xref: /llvm-project-15.0.7/libcxx/include/mutex (revision 052d95a6) 
1// -*- C++ -*-
2//===--------------------------- mutex ------------------------------------===//
3//
4//                     The LLVM Compiler Infrastructure
5//
6// This file is dual licensed under the MIT and the University of Illinois Open
7// Source Licenses. See LICENSE.TXT for details.
8//
9//===----------------------------------------------------------------------===//
10
11#ifndef _LIBCPP_MUTEX
12#define _LIBCPP_MUTEX
13
14/*
15    mutex synopsis
16
17namespace std
18{
19
20class mutex
21{
22public:
23     constexpr mutex() noexcept;
24     ~mutex();
25
26    mutex(const mutex&) = delete;
27    mutex& operator=(const mutex&) = delete;
28
29    void lock();
30    bool try_lock();
31    void unlock();
32
33    typedef pthread_mutex_t* native_handle_type;
34    native_handle_type native_handle();
35};
36
37class recursive_mutex
38{
39public:
40     recursive_mutex();
41     ~recursive_mutex();
42
43    recursive_mutex(const recursive_mutex&) = delete;
44    recursive_mutex& operator=(const recursive_mutex&) = delete;
45
46    void lock();
47    bool try_lock() noexcept;
48    void unlock();
49
50    typedef pthread_mutex_t* native_handle_type;
51    native_handle_type native_handle();
52};
53
54class timed_mutex
55{
56public:
57     timed_mutex();
58     ~timed_mutex();
59
60    timed_mutex(const timed_mutex&) = delete;
61    timed_mutex& operator=(const timed_mutex&) = delete;
62
63    void lock();
64    bool try_lock();
65    template <class Rep, class Period>
66        bool try_lock_for(const chrono::duration<Rep, Period>& rel_time);
67    template <class Clock, class Duration>
68        bool try_lock_until(const chrono::time_point<Clock, Duration>& abs_time);
69    void unlock();
70};
71
72class recursive_timed_mutex
73{
74public:
75     recursive_timed_mutex();
76     ~recursive_timed_mutex();
77
78    recursive_timed_mutex(const recursive_timed_mutex&) = delete;
79    recursive_timed_mutex& operator=(const recursive_timed_mutex&) = delete;
80
81    void lock();
82    bool try_lock() noexcept;
83    template <class Rep, class Period>
84        bool try_lock_for(const chrono::duration<Rep, Period>& rel_time);
85    template <class Clock, class Duration>
86        bool try_lock_until(const chrono::time_point<Clock, Duration>& abs_time);
87    void unlock();
88};
89
90struct defer_lock_t {};
91struct try_to_lock_t {};
92struct adopt_lock_t {};
93
94constexpr defer_lock_t  defer_lock{};
95constexpr try_to_lock_t try_to_lock{};
96constexpr adopt_lock_t  adopt_lock{};
97
98template <class Mutex>
99class lock_guard
100{
101public:
102    typedef Mutex mutex_type;
103
104    explicit lock_guard(mutex_type& m);
105    lock_guard(mutex_type& m, adopt_lock_t);
106    ~lock_guard();
107
108    lock_guard(lock_guard const&) = delete;
109    lock_guard& operator=(lock_guard const&) = delete;
110};
111
112template <class... MutexTypes> // Variadic lock_guard only provided in ABI V2.
113class lock_guard
114{
115public:
116    explicit lock_guard(MutexTypes&... m);
117    lock_guard(MutexTypes&... m, adopt_lock_t);
118    ~lock_guard();
119    lock_guard(lock_guard const&) = delete;
120    lock_guard& operator=(lock_guard const&) = delete;
121private:
122    tuple<MutexTypes&...> pm; // exposition only
123};
124
125template <class Mutex>
126class unique_lock
127{
128public:
129    typedef Mutex mutex_type;
130    unique_lock() noexcept;
131    explicit unique_lock(mutex_type& m);
132    unique_lock(mutex_type& m, defer_lock_t) noexcept;
133    unique_lock(mutex_type& m, try_to_lock_t);
134    unique_lock(mutex_type& m, adopt_lock_t);
135    template <class Clock, class Duration>
136        unique_lock(mutex_type& m, const chrono::time_point<Clock, Duration>& abs_time);
137    template <class Rep, class Period>
138        unique_lock(mutex_type& m, const chrono::duration<Rep, Period>& rel_time);
139    ~unique_lock();
140
141    unique_lock(unique_lock const&) = delete;
142    unique_lock& operator=(unique_lock const&) = delete;
143
144    unique_lock(unique_lock&& u) noexcept;
145    unique_lock& operator=(unique_lock&& u) noexcept;
146
147    void lock();
148    bool try_lock();
149
150    template <class Rep, class Period>
151        bool try_lock_for(const chrono::duration<Rep, Period>& rel_time);
152    template <class Clock, class Duration>
153        bool try_lock_until(const chrono::time_point<Clock, Duration>& abs_time);
154
155    void unlock();
156
157    void swap(unique_lock& u) noexcept;
158    mutex_type* release() noexcept;
159
160    bool owns_lock() const noexcept;
161    explicit operator bool () const noexcept;
162    mutex_type* mutex() const noexcept;
163};
164
165template <class Mutex>
166  void swap(unique_lock<Mutex>& x, unique_lock<Mutex>& y) noexcept;
167
168template <class L1, class L2, class... L3>
169  int try_lock(L1&, L2&, L3&...);
170template <class L1, class L2, class... L3>
171  void lock(L1&, L2&, L3&...);
172
173struct once_flag
174{
175    constexpr once_flag() noexcept;
176
177    once_flag(const once_flag&) = delete;
178    once_flag& operator=(const once_flag&) = delete;
179};
180
181template<class Callable, class ...Args>
182  void call_once(once_flag& flag, Callable&& func, Args&&... args);
183
184}  // std
185
186*/
187
188#include <__config>
189#include <__mutex_base>
190#include <functional>
191#include <memory>
192#ifndef _LIBCPP_HAS_NO_VARIADICS
193#include <tuple>
194#endif
195#include <__threading_support>
196
197#include <__undef_min_max>
198
199#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
200#pragma GCC system_header
201#endif
202
203_LIBCPP_BEGIN_NAMESPACE_STD
204
205#ifndef _LIBCPP_HAS_NO_THREADS
206
207class _LIBCPP_TYPE_VIS recursive_mutex
208{
209    __libcpp_recursive_mutex_t __m_;
210
211public:
212     recursive_mutex();
213     ~recursive_mutex();
214
215private:
216    recursive_mutex(const recursive_mutex&); // = delete;
217    recursive_mutex& operator=(const recursive_mutex&); // = delete;
218
219public:
220    void lock();
221    bool try_lock() _NOEXCEPT;
222    void unlock()  _NOEXCEPT;
223
224    typedef __libcpp_recursive_mutex_t* native_handle_type;
225
226    _LIBCPP_INLINE_VISIBILITY
227    native_handle_type native_handle() {return &__m_;}
228};
229
230class _LIBCPP_TYPE_VIS timed_mutex
231{
232    mutex              __m_;
233    condition_variable __cv_;
234    bool               __locked_;
235public:
236     timed_mutex();
237     ~timed_mutex();
238
239private:
240    timed_mutex(const timed_mutex&); // = delete;
241    timed_mutex& operator=(const timed_mutex&); // = delete;
242
243public:
244    void lock();
245    bool try_lock() _NOEXCEPT;
246    template <class _Rep, class _Period>
247        _LIBCPP_INLINE_VISIBILITY
248        bool try_lock_for(const chrono::duration<_Rep, _Period>& __d)
249            {return try_lock_until(chrono::steady_clock::now() + __d);}
250    template <class _Clock, class _Duration>
251        bool try_lock_until(const chrono::time_point<_Clock, _Duration>& __t);
252    void unlock() _NOEXCEPT;
253};
254
255template <class _Clock, class _Duration>
256bool
257timed_mutex::try_lock_until(const chrono::time_point<_Clock, _Duration>& __t)
258{
259    using namespace chrono;
260    unique_lock<mutex> __lk(__m_);
261    bool no_timeout = _Clock::now() < __t;
262    while (no_timeout && __locked_)
263        no_timeout = __cv_.wait_until(__lk, __t) == cv_status::no_timeout;
264    if (!__locked_)
265    {
266        __locked_ = true;
267        return true;
268    }
269    return false;
270}
271
272class _LIBCPP_TYPE_VIS recursive_timed_mutex
273{
274    mutex              __m_;
275    condition_variable __cv_;
276    size_t             __count_;
277    __libcpp_thread_id __id_;
278public:
279     recursive_timed_mutex();
280     ~recursive_timed_mutex();
281
282private:
283    recursive_timed_mutex(const recursive_timed_mutex&); // = delete;
284    recursive_timed_mutex& operator=(const recursive_timed_mutex&); // = delete;
285
286public:
287    void lock();
288    bool try_lock() _NOEXCEPT;
289    template <class _Rep, class _Period>
290        _LIBCPP_INLINE_VISIBILITY
291        bool try_lock_for(const chrono::duration<_Rep, _Period>& __d)
292            {return try_lock_until(chrono::steady_clock::now() + __d);}
293    template <class _Clock, class _Duration>
294        bool try_lock_until(const chrono::time_point<_Clock, _Duration>& __t);
295    void unlock() _NOEXCEPT;
296};
297
298template <class _Clock, class _Duration>
299bool
300recursive_timed_mutex::try_lock_until(const chrono::time_point<_Clock, _Duration>& __t)
301{
302    using namespace chrono;
303    __libcpp_thread_id __id = __libcpp_thread_get_current_id();
304    unique_lock<mutex> lk(__m_);
305    if (__libcpp_thread_id_equal(__id, __id_))
306    {
307        if (__count_ == numeric_limits<size_t>::max())
308            return false;
309        ++__count_;
310        return true;
311    }
312    bool no_timeout = _Clock::now() < __t;
313    while (no_timeout && __count_ != 0)
314        no_timeout = __cv_.wait_until(lk, __t) == cv_status::no_timeout;
315    if (__count_ == 0)
316    {
317        __count_ = 1;
318        __id_ = __id;
319        return true;
320    }
321    return false;
322}
323
324template <class _L0, class _L1>
325int
326try_lock(_L0& __l0, _L1& __l1)
327{
328    unique_lock<_L0> __u0(__l0, try_to_lock);
329    if (__u0.owns_lock())
330    {
331        if (__l1.try_lock())
332        {
333            __u0.release();
334            return -1;
335        }
336        else
337            return 1;
338    }
339    return 0;
340}
341
342#ifndef _LIBCPP_HAS_NO_VARIADICS
343
344template <class _L0, class _L1, class _L2, class... _L3>
345int
346try_lock(_L0& __l0, _L1& __l1, _L2& __l2, _L3&... __l3)
347{
348    int __r = 0;
349    unique_lock<_L0> __u0(__l0, try_to_lock);
350    if (__u0.owns_lock())
351    {
352        __r = try_lock(__l1, __l2, __l3...);
353        if (__r == -1)
354            __u0.release();
355        else
356            ++__r;
357    }
358    return __r;
359}
360
361#endif  // _LIBCPP_HAS_NO_VARIADICS
362
363template <class _L0, class _L1>
364void
365lock(_L0& __l0, _L1& __l1)
366{
367    while (true)
368    {
369        {
370            unique_lock<_L0> __u0(__l0);
371            if (__l1.try_lock())
372            {
373                __u0.release();
374                break;
375            }
376        }
377        __libcpp_thread_yield();
378        {
379            unique_lock<_L1> __u1(__l1);
380            if (__l0.try_lock())
381            {
382                __u1.release();
383                break;
384            }
385        }
386        __libcpp_thread_yield();
387    }
388}
389
390#ifndef _LIBCPP_HAS_NO_VARIADICS
391
392template <class _L0, class _L1, class _L2, class ..._L3>
393void
394__lock_first(int __i, _L0& __l0, _L1& __l1, _L2& __l2, _L3& ...__l3)
395{
396    while (true)
397    {
398        switch (__i)
399        {
400        case 0:
401            {
402                unique_lock<_L0> __u0(__l0);
403                __i = try_lock(__l1, __l2, __l3...);
404                if (__i == -1)
405                {
406                    __u0.release();
407                    return;
408                }
409            }
410            ++__i;
411            __libcpp_thread_yield();
412            break;
413        case 1:
414            {
415                unique_lock<_L1> __u1(__l1);
416                __i = try_lock(__l2, __l3..., __l0);
417                if (__i == -1)
418                {
419                    __u1.release();
420                    return;
421                }
422            }
423            if (__i == sizeof...(_L3) + 1)
424                __i = 0;
425            else
426                __i += 2;
427            __libcpp_thread_yield();
428            break;
429        default:
430            __lock_first(__i - 2, __l2, __l3..., __l0, __l1);
431            return;
432        }
433    }
434}
435
436template <class _L0, class _L1, class _L2, class ..._L3>
437inline _LIBCPP_INLINE_VISIBILITY
438void
439lock(_L0& __l0, _L1& __l1, _L2& __l2, _L3& ...__l3)
440{
441    __lock_first(0, __l0, __l1, __l2, __l3...);
442}
443
444template <class _L0>
445inline _LIBCPP_INLINE_VISIBILITY
446void __unlock(_L0& __l0) {
447    __l0.unlock();
448}
449
450template <class _L0, class _L1>
451inline _LIBCPP_INLINE_VISIBILITY
452void __unlock(_L0& __l0, _L1& __l1) {
453    __l0.unlock();
454    __l1.unlock();
455}
456
457template <class _L0, class _L1, class _L2, class ..._L3>
458inline _LIBCPP_INLINE_VISIBILITY
459void __unlock(_L0& __l0, _L1& __l1, _L2& __l2, _L3&... __l3) {
460    __l0.unlock();
461    __l1.unlock();
462    _VSTD::__unlock(__l2, __l3...);
463}
464
465#endif  // _LIBCPP_HAS_NO_VARIADICS
466
467#endif // !_LIBCPP_HAS_NO_THREADS
468
469struct _LIBCPP_TEMPLATE_VIS once_flag;
470
471#ifndef _LIBCPP_HAS_NO_VARIADICS
472
473template<class _Callable, class... _Args>
474_LIBCPP_INLINE_VISIBILITY
475void call_once(once_flag&, _Callable&&, _Args&&...);
476
477#else  // _LIBCPP_HAS_NO_VARIADICS
478
479template<class _Callable>
480_LIBCPP_INLINE_VISIBILITY
481void call_once(once_flag&, _Callable&);
482
483template<class _Callable>
484_LIBCPP_INLINE_VISIBILITY
485void call_once(once_flag&, const _Callable&);
486
487#endif  // _LIBCPP_HAS_NO_VARIADICS
488
489struct _LIBCPP_TEMPLATE_VIS once_flag
490{
491    _LIBCPP_INLINE_VISIBILITY
492    _LIBCPP_CONSTEXPR
493        once_flag() _NOEXCEPT : __state_(0) {}
494
495private:
496    once_flag(const once_flag&); // = delete;
497    once_flag& operator=(const once_flag&); // = delete;
498
499    unsigned long __state_;
500
501#ifndef _LIBCPP_HAS_NO_VARIADICS
502    template<class _Callable, class... _Args>
503    friend
504    void call_once(once_flag&, _Callable&&, _Args&&...);
505#else  // _LIBCPP_HAS_NO_VARIADICS
506    template<class _Callable>
507    friend
508    void call_once(once_flag&, _Callable&);
509
510    template<class _Callable>
511    friend
512    void call_once(once_flag&, const _Callable&);
513#endif  // _LIBCPP_HAS_NO_VARIADICS
514};
515
516#ifndef _LIBCPP_HAS_NO_VARIADICS
517
518template <class _Fp>
519class __call_once_param
520{
521    _Fp& __f_;
522public:
523    _LIBCPP_INLINE_VISIBILITY
524    explicit __call_once_param(_Fp& __f) : __f_(__f) {}
525
526    _LIBCPP_INLINE_VISIBILITY
527    void operator()()
528    {
529        typedef typename __make_tuple_indices<tuple_size<_Fp>::value, 1>::type _Index;
530        __execute(_Index());
531    }
532
533private:
534    template <size_t ..._Indices>
535    _LIBCPP_INLINE_VISIBILITY
536    void __execute(__tuple_indices<_Indices...>)
537    {
538        __invoke(_VSTD::get<0>(_VSTD::move(__f_)), _VSTD::get<_Indices>(_VSTD::move(__f_))...);
539    }
540};
541
542#else
543
544template <class _Fp>
545class __call_once_param
546{
547    _Fp& __f_;
548public:
549    _LIBCPP_INLINE_VISIBILITY
550    explicit __call_once_param(_Fp& __f) : __f_(__f) {}
551
552    _LIBCPP_INLINE_VISIBILITY
553    void operator()()
554    {
555        __f_();
556    }
557};
558
559#endif
560
561template <class _Fp>
562inline _LIBCPP_INLINE_VISIBILITY
563void
564__call_once_proxy(void* __vp)
565{
566    __call_once_param<_Fp>* __p = static_cast<__call_once_param<_Fp>*>(__vp);
567    (*__p)();
568}
569
570_LIBCPP_FUNC_VIS void __call_once(volatile unsigned long&, void*, void(*)(void*));
571
572#ifndef _LIBCPP_HAS_NO_VARIADICS
573
574template<class _Callable, class... _Args>
575inline _LIBCPP_INLINE_VISIBILITY
576void
577call_once(once_flag& __flag, _Callable&& __func, _Args&&... __args)
578{
579    if (__libcpp_acquire_load(&__flag.__state_) != ~0ul)
580    {
581        typedef tuple<_Callable&&, _Args&&...> _Gp;
582        _Gp __f(_VSTD::forward<_Callable>(__func), _VSTD::forward<_Args>(__args)...);
583        __call_once_param<_Gp> __p(__f);
584        __call_once(__flag.__state_, &__p, &__call_once_proxy<_Gp>);
585    }
586}
587
588#else  // _LIBCPP_HAS_NO_VARIADICS
589
590template<class _Callable>
591inline _LIBCPP_INLINE_VISIBILITY
592void
593call_once(once_flag& __flag, _Callable& __func)
594{
595    if (__libcpp_acquire_load(&__flag.__state_) != ~0ul)
596    {
597        __call_once_param<_Callable> __p(__func);
598        __call_once(__flag.__state_, &__p, &__call_once_proxy<_Callable>);
599    }
600}
601
602template<class _Callable>
603inline _LIBCPP_INLINE_VISIBILITY
604void
605call_once(once_flag& __flag, const _Callable& __func)
606{
607    if (__flag.__state_ != ~0ul)
608    {
609        __call_once_param<const _Callable> __p(__func);
610        __call_once(__flag.__state_, &__p, &__call_once_proxy<const _Callable>);
611    }
612}
613
614#endif  // _LIBCPP_HAS_NO_VARIADICS
615
616
617#if defined(_LIBCPP_ABI_VARIADIC_LOCK_GUARD) \
618    && !defined(_LIBCPP_CXX03_LANG)
619template <>
620class _LIBCPP_TEMPLATE_VIS lock_guard<> {
621public:
622    explicit lock_guard() {}
623    ~lock_guard() = default;
624
625    _LIBCPP_INLINE_VISIBILITY
626    explicit lock_guard(adopt_lock_t) {}
627
628    lock_guard(lock_guard const&) = delete;
629    lock_guard& operator=(lock_guard const&) = delete;
630};
631
632template <class ..._MArgs>
633class _LIBCPP_TEMPLATE_VIS lock_guard
634{
635    static_assert(sizeof...(_MArgs) >= 2, "At least 2 lock types required");
636    typedef tuple<_MArgs&...> _MutexTuple;
637
638public:
639    _LIBCPP_INLINE_VISIBILITY
640    explicit lock_guard(_MArgs&... __margs)
641      : __t_(__margs...)
642    {
643        _VSTD::lock(__margs...);
644    }
645
646    _LIBCPP_INLINE_VISIBILITY
647    lock_guard(_MArgs&... __margs, adopt_lock_t)
648        : __t_(__margs...)
649    {
650    }
651
652    _LIBCPP_INLINE_VISIBILITY
653    ~lock_guard() {
654        typedef typename __make_tuple_indices<sizeof...(_MArgs)>::type _Indices;
655        __unlock_unpack(_Indices{}, __t_);
656    }
657
658    lock_guard(lock_guard const&) = delete;
659    lock_guard& operator=(lock_guard const&) = delete;
660
661private:
662    template <size_t ..._Indx>
663    _LIBCPP_INLINE_VISIBILITY
664    static void __unlock_unpack(__tuple_indices<_Indx...>, _MutexTuple& __mt) {
665        _VSTD::__unlock(_VSTD::get<_Indx>(__mt)...);
666    }
667
668    _MutexTuple __t_;
669};
670
671#endif // _LIBCPP_ABI_VARIADIC_LOCK_GUARD
672
673_LIBCPP_END_NAMESPACE_STD
674
675#endif  // _LIBCPP_MUTEX
676