1 // std::mutex implementation -*- C++ -*-
3 // Copyright (C) 2003-2024 Free Software Foundation, Inc.
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)
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.
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.
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/>.
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}
30 #ifndef _GLIBCXX_MUTEX_H
31 #define _GLIBCXX_MUTEX_H 1
33 #pragma GCC system_header
35 #if __cplusplus < 201103L
36 # include <bits/c++0x_warning.h>
39 #include <errno.h> // EBUSY
40 #include <bits/functexcept.h>
41 #include <bits/gthr.h>
43 namespace std
_GLIBCXX_VISIBILITY(default)
45 _GLIBCXX_BEGIN_NAMESPACE_VERSION
48 * @defgroup mutexes Mutexes
49 * @ingroup concurrency
51 * Classes for mutex support.
55 #ifdef _GLIBCXX_HAS_GTHREADS
56 /// @cond undocumented
58 // Common base class for std::mutex and std::timed_mutex
62 typedef __gthread_mutex_t __native_type
;
64 #ifdef __GTHREAD_MUTEX_INIT
65 __native_type _M_mutex
= __GTHREAD_MUTEX_INIT
;
67 constexpr __mutex_base() noexcept
= default;
69 __native_type _M_mutex
;
71 __mutex_base() noexcept
73 // XXX EAGAIN, ENOMEM, EPERM, EBUSY(may), EINVAL(may)
74 __GTHREAD_MUTEX_INIT_FUNCTION(&_M_mutex
);
77 ~__mutex_base() noexcept
{ __gthread_mutex_destroy(&_M_mutex
); }
80 __mutex_base(const __mutex_base
&) = delete;
81 __mutex_base
& operator=(const __mutex_base
&) = delete;
85 /** The standard mutex type.
87 * A simple, non-recursive, non-timed mutex.
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)
96 class mutex
: private __mutex_base
99 typedef __native_type
* native_handle_type
;
101 #ifdef __GTHREAD_MUTEX_INIT
104 mutex() noexcept
= default;
107 mutex(const mutex
&) = delete;
108 mutex
& operator=(const mutex
&) = delete;
113 int __e
= __gthread_mutex_lock(&_M_mutex
);
115 // EINVAL, EAGAIN, EBUSY, EINVAL, EDEADLK(may)
117 __throw_system_error(__e
);
124 // XXX EINVAL, EAGAIN, EBUSY
125 return !__gthread_mutex_trylock(&_M_mutex
);
131 // XXX EINVAL, EAGAIN, EPERM
132 __gthread_mutex_unlock(&_M_mutex
);
136 native_handle() noexcept
137 { return &_M_mutex
; }
140 /// @cond undocumented
142 // Implementation details for std::condition_variable
145 using timespec
= __gthread_time_t
;
150 #ifndef __GTHREAD_COND_INIT
151 __GTHREAD_COND_INIT_FUNCTION(&_M_cond
);
157 int __e
__attribute__((__unused__
)) = __gthread_cond_destroy(&_M_cond
);
158 __glibcxx_assert(__e
!= EBUSY
); // threads are still blocked
161 __condvar(const __condvar
&) = delete;
162 __condvar
& operator=(const __condvar
&) = delete;
164 __gthread_cond_t
* native_handle() noexcept
{ return &_M_cond
; }
166 // Expects: Calling thread has locked __m.
170 int __e
__attribute__((__unused__
))
171 = __gthread_cond_wait(&_M_cond
, __m
.native_handle());
172 __glibcxx_assert(__e
== 0);
176 wait_until(mutex
& __m
, timespec
& __abs_time
)
178 __gthread_cond_timedwait(&_M_cond
, __m
.native_handle(), &__abs_time
);
181 #ifdef _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT
183 wait_until(mutex
& __m
, clockid_t __clock
, timespec
& __abs_time
)
185 pthread_cond_clockwait(&_M_cond
, __m
.native_handle(), __clock
,
191 notify_one() noexcept
193 int __e
__attribute__((__unused__
)) = __gthread_cond_signal(&_M_cond
);
194 __glibcxx_assert(__e
== 0);
198 notify_all() noexcept
200 int __e
__attribute__((__unused__
)) = __gthread_cond_broadcast(&_M_cond
);
201 __glibcxx_assert(__e
== 0);
205 #ifdef __GTHREAD_COND_INIT
206 __gthread_cond_t _M_cond
= __GTHREAD_COND_INIT
;
208 __gthread_cond_t _M_cond
;
213 #endif // _GLIBCXX_HAS_GTHREADS
215 /// Do not acquire ownership of the mutex.
216 struct defer_lock_t
{ explicit defer_lock_t() = default; };
218 /// Try to acquire ownership of the mutex without blocking.
219 struct try_to_lock_t
{ explicit try_to_lock_t() = default; };
221 /// Assume the calling thread has already obtained mutex ownership
223 struct adopt_lock_t
{ explicit adopt_lock_t() = default; };
225 /// Tag used to prevent a scoped lock from acquiring ownership of a mutex.
226 _GLIBCXX17_INLINE
constexpr defer_lock_t defer_lock
{ };
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
{ };
231 /// Tag used to make a scoped lock take ownership of a locked mutex.
232 _GLIBCXX17_INLINE
constexpr adopt_lock_t adopt_lock
{ };
234 /** @brief A simple scoped lock type.
236 * A lock_guard controls mutex ownership within a scope, releasing
237 * ownership in the destructor.
242 template<typename _Mutex
>
246 typedef _Mutex mutex_type
;
249 explicit lock_guard(mutex_type
& __m
) : _M_device(__m
)
250 { _M_device
.lock(); }
253 lock_guard(mutex_type
& __m
, adopt_lock_t
) noexcept
: _M_device(__m
)
254 { } // calling thread owns mutex
257 { _M_device
.unlock(); }
259 lock_guard(const lock_guard
&) = delete;
260 lock_guard
& operator=(const lock_guard
&) = delete;
263 mutex_type
& _M_device
;
267 _GLIBCXX_END_NAMESPACE_VERSION
270 #endif // _GLIBCXX_MUTEX_H