xref: /llvm-project-15.0.7/libcxx/include/thread (revision 16dcbb53) 
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 <__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 <cstddef>
93#include <iosfwd>
94#include <memory>
95#include <system_error>
96#include <tuple>
97#include <type_traits>
98#include <version>
99
100#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
101#  pragma GCC system_header
102#endif
103
104_LIBCPP_PUSH_MACROS
105#include <__undef_macros>
106
107#ifdef _LIBCPP_HAS_NO_THREADS
108#error <thread> is not supported on this single threaded system
109#else // !_LIBCPP_HAS_NO_THREADS
110
111_LIBCPP_BEGIN_NAMESPACE_STD
112
113template <class _Tp> class __thread_specific_ptr;
114class _LIBCPP_TYPE_VIS __thread_struct;
115class _LIBCPP_HIDDEN __thread_struct_imp;
116class __assoc_sub_state;
117
118_LIBCPP_FUNC_VIS __thread_specific_ptr<__thread_struct>& __thread_local_data();
119
120class _LIBCPP_TYPE_VIS __thread_struct
121{
122    __thread_struct_imp* __p_;
123
124    __thread_struct(const __thread_struct&);
125    __thread_struct& operator=(const __thread_struct&);
126public:
127    __thread_struct();
128    ~__thread_struct();
129
130    void notify_all_at_thread_exit(condition_variable*, mutex*);
131    void __make_ready_at_thread_exit(__assoc_sub_state*);
132};
133
134template <class _Tp>
135class __thread_specific_ptr
136{
137    __libcpp_tls_key __key_;
138
139     // Only __thread_local_data() may construct a __thread_specific_ptr
140     // and only with _Tp == __thread_struct.
141    static_assert((is_same<_Tp, __thread_struct>::value), "");
142    __thread_specific_ptr();
143    friend _LIBCPP_FUNC_VIS __thread_specific_ptr<__thread_struct>& __thread_local_data();
144
145    __thread_specific_ptr(const __thread_specific_ptr&);
146    __thread_specific_ptr& operator=(const __thread_specific_ptr&);
147
148    _LIBCPP_HIDDEN static void _LIBCPP_TLS_DESTRUCTOR_CC __at_thread_exit(void*);
149
150public:
151    typedef _Tp* pointer;
152
153    ~__thread_specific_ptr();
154
155    _LIBCPP_INLINE_VISIBILITY
156    pointer get() const {return static_cast<_Tp*>(__libcpp_tls_get(__key_));}
157    _LIBCPP_INLINE_VISIBILITY
158    pointer operator*() const {return *get();}
159    _LIBCPP_INLINE_VISIBILITY
160    pointer operator->() const {return get();}
161    void set_pointer(pointer __p);
162};
163
164template <class _Tp>
165void _LIBCPP_TLS_DESTRUCTOR_CC
166__thread_specific_ptr<_Tp>::__at_thread_exit(void* __p)
167{
168    delete static_cast<pointer>(__p);
169}
170
171template <class _Tp>
172__thread_specific_ptr<_Tp>::__thread_specific_ptr()
173{
174  int __ec =
175      __libcpp_tls_create(&__key_, &__thread_specific_ptr::__at_thread_exit);
176  if (__ec)
177    __throw_system_error(__ec, "__thread_specific_ptr construction failed");
178}
179
180template <class _Tp>
181__thread_specific_ptr<_Tp>::~__thread_specific_ptr()
182{
183    // __thread_specific_ptr is only created with a static storage duration
184    // so this destructor is only invoked during program termination. Invoking
185    // pthread_key_delete(__key_) may prevent other threads from deleting their
186    // thread local data. For this reason we leak the key.
187}
188
189template <class _Tp>
190void
191__thread_specific_ptr<_Tp>::set_pointer(pointer __p)
192{
193    _LIBCPP_ASSERT(get() == nullptr,
194                   "Attempting to overwrite thread local data");
195    __libcpp_tls_set(__key_, __p);
196}
197
198template<>
199struct _LIBCPP_TEMPLATE_VIS hash<__thread_id>
200    : public unary_function<__thread_id, size_t>
201{
202    _LIBCPP_INLINE_VISIBILITY
203    size_t operator()(__thread_id __v) const _NOEXCEPT
204    {
205        return hash<__libcpp_thread_id>()(__v.__id_);
206    }
207};
208
209template<class _CharT, class _Traits>
210_LIBCPP_INLINE_VISIBILITY
211basic_ostream<_CharT, _Traits>&
212operator<<(basic_ostream<_CharT, _Traits>& __os, __thread_id __id)
213{return __os << __id.__id_;}
214
215class _LIBCPP_TYPE_VIS thread
216{
217    __libcpp_thread_t __t_;
218
219    thread(const thread&);
220    thread& operator=(const thread&);
221public:
222    typedef __thread_id id;
223    typedef __libcpp_thread_t native_handle_type;
224
225    _LIBCPP_INLINE_VISIBILITY
226    thread() _NOEXCEPT : __t_(_LIBCPP_NULL_THREAD) {}
227#ifndef _LIBCPP_CXX03_LANG
228    template <class _Fp, class ..._Args,
229              class = __enable_if_t<!is_same<__uncvref_t<_Fp>, thread>::value> >
230        _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
231        explicit thread(_Fp&& __f, _Args&&... __args);
232#else  // _LIBCPP_CXX03_LANG
233    template <class _Fp>
234    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
235    explicit thread(_Fp __f);
236#endif
237    ~thread();
238
239    _LIBCPP_INLINE_VISIBILITY
240    thread(thread&& __t) _NOEXCEPT : __t_(__t.__t_) {
241        __t.__t_ = _LIBCPP_NULL_THREAD;
242    }
243
244    _LIBCPP_INLINE_VISIBILITY
245    thread& operator=(thread&& __t) _NOEXCEPT {
246        if (!__libcpp_thread_isnull(&__t_))
247            terminate();
248        __t_ = __t.__t_;
249        __t.__t_ = _LIBCPP_NULL_THREAD;
250        return *this;
251    }
252
253    _LIBCPP_INLINE_VISIBILITY
254    void swap(thread& __t) _NOEXCEPT {_VSTD::swap(__t_, __t.__t_);}
255
256    _LIBCPP_INLINE_VISIBILITY
257    bool joinable() const _NOEXCEPT {return !__libcpp_thread_isnull(&__t_);}
258    void join();
259    void detach();
260    _LIBCPP_INLINE_VISIBILITY
261    id get_id() const _NOEXCEPT {return __libcpp_thread_get_id(&__t_);}
262    _LIBCPP_INLINE_VISIBILITY
263    native_handle_type native_handle() _NOEXCEPT {return __t_;}
264
265    static unsigned hardware_concurrency() _NOEXCEPT;
266};
267
268#ifndef _LIBCPP_CXX03_LANG
269
270template <class _TSp, class _Fp, class ..._Args, size_t ..._Indices>
271inline _LIBCPP_INLINE_VISIBILITY
272void
273__thread_execute(tuple<_TSp, _Fp, _Args...>& __t, __tuple_indices<_Indices...>)
274{
275    _VSTD::__invoke(_VSTD::move(_VSTD::get<1>(__t)), _VSTD::move(_VSTD::get<_Indices>(__t))...);
276}
277
278template <class _Fp>
279_LIBCPP_INLINE_VISIBILITY
280void* __thread_proxy(void* __vp)
281{
282    // _Fp = tuple< unique_ptr<__thread_struct>, Functor, Args...>
283    unique_ptr<_Fp> __p(static_cast<_Fp*>(__vp));
284    __thread_local_data().set_pointer(_VSTD::get<0>(*__p.get()).release());
285    typedef typename __make_tuple_indices<tuple_size<_Fp>::value, 2>::type _Index;
286    _VSTD::__thread_execute(*__p.get(), _Index());
287    return nullptr;
288}
289
290template <class _Fp, class ..._Args,
291          class
292         >
293thread::thread(_Fp&& __f, _Args&&... __args)
294{
295    typedef unique_ptr<__thread_struct> _TSPtr;
296    _TSPtr __tsp(new __thread_struct);
297    typedef tuple<_TSPtr, typename decay<_Fp>::type, typename decay<_Args>::type...> _Gp;
298    unique_ptr<_Gp> __p(
299            new _Gp(_VSTD::move(__tsp),
300                    _VSTD::forward<_Fp>(__f),
301                    _VSTD::forward<_Args>(__args)...));
302    int __ec = _VSTD::__libcpp_thread_create(&__t_, &__thread_proxy<_Gp>, __p.get());
303    if (__ec == 0)
304        __p.release();
305    else
306        __throw_system_error(__ec, "thread constructor failed");
307}
308
309#else  // _LIBCPP_CXX03_LANG
310
311template <class _Fp>
312struct __thread_invoke_pair {
313    // This type is used to pass memory for thread local storage and a functor
314    // to a newly created thread because std::pair doesn't work with
315    // std::unique_ptr in C++03.
316    __thread_invoke_pair(_Fp& __f) : __tsp_(new __thread_struct), __fn_(__f) {}
317    unique_ptr<__thread_struct> __tsp_;
318    _Fp __fn_;
319};
320
321template <class _Fp>
322void* __thread_proxy_cxx03(void* __vp)
323{
324    unique_ptr<_Fp> __p(static_cast<_Fp*>(__vp));
325    __thread_local_data().set_pointer(__p->__tsp_.release());
326    (__p->__fn_)();
327    return nullptr;
328}
329
330template <class _Fp>
331thread::thread(_Fp __f)
332{
333
334    typedef __thread_invoke_pair<_Fp> _InvokePair;
335    typedef unique_ptr<_InvokePair> _PairPtr;
336    _PairPtr __pp(new _InvokePair(__f));
337    int __ec = _VSTD::__libcpp_thread_create(&__t_, &__thread_proxy_cxx03<_InvokePair>, __pp.get());
338    if (__ec == 0)
339        __pp.release();
340    else
341        __throw_system_error(__ec, "thread constructor failed");
342}
343
344#endif // _LIBCPP_CXX03_LANG
345
346inline _LIBCPP_INLINE_VISIBILITY
347void swap(thread& __x, thread& __y) _NOEXCEPT {__x.swap(__y);}
348
349namespace this_thread
350{
351
352_LIBCPP_FUNC_VIS void sleep_for(const chrono::nanoseconds& __ns);
353
354template <class _Rep, class _Period>
355void
356sleep_for(const chrono::duration<_Rep, _Period>& __d)
357{
358    if (__d > chrono::duration<_Rep, _Period>::zero())
359    {
360        // The standard guarantees a 64bit signed integer resolution for nanoseconds,
361        // so use INT64_MAX / 1e9 as cut-off point. Use a constant to avoid <climits>
362        // and issues with long double folding on PowerPC with GCC.
363        _LIBCPP_CONSTEXPR chrono::duration<long double> _Max =
364            chrono::duration<long double>(9223372036.0L);
365        chrono::nanoseconds __ns;
366        if (__d < _Max)
367        {
368            __ns = chrono::duration_cast<chrono::nanoseconds>(__d);
369            if (__ns < __d)
370                ++__ns;
371        }
372        else
373            __ns = chrono::nanoseconds::max();
374        this_thread::sleep_for(__ns);
375    }
376}
377
378template <class _Clock, class _Duration>
379void
380sleep_until(const chrono::time_point<_Clock, _Duration>& __t)
381{
382    mutex __mut;
383    condition_variable __cv;
384    unique_lock<mutex> __lk(__mut);
385    while (_Clock::now() < __t)
386        __cv.wait_until(__lk, __t);
387}
388
389template <class _Duration>
390inline _LIBCPP_INLINE_VISIBILITY
391void
392sleep_until(const chrono::time_point<chrono::steady_clock, _Duration>& __t)
393{
394    this_thread::sleep_for(__t - chrono::steady_clock::now());
395}
396
397inline _LIBCPP_INLINE_VISIBILITY
398void yield() _NOEXCEPT {__libcpp_thread_yield();}
399
400} // namespace this_thread
401
402_LIBCPP_END_NAMESPACE_STD
403
404#endif // !_LIBCPP_HAS_NO_THREADS
405
406_LIBCPP_POP_MACROS
407
408#endif // _LIBCPP_THREAD
409