xref: /llvm-project-15.0.7/libcxx/include/thread (revision 07f93a1e) 
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>
86#include <__config>
87#include <__mutex_base>
88#include <__thread/poll_with_backoff.h>
89#include <__thread/timed_backoff_policy.h>
90#include <__threading_support>
91#include <__utility/forward.h>
92#include <chrono>
93#include <cstddef>
94#include <functional>
95#include <iosfwd>
96#include <memory>
97#include <system_error>
98#include <tuple>
99#include <type_traits>
100#include <version>
101
102#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
103#  pragma GCC system_header
104#endif
105
106_LIBCPP_PUSH_MACROS
107#include <__undef_macros>
108
109#ifdef _LIBCPP_HAS_NO_THREADS
110#error <thread> is not supported on this single threaded system
111#else // !_LIBCPP_HAS_NO_THREADS
112
113_LIBCPP_BEGIN_NAMESPACE_STD
114
115template <class _Tp> class __thread_specific_ptr;
116class _LIBCPP_TYPE_VIS __thread_struct;
117class _LIBCPP_HIDDEN __thread_struct_imp;
118class __assoc_sub_state;
119
120_LIBCPP_FUNC_VIS __thread_specific_ptr<__thread_struct>& __thread_local_data();
121
122class _LIBCPP_TYPE_VIS __thread_struct
123{
124    __thread_struct_imp* __p_;
125
126    __thread_struct(const __thread_struct&);
127    __thread_struct& operator=(const __thread_struct&);
128public:
129    __thread_struct();
130    ~__thread_struct();
131
132    void notify_all_at_thread_exit(condition_variable*, mutex*);
133    void __make_ready_at_thread_exit(__assoc_sub_state*);
134};
135
136template <class _Tp>
137class __thread_specific_ptr
138{
139    __libcpp_tls_key __key_;
140
141     // Only __thread_local_data() may construct a __thread_specific_ptr
142     // and only with _Tp == __thread_struct.
143    static_assert((is_same<_Tp, __thread_struct>::value), "");
144    __thread_specific_ptr();
145    friend _LIBCPP_FUNC_VIS __thread_specific_ptr<__thread_struct>& __thread_local_data();
146
147    __thread_specific_ptr(const __thread_specific_ptr&);
148    __thread_specific_ptr& operator=(const __thread_specific_ptr&);
149
150    _LIBCPP_HIDDEN static void _LIBCPP_TLS_DESTRUCTOR_CC __at_thread_exit(void*);
151
152public:
153    typedef _Tp* pointer;
154
155    ~__thread_specific_ptr();
156
157    _LIBCPP_INLINE_VISIBILITY
158    pointer get() const {return static_cast<_Tp*>(__libcpp_tls_get(__key_));}
159    _LIBCPP_INLINE_VISIBILITY
160    pointer operator*() const {return *get();}
161    _LIBCPP_INLINE_VISIBILITY
162    pointer operator->() const {return get();}
163    void set_pointer(pointer __p);
164};
165
166template <class _Tp>
167void _LIBCPP_TLS_DESTRUCTOR_CC
168__thread_specific_ptr<_Tp>::__at_thread_exit(void* __p)
169{
170    delete static_cast<pointer>(__p);
171}
172
173template <class _Tp>
174__thread_specific_ptr<_Tp>::__thread_specific_ptr()
175{
176  int __ec =
177      __libcpp_tls_create(&__key_, &__thread_specific_ptr::__at_thread_exit);
178  if (__ec)
179    __throw_system_error(__ec, "__thread_specific_ptr construction failed");
180}
181
182template <class _Tp>
183__thread_specific_ptr<_Tp>::~__thread_specific_ptr()
184{
185    // __thread_specific_ptr is only created with a static storage duration
186    // so this destructor is only invoked during program termination. Invoking
187    // pthread_key_delete(__key_) may prevent other threads from deleting their
188    // thread local data. For this reason we leak the key.
189}
190
191template <class _Tp>
192void
193__thread_specific_ptr<_Tp>::set_pointer(pointer __p)
194{
195    _LIBCPP_ASSERT(get() == nullptr,
196                   "Attempting to overwrite thread local data");
197    __libcpp_tls_set(__key_, __p);
198}
199
200template<>
201struct _LIBCPP_TEMPLATE_VIS hash<__thread_id>
202    : public unary_function<__thread_id, size_t>
203{
204    _LIBCPP_INLINE_VISIBILITY
205    size_t operator()(__thread_id __v) const _NOEXCEPT
206    {
207        return hash<__libcpp_thread_id>()(__v.__id_);
208    }
209};
210
211template<class _CharT, class _Traits>
212_LIBCPP_INLINE_VISIBILITY
213basic_ostream<_CharT, _Traits>&
214operator<<(basic_ostream<_CharT, _Traits>& __os, __thread_id __id)
215{return __os << __id.__id_;}
216
217class _LIBCPP_TYPE_VIS thread
218{
219    __libcpp_thread_t __t_;
220
221    thread(const thread&);
222    thread& operator=(const thread&);
223public:
224    typedef __thread_id id;
225    typedef __libcpp_thread_t native_handle_type;
226
227    _LIBCPP_INLINE_VISIBILITY
228    thread() _NOEXCEPT : __t_(_LIBCPP_NULL_THREAD) {}
229#ifndef _LIBCPP_CXX03_LANG
230    template <class _Fp, class ..._Args,
231              class = __enable_if_t<!is_same<__uncvref_t<_Fp>, thread>::value> >
232        _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
233        explicit thread(_Fp&& __f, _Args&&... __args);
234#else  // _LIBCPP_CXX03_LANG
235    template <class _Fp>
236    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
237    explicit thread(_Fp __f);
238#endif
239    ~thread();
240
241    _LIBCPP_INLINE_VISIBILITY
242    thread(thread&& __t) _NOEXCEPT : __t_(__t.__t_) {
243        __t.__t_ = _LIBCPP_NULL_THREAD;
244    }
245
246    _LIBCPP_INLINE_VISIBILITY
247    thread& operator=(thread&& __t) _NOEXCEPT {
248        if (!__libcpp_thread_isnull(&__t_))
249            terminate();
250        __t_ = __t.__t_;
251        __t.__t_ = _LIBCPP_NULL_THREAD;
252        return *this;
253    }
254
255    _LIBCPP_INLINE_VISIBILITY
256    void swap(thread& __t) _NOEXCEPT {_VSTD::swap(__t_, __t.__t_);}
257
258    _LIBCPP_INLINE_VISIBILITY
259    bool joinable() const _NOEXCEPT {return !__libcpp_thread_isnull(&__t_);}
260    void join();
261    void detach();
262    _LIBCPP_INLINE_VISIBILITY
263    id get_id() const _NOEXCEPT {return __libcpp_thread_get_id(&__t_);}
264    _LIBCPP_INLINE_VISIBILITY
265    native_handle_type native_handle() _NOEXCEPT {return __t_;}
266
267    static unsigned hardware_concurrency() _NOEXCEPT;
268};
269
270#ifndef _LIBCPP_CXX03_LANG
271
272template <class _TSp, class _Fp, class ..._Args, size_t ..._Indices>
273inline _LIBCPP_INLINE_VISIBILITY
274void
275__thread_execute(tuple<_TSp, _Fp, _Args...>& __t, __tuple_indices<_Indices...>)
276{
277    _VSTD::__invoke(_VSTD::move(_VSTD::get<1>(__t)), _VSTD::move(_VSTD::get<_Indices>(__t))...);
278}
279
280template <class _Fp>
281_LIBCPP_INLINE_VISIBILITY
282void* __thread_proxy(void* __vp)
283{
284    // _Fp = tuple< unique_ptr<__thread_struct>, Functor, Args...>
285    unique_ptr<_Fp> __p(static_cast<_Fp*>(__vp));
286    __thread_local_data().set_pointer(_VSTD::get<0>(*__p.get()).release());
287    typedef typename __make_tuple_indices<tuple_size<_Fp>::value, 2>::type _Index;
288    _VSTD::__thread_execute(*__p.get(), _Index());
289    return nullptr;
290}
291
292template <class _Fp, class ..._Args,
293          class
294         >
295thread::thread(_Fp&& __f, _Args&&... __args)
296{
297    typedef unique_ptr<__thread_struct> _TSPtr;
298    _TSPtr __tsp(new __thread_struct);
299    typedef tuple<_TSPtr, typename decay<_Fp>::type, typename decay<_Args>::type...> _Gp;
300    unique_ptr<_Gp> __p(
301            new _Gp(_VSTD::move(__tsp),
302                    _VSTD::forward<_Fp>(__f),
303                    _VSTD::forward<_Args>(__args)...));
304    int __ec = _VSTD::__libcpp_thread_create(&__t_, &__thread_proxy<_Gp>, __p.get());
305    if (__ec == 0)
306        __p.release();
307    else
308        __throw_system_error(__ec, "thread constructor failed");
309}
310
311#else  // _LIBCPP_CXX03_LANG
312
313template <class _Fp>
314struct __thread_invoke_pair {
315    // This type is used to pass memory for thread local storage and a functor
316    // to a newly created thread because std::pair doesn't work with
317    // std::unique_ptr in C++03.
318    __thread_invoke_pair(_Fp& __f) : __tsp_(new __thread_struct), __fn_(__f) {}
319    unique_ptr<__thread_struct> __tsp_;
320    _Fp __fn_;
321};
322
323template <class _Fp>
324void* __thread_proxy_cxx03(void* __vp)
325{
326    unique_ptr<_Fp> __p(static_cast<_Fp*>(__vp));
327    __thread_local_data().set_pointer(__p->__tsp_.release());
328    (__p->__fn_)();
329    return nullptr;
330}
331
332template <class _Fp>
333thread::thread(_Fp __f)
334{
335
336    typedef __thread_invoke_pair<_Fp> _InvokePair;
337    typedef unique_ptr<_InvokePair> _PairPtr;
338    _PairPtr __pp(new _InvokePair(__f));
339    int __ec = _VSTD::__libcpp_thread_create(&__t_, &__thread_proxy_cxx03<_InvokePair>, __pp.get());
340    if (__ec == 0)
341        __pp.release();
342    else
343        __throw_system_error(__ec, "thread constructor failed");
344}
345
346#endif // _LIBCPP_CXX03_LANG
347
348inline _LIBCPP_INLINE_VISIBILITY
349void swap(thread& __x, thread& __y) _NOEXCEPT {__x.swap(__y);}
350
351namespace this_thread
352{
353
354_LIBCPP_FUNC_VIS void sleep_for(const chrono::nanoseconds& __ns);
355
356template <class _Rep, class _Period>
357void
358sleep_for(const chrono::duration<_Rep, _Period>& __d)
359{
360    if (__d > chrono::duration<_Rep, _Period>::zero())
361    {
362        // The standard guarantees a 64bit signed integer resolution for nanoseconds,
363        // so use INT64_MAX / 1e9 as cut-off point. Use a constant to avoid <climits>
364        // and issues with long double folding on PowerPC with GCC.
365        _LIBCPP_CONSTEXPR chrono::duration<long double> _Max =
366            chrono::duration<long double>(9223372036.0L);
367        chrono::nanoseconds __ns;
368        if (__d < _Max)
369        {
370            __ns = chrono::duration_cast<chrono::nanoseconds>(__d);
371            if (__ns < __d)
372                ++__ns;
373        }
374        else
375            __ns = chrono::nanoseconds::max();
376        this_thread::sleep_for(__ns);
377    }
378}
379
380template <class _Clock, class _Duration>
381void
382sleep_until(const chrono::time_point<_Clock, _Duration>& __t)
383{
384    mutex __mut;
385    condition_variable __cv;
386    unique_lock<mutex> __lk(__mut);
387    while (_Clock::now() < __t)
388        __cv.wait_until(__lk, __t);
389}
390
391template <class _Duration>
392inline _LIBCPP_INLINE_VISIBILITY
393void
394sleep_until(const chrono::time_point<chrono::steady_clock, _Duration>& __t)
395{
396    this_thread::sleep_for(__t - chrono::steady_clock::now());
397}
398
399inline _LIBCPP_INLINE_VISIBILITY
400void yield() _NOEXCEPT {__libcpp_thread_yield();}
401
402} // namespace this_thread
403
404_LIBCPP_END_NAMESPACE_STD
405
406#endif // !_LIBCPP_HAS_NO_THREADS
407
408_LIBCPP_POP_MACROS
409
410#endif // _LIBCPP_THREAD
411