1// <mutex> -*- C++ -*-
2
3// Copyright (C) 2003-2017 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 include/mutex
26 * This is a Standard C++ Library header.
27 */
28
29#ifndef _GLIBCXX_MUTEX
30#define _GLIBCXX_MUTEX 1
31
32#pragma GCC system_header
33
34#if __cplusplus < 201103L
35# include <bits/c++0x_warning.h>
36#else
37
38#include <tuple>
39#include <chrono>
40#include <exception>
41#include <type_traits>
42#include <system_error>
43#include <bits/std_mutex.h>
44#if ! _GTHREAD_USE_MUTEX_TIMEDLOCK
45# include <condition_variable>
46# include <thread>
47#endif
48#ifndef _GLIBCXX_HAVE_TLS
49# include <bits/std_function.h>
50#endif
51
52#ifdef _GLIBCXX_USE_C99_STDINT_TR1
53
54namespace std _GLIBCXX_VISIBILITY(default)
55{
56_GLIBCXX_BEGIN_NAMESPACE_VERSION
57
58 /**
59 * @ingroup mutexes
60 * @{
61 */
62
63#ifdef _GLIBCXX_HAS_GTHREADS
64
65 // Common base class for std::recursive_mutex and std::recursive_timed_mutex
66 class __recursive_mutex_base
67 {
68 protected:
69 typedef __gthread_recursive_mutex_t __native_type;
70
71 __recursive_mutex_base(const __recursive_mutex_base&) = delete;
72 __recursive_mutex_base& operator=(const __recursive_mutex_base&) = delete;
73
74#ifdef __GTHREAD_RECURSIVE_MUTEX_INIT
75 __native_type _M_mutex = __GTHREAD_RECURSIVE_MUTEX_INIT;
76
77 __recursive_mutex_base() = default;
78#else
79 __native_type _M_mutex;
80
81 __recursive_mutex_base()
82 {
83 // XXX EAGAIN, ENOMEM, EPERM, EBUSY(may), EINVAL(may)
84 __GTHREAD_RECURSIVE_MUTEX_INIT_FUNCTION(&_M_mutex);
85 }
86
87 ~__recursive_mutex_base()
88 { __gthread_recursive_mutex_destroy(&_M_mutex); }
89#endif
90 };
91
92 /// The standard recursive mutex type.
93 class recursive_mutex : private __recursive_mutex_base
94 {
95 public:
96 typedef __native_type* native_handle_type;
97
98 recursive_mutex() = default;
99 ~recursive_mutex() = default;
100
101 recursive_mutex(const recursive_mutex&) = delete;
102 recursive_mutex& operator=(const recursive_mutex&) = delete;
103
104 void
105 lock()
106 {
107 int __e = __gthread_recursive_mutex_lock(&_M_mutex);
108
109 // EINVAL, EAGAIN, EBUSY, EINVAL, EDEADLK(may)
110 if (__e)
111 __throw_system_error(__e);
112 }
113
114 bool
115 try_lock() noexcept
116 {
117 // XXX EINVAL, EAGAIN, EBUSY
118 return !__gthread_recursive_mutex_trylock(&_M_mutex);
119 }
120
121 void
122 unlock()
123 {
124 // XXX EINVAL, EAGAIN, EBUSY
125 __gthread_recursive_mutex_unlock(&_M_mutex);
126 }
127
128 native_handle_type
129 native_handle() noexcept
130 { return &_M_mutex; }
131 };
132
133#if _GTHREAD_USE_MUTEX_TIMEDLOCK
134 template<typename _Derived>
135 class __timed_mutex_impl
136 {
137 protected:
138 typedef chrono::high_resolution_clock __clock_t;
139
140 template<typename _Rep, typename _Period>
141 bool
142 _M_try_lock_for(const chrono::duration<_Rep, _Period>& __rtime)
143 {
144 using chrono::steady_clock;
145 auto __rt = chrono::duration_cast<steady_clock::duration>(__rtime);
146 if (ratio_greater<steady_clock::period, _Period>())
147 ++__rt;
148 return _M_try_lock_until(steady_clock::now() + __rt);
149 }
150
151 template<typename _Duration>
152 bool
153 _M_try_lock_until(const chrono::time_point<__clock_t,
154 _Duration>& __atime)
155 {
156 auto __s = chrono::time_point_cast<chrono::seconds>(__atime);
157 auto __ns = chrono::duration_cast<chrono::nanoseconds>(__atime - __s);
158
159 __gthread_time_t __ts = {
160 static_cast<std::time_t>(__s.time_since_epoch().count()),
161 static_cast<long>(__ns.count())
162 };
163
164 return static_cast<_Derived*>(this)->_M_timedlock(__ts);
165 }
166
167 template<typename _Clock, typename _Duration>
168 bool
169 _M_try_lock_until(const chrono::time_point<_Clock, _Duration>& __atime)
170 {
171 auto __rtime = __atime - _Clock::now();
172 return _M_try_lock_until(__clock_t::now() + __rtime);
173 }
174 };
175
176 /// The standard timed mutex type.
177 class timed_mutex
178 : private __mutex_base, public __timed_mutex_impl<timed_mutex>
179 {
180 public:
181 typedef __native_type* native_handle_type;
182
183 timed_mutex() = default;
184 ~timed_mutex() = default;
185
186 timed_mutex(const timed_mutex&) = delete;
187 timed_mutex& operator=(const timed_mutex&) = delete;
188
189 void
190 lock()
191 {
192 int __e = __gthread_mutex_lock(&_M_mutex);
193
194 // EINVAL, EAGAIN, EBUSY, EINVAL, EDEADLK(may)
195 if (__e)
196 __throw_system_error(__e);
197 }
198
199 bool
200 try_lock() noexcept
201 {
202 // XXX EINVAL, EAGAIN, EBUSY
203 return !__gthread_mutex_trylock(&_M_mutex);
204 }
205
206 template <class _Rep, class _Period>
207 bool
208 try_lock_for(const chrono::duration<_Rep, _Period>& __rtime)
209 { return _M_try_lock_for(__rtime); }
210
211 template <class _Clock, class _Duration>
212 bool
213 try_lock_until(const chrono::time_point<_Clock, _Duration>& __atime)
214 { return _M_try_lock_until(__atime); }
215
216 void
217 unlock()
218 {
219 // XXX EINVAL, EAGAIN, EBUSY
220 __gthread_mutex_unlock(&_M_mutex);
221 }
222
223 native_handle_type
224 native_handle() noexcept
225 { return &_M_mutex; }
226
227 private:
228 friend class __timed_mutex_impl<timed_mutex>;
229
230 bool
231 _M_timedlock(const __gthread_time_t& __ts)
232 { return !__gthread_mutex_timedlock(&_M_mutex, &__ts); }
233 };
234
235 /// recursive_timed_mutex
236 class recursive_timed_mutex
237 : private __recursive_mutex_base,
238 public __timed_mutex_impl<recursive_timed_mutex>
239 {
240 public:
241 typedef __native_type* native_handle_type;
242
243 recursive_timed_mutex() = default;
244 ~recursive_timed_mutex() = default;
245
246 recursive_timed_mutex(const recursive_timed_mutex&) = delete;
247 recursive_timed_mutex& operator=(const recursive_timed_mutex&) = delete;
248
249 void
250 lock()
251 {
252 int __e = __gthread_recursive_mutex_lock(&_M_mutex);
253
254 // EINVAL, EAGAIN, EBUSY, EINVAL, EDEADLK(may)
255 if (__e)
256 __throw_system_error(__e);
257 }
258
259 bool
260 try_lock() noexcept
261 {
262 // XXX EINVAL, EAGAIN, EBUSY
263 return !__gthread_recursive_mutex_trylock(&_M_mutex);
264 }
265
266 template <class _Rep, class _Period>
267 bool
268 try_lock_for(const chrono::duration<_Rep, _Period>& __rtime)
269 { return _M_try_lock_for(__rtime); }
270
271 template <class _Clock, class _Duration>
272 bool
273 try_lock_until(const chrono::time_point<_Clock, _Duration>& __atime)
274 { return _M_try_lock_until(__atime); }
275
276 void
277 unlock()
278 {
279 // XXX EINVAL, EAGAIN, EBUSY
280 __gthread_recursive_mutex_unlock(&_M_mutex);
281 }
282
283 native_handle_type
284 native_handle() noexcept
285 { return &_M_mutex; }
286
287 private:
288 friend class __timed_mutex_impl<recursive_timed_mutex>;
289
290 bool
291 _M_timedlock(const __gthread_time_t& __ts)
292 { return !__gthread_recursive_mutex_timedlock(&_M_mutex, &__ts); }
293 };
294
295#else // !_GTHREAD_USE_MUTEX_TIMEDLOCK
296
297 /// timed_mutex
298 class timed_mutex
299 {
300 mutex _M_mut;
301 condition_variable _M_cv;
302 bool _M_locked = false;
303
304 public:
305
306 timed_mutex() = default;
307 ~timed_mutex() { __glibcxx_assert( !_M_locked ); }
308
309 timed_mutex(const timed_mutex&) = delete;
310 timed_mutex& operator=(const timed_mutex&) = delete;
311
312 void
313 lock()
314 {
315 unique_lock<mutex> __lk(_M_mut);
316 _M_cv.wait(__lk, [&]{ return !_M_locked; });
317 _M_locked = true;
318 }
319
320 bool
321 try_lock()
322 {
323 lock_guard<mutex> __lk(_M_mut);
324 if (_M_locked)
325 return false;
326 _M_locked = true;
327 return true;
328 }
329
330 template<typename _Rep, typename _Period>
331 bool
332 try_lock_for(const chrono::duration<_Rep, _Period>& __rtime)
333 {
334 unique_lock<mutex> __lk(_M_mut);
335 if (!_M_cv.wait_for(__lk, __rtime, [&]{ return !_M_locked; }))
336 return false;
337 _M_locked = true;
338 return true;
339 }
340
341 template<typename _Clock, typename _Duration>
342 bool
343 try_lock_until(const chrono::time_point<_Clock, _Duration>& __atime)
344 {
345 unique_lock<mutex> __lk(_M_mut);
346 if (!_M_cv.wait_until(__lk, __atime, [&]{ return !_M_locked; }))
347 return false;
348 _M_locked = true;
349 return true;
350 }
351
352 void
353 unlock()
354 {
355 lock_guard<mutex> __lk(_M_mut);
356 __glibcxx_assert( _M_locked );
357 _M_locked = false;
358 _M_cv.notify_one();
359 }
360 };
361
362 /// recursive_timed_mutex
363 class recursive_timed_mutex
364 {
365 mutex _M_mut;
366 condition_variable _M_cv;
367 thread::id _M_owner;
368 unsigned _M_count = 0;
369
370 // Predicate type that tests whether the current thread can lock a mutex.
371 struct _Can_lock
372 {
373 // Returns true if the mutex is unlocked or is locked by _M_caller.
374 bool
375 operator()() const noexcept
376 { return _M_mx->_M_count == 0 || _M_mx->_M_owner == _M_caller; }
377
378 const recursive_timed_mutex* _M_mx;
379 thread::id _M_caller;
380 };
381
382 public:
383
384 recursive_timed_mutex() = default;
385 ~recursive_timed_mutex() { __glibcxx_assert( _M_count == 0 ); }
386
387 recursive_timed_mutex(const recursive_timed_mutex&) = delete;
388 recursive_timed_mutex& operator=(const recursive_timed_mutex&) = delete;
389
390 void
391 lock()
392 {
393 auto __id = this_thread::get_id();
394 _Can_lock __can_lock{this, __id};
395 unique_lock<mutex> __lk(_M_mut);
396 _M_cv.wait(__lk, __can_lock);
397 if (_M_count == -1u)
398 __throw_system_error(EAGAIN); // [thread.timedmutex.recursive]/3
399 _M_owner = __id;
400 ++_M_count;
401 }
402
403 bool
404 try_lock()
405 {
406 auto __id = this_thread::get_id();
407 _Can_lock __can_lock{this, __id};
408 lock_guard<mutex> __lk(_M_mut);
409 if (!__can_lock())
410 return false;
411 if (_M_count == -1u)
412 return false;
413 _M_owner = __id;
414 ++_M_count;
415 return true;
416 }
417
418 template<typename _Rep, typename _Period>
419 bool
420 try_lock_for(const chrono::duration<_Rep, _Period>& __rtime)
421 {
422 auto __id = this_thread::get_id();
423 _Can_lock __can_lock{this, __id};
424 unique_lock<mutex> __lk(_M_mut);
425 if (!_M_cv.wait_for(__lk, __rtime, __can_lock))
426 return false;
427 if (_M_count == -1u)
428 return false;
429 _M_owner = __id;
430 ++_M_count;
431 return true;
432 }
433
434 template<typename _Clock, typename _Duration>
435 bool
436 try_lock_until(const chrono::time_point<_Clock, _Duration>& __atime)
437 {
438 auto __id = this_thread::get_id();
439 _Can_lock __can_lock{this, __id};
440 unique_lock<mutex> __lk(_M_mut);
441 if (!_M_cv.wait_until(__lk, __atime, __can_lock))
442 return false;
443 if (_M_count == -1u)
444 return false;
445 _M_owner = __id;
446 ++_M_count;
447 return true;
448 }
449
450 void
451 unlock()
452 {
453 lock_guard<mutex> __lk(_M_mut);
454 __glibcxx_assert( _M_owner == this_thread::get_id() );
455 __glibcxx_assert( _M_count > 0 );
456 if (--_M_count == 0)
457 {
458 _M_owner = {};
459 _M_cv.notify_one();
460 }
461 }
462 };
463
464#endif
465#endif // _GLIBCXX_HAS_GTHREADS
466
467 template<typename _Lock>
468 inline unique_lock<_Lock>
469 __try_to_lock(_Lock& __l)
470 { return unique_lock<_Lock>{__l, try_to_lock}; }
471
472 template<int _Idx, bool _Continue = true>
473 struct __try_lock_impl
474 {
475 template<typename... _Lock>
476 static void
477 __do_try_lock(tuple<_Lock&...>& __locks, int& __idx)
478 {
479 __idx = _Idx;
480 auto __lock = std::__try_to_lock(std::get<_Idx>(__locks));
481 if (__lock.owns_lock())
482 {
483 constexpr bool __cont = _Idx + 2 < sizeof...(_Lock);
484 using __try_locker = __try_lock_impl<_Idx + 1, __cont>;
485 __try_locker::__do_try_lock(__locks, __idx);
486 if (__idx == -1)
487 __lock.release();
488 }
489 }
490 };
491
492 template<int _Idx>
493 struct __try_lock_impl<_Idx, false>
494 {
495 template<typename... _Lock>
496 static void
497 __do_try_lock(tuple<_Lock&...>& __locks, int& __idx)
498 {
499 __idx = _Idx;
500 auto __lock = std::__try_to_lock(std::get<_Idx>(__locks));
501 if (__lock.owns_lock())
502 {
503 __idx = -1;
504 __lock.release();
505 }
506 }
507 };
508
509 /** @brief Generic try_lock.
510 * @param __l1 Meets Lockable requirements (try_lock() may throw).
511 * @param __l2 Meets Lockable requirements (try_lock() may throw).
512 * @param __l3 Meets Lockable requirements (try_lock() may throw).
513 * @return Returns -1 if all try_lock() calls return true. Otherwise returns
514 * a 0-based index corresponding to the argument that returned false.
515 * @post Either all arguments are locked, or none will be.
516 *
517 * Sequentially calls try_lock() on each argument.
518 */
519 template<typename _Lock1, typename _Lock2, typename... _Lock3>
520 int
521 try_lock(_Lock1& __l1, _Lock2& __l2, _Lock3&... __l3)
522 {
523 int __idx;
524 auto __locks = std::tie(__l1, __l2, __l3...);
525 __try_lock_impl<0>::__do_try_lock(__locks, __idx);
526 return __idx;
527 }
528
529 /** @brief Generic lock.
530 * @param __l1 Meets Lockable requirements (try_lock() may throw).
531 * @param __l2 Meets Lockable requirements (try_lock() may throw).
532 * @param __l3 Meets Lockable requirements (try_lock() may throw).
533 * @throw An exception thrown by an argument's lock() or try_lock() member.
534 * @post All arguments are locked.
535 *
536 * All arguments are locked via a sequence of calls to lock(), try_lock()
537 * and unlock(). If the call exits via an exception any locks that were
538 * obtained will be released.
539 */
540 template<typename _L1, typename _L2, typename... _L3>
541 void
542 lock(_L1& __l1, _L2& __l2, _L3&... __l3)
543 {
544 while (true)
545 {
546 using __try_locker = __try_lock_impl<0, sizeof...(_L3) != 0>;
547 unique_lock<_L1> __first(__l1);
548 int __idx;
549 auto __locks = std::tie(__l2, __l3...);
550 __try_locker::__do_try_lock(__locks, __idx);
551 if (__idx == -1)
552 {
553 __first.release();
554 return;
555 }
556 }
557 }
558
559#if __cplusplus >= 201703L
560#define __cpp_lib_scoped_lock 201703
561 /** @brief A scoped lock type for multiple lockable objects.
562 *
563 * A scoped_lock controls mutex ownership within a scope, releasing
564 * ownership in the destructor.
565 */
566 template<typename... _MutexTypes>
567 class scoped_lock
568 {
569 public:
570 explicit scoped_lock(_MutexTypes&... __m) : _M_devices(std::tie(__m...))
571 { std::lock(__m...); }
572
573 explicit scoped_lock(adopt_lock_t, _MutexTypes&... __m) noexcept
574 : _M_devices(std::tie(__m...))
575 { } // calling thread owns mutex
576
577 ~scoped_lock()
578 {
579 std::apply([](_MutexTypes&... __m) {
580 char __i[] __attribute__((__unused__)) = { (__m.unlock(), 0)... };
581 }, _M_devices);
582 }
583
584 scoped_lock(const scoped_lock&) = delete;
585 scoped_lock& operator=(const scoped_lock&) = delete;
586
587 private:
588 tuple<_MutexTypes&...> _M_devices;
589 };
590
591 template<>
592 class scoped_lock<>
593 {
594 public:
595 explicit scoped_lock() = default;
596 explicit scoped_lock(adopt_lock_t) noexcept { }
597 ~scoped_lock() = default;
598
599 scoped_lock(const scoped_lock&) = delete;
600 scoped_lock& operator=(const scoped_lock&) = delete;
601 };
602
603 template<typename _Mutex>
604 class scoped_lock<_Mutex>
605 {
606 public:
607 using mutex_type = _Mutex;
608
609 explicit scoped_lock(mutex_type& __m) : _M_device(__m)
610 { _M_device.lock(); }
611
612 explicit scoped_lock(adopt_lock_t, mutex_type& __m) noexcept
613 : _M_device(__m)
614 { } // calling thread owns mutex
615
616 ~scoped_lock()
617 { _M_device.unlock(); }
618
619 scoped_lock(const scoped_lock&) = delete;
620 scoped_lock& operator=(const scoped_lock&) = delete;
621
622 private:
623 mutex_type& _M_device;
624 };
625#endif // C++17
626
627#ifdef _GLIBCXX_HAS_GTHREADS
628 /// once_flag
629 struct once_flag
630 {
631 private:
632 typedef __gthread_once_t __native_type;
633 __native_type _M_once = __GTHREAD_ONCE_INIT;
634
635 public:
636 /// Constructor
637 constexpr once_flag() noexcept = default;
638
639 /// Deleted copy constructor
640 once_flag(const once_flag&) = delete;
641 /// Deleted assignment operator
642 once_flag& operator=(const once_flag&) = delete;
643
644 template<typename _Callable, typename... _Args>
645 friend void
646 call_once(once_flag& __once, _Callable&& __f, _Args&&... __args);
647 };
648
649#ifdef _GLIBCXX_HAVE_TLS
650 extern __thread void* __once_callable;
651 extern __thread void (*__once_call)();
652#else
653 extern function<void()> __once_functor;
654
655 extern void
656 __set_once_functor_lock_ptr(unique_lock<mutex>*);
657
658 extern mutex&
659 __get_once_mutex();
660#endif
661
662 extern "C" void __once_proxy(void);
663
664 /// call_once
665 template<typename _Callable, typename... _Args>
666 void
667 call_once(once_flag& __once, _Callable&& __f, _Args&&... __args)
668 {
669 // _GLIBCXX_RESOLVE_LIB_DEFECTS
670 // 2442. call_once() shouldn't DECAY_COPY()
671 auto __callable = [&] {
672 std::__invoke(std::forward<_Callable>(__f),
673 std::forward<_Args>(__args)...);
674 };
675#ifdef _GLIBCXX_HAVE_TLS
676 __once_callable = std::__addressof(__callable);
677 __once_call = []{ (*(decltype(__callable)*)__once_callable)(); };
678#else
679 unique_lock<mutex> __functor_lock(__get_once_mutex());
680 __once_functor = __callable;
681 __set_once_functor_lock_ptr(&__functor_lock);
682#endif
683
684 int __e = __gthread_once(&__once._M_once, &__once_proxy);
685
686#ifndef _GLIBCXX_HAVE_TLS
687 if (__functor_lock)
688 __set_once_functor_lock_ptr(0);
689#endif
690
691#ifdef __clang_analyzer__
692 // PR libstdc++/82481
693 __once_callable = nullptr;
694 __once_call = nullptr;
695#endif
696
697 if (__e)
698 __throw_system_error(__e);
699 }
700#endif // _GLIBCXX_HAS_GTHREADS
701
702 // @} group mutexes
703_GLIBCXX_END_NAMESPACE_VERSION
704} // namespace
705#endif // _GLIBCXX_USE_C99_STDINT_TR1
706
707#endif // C++11
708
709#endif // _GLIBCXX_MUTEX
710