xref: /llvm-project-15.0.7/libcxx/include/thread (revision 525cd59f) 
1// -*- C++ -*-
2//===--------------------------- thread -----------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef _LIBCPP_THREAD
11#define _LIBCPP_THREAD
12
13/*
14
15    thread synopsis
16
17#define __STDCPP_THREADS__ __cplusplus
18
19namespace std
20{
21
22class thread
23{
24public:
25    class id;
26    typedef pthread_t native_handle_type;
27
28    thread() noexcept;
29    template <class F, class ...Args> explicit thread(F&& f, Args&&... args);
30    ~thread();
31
32    thread(const thread&) = delete;
33    thread(thread&& t) noexcept;
34
35    thread& operator=(const thread&) = delete;
36    thread& operator=(thread&& t) noexcept;
37
38    void swap(thread& t) noexcept;
39
40    bool joinable() const noexcept;
41    void join();
42    void detach();
43    id get_id() const noexcept;
44    native_handle_type native_handle();
45
46    static unsigned hardware_concurrency() noexcept;
47};
48
49void swap(thread& x, thread& y) noexcept;
50
51class thread::id
52{
53public:
54    id() noexcept;
55};
56
57bool operator==(thread::id x, thread::id y) noexcept;
58bool operator!=(thread::id x, thread::id y) noexcept;
59bool operator< (thread::id x, thread::id y) noexcept;
60bool operator<=(thread::id x, thread::id y) noexcept;
61bool operator> (thread::id x, thread::id y) noexcept;
62bool operator>=(thread::id x, thread::id y) noexcept;
63
64template<class charT, class traits>
65basic_ostream<charT, traits>&
66operator<<(basic_ostream<charT, traits>& out, thread::id id);
67
68namespace this_thread
69{
70
71thread::id get_id() noexcept;
72
73void yield() noexcept;
74
75template <class Clock, class Duration>
76void sleep_until(const chrono::time_point<Clock, Duration>& abs_time);
77
78template <class Rep, class Period>
79void sleep_for(const chrono::duration<Rep, Period>& rel_time);
80
81}  // this_thread
82
83}  // std
84
85*/
86
87#include <__config>
88#include <iosfwd>
89#include <__functional_base>
90#include <type_traits>
91#include <cstddef>
92#include <functional>
93#include <memory>
94#include <system_error>
95#include <chrono>
96#include <__mutex_base>
97#ifndef _LIBCPP_CXX03_LANG
98#include <tuple>
99#endif
100#include <__threading_support>
101#include <__debug>
102
103#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
104#pragma GCC system_header
105#endif
106
107_LIBCPP_PUSH_MACROS
108#include <__undef_macros>
109
110#define __STDCPP_THREADS__ __cplusplus
111
112#ifdef _LIBCPP_HAS_NO_THREADS
113#error <thread> is not supported on this single threaded system
114#else // !_LIBCPP_HAS_NO_THREADS
115
116_LIBCPP_BEGIN_NAMESPACE_STD
117
118template <class _Tp> class __thread_specific_ptr;
119class _LIBCPP_TYPE_VIS __thread_struct;
120class _LIBCPP_HIDDEN __thread_struct_imp;
121class __assoc_sub_state;
122
123_LIBCPP_FUNC_VIS __thread_specific_ptr<__thread_struct>& __thread_local_data();
124
125class _LIBCPP_TYPE_VIS __thread_struct
126{
127    __thread_struct_imp* __p_;
128
129    __thread_struct(const __thread_struct&);
130    __thread_struct& operator=(const __thread_struct&);
131public:
132    __thread_struct();
133    ~__thread_struct();
134
135    void notify_all_at_thread_exit(condition_variable*, mutex*);
136    void __make_ready_at_thread_exit(__assoc_sub_state*);
137};
138
139template <class _Tp>
140class __thread_specific_ptr
141{
142    __libcpp_tls_key __key_;
143
144     // Only __thread_local_data() may construct a __thread_specific_ptr
145     // and only with _Tp == __thread_struct.
146    static_assert((is_same<_Tp, __thread_struct>::value), "");
147    __thread_specific_ptr();
148    friend _LIBCPP_FUNC_VIS __thread_specific_ptr<__thread_struct>& __thread_local_data();
149
150    __thread_specific_ptr(const __thread_specific_ptr&);
151    __thread_specific_ptr& operator=(const __thread_specific_ptr&);
152
153    _LIBCPP_HIDDEN static void _LIBCPP_TLS_DESTRUCTOR_CC __at_thread_exit(void*);
154
155public:
156    typedef _Tp* pointer;
157
158    ~__thread_specific_ptr();
159
160    _LIBCPP_INLINE_VISIBILITY
161    pointer get() const {return static_cast<_Tp*>(__libcpp_tls_get(__key_));}
162    _LIBCPP_INLINE_VISIBILITY
163    pointer operator*() const {return *get();}
164    _LIBCPP_INLINE_VISIBILITY
165    pointer operator->() const {return get();}
166    void set_pointer(pointer __p);
167};
168
169template <class _Tp>
170void _LIBCPP_TLS_DESTRUCTOR_CC
171__thread_specific_ptr<_Tp>::__at_thread_exit(void* __p)
172{
173    delete static_cast<pointer>(__p);
174}
175
176template <class _Tp>
177__thread_specific_ptr<_Tp>::__thread_specific_ptr()
178{
179  int __ec =
180      __libcpp_tls_create(&__key_, &__thread_specific_ptr::__at_thread_exit);
181  if (__ec)
182    __throw_system_error(__ec, "__thread_specific_ptr construction failed");
183}
184
185template <class _Tp>
186__thread_specific_ptr<_Tp>::~__thread_specific_ptr()
187{
188    // __thread_specific_ptr is only created with a static storage duration
189    // so this destructor is only invoked during program termination. Invoking
190    // pthread_key_delete(__key_) may prevent other threads from deleting their
191    // thread local data. For this reason we leak the key.
192}
193
194template <class _Tp>
195void
196__thread_specific_ptr<_Tp>::set_pointer(pointer __p)
197{
198    _LIBCPP_ASSERT(get() == nullptr,
199                   "Attempting to overwrite thread local data");
200    __libcpp_tls_set(__key_, __p);
201}
202
203class _LIBCPP_TYPE_VIS thread;
204class _LIBCPP_TYPE_VIS __thread_id;
205
206namespace this_thread
207{
208
209_LIBCPP_INLINE_VISIBILITY __thread_id get_id() _NOEXCEPT;
210
211}  // this_thread
212
213template<> struct hash<__thread_id>;
214
215class _LIBCPP_TEMPLATE_VIS __thread_id
216{
217    // FIXME: pthread_t is a pointer on Darwin but a long on Linux.
218    // NULL is the no-thread value on Darwin.  Someone needs to check
219    // on other platforms.  We assume 0 works everywhere for now.
220    __libcpp_thread_id __id_;
221
222public:
223    _LIBCPP_INLINE_VISIBILITY
224    __thread_id() _NOEXCEPT : __id_(0) {}
225
226    friend _LIBCPP_INLINE_VISIBILITY
227        bool operator==(__thread_id __x, __thread_id __y) _NOEXCEPT
228        {return __libcpp_thread_id_equal(__x.__id_, __y.__id_);}
229    friend _LIBCPP_INLINE_VISIBILITY
230        bool operator!=(__thread_id __x, __thread_id __y) _NOEXCEPT
231        {return !(__x == __y);}
232    friend _LIBCPP_INLINE_VISIBILITY
233        bool operator< (__thread_id __x, __thread_id __y) _NOEXCEPT
234        {return  __libcpp_thread_id_less(__x.__id_, __y.__id_);}
235    friend _LIBCPP_INLINE_VISIBILITY
236        bool operator<=(__thread_id __x, __thread_id __y) _NOEXCEPT
237        {return !(__y < __x);}
238    friend _LIBCPP_INLINE_VISIBILITY
239        bool operator> (__thread_id __x, __thread_id __y) _NOEXCEPT
240        {return   __y < __x ;}
241    friend _LIBCPP_INLINE_VISIBILITY
242        bool operator>=(__thread_id __x, __thread_id __y) _NOEXCEPT
243        {return !(__x < __y);}
244
245    template<class _CharT, class _Traits>
246    friend
247    _LIBCPP_INLINE_VISIBILITY
248    basic_ostream<_CharT, _Traits>&
249    operator<<(basic_ostream<_CharT, _Traits>& __os, __thread_id __id)
250        {return __os << __id.__id_;}
251
252private:
253    _LIBCPP_INLINE_VISIBILITY
254    __thread_id(__libcpp_thread_id __id) : __id_(__id) {}
255
256    friend __thread_id this_thread::get_id() _NOEXCEPT;
257    friend class _LIBCPP_TYPE_VIS thread;
258    friend struct _LIBCPP_TEMPLATE_VIS hash<__thread_id>;
259};
260
261template<>
262struct _LIBCPP_TEMPLATE_VIS hash<__thread_id>
263    : public unary_function<__thread_id, size_t>
264{
265    _LIBCPP_INLINE_VISIBILITY
266    size_t operator()(__thread_id __v) const _NOEXCEPT
267    {
268        return hash<__libcpp_thread_id>()(__v.__id_);
269    }
270};
271
272namespace this_thread
273{
274
275inline _LIBCPP_INLINE_VISIBILITY
276__thread_id
277get_id() _NOEXCEPT
278{
279    return __libcpp_thread_get_current_id();
280}
281
282}  // this_thread
283
284class _LIBCPP_TYPE_VIS thread
285{
286    __libcpp_thread_t __t_;
287
288    thread(const thread&);
289    thread& operator=(const thread&);
290public:
291    typedef __thread_id id;
292    typedef __libcpp_thread_t native_handle_type;
293
294    _LIBCPP_INLINE_VISIBILITY
295    thread() _NOEXCEPT : __t_(_LIBCPP_NULL_THREAD) {}
296#ifndef _LIBCPP_CXX03_LANG
297    template <class _Fp, class ..._Args,
298              class = typename enable_if
299              <
300                   !is_same<typename __uncvref<_Fp>::type, thread>::value
301              >::type
302             >
303        _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
304        explicit thread(_Fp&& __f, _Args&&... __args);
305#else  // _LIBCPP_CXX03_LANG
306    template <class _Fp>
307    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
308    explicit thread(_Fp __f);
309#endif
310    ~thread();
311
312#ifndef _LIBCPP_CXX03_LANG
313    _LIBCPP_INLINE_VISIBILITY
314    thread(thread&& __t) _NOEXCEPT : __t_(__t.__t_) {__t.__t_ = _LIBCPP_NULL_THREAD;}
315    _LIBCPP_INLINE_VISIBILITY
316    thread& operator=(thread&& __t) _NOEXCEPT;
317#endif  // _LIBCPP_CXX03_LANG
318
319    _LIBCPP_INLINE_VISIBILITY
320    void swap(thread& __t) _NOEXCEPT {_VSTD::swap(__t_, __t.__t_);}
321
322    _LIBCPP_INLINE_VISIBILITY
323    bool joinable() const _NOEXCEPT {return !__libcpp_thread_isnull(&__t_);}
324    void join();
325    void detach();
326    _LIBCPP_INLINE_VISIBILITY
327    id get_id() const _NOEXCEPT {return __libcpp_thread_get_id(&__t_);}
328    _LIBCPP_INLINE_VISIBILITY
329    native_handle_type native_handle() _NOEXCEPT {return __t_;}
330
331    static unsigned hardware_concurrency() _NOEXCEPT;
332};
333
334#ifndef _LIBCPP_CXX03_LANG
335
336template <class _TSp, class _Fp, class ..._Args, size_t ..._Indices>
337inline _LIBCPP_INLINE_VISIBILITY
338void
339__thread_execute(tuple<_TSp, _Fp, _Args...>& __t, __tuple_indices<_Indices...>)
340{
341    __invoke(_VSTD::move(_VSTD::get<1>(__t)), _VSTD::move(_VSTD::get<_Indices>(__t))...);
342}
343
344template <class _Fp>
345void* __thread_proxy(void* __vp)
346{
347    // _Fp = std::tuple< unique_ptr<__thread_struct>, Functor, Args...>
348    std::unique_ptr<_Fp> __p(static_cast<_Fp*>(__vp));
349    __thread_local_data().set_pointer(_VSTD::get<0>(*__p).release());
350    typedef typename __make_tuple_indices<tuple_size<_Fp>::value, 2>::type _Index;
351    __thread_execute(*__p, _Index());
352    return nullptr;
353}
354
355template <class _Fp, class ..._Args,
356          class
357         >
358thread::thread(_Fp&& __f, _Args&&... __args)
359{
360    typedef unique_ptr<__thread_struct> _TSPtr;
361    _TSPtr __tsp(new __thread_struct);
362    typedef tuple<_TSPtr, typename decay<_Fp>::type, typename decay<_Args>::type...> _Gp;
363    _VSTD::unique_ptr<_Gp> __p(
364            new _Gp(std::move(__tsp),
365                    __decay_copy(_VSTD::forward<_Fp>(__f)),
366                    __decay_copy(_VSTD::forward<_Args>(__args))...));
367    int __ec = __libcpp_thread_create(&__t_, &__thread_proxy<_Gp>, __p.get());
368    if (__ec == 0)
369        __p.release();
370    else
371        __throw_system_error(__ec, "thread constructor failed");
372}
373
374inline
375thread&
376thread::operator=(thread&& __t) _NOEXCEPT
377{
378    if (!__libcpp_thread_isnull(&__t_))
379        terminate();
380    __t_ = __t.__t_;
381    __t.__t_ = _LIBCPP_NULL_THREAD;
382    return *this;
383}
384
385#else  // _LIBCPP_CXX03_LANG
386
387template <class _Fp>
388struct __thread_invoke_pair {
389    // This type is used to pass memory for thread local storage and a functor
390    // to a newly created thread because std::pair doesn't work with
391    // std::unique_ptr in C++03.
392    __thread_invoke_pair(_Fp& __f) : __tsp_(new __thread_struct), __fn_(__f) {}
393    unique_ptr<__thread_struct> __tsp_;
394    _Fp __fn_;
395};
396
397template <class _Fp>
398void* __thread_proxy_cxx03(void* __vp)
399{
400    std::unique_ptr<_Fp> __p(static_cast<_Fp*>(__vp));
401    __thread_local_data().set_pointer(__p->__tsp_.release());
402    (__p->__fn_)();
403    return nullptr;
404}
405
406template <class _Fp>
407thread::thread(_Fp __f)
408{
409
410    typedef __thread_invoke_pair<_Fp> _InvokePair;
411    typedef std::unique_ptr<_InvokePair> _PairPtr;
412    _PairPtr __pp(new _InvokePair(__f));
413    int __ec = __libcpp_thread_create(&__t_, &__thread_proxy_cxx03<_InvokePair>, __pp.get());
414    if (__ec == 0)
415        __pp.release();
416    else
417        __throw_system_error(__ec, "thread constructor failed");
418}
419
420#endif  // _LIBCPP_CXX03_LANG
421
422inline _LIBCPP_INLINE_VISIBILITY
423void swap(thread& __x, thread& __y) _NOEXCEPT {__x.swap(__y);}
424
425namespace this_thread
426{
427
428_LIBCPP_FUNC_VIS void sleep_for(const chrono::nanoseconds& __ns);
429
430template <class _Rep, class _Period>
431void
432sleep_for(const chrono::duration<_Rep, _Period>& __d)
433{
434    using namespace chrono;
435    if (__d > duration<_Rep, _Period>::zero())
436    {
437        _LIBCPP_CONSTEXPR duration<long double> _Max = nanoseconds::max();
438        nanoseconds __ns;
439        if (__d < _Max)
440        {
441            __ns = duration_cast<nanoseconds>(__d);
442            if (__ns < __d)
443                ++__ns;
444        }
445        else
446            __ns = nanoseconds::max();
447        sleep_for(__ns);
448    }
449}
450
451template <class _Clock, class _Duration>
452void
453sleep_until(const chrono::time_point<_Clock, _Duration>& __t)
454{
455    using namespace chrono;
456    mutex __mut;
457    condition_variable __cv;
458    unique_lock<mutex> __lk(__mut);
459    while (_Clock::now() < __t)
460        __cv.wait_until(__lk, __t);
461}
462
463template <class _Duration>
464inline _LIBCPP_INLINE_VISIBILITY
465void
466sleep_until(const chrono::time_point<chrono::steady_clock, _Duration>& __t)
467{
468    using namespace chrono;
469    sleep_for(__t - steady_clock::now());
470}
471
472inline _LIBCPP_INLINE_VISIBILITY
473void yield() _NOEXCEPT {__libcpp_thread_yield();}
474
475}  // this_thread
476
477_LIBCPP_END_NAMESPACE_STD
478
479#endif // !_LIBCPP_HAS_NO_THREADS
480
481_LIBCPP_POP_MACROS
482
483#endif  // _LIBCPP_THREAD
484