libstdc++
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00001 // std::mutex implementation -*- C++ -*- 00002 00003 // Copyright (C) 2003-2019 Free Software Foundation, Inc. 00004 // 00005 // This file is part of the GNU ISO C++ Library. This library is free 00006 // software; you can redistribute it and/or modify it under the 00007 // terms of the GNU General Public License as published by the 00008 // Free Software Foundation; either version 3, or (at your option) 00009 // any later version. 00010 00011 // This library is distributed in the hope that it will be useful, 00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00014 // GNU General Public License for more details. 00015 00016 // Under Section 7 of GPL version 3, you are granted additional 00017 // permissions described in the GCC Runtime Library Exception, version 00018 // 3.1, as published by the Free Software Foundation. 00019 00020 // You should have received a copy of the GNU General Public License and 00021 // a copy of the GCC Runtime Library Exception along with this program; 00022 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 00023 // <http://www.gnu.org/licenses/>. 00024 00025 /** @file bits/std_mutex.h 00026 * This is an internal header file, included by other library headers. 00027 * Do not attempt to use it directly. @headername{mutex} 00028 */ 00029 00030 #ifndef _GLIBCXX_MUTEX_H 00031 #define _GLIBCXX_MUTEX_H 1 00032 00033 #pragma GCC system_header 00034 00035 #if __cplusplus < 201103L 00036 # include <bits/c++0x_warning.h> 00037 #else 00038 00039 #include <system_error> 00040 #include <bits/functexcept.h> 00041 #include <bits/gthr.h> 00042 00043 namespace std _GLIBCXX_VISIBILITY(default) 00044 { 00045 _GLIBCXX_BEGIN_NAMESPACE_VERSION 00046 00047 /** 00048 * @defgroup mutexes Mutexes 00049 * @ingroup concurrency 00050 * 00051 * Classes for mutex support. 00052 * @{ 00053 */ 00054 00055 #ifdef _GLIBCXX_HAS_GTHREADS 00056 // Common base class for std::mutex and std::timed_mutex 00057 class __mutex_base 00058 { 00059 protected: 00060 typedef __gthread_mutex_t __native_type; 00061 00062 #ifdef __GTHREAD_MUTEX_INIT 00063 __native_type _M_mutex = __GTHREAD_MUTEX_INIT; 00064 00065 constexpr __mutex_base() noexcept = default; 00066 #else 00067 __native_type _M_mutex; 00068 00069 __mutex_base() noexcept 00070 { 00071 // XXX EAGAIN, ENOMEM, EPERM, EBUSY(may), EINVAL(may) 00072 __GTHREAD_MUTEX_INIT_FUNCTION(&_M_mutex); 00073 } 00074 00075 ~__mutex_base() noexcept { __gthread_mutex_destroy(&_M_mutex); } 00076 #endif 00077 00078 __mutex_base(const __mutex_base&) = delete; 00079 __mutex_base& operator=(const __mutex_base&) = delete; 00080 }; 00081 00082 /// The standard mutex type. 00083 class mutex : private __mutex_base 00084 { 00085 public: 00086 typedef __native_type* native_handle_type; 00087 00088 #ifdef __GTHREAD_MUTEX_INIT 00089 constexpr 00090 #endif 00091 mutex() noexcept = default; 00092 ~mutex() = default; 00093 00094 mutex(const mutex&) = delete; 00095 mutex& operator=(const mutex&) = delete; 00096 00097 void 00098 lock() 00099 { 00100 int __e = __gthread_mutex_lock(&_M_mutex); 00101 00102 // EINVAL, EAGAIN, EBUSY, EINVAL, EDEADLK(may) 00103 if (__e) 00104 __throw_system_error(__e); 00105 } 00106 00107 bool 00108 try_lock() noexcept 00109 { 00110 // XXX EINVAL, EAGAIN, EBUSY 00111 return !__gthread_mutex_trylock(&_M_mutex); 00112 } 00113 00114 void 00115 unlock() 00116 { 00117 // XXX EINVAL, EAGAIN, EPERM 00118 __gthread_mutex_unlock(&_M_mutex); 00119 } 00120 00121 native_handle_type 00122 native_handle() noexcept 00123 { return &_M_mutex; } 00124 }; 00125 00126 #endif // _GLIBCXX_HAS_GTHREADS 00127 00128 /// Do not acquire ownership of the mutex. 00129 struct defer_lock_t { explicit defer_lock_t() = default; }; 00130 00131 /// Try to acquire ownership of the mutex without blocking. 00132 struct try_to_lock_t { explicit try_to_lock_t() = default; }; 00133 00134 /// Assume the calling thread has already obtained mutex ownership 00135 /// and manage it. 00136 struct adopt_lock_t { explicit adopt_lock_t() = default; }; 00137 00138 /// Tag used to prevent a scoped lock from acquiring ownership of a mutex. 00139 _GLIBCXX17_INLINE constexpr defer_lock_t defer_lock { }; 00140 00141 /// Tag used to prevent a scoped lock from blocking if a mutex is locked. 00142 _GLIBCXX17_INLINE constexpr try_to_lock_t try_to_lock { }; 00143 00144 /// Tag used to make a scoped lock take ownership of a locked mutex. 00145 _GLIBCXX17_INLINE constexpr adopt_lock_t adopt_lock { }; 00146 00147 /** @brief A simple scoped lock type. 00148 * 00149 * A lock_guard controls mutex ownership within a scope, releasing 00150 * ownership in the destructor. 00151 */ 00152 template<typename _Mutex> 00153 class lock_guard 00154 { 00155 public: 00156 typedef _Mutex mutex_type; 00157 00158 explicit lock_guard(mutex_type& __m) : _M_device(__m) 00159 { _M_device.lock(); } 00160 00161 lock_guard(mutex_type& __m, adopt_lock_t) noexcept : _M_device(__m) 00162 { } // calling thread owns mutex 00163 00164 ~lock_guard() 00165 { _M_device.unlock(); } 00166 00167 lock_guard(const lock_guard&) = delete; 00168 lock_guard& operator=(const lock_guard&) = delete; 00169 00170 private: 00171 mutex_type& _M_device; 00172 }; 00173 00174 // @} group mutexes 00175 _GLIBCXX_END_NAMESPACE_VERSION 00176 } // namespace 00177 #endif // C++11 00178 #endif // _GLIBCXX_MUTEX_H