// std::mutex implementation -*- C++ -*- // Copyright (C) 2003-2018 Free Software Foundation, Inc. // // This file is part of the GNU ISO C++ Library. This library is free // software; you can redistribute it and/or modify it under the // terms of the GNU General Public License as published by the // Free Software Foundation; either version 3, or (at your option) // any later version. // This library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // Under Section 7 of GPL version 3, you are granted additional // permissions described in the GCC Runtime Library Exception, version // 3.1, as published by the Free Software Foundation. // You should have received a copy of the GNU General Public License and // a copy of the GCC Runtime Library Exception along with this program; // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see // <http://www.gnu.org/licenses/>. /** @file bits/std_mutex.h * This is an internal header file, included by other library headers. * Do not attempt to use it directly. @headername{mutex} */ #ifndef _GLIBCXX_MUTEX_H #define _GLIBCXX_MUTEX_H 1 #pragma GCC system_header #if __cplusplus < 201103L # include <bits/c++0x_warning.h> #else #include <system_error> #include <bits/functexcept.h> #include <bits/gthr.h> #include <bits/move.h> // for std::swap #ifdef _GLIBCXX_USE_C99_STDINT_TR1 namespace std _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION /** * @defgroup mutexes Mutexes * @ingroup concurrency * * Classes for mutex support. * @{ */ #ifdef _GLIBCXX_HAS_GTHREADS // Common base class for std::mutex and std::timed_mutex class __mutex_base { protected: typedef __gthread_mutex_t __native_type; #ifdef __GTHREAD_MUTEX_INIT __native_type _M_mutex = __GTHREAD_MUTEX_INIT; constexpr __mutex_base() noexcept = default; #else __native_type _M_mutex; __mutex_base() noexcept { // XXX EAGAIN, ENOMEM, EPERM, EBUSY(may), EINVAL(may) __GTHREAD_MUTEX_INIT_FUNCTION(&_M_mutex); } ~__mutex_base() noexcept { __gthread_mutex_destroy(&_M_mutex); } #endif __mutex_base(const __mutex_base&) = delete; __mutex_base& operator=(const __mutex_base&) = delete; }; /// The standard mutex type. class mutex : private __mutex_base { public: typedef __native_type* native_handle_type; #ifdef __GTHREAD_MUTEX_INIT constexpr #endif mutex() noexcept = default; ~mutex() = default; mutex(const mutex&) = delete; mutex& operator=(const mutex&) = delete; void lock() { int __e = __gthread_mutex_lock(&_M_mutex); // EINVAL, EAGAIN, EBUSY, EINVAL, EDEADLK(may) if (__e) __throw_system_error(__e); } bool try_lock() noexcept { // XXX EINVAL, EAGAIN, EBUSY return !__gthread_mutex_trylock(&_M_mutex); } void unlock() { // XXX EINVAL, EAGAIN, EPERM __gthread_mutex_unlock(&_M_mutex); } native_handle_type native_handle() noexcept { return &_M_mutex; } }; #endif // _GLIBCXX_HAS_GTHREADS /// Do not acquire ownership of the mutex. struct defer_lock_t { explicit defer_lock_t() = default; }; /// Try to acquire ownership of the mutex without blocking. struct try_to_lock_t { explicit try_to_lock_t() = default; }; /// Assume the calling thread has already obtained mutex ownership /// and manage it. struct adopt_lock_t { explicit adopt_lock_t() = default; }; /// Tag used to prevent a scoped lock from acquiring ownership of a mutex. _GLIBCXX17_INLINE constexpr defer_lock_t defer_lock { }; /// Tag used to prevent a scoped lock from blocking if a mutex is locked. _GLIBCXX17_INLINE constexpr try_to_lock_t try_to_lock { }; /// Tag used to make a scoped lock take ownership of a locked mutex. _GLIBCXX17_INLINE constexpr adopt_lock_t adopt_lock { }; /** @brief A simple scoped lock type. * * A lock_guard controls mutex ownership within a scope, releasing * ownership in the destructor. */ template<typename _Mutex> class lock_guard { public: typedef _Mutex mutex_type; explicit lock_guard(mutex_type& __m) : _M_device(__m) { _M_device.lock(); } lock_guard(mutex_type& __m, adopt_lock_t) noexcept : _M_device(__m) { } // calling thread owns mutex ~lock_guard() { _M_device.unlock(); } lock_guard(const lock_guard&) = delete; lock_guard& operator=(const lock_guard&) = delete; private: mutex_type& _M_device; }; /** @brief A movable scoped lock type. * * A unique_lock controls mutex ownership within a scope. Ownership of the * mutex can be delayed until after construction and can be transferred * to another unique_lock by move construction or move assignment. If a * mutex lock is owned when the destructor runs ownership will be released. */ template<typename _Mutex> class unique_lock { public: typedef _Mutex mutex_type; unique_lock() noexcept : _M_device(0), _M_owns(false) { } explicit unique_lock(mutex_type& __m) : _M_device(std::__addressof(__m)), _M_owns(false) { lock(); _M_owns = true; } unique_lock(mutex_type& __m, defer_lock_t) noexcept : _M_device(std::__addressof(__m)), _M_owns(false) { } unique_lock(mutex_type& __m, try_to_lock_t) : _M_device(std::__addressof(__m)), _M_owns(_M_device->try_lock()) { } unique_lock(mutex_type& __m, adopt_lock_t) noexcept : _M_device(std::__addressof(__m)), _M_owns(true) { // XXX calling thread owns mutex } template<typename _Clock, typename _Duration> unique_lock(mutex_type& __m, const chrono::time_point<_Clock, _Duration>& __atime) : _M_device(std::__addressof(__m)), _M_owns(_M_device->try_lock_until(__atime)) { } template<typename _Rep, typename _Period> unique_lock(mutex_type& __m, const chrono::duration<_Rep, _Period>& __rtime) : _M_device(std::__addressof(__m)), _M_owns(_M_device->try_lock_for(__rtime)) { } ~unique_lock() { if (_M_owns) unlock(); } unique_lock(const unique_lock&) = delete; unique_lock& operator=(const unique_lock&) = delete; unique_lock(unique_lock&& __u) noexcept : _M_device(__u._M_device), _M_owns(__u._M_owns) { __u._M_device = 0; __u._M_owns = false; } unique_lock& operator=(unique_lock&& __u) noexcept { if(_M_owns) unlock(); unique_lock(std::move(__u)).swap(*this); __u._M_device = 0; __u._M_owns = false; return *this; } void lock() { if (!_M_device) __throw_system_error(int(errc::operation_not_permitted)); else if (_M_owns) __throw_system_error(int(errc::resource_deadlock_would_occur)); else { _M_device->lock(); _M_owns = true; } } bool try_lock() { if (!_M_device) __throw_system_error(int(errc::operation_not_permitted)); else if (_M_owns) __throw_system_error(int(errc::resource_deadlock_would_occur)); else { _M_owns = _M_device->try_lock(); return _M_owns; } } template<typename _Clock, typename _Duration> bool try_lock_until(const chrono::time_point<_Clock, _Duration>& __atime) { if (!_M_device) __throw_system_error(int(errc::operation_not_permitted)); else if (_M_owns) __throw_system_error(int(errc::resource_deadlock_would_occur)); else { _M_owns = _M_device->try_lock_until(__atime); return _M_owns; } } template<typename _Rep, typename _Period> bool try_lock_for(const chrono::duration<_Rep, _Period>& __rtime) { if (!_M_device) __throw_system_error(int(errc::operation_not_permitted)); else if (_M_owns) __throw_system_error(int(errc::resource_deadlock_would_occur)); else { _M_owns = _M_device->try_lock_for(__rtime); return _M_owns; } } void unlock() { if (!_M_owns) __throw_system_error(int(errc::operation_not_permitted)); else if (_M_device) { _M_device->unlock(); _M_owns = false; } } void swap(unique_lock& __u) noexcept { std::swap(_M_device, __u._M_device); std::swap(_M_owns, __u._M_owns); } mutex_type* release() noexcept { mutex_type* __ret = _M_device; _M_device = 0; _M_owns = false; return __ret; } bool owns_lock() const noexcept { return _M_owns; } explicit operator bool() const noexcept { return owns_lock(); } mutex_type* mutex() const noexcept { return _M_device; } private: mutex_type* _M_device; bool _M_owns; // XXX use atomic_bool }; /// Swap overload for unique_lock objects. template<typename _Mutex> inline void swap(unique_lock<_Mutex>& __x, unique_lock<_Mutex>& __y) noexcept { __x.swap(__y); } // @} group mutexes _GLIBCXX_END_NAMESPACE_VERSION } // namespace #endif // _GLIBCXX_USE_C99_STDINT_TR1 #endif // C++11 #endif // _GLIBCXX_MUTEX_H