xref: /llvm-project-15.0.7/libcxx/include/thread (revision bfbd73f8) 
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
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 <__config>
86#include <__debug>
87#include <__functional_base>
88#include <__mutex_base>
89#include <__threading_support>
90#include <chrono>
91#include <cstddef>
92#include <functional>
93#include <iosfwd>
94#include <memory>
95#include <system_error>
96#include <tuple>
97#include <type_traits>
98
99#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
100#pragma GCC system_header
101#endif
102
103_LIBCPP_PUSH_MACROS
104#include <__undef_macros>
105
106#ifdef _LIBCPP_HAS_NO_THREADS
107#error <thread> is not supported on this single threaded system
108#else // !_LIBCPP_HAS_NO_THREADS
109
110_LIBCPP_BEGIN_NAMESPACE_STD
111
112template <class _Tp> class __thread_specific_ptr;
113class _LIBCPP_TYPE_VIS __thread_struct;
114class _LIBCPP_HIDDEN __thread_struct_imp;
115class __assoc_sub_state;
116
117_LIBCPP_FUNC_VIS __thread_specific_ptr<__thread_struct>& __thread_local_data();
118
119class _LIBCPP_TYPE_VIS __thread_struct
120{
121    __thread_struct_imp* __p_;
122
123    __thread_struct(const __thread_struct&);
124    __thread_struct& operator=(const __thread_struct&);
125public:
126    __thread_struct();
127    ~__thread_struct();
128
129    void notify_all_at_thread_exit(condition_variable*, mutex*);
130    void __make_ready_at_thread_exit(__assoc_sub_state*);
131};
132
133template <class _Tp>
134class __thread_specific_ptr
135{
136    __libcpp_tls_key __key_;
137
138     // Only __thread_local_data() may construct a __thread_specific_ptr
139     // and only with _Tp == __thread_struct.
140    static_assert((is_same<_Tp, __thread_struct>::value), "");
141    __thread_specific_ptr();
142    friend _LIBCPP_FUNC_VIS __thread_specific_ptr<__thread_struct>& __thread_local_data();
143
144    __thread_specific_ptr(const __thread_specific_ptr&);
145    __thread_specific_ptr& operator=(const __thread_specific_ptr&);
146
147    _LIBCPP_HIDDEN static void _LIBCPP_TLS_DESTRUCTOR_CC __at_thread_exit(void*);
148
149public:
150    typedef _Tp* pointer;
151
152    ~__thread_specific_ptr();
153
154    _LIBCPP_INLINE_VISIBILITY
155    pointer get() const {return static_cast<_Tp*>(__libcpp_tls_get(__key_));}
156    _LIBCPP_INLINE_VISIBILITY
157    pointer operator*() const {return *get();}
158    _LIBCPP_INLINE_VISIBILITY
159    pointer operator->() const {return get();}
160    void set_pointer(pointer __p);
161};
162
163template <class _Tp>
164void _LIBCPP_TLS_DESTRUCTOR_CC
165__thread_specific_ptr<_Tp>::__at_thread_exit(void* __p)
166{
167    delete static_cast<pointer>(__p);
168}
169
170template <class _Tp>
171__thread_specific_ptr<_Tp>::__thread_specific_ptr()
172{
173  int __ec =
174      __libcpp_tls_create(&__key_, &__thread_specific_ptr::__at_thread_exit);
175  if (__ec)
176    __throw_system_error(__ec, "__thread_specific_ptr construction failed");
177}
178
179template <class _Tp>
180__thread_specific_ptr<_Tp>::~__thread_specific_ptr()
181{
182    // __thread_specific_ptr is only created with a static storage duration
183    // so this destructor is only invoked during program termination. Invoking
184    // pthread_key_delete(__key_) may prevent other threads from deleting their
185    // thread local data. For this reason we leak the key.
186}
187
188template <class _Tp>
189void
190__thread_specific_ptr<_Tp>::set_pointer(pointer __p)
191{
192    _LIBCPP_ASSERT(get() == nullptr,
193                   "Attempting to overwrite thread local data");
194    __libcpp_tls_set(__key_, __p);
195}
196
197template<>
198struct _LIBCPP_TEMPLATE_VIS hash<__thread_id>
199    : public unary_function<__thread_id, size_t>
200{
201    _LIBCPP_INLINE_VISIBILITY
202    size_t operator()(__thread_id __v) const _NOEXCEPT
203    {
204        return hash<__libcpp_thread_id>()(__v.__id_);
205    }
206};
207
208template<class _CharT, class _Traits>
209_LIBCPP_INLINE_VISIBILITY
210basic_ostream<_CharT, _Traits>&
211operator<<(basic_ostream<_CharT, _Traits>& __os, __thread_id __id)
212{return __os << __id.__id_;}
213
214class _LIBCPP_TYPE_VIS thread
215{
216    __libcpp_thread_t __t_;
217
218    thread(const thread&);
219    thread& operator=(const thread&);
220public:
221    typedef __thread_id id;
222    typedef __libcpp_thread_t native_handle_type;
223
224    _LIBCPP_INLINE_VISIBILITY
225    thread() _NOEXCEPT : __t_(_LIBCPP_NULL_THREAD) {}
226#ifndef _LIBCPP_CXX03_LANG
227    template <class _Fp, class ..._Args,
228              class = typename enable_if
229              <
230                   !is_same<typename __uncvref<_Fp>::type, thread>::value
231              >::type
232             >
233        _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
234        explicit thread(_Fp&& __f, _Args&&... __args);
235#else  // _LIBCPP_CXX03_LANG
236    template <class _Fp>
237    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
238    explicit thread(_Fp __f);
239#endif
240    ~thread();
241
242    _LIBCPP_INLINE_VISIBILITY
243    thread(thread&& __t) _NOEXCEPT : __t_(__t.__t_) {
244        __t.__t_ = _LIBCPP_NULL_THREAD;
245    }
246
247    _LIBCPP_INLINE_VISIBILITY
248    thread& operator=(thread&& __t) _NOEXCEPT {
249        if (!__libcpp_thread_isnull(&__t_))
250            terminate();
251        __t_ = __t.__t_;
252        __t.__t_ = _LIBCPP_NULL_THREAD;
253        return *this;
254    }
255
256    _LIBCPP_INLINE_VISIBILITY
257    void swap(thread& __t) _NOEXCEPT {_VSTD::swap(__t_, __t.__t_);}
258
259    _LIBCPP_INLINE_VISIBILITY
260    bool joinable() const _NOEXCEPT {return !__libcpp_thread_isnull(&__t_);}
261    void join();
262    void detach();
263    _LIBCPP_INLINE_VISIBILITY
264    id get_id() const _NOEXCEPT {return __libcpp_thread_get_id(&__t_);}
265    _LIBCPP_INLINE_VISIBILITY
266    native_handle_type native_handle() _NOEXCEPT {return __t_;}
267
268    static unsigned hardware_concurrency() _NOEXCEPT;
269};
270
271#ifndef _LIBCPP_CXX03_LANG
272
273template <class _TSp, class _Fp, class ..._Args, size_t ..._Indices>
274inline _LIBCPP_INLINE_VISIBILITY
275void
276__thread_execute(tuple<_TSp, _Fp, _Args...>& __t, __tuple_indices<_Indices...>)
277{
278    _VSTD::__invoke(_VSTD::move(_VSTD::get<1>(__t)), _VSTD::move(_VSTD::get<_Indices>(__t))...);
279}
280
281template <class _Fp>
282_LIBCPP_INLINE_VISIBILITY
283void* __thread_proxy(void* __vp)
284{
285    // _Fp = tuple< unique_ptr<__thread_struct>, Functor, Args...>
286    unique_ptr<_Fp> __p(static_cast<_Fp*>(__vp));
287    __thread_local_data().set_pointer(_VSTD::get<0>(*__p.get()).release());
288    typedef typename __make_tuple_indices<tuple_size<_Fp>::value, 2>::type _Index;
289    _VSTD::__thread_execute(*__p.get(), _Index());
290    return nullptr;
291}
292
293template <class _Fp, class ..._Args,
294          class
295         >
296thread::thread(_Fp&& __f, _Args&&... __args)
297{
298    typedef unique_ptr<__thread_struct> _TSPtr;
299    _TSPtr __tsp(new __thread_struct);
300    typedef tuple<_TSPtr, typename decay<_Fp>::type, typename decay<_Args>::type...> _Gp;
301    unique_ptr<_Gp> __p(
302            new _Gp(_VSTD::move(__tsp),
303                    _VSTD::__decay_copy(_VSTD::forward<_Fp>(__f)),
304                    _VSTD::__decay_copy(_VSTD::forward<_Args>(__args))...));
305    int __ec = _VSTD::__libcpp_thread_create(&__t_, &__thread_proxy<_Gp>, __p.get());
306    if (__ec == 0)
307        __p.release();
308    else
309        __throw_system_error(__ec, "thread constructor failed");
310}
311
312#else  // _LIBCPP_CXX03_LANG
313
314template <class _Fp>
315struct __thread_invoke_pair {
316    // This type is used to pass memory for thread local storage and a functor
317    // to a newly created thread because std::pair doesn't work with
318    // std::unique_ptr in C++03.
319    __thread_invoke_pair(_Fp& __f) : __tsp_(new __thread_struct), __fn_(__f) {}
320    unique_ptr<__thread_struct> __tsp_;
321    _Fp __fn_;
322};
323
324template <class _Fp>
325void* __thread_proxy_cxx03(void* __vp)
326{
327    unique_ptr<_Fp> __p(static_cast<_Fp*>(__vp));
328    __thread_local_data().set_pointer(__p->__tsp_.release());
329    (__p->__fn_)();
330    return nullptr;
331}
332
333template <class _Fp>
334thread::thread(_Fp __f)
335{
336
337    typedef __thread_invoke_pair<_Fp> _InvokePair;
338    typedef unique_ptr<_InvokePair> _PairPtr;
339    _PairPtr __pp(new _InvokePair(__f));
340    int __ec = _VSTD::__libcpp_thread_create(&__t_, &__thread_proxy_cxx03<_InvokePair>, __pp.get());
341    if (__ec == 0)
342        __pp.release();
343    else
344        __throw_system_error(__ec, "thread constructor failed");
345}
346
347#endif // _LIBCPP_CXX03_LANG
348
349inline _LIBCPP_INLINE_VISIBILITY
350void swap(thread& __x, thread& __y) _NOEXCEPT {__x.swap(__y);}
351
352namespace this_thread
353{
354
355_LIBCPP_FUNC_VIS void sleep_for(const chrono::nanoseconds& __ns);
356
357template <class _Rep, class _Period>
358void
359sleep_for(const chrono::duration<_Rep, _Period>& __d)
360{
361    if (__d > chrono::duration<_Rep, _Period>::zero())
362    {
363        // The standard guarantees a 64bit signed integer resolution for nanoseconds,
364        // so use INT64_MAX / 1e9 as cut-off point. Use a constant to avoid <climits>
365        // and issues with long double folding on PowerPC with GCC.
366        _LIBCPP_CONSTEXPR chrono::duration<long double> _Max =
367            chrono::duration<long double>(9223372036.0L);
368        chrono::nanoseconds __ns;
369        if (__d < _Max)
370        {
371            __ns = chrono::duration_cast<chrono::nanoseconds>(__d);
372            if (__ns < __d)
373                ++__ns;
374        }
375        else
376            __ns = chrono::nanoseconds::max();
377        this_thread::sleep_for(__ns);
378    }
379}
380
381template <class _Clock, class _Duration>
382void
383sleep_until(const chrono::time_point<_Clock, _Duration>& __t)
384{
385    mutex __mut;
386    condition_variable __cv;
387    unique_lock<mutex> __lk(__mut);
388    while (_Clock::now() < __t)
389        __cv.wait_until(__lk, __t);
390}
391
392template <class _Duration>
393inline _LIBCPP_INLINE_VISIBILITY
394void
395sleep_until(const chrono::time_point<chrono::steady_clock, _Duration>& __t)
396{
397    this_thread::sleep_for(__t - chrono::steady_clock::now());
398}
399
400inline _LIBCPP_INLINE_VISIBILITY
401void yield() _NOEXCEPT {__libcpp_thread_yield();}
402
403}  // this_thread
404
405_LIBCPP_END_NAMESPACE_STD
406
407#endif // !_LIBCPP_HAS_NO_THREADS
408
409_LIBCPP_POP_MACROS
410
411#endif // _LIBCPP_THREAD
412