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1 : // std::mutex implementation -*- C++ -*-
2 :
3 : // Copyright (C) 2003-2018 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 : #include <bits/move.h> // for std::swap
43 :
44 : #ifdef _GLIBCXX_USE_C99_STDINT_TR1
45 :
46 : namespace std _GLIBCXX_VISIBILITY(default)
47 : {
48 : _GLIBCXX_BEGIN_NAMESPACE_VERSION
49 :
50 : /**
51 : * @defgroup mutexes Mutexes
52 : * @ingroup concurrency
53 : *
54 : * Classes for mutex support.
55 : * @{
56 : */
57 :
58 : #ifdef _GLIBCXX_HAS_GTHREADS
59 : // Common base class for std::mutex and std::timed_mutex
60 : class __mutex_base
61 : {
62 : protected:
63 : typedef __gthread_mutex_t __native_type;
64 :
65 : #ifdef __GTHREAD_MUTEX_INIT
66 : __native_type _M_mutex = __GTHREAD_MUTEX_INIT;
67 :
68 4212 : constexpr __mutex_base() noexcept = default;
69 : #else
70 : __native_type _M_mutex;
71 :
72 : __mutex_base() noexcept
73 : {
74 : // XXX EAGAIN, ENOMEM, EPERM, EBUSY(may), EINVAL(may)
75 : __GTHREAD_MUTEX_INIT_FUNCTION(&_M_mutex);
76 : }
77 :
78 : ~__mutex_base() noexcept { __gthread_mutex_destroy(&_M_mutex); }
79 : #endif
80 :
81 : __mutex_base(const __mutex_base&) = delete;
82 : __mutex_base& operator=(const __mutex_base&) = delete;
83 : };
84 :
85 : /// The standard mutex type.
86 : class mutex : private __mutex_base
87 : {
88 : public:
89 : typedef __native_type* native_handle_type;
90 :
91 : #ifdef __GTHREAD_MUTEX_INIT
92 : constexpr
93 : #endif
94 4212 : mutex() noexcept = default;
95 : ~mutex() = default;
96 :
97 : mutex(const mutex&) = delete;
98 : mutex& operator=(const mutex&) = delete;
99 :
100 : void
101 40518 : lock()
102 : {
103 40518 : int __e = __gthread_mutex_lock(&_M_mutex);
104 :
105 : // EINVAL, EAGAIN, EBUSY, EINVAL, EDEADLK(may)
106 40573 : if (__e)
107 0 : __throw_system_error(__e);
108 40573 : }
109 :
110 : bool
111 46 : try_lock() noexcept
112 : {
113 : // XXX EINVAL, EAGAIN, EBUSY
114 46 : return !__gthread_mutex_trylock(&_M_mutex);
115 : }
116 :
117 : void
118 40573 : unlock()
119 : {
120 : // XXX EINVAL, EAGAIN, EPERM
121 40573 : __gthread_mutex_unlock(&_M_mutex);
122 40606 : }
123 :
124 : native_handle_type
125 : native_handle() noexcept
126 : { return &_M_mutex; }
127 : };
128 :
129 : #endif // _GLIBCXX_HAS_GTHREADS
130 :
131 : /// Do not acquire ownership of the mutex.
132 : struct defer_lock_t { explicit defer_lock_t() = default; };
133 :
134 : /// Try to acquire ownership of the mutex without blocking.
135 : struct try_to_lock_t { explicit try_to_lock_t() = default; };
136 :
137 : /// Assume the calling thread has already obtained mutex ownership
138 : /// and manage it.
139 : struct adopt_lock_t { explicit adopt_lock_t() = default; };
140 :
141 : /// Tag used to prevent a scoped lock from acquiring ownership of a mutex.
142 : _GLIBCXX17_INLINE constexpr defer_lock_t defer_lock { };
143 :
144 : /// Tag used to prevent a scoped lock from blocking if a mutex is locked.
145 : _GLIBCXX17_INLINE constexpr try_to_lock_t try_to_lock { };
146 :
147 : /// Tag used to make a scoped lock take ownership of a locked mutex.
148 : _GLIBCXX17_INLINE constexpr adopt_lock_t adopt_lock { };
149 :
150 : /** @brief A simple scoped lock type.
151 : *
152 : * A lock_guard controls mutex ownership within a scope, releasing
153 : * ownership in the destructor.
154 : */
155 : template<typename _Mutex>
156 : class lock_guard
157 : {
158 : public:
159 : typedef _Mutex mutex_type;
160 :
161 : explicit lock_guard(mutex_type& __m) : _M_device(__m)
162 : { _M_device.lock(); }
163 :
164 : lock_guard(mutex_type& __m, adopt_lock_t) noexcept : _M_device(__m)
165 : { } // calling thread owns mutex
166 :
167 : ~lock_guard()
168 : { _M_device.unlock(); }
169 :
170 : lock_guard(const lock_guard&) = delete;
171 : lock_guard& operator=(const lock_guard&) = delete;
172 :
173 : private:
174 : mutex_type& _M_device;
175 : };
176 :
177 : /** @brief A movable scoped lock type.
178 : *
179 : * A unique_lock controls mutex ownership within a scope. Ownership of the
180 : * mutex can be delayed until after construction and can be transferred
181 : * to another unique_lock by move construction or move assignment. If a
182 : * mutex lock is owned when the destructor runs ownership will be released.
183 : */
184 : template<typename _Mutex>
185 : class unique_lock
186 : {
187 : public:
188 : typedef _Mutex mutex_type;
189 :
190 : unique_lock() noexcept
191 : : _M_device(0), _M_owns(false)
192 : { }
193 :
194 35023 : explicit unique_lock(mutex_type& __m)
195 35023 : : _M_device(std::__addressof(__m)), _M_owns(false)
196 : {
197 35016 : lock();
198 35046 : _M_owns = true;
199 35046 : }
200 :
201 : unique_lock(mutex_type& __m, defer_lock_t) noexcept
202 : : _M_device(std::__addressof(__m)), _M_owns(false)
203 : { }
204 :
205 : unique_lock(mutex_type& __m, try_to_lock_t)
206 : : _M_device(std::__addressof(__m)), _M_owns(_M_device->try_lock())
207 : { }
208 :
209 : unique_lock(mutex_type& __m, adopt_lock_t) noexcept
210 : : _M_device(std::__addressof(__m)), _M_owns(true)
211 : {
212 : // XXX calling thread owns mutex
213 : }
214 :
215 : template<typename _Clock, typename _Duration>
216 : unique_lock(mutex_type& __m,
217 : const chrono::time_point<_Clock, _Duration>& __atime)
218 : : _M_device(std::__addressof(__m)),
219 : _M_owns(_M_device->try_lock_until(__atime))
220 : { }
221 :
222 : template<typename _Rep, typename _Period>
223 : unique_lock(mutex_type& __m,
224 : const chrono::duration<_Rep, _Period>& __rtime)
225 : : _M_device(std::__addressof(__m)),
226 : _M_owns(_M_device->try_lock_for(__rtime))
227 : { }
228 :
229 35032 : ~unique_lock()
230 : {
231 35032 : if (_M_owns)
232 35031 : unlock();
233 35052 : }
234 :
235 : unique_lock(const unique_lock&) = delete;
236 : unique_lock& operator=(const unique_lock&) = delete;
237 :
238 : unique_lock(unique_lock&& __u) noexcept
239 : : _M_device(__u._M_device), _M_owns(__u._M_owns)
240 : {
241 : __u._M_device = 0;
242 : __u._M_owns = false;
243 : }
244 :
245 : unique_lock& operator=(unique_lock&& __u) noexcept
246 : {
247 : if(_M_owns)
248 : unlock();
249 :
250 : unique_lock(std::move(__u)).swap(*this);
251 :
252 : __u._M_device = 0;
253 : __u._M_owns = false;
254 :
255 : return *this;
256 : }
257 :
258 : void
259 35013 : lock()
260 : {
261 35013 : if (!_M_device)
262 0 : __throw_system_error(int(errc::operation_not_permitted));
263 35013 : else if (_M_owns)
264 0 : __throw_system_error(int(errc::resource_deadlock_would_occur));
265 : else
266 : {
267 35013 : _M_device->lock();
268 35054 : _M_owns = true;
269 : }
270 35054 : }
271 :
272 : bool
273 : try_lock()
274 : {
275 : if (!_M_device)
276 : __throw_system_error(int(errc::operation_not_permitted));
277 : else if (_M_owns)
278 : __throw_system_error(int(errc::resource_deadlock_would_occur));
279 : else
280 : {
281 : _M_owns = _M_device->try_lock();
282 : return _M_owns;
283 : }
284 : }
285 :
286 : template<typename _Clock, typename _Duration>
287 : bool
288 : try_lock_until(const chrono::time_point<_Clock, _Duration>& __atime)
289 : {
290 : if (!_M_device)
291 : __throw_system_error(int(errc::operation_not_permitted));
292 : else if (_M_owns)
293 : __throw_system_error(int(errc::resource_deadlock_would_occur));
294 : else
295 : {
296 : _M_owns = _M_device->try_lock_until(__atime);
297 : return _M_owns;
298 : }
299 : }
300 :
301 : template<typename _Rep, typename _Period>
302 : bool
303 : try_lock_for(const chrono::duration<_Rep, _Period>& __rtime)
304 : {
305 : if (!_M_device)
306 : __throw_system_error(int(errc::operation_not_permitted));
307 : else if (_M_owns)
308 : __throw_system_error(int(errc::resource_deadlock_would_occur));
309 : else
310 : {
311 : _M_owns = _M_device->try_lock_for(__rtime);
312 : return _M_owns;
313 : }
314 : }
315 :
316 : void
317 35027 : unlock()
318 : {
319 35027 : if (!_M_owns)
320 0 : __throw_system_error(int(errc::operation_not_permitted));
321 35027 : else if (_M_device)
322 : {
323 35028 : _M_device->unlock();
324 35052 : _M_owns = false;
325 : }
326 35051 : }
327 :
328 : void
329 : swap(unique_lock& __u) noexcept
330 : {
331 : std::swap(_M_device, __u._M_device);
332 : std::swap(_M_owns, __u._M_owns);
333 : }
334 :
335 : mutex_type*
336 : release() noexcept
337 : {
338 : mutex_type* __ret = _M_device;
339 : _M_device = 0;
340 : _M_owns = false;
341 : return __ret;
342 : }
343 :
344 : bool
345 : owns_lock() const noexcept
346 : { return _M_owns; }
347 :
348 : explicit operator bool() const noexcept
349 : { return owns_lock(); }
350 :
351 : mutex_type*
352 : mutex() const noexcept
353 : { return _M_device; }
354 :
355 : private:
356 : mutex_type* _M_device;
357 : bool _M_owns; // XXX use atomic_bool
358 : };
359 :
360 : /// Swap overload for unique_lock objects.
361 : template<typename _Mutex>
362 : inline void
363 : swap(unique_lock<_Mutex>& __x, unique_lock<_Mutex>& __y) noexcept
364 : { __x.swap(__y); }
365 :
366 : // @} group mutexes
367 : _GLIBCXX_END_NAMESPACE_VERSION
368 : } // namespace
369 : #endif // _GLIBCXX_USE_C99_STDINT_TR1
370 :
371 : #endif // C++11
372 :
373 : #endif // _GLIBCXX_MUTEX_H
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