gthread_cond_t _M_cond; 193 #endif 194 }; 195 196 #endif // _GLIBCXX_HAS_GTHREADS 197 198 /// Do not acquire ownership of the mutex. 199 struct defer_lock_t { explicit defer_lock_t() = default; }; 200 201 /// Try to acquire ownership of the mutex without blocking. 202 struct try_to_lock_t { explicit try_to_lock_t() = default; }; 203 204 /// Assume the calling thread has already obtained mutex ownership 205 /// and manage it. 206 struct adopt_lock_t { explicit adopt_lock_t() = default; }; 207 208 /// Tag used to prevent a scoped lock from acquiring ownership of a mutex. 209 _GLIBCXX17_INLINE constexpr defer_lock_t defer_lock { }; 210 211 /// Tag used to prevent a scoped lock from blocking if a mutex is locked. 212 _GLIBCXX17_INLINE constexpr try_to_lock_t try_to_lock { }; 213 214 /// Tag used to make a scoped lock take ownership of a locked mutex. 215 _GLIBCXX17_INLINE constexpr adopt_lock_t adopt_lock { }; 216 217 /** @brief A simple scoped lock type. 218 * 219 * A lock_guard controls mutex ownership within a scope, releasing 220 * ownership in the destructor. 221 */ 222 template<typename _Mutex> 223 class lock_guard 224 { 225 public: 226 typedef _Mutex mutex_type; 227 228 explicit lock_guard(mutex_type& __m) : _M_device(__m) 229 { _M_device.lock(); } 230 231 lock_guard(mutex_type& __m, adopt_lock_t) noexcept : _M_device(__m) 232 { } // calling thread owns mutex 233 234 ~lock_guard() 235 { _M_device.unlock(); } 236 237 lock_guard(const lock_guard&) = delete; 238 lock_guard& operator=(const lock_guard&) = delete; 239 240 private: 241 mutex_type& _M_device; 242 }; 243 244 /// @} group mutexes 245 _GLIBCXX_END_NAMESPACE_VERSION 246 } // namespace 247 #endif // C++11 248 #endif // _GLIBCXX_MUTEX_H
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