xref: /llvm-project-15.0.7/libcxx/include/thread (revision cf6a7c19) 
1// -*- C++ -*-
2//===----------------------------------------------------------------------===//
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
17namespace std
18{
19
20class thread
21{
22public:
23    class id;
24    typedef pthread_t native_handle_type;
25
26    thread() noexcept;
27    template <class F, class ...Args> explicit thread(F&& f, Args&&... args);
28    ~thread();
29
30    thread(const thread&) = delete;
31    thread(thread&& t) noexcept;
32
33    thread& operator=(const thread&) = delete;
34    thread& operator=(thread&& t) noexcept;
35
36    void swap(thread& t) noexcept;
37
38    bool joinable() const noexcept;
39    void join();
40    void detach();
41    id get_id() const noexcept;
42    native_handle_type native_handle();
43
44    static unsigned hardware_concurrency() noexcept;
45};
46
47void swap(thread& x, thread& y) noexcept;
48
49class thread::id
50{
51public:
52    id() noexcept;
53};
54
55bool operator==(thread::id x, thread::id y) noexcept;
56bool operator!=(thread::id x, thread::id y) noexcept;
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;
61
62template<class charT, class traits>
63basic_ostream<charT, traits>&
64operator<<(basic_ostream<charT, traits>& out, thread::id id);
65
66namespace this_thread
67{
68
69thread::id get_id() noexcept;
70
71void yield() noexcept;
72
73template <class Clock, class Duration>
74void sleep_until(const chrono::time_point<Clock, Duration>& abs_time);
75
76template <class Rep, class Period>
77void sleep_for(const chrono::duration<Rep, Period>& rel_time);
78
79}  // this_thread
80
81}  // std
82
83*/
84
85#include <__assert> // all public C++ headers provide the assertion handler
86#include <__config>
87#include <__functional/hash.h>
88#include <__mutex_base>
89#include <__thread/poll_with_backoff.h>
90#include <__thread/timed_backoff_policy.h>
91#include <__threading_support>
92#include <__utility/forward.h>
93#include <cstddef>
94#include <iosfwd>
95#include <memory>
96#include <system_error>
97#include <tuple>
98#include <type_traits>
99#include <version>
100
101#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
102#  pragma GCC system_header
103#endif
104
105_LIBCPP_PUSH_MACROS
106#include <__undef_macros>
107
108#ifdef _LIBCPP_HAS_NO_THREADS
109# error "<thread> is not supported since libc++ has been configured without support for threads."
110#endif
111
112_LIBCPP_BEGIN_NAMESPACE_STD
113
114template <class _Tp> class __thread_specific_ptr;
115class _LIBCPP_TYPE_VIS __thread_struct;
116class _LIBCPP_HIDDEN __thread_struct_imp;
117class __assoc_sub_state;
118
119_LIBCPP_FUNC_VIS __thread_specific_ptr<__thread_struct>& __thread_local_data();
120
121class _LIBCPP_TYPE_VIS __thread_struct
122{
123    __thread_struct_imp* __p_;
124
125    __thread_struct(const __thread_struct&);
126    __thread_struct& operator=(const __thread_struct&);
127public:
128    __thread_struct();
129    ~__thread_struct();
130
131    void notify_all_at_thread_exit(condition_variable*, mutex*);
132    void __make_ready_at_thread_exit(__assoc_sub_state*);
133};
134
135template <class _Tp>
136class __thread_specific_ptr
137{
138    __libcpp_tls_key __key_;
139
140     // Only __thread_local_data() may construct a __thread_specific_ptr
141     // and only with _Tp == __thread_struct.
142    static_assert((is_same<_Tp, __thread_struct>::value), "");
143    __thread_specific_ptr();
144    friend _LIBCPP_FUNC_VIS __thread_specific_ptr<__thread_struct>& __thread_local_data();
145
146    __thread_specific_ptr(const __thread_specific_ptr&);
147    __thread_specific_ptr& operator=(const __thread_specific_ptr&);
148
149    _LIBCPP_HIDDEN static void _LIBCPP_TLS_DESTRUCTOR_CC __at_thread_exit(void*);
150
151public:
152    typedef _Tp* pointer;
153
154    ~__thread_specific_ptr();
155
156    _LIBCPP_INLINE_VISIBILITY
157    pointer get() const {return static_cast<_Tp*>(__libcpp_tls_get(__key_));}
158    _LIBCPP_INLINE_VISIBILITY
159    pointer operator*() const {return *get();}
160    _LIBCPP_INLINE_VISIBILITY
161    pointer operator->() const {return get();}
162    void set_pointer(pointer __p);
163};
164
165template <class _Tp>
166void _LIBCPP_TLS_DESTRUCTOR_CC
167__thread_specific_ptr<_Tp>::__at_thread_exit(void* __p)
168{
169    delete static_cast<pointer>(__p);
170}
171
172template <class _Tp>
173__thread_specific_ptr<_Tp>::__thread_specific_ptr()
174{
175  int __ec =
176      __libcpp_tls_create(&__key_, &__thread_specific_ptr::__at_thread_exit);
177  if (__ec)
178    __throw_system_error(__ec, "__thread_specific_ptr construction failed");
179}
180
181template <class _Tp>
182__thread_specific_ptr<_Tp>::~__thread_specific_ptr()
183{
184    // __thread_specific_ptr is only created with a static storage duration
185    // so this destructor is only invoked during program termination. Invoking
186    // pthread_key_delete(__key_) may prevent other threads from deleting their
187    // thread local data. For this reason we leak the key.
188}
189
190template <class _Tp>
191void
192__thread_specific_ptr<_Tp>::set_pointer(pointer __p)
193{
194    _LIBCPP_ASSERT(get() == nullptr,
195                   "Attempting to overwrite thread local data");
196    __libcpp_tls_set(__key_, __p);
197}
198
199template<>
200struct _LIBCPP_TEMPLATE_VIS hash<__thread_id>
201    : public unary_function<__thread_id, size_t>
202{
203    _LIBCPP_INLINE_VISIBILITY
204    size_t operator()(__thread_id __v) const _NOEXCEPT
205    {
206        return hash<__libcpp_thread_id>()(__v.__id_);
207    }
208};
209
210template<class _CharT, class _Traits>
211_LIBCPP_INLINE_VISIBILITY
212basic_ostream<_CharT, _Traits>&
213operator<<(basic_ostream<_CharT, _Traits>& __os, __thread_id __id)
214{return __os << __id.__id_;}
215
216class _LIBCPP_TYPE_VIS thread
217{
218    __libcpp_thread_t __t_;
219
220    thread(const thread&);
221    thread& operator=(const thread&);
222public:
223    typedef __thread_id id;
224    typedef __libcpp_thread_t native_handle_type;
225
226    _LIBCPP_INLINE_VISIBILITY
227    thread() _NOEXCEPT : __t_(_LIBCPP_NULL_THREAD) {}
228#ifndef _LIBCPP_CXX03_LANG
229    template <class _Fp, class ..._Args,
230              class = __enable_if_t<!is_same<__uncvref_t<_Fp>, thread>::value> >
231        _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
232        explicit thread(_Fp&& __f, _Args&&... __args);
233#else  // _LIBCPP_CXX03_LANG
234    template <class _Fp>
235    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
236    explicit thread(_Fp __f);
237#endif
238    ~thread();
239
240    _LIBCPP_INLINE_VISIBILITY
241    thread(thread&& __t) _NOEXCEPT : __t_(__t.__t_) {
242        __t.__t_ = _LIBCPP_NULL_THREAD;
243    }
244
245    _LIBCPP_INLINE_VISIBILITY
246    thread& operator=(thread&& __t) _NOEXCEPT {
247        if (!__libcpp_thread_isnull(&__t_))
248            terminate();
249        __t_ = __t.__t_;
250        __t.__t_ = _LIBCPP_NULL_THREAD;
251        return *this;
252    }
253
254    _LIBCPP_INLINE_VISIBILITY
255    void swap(thread& __t) _NOEXCEPT {_VSTD::swap(__t_, __t.__t_);}
256
257    _LIBCPP_INLINE_VISIBILITY
258    bool joinable() const _NOEXCEPT {return !__libcpp_thread_isnull(&__t_);}
259    void join();
260    void detach();
261    _LIBCPP_INLINE_VISIBILITY
262    id get_id() const _NOEXCEPT {return __libcpp_thread_get_id(&__t_);}
263    _LIBCPP_INLINE_VISIBILITY
264    native_handle_type native_handle() _NOEXCEPT {return __t_;}
265
266    static unsigned hardware_concurrency() _NOEXCEPT;
267};
268
269#ifndef _LIBCPP_CXX03_LANG
270
271template <class _TSp, class _Fp, class ..._Args, size_t ..._Indices>
272inline _LIBCPP_INLINE_VISIBILITY
273void
274__thread_execute(tuple<_TSp, _Fp, _Args...>& __t, __tuple_indices<_Indices...>)
275{
276    _VSTD::__invoke(_VSTD::move(_VSTD::get<1>(__t)), _VSTD::move(_VSTD::get<_Indices>(__t))...);
277}
278
279template <class _Fp>
280_LIBCPP_INLINE_VISIBILITY
281void* __thread_proxy(void* __vp)
282{
283    // _Fp = tuple< unique_ptr<__thread_struct>, Functor, Args...>
284    unique_ptr<_Fp> __p(static_cast<_Fp*>(__vp));
285    __thread_local_data().set_pointer(_VSTD::get<0>(*__p.get()).release());
286    typedef typename __make_tuple_indices<tuple_size<_Fp>::value, 2>::type _Index;
287    _VSTD::__thread_execute(*__p.get(), _Index());
288    return nullptr;
289}
290
291template <class _Fp, class ..._Args,
292          class
293         >
294thread::thread(_Fp&& __f, _Args&&... __args)
295{
296    typedef unique_ptr<__thread_struct> _TSPtr;
297    _TSPtr __tsp(new __thread_struct);
298    typedef tuple<_TSPtr, typename decay<_Fp>::type, typename decay<_Args>::type...> _Gp;
299    unique_ptr<_Gp> __p(
300            new _Gp(_VSTD::move(__tsp),
301                    _VSTD::forward<_Fp>(__f),
302                    _VSTD::forward<_Args>(__args)...));
303    int __ec = _VSTD::__libcpp_thread_create(&__t_, &__thread_proxy<_Gp>, __p.get());
304    if (__ec == 0)
305        __p.release();
306    else
307        __throw_system_error(__ec, "thread constructor failed");
308}
309
310#else  // _LIBCPP_CXX03_LANG
311
312template <class _Fp>
313struct __thread_invoke_pair {
314    // This type is used to pass memory for thread local storage and a functor
315    // to a newly created thread because std::pair doesn't work with
316    // std::unique_ptr in C++03.
317    __thread_invoke_pair(_Fp& __f) : __tsp_(new __thread_struct), __fn_(__f) {}
318    unique_ptr<__thread_struct> __tsp_;
319    _Fp __fn_;
320};
321
322template <class _Fp>
323void* __thread_proxy_cxx03(void* __vp)
324{
325    unique_ptr<_Fp> __p(static_cast<_Fp*>(__vp));
326    __thread_local_data().set_pointer(__p->__tsp_.release());
327    (__p->__fn_)();
328    return nullptr;
329}
330
331template <class _Fp>
332thread::thread(_Fp __f)
333{
334
335    typedef __thread_invoke_pair<_Fp> _InvokePair;
336    typedef unique_ptr<_InvokePair> _PairPtr;
337    _PairPtr __pp(new _InvokePair(__f));
338    int __ec = _VSTD::__libcpp_thread_create(&__t_, &__thread_proxy_cxx03<_InvokePair>, __pp.get());
339    if (__ec == 0)
340        __pp.release();
341    else
342        __throw_system_error(__ec, "thread constructor failed");
343}
344
345#endif // _LIBCPP_CXX03_LANG
346
347inline _LIBCPP_INLINE_VISIBILITY
348void swap(thread& __x, thread& __y) _NOEXCEPT {__x.swap(__y);}
349
350namespace this_thread
351{
352
353_LIBCPP_FUNC_VIS void sleep_for(const chrono::nanoseconds& __ns);
354
355template <class _Rep, class _Period>
356void
357sleep_for(const chrono::duration<_Rep, _Period>& __d)
358{
359    if (__d > chrono::duration<_Rep, _Period>::zero())
360    {
361        // The standard guarantees a 64bit signed integer resolution for nanoseconds,
362        // so use INT64_MAX / 1e9 as cut-off point. Use a constant to avoid <climits>
363        // and issues with long double folding on PowerPC with GCC.
364        _LIBCPP_CONSTEXPR chrono::duration<long double> _Max =
365            chrono::duration<long double>(9223372036.0L);
366        chrono::nanoseconds __ns;
367        if (__d < _Max)
368        {
369            __ns = chrono::duration_cast<chrono::nanoseconds>(__d);
370            if (__ns < __d)
371                ++__ns;
372        }
373        else
374            __ns = chrono::nanoseconds::max();
375        this_thread::sleep_for(__ns);
376    }
377}
378
379template <class _Clock, class _Duration>
380void
381sleep_until(const chrono::time_point<_Clock, _Duration>& __t)
382{
383    mutex __mut;
384    condition_variable __cv;
385    unique_lock<mutex> __lk(__mut);
386    while (_Clock::now() < __t)
387        __cv.wait_until(__lk, __t);
388}
389
390template <class _Duration>
391inline _LIBCPP_INLINE_VISIBILITY
392void
393sleep_until(const chrono::time_point<chrono::steady_clock, _Duration>& __t)
394{
395    this_thread::sleep_for(__t - chrono::steady_clock::now());
396}
397
398inline _LIBCPP_INLINE_VISIBILITY
399void yield() _NOEXCEPT {__libcpp_thread_yield();}
400
401} // namespace this_thread
402
403_LIBCPP_END_NAMESPACE_STD
404
405_LIBCPP_POP_MACROS
406
407#endif // _LIBCPP_THREAD
408