1 // std::mutex implementation -*- C++ -*-
3 // Copyright (C) 2003-2020 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 <system_error>
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 // Common base class for std::mutex and std::timed_mutex
60 typedef __gthread_mutex_t __native_type
;
62 #ifdef __GTHREAD_MUTEX_INIT
63 __native_type _M_mutex
= __GTHREAD_MUTEX_INIT
;
65 constexpr __mutex_base() noexcept
= default;
67 __native_type _M_mutex
;
69 __mutex_base() noexcept
71 // XXX EAGAIN, ENOMEM, EPERM, EBUSY(may), EINVAL(may)
72 __GTHREAD_MUTEX_INIT_FUNCTION(&_M_mutex
);
75 ~__mutex_base() noexcept
{ __gthread_mutex_destroy(&_M_mutex
); }
78 __mutex_base(const __mutex_base
&) = delete;
79 __mutex_base
& operator=(const __mutex_base
&) = delete;
82 /// The standard mutex type.
83 class mutex
: private __mutex_base
86 typedef __native_type
* native_handle_type
;
88 #ifdef __GTHREAD_MUTEX_INIT
91 mutex() noexcept
= default;
94 mutex(const mutex
&) = delete;
95 mutex
& operator=(const mutex
&) = delete;
100 int __e
= __gthread_mutex_lock(&_M_mutex
);
102 // EINVAL, EAGAIN, EBUSY, EINVAL, EDEADLK(may)
104 __throw_system_error(__e
);
110 // XXX EINVAL, EAGAIN, EBUSY
111 return !__gthread_mutex_trylock(&_M_mutex
);
117 // XXX EINVAL, EAGAIN, EPERM
118 __gthread_mutex_unlock(&_M_mutex
);
122 native_handle() noexcept
123 { return &_M_mutex
; }
126 // Implementation details for std::condition_variable
129 using timespec
= __gthread_time_t
;
134 #ifndef __GTHREAD_COND_INIT
135 __GTHREAD_COND_INIT_FUNCTION(&_M_cond
);
141 int __e
__attribute__((__unused__
)) = __gthread_cond_destroy(&_M_cond
);
142 __glibcxx_assert(__e
!= EBUSY
); // threads are still blocked
145 __condvar(const __condvar
&) = delete;
146 __condvar
& operator=(const __condvar
&) = delete;
148 __gthread_cond_t
* native_handle() noexcept
{ return &_M_cond
; }
150 // Expects: Calling thread has locked __m.
152 wait(mutex
& __m
) noexcept
154 int __e
__attribute__((__unused__
))
155 = __gthread_cond_wait(&_M_cond
, __m
.native_handle());
156 __glibcxx_assert(__e
== 0);
160 wait_until(mutex
& __m
, timespec
& __abs_time
) noexcept
162 __gthread_cond_timedwait(&_M_cond
, __m
.native_handle(), &__abs_time
);
165 #ifdef _GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT
167 wait_until(mutex
& __m
, clockid_t __clock
, timespec
& __abs_time
) noexcept
169 pthread_cond_clockwait(&_M_cond
, __m
.native_handle(), __clock
,
175 notify_one() noexcept
177 int __e
__attribute__((__unused__
)) = __gthread_cond_signal(&_M_cond
);
178 __glibcxx_assert(__e
== 0);
182 notify_all() noexcept
184 int __e
__attribute__((__unused__
)) = __gthread_cond_broadcast(&_M_cond
);
185 __glibcxx_assert(__e
== 0);
189 #ifdef __GTHREAD_COND_INIT
190 __gthread_cond_t _M_cond
= __GTHREAD_COND_INIT
;
192 __gthread_cond_t _M_cond
;
196 #endif // _GLIBCXX_HAS_GTHREADS
198 /// Do not acquire ownership of the mutex.
199 struct defer_lock_t
{ explicit defer_lock_t() = default; };
201 /// Try to acquire ownership of the mutex without blocking.
202 struct try_to_lock_t
{ explicit try_to_lock_t() = default; };
204 /// Assume the calling thread has already obtained mutex ownership
206 struct adopt_lock_t
{ explicit adopt_lock_t() = default; };
208 /// Tag used to prevent a scoped lock from acquiring ownership of a mutex.
209 _GLIBCXX17_INLINE
constexpr defer_lock_t defer_lock
{ };
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
{ };
214 /// Tag used to make a scoped lock take ownership of a locked mutex.
215 _GLIBCXX17_INLINE
constexpr adopt_lock_t adopt_lock
{ };
217 /** @brief A simple scoped lock type.
219 * A lock_guard controls mutex ownership within a scope, releasing
220 * ownership in the destructor.
222 template<typename _Mutex
>
226 typedef _Mutex mutex_type
;
228 explicit lock_guard(mutex_type
& __m
) : _M_device(__m
)
229 { _M_device
.lock(); }
231 lock_guard(mutex_type
& __m
, adopt_lock_t
) noexcept
: _M_device(__m
)
232 { } // calling thread owns mutex
235 { _M_device
.unlock(); }
237 lock_guard(const lock_guard
&) = delete;
238 lock_guard
& operator=(const lock_guard
&) = delete;
241 mutex_type
& _M_device
;
245 _GLIBCXX_END_NAMESPACE_VERSION
248 #endif // _GLIBCXX_MUTEX_H