xref: /freebsd/contrib/llvm-project/libcxx/include/thread (revision 525fe93dc7487a1e63a90f6a2b956abc601963c1) 
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;             // removed in C++20
57bool operator< (thread::id x, thread::id y) noexcept;             // removed in C++20
58bool operator<=(thread::id x, thread::id y) noexcept;             // removed in C++20
59bool operator> (thread::id x, thread::id y) noexcept;             // removed in C++20
60bool operator>=(thread::id x, thread::id y) noexcept;             // removed in C++20
61strong_ordering operator<=>(thread::id x, thread::id y) noexcept; // C++20
62
63template<class charT, class traits>
64basic_ostream<charT, traits>&
65operator<<(basic_ostream<charT, traits>& out, thread::id id);
66
67namespace this_thread
68{
69
70thread::id get_id() noexcept;
71
72void yield() noexcept;
73
74template <class Clock, class Duration>
75void sleep_until(const chrono::time_point<Clock, Duration>& abs_time);
76
77template <class Rep, class Period>
78void sleep_for(const chrono::duration<Rep, Period>& rel_time);
79
80}  // this_thread
81
82}  // std
83
84*/
85
86#include <__assert> // all public C++ headers provide the assertion handler
87#include <__config>
88#include <__functional/hash.h>
89#include <__memory/unique_ptr.h>
90#include <__mutex_base>
91#include <__thread/poll_with_backoff.h>
92#include <__thread/timed_backoff_policy.h>
93#include <__threading_support>
94#include <__utility/forward.h>
95#include <cstddef>
96#include <iosfwd>
97#include <system_error>
98#include <tuple>
99#include <type_traits>
100#include <version>
101
102// standard-mandated includes
103
104// [thread.syn]
105#include <compare>
106
107#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
108#  pragma GCC system_header
109#endif
110
111_LIBCPP_PUSH_MACROS
112#include <__undef_macros>
113
114#ifdef _LIBCPP_HAS_NO_THREADS
115# error "<thread> is not supported since libc++ has been configured without support for threads."
116#endif
117
118_LIBCPP_BEGIN_NAMESPACE_STD
119
120template <class _Tp> class __thread_specific_ptr;
121class _LIBCPP_TYPE_VIS __thread_struct;
122class _LIBCPP_HIDDEN __thread_struct_imp;
123class __assoc_sub_state;
124
125_LIBCPP_FUNC_VIS __thread_specific_ptr<__thread_struct>& __thread_local_data();
126
127class _LIBCPP_TYPE_VIS __thread_struct
128{
129    __thread_struct_imp* __p_;
130
131    __thread_struct(const __thread_struct&);
132    __thread_struct& operator=(const __thread_struct&);
133public:
134    __thread_struct();
135    ~__thread_struct();
136
137    void notify_all_at_thread_exit(condition_variable*, mutex*);
138    void __make_ready_at_thread_exit(__assoc_sub_state*);
139};
140
141template <class _Tp>
142class __thread_specific_ptr
143{
144    __libcpp_tls_key __key_;
145
146     // Only __thread_local_data() may construct a __thread_specific_ptr
147     // and only with _Tp == __thread_struct.
148    static_assert((is_same<_Tp, __thread_struct>::value), "");
149    __thread_specific_ptr();
150    friend _LIBCPP_FUNC_VIS __thread_specific_ptr<__thread_struct>& __thread_local_data();
151
152    __thread_specific_ptr(const __thread_specific_ptr&);
153    __thread_specific_ptr& operator=(const __thread_specific_ptr&);
154
155    _LIBCPP_HIDDEN static void _LIBCPP_TLS_DESTRUCTOR_CC __at_thread_exit(void*);
156
157public:
158    typedef _Tp* pointer;
159
160    ~__thread_specific_ptr();
161
162    _LIBCPP_INLINE_VISIBILITY
163    pointer get() const {return static_cast<_Tp*>(__libcpp_tls_get(__key_));}
164    _LIBCPP_INLINE_VISIBILITY
165    pointer operator*() const {return *get();}
166    _LIBCPP_INLINE_VISIBILITY
167    pointer operator->() const {return get();}
168    void set_pointer(pointer __p);
169};
170
171template <class _Tp>
172void _LIBCPP_TLS_DESTRUCTOR_CC
173__thread_specific_ptr<_Tp>::__at_thread_exit(void* __p)
174{
175    delete static_cast<pointer>(__p);
176}
177
178template <class _Tp>
179__thread_specific_ptr<_Tp>::__thread_specific_ptr()
180{
181  int __ec =
182      __libcpp_tls_create(&__key_, &__thread_specific_ptr::__at_thread_exit);
183  if (__ec)
184    __throw_system_error(__ec, "__thread_specific_ptr construction failed");
185}
186
187template <class _Tp>
188__thread_specific_ptr<_Tp>::~__thread_specific_ptr()
189{
190    // __thread_specific_ptr is only created with a static storage duration
191    // so this destructor is only invoked during program termination. Invoking
192    // pthread_key_delete(__key_) may prevent other threads from deleting their
193    // thread local data. For this reason we leak the key.
194}
195
196template <class _Tp>
197void
198__thread_specific_ptr<_Tp>::set_pointer(pointer __p)
199{
200    _LIBCPP_ASSERT(get() == nullptr,
201                   "Attempting to overwrite thread local data");
202    std::__libcpp_tls_set(__key_, __p);
203}
204
205template<>
206struct _LIBCPP_TEMPLATE_VIS hash<__thread_id>
207    : public __unary_function<__thread_id, size_t>
208{
209    _LIBCPP_INLINE_VISIBILITY
210    size_t operator()(__thread_id __v) const _NOEXCEPT
211    {
212        return hash<__libcpp_thread_id>()(__v.__id_);
213    }
214};
215
216template<class _CharT, class _Traits>
217_LIBCPP_INLINE_VISIBILITY
218basic_ostream<_CharT, _Traits>&
219operator<<(basic_ostream<_CharT, _Traits>& __os, __thread_id __id)
220{return __os << __id.__id_;}
221
222class _LIBCPP_TYPE_VIS thread
223{
224    __libcpp_thread_t __t_;
225
226    thread(const thread&);
227    thread& operator=(const thread&);
228public:
229    typedef __thread_id id;
230    typedef __libcpp_thread_t native_handle_type;
231
232    _LIBCPP_INLINE_VISIBILITY
233    thread() _NOEXCEPT : __t_(_LIBCPP_NULL_THREAD) {}
234#ifndef _LIBCPP_CXX03_LANG
235    template <class _Fp, class ..._Args,
236              class = __enable_if_t<!is_same<__remove_cvref_t<_Fp>, thread>::value> >
237        _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
238        explicit thread(_Fp&& __f, _Args&&... __args);
239#else  // _LIBCPP_CXX03_LANG
240    template <class _Fp>
241    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
242    explicit thread(_Fp __f);
243#endif
244    ~thread();
245
246    _LIBCPP_INLINE_VISIBILITY
247    thread(thread&& __t) _NOEXCEPT : __t_(__t.__t_) {
248        __t.__t_ = _LIBCPP_NULL_THREAD;
249    }
250
251    _LIBCPP_INLINE_VISIBILITY
252    thread& operator=(thread&& __t) _NOEXCEPT {
253        if (!__libcpp_thread_isnull(&__t_))
254            terminate();
255        __t_ = __t.__t_;
256        __t.__t_ = _LIBCPP_NULL_THREAD;
257        return *this;
258    }
259
260    _LIBCPP_INLINE_VISIBILITY
261    void swap(thread& __t) _NOEXCEPT {_VSTD::swap(__t_, __t.__t_);}
262
263    _LIBCPP_INLINE_VISIBILITY
264    bool joinable() const _NOEXCEPT {return !__libcpp_thread_isnull(&__t_);}
265    void join();
266    void detach();
267    _LIBCPP_INLINE_VISIBILITY
268    id get_id() const _NOEXCEPT {return __libcpp_thread_get_id(&__t_);}
269    _LIBCPP_INLINE_VISIBILITY
270    native_handle_type native_handle() _NOEXCEPT {return __t_;}
271
272    static unsigned hardware_concurrency() _NOEXCEPT;
273};
274
275#ifndef _LIBCPP_CXX03_LANG
276
277template <class _TSp, class _Fp, class ..._Args, size_t ..._Indices>
278inline _LIBCPP_INLINE_VISIBILITY
279void
280__thread_execute(tuple<_TSp, _Fp, _Args...>& __t, __tuple_indices<_Indices...>)
281{
282    _VSTD::__invoke(_VSTD::move(_VSTD::get<1>(__t)), _VSTD::move(_VSTD::get<_Indices>(__t))...);
283}
284
285template <class _Fp>
286_LIBCPP_INLINE_VISIBILITY
287void* __thread_proxy(void* __vp)
288{
289    // _Fp = tuple< unique_ptr<__thread_struct>, Functor, Args...>
290    unique_ptr<_Fp> __p(static_cast<_Fp*>(__vp));
291    __thread_local_data().set_pointer(_VSTD::get<0>(*__p.get()).release());
292    typedef typename __make_tuple_indices<tuple_size<_Fp>::value, 2>::type _Index;
293    _VSTD::__thread_execute(*__p.get(), _Index());
294    return nullptr;
295}
296
297template <class _Fp, class ..._Args,
298          class
299         >
300thread::thread(_Fp&& __f, _Args&&... __args)
301{
302    typedef unique_ptr<__thread_struct> _TSPtr;
303    _TSPtr __tsp(new __thread_struct);
304    typedef tuple<_TSPtr, typename decay<_Fp>::type, typename decay<_Args>::type...> _Gp;
305    unique_ptr<_Gp> __p(
306            new _Gp(_VSTD::move(__tsp),
307                    _VSTD::forward<_Fp>(__f),
308                    _VSTD::forward<_Args>(__args)...));
309    int __ec = _VSTD::__libcpp_thread_create(&__t_, &__thread_proxy<_Gp>, __p.get());
310    if (__ec == 0)
311        __p.release();
312    else
313        __throw_system_error(__ec, "thread constructor failed");
314}
315
316#else  // _LIBCPP_CXX03_LANG
317
318template <class _Fp>
319struct __thread_invoke_pair {
320    // This type is used to pass memory for thread local storage and a functor
321    // to a newly created thread because std::pair doesn't work with
322    // std::unique_ptr in C++03.
323    __thread_invoke_pair(_Fp& __f) : __tsp_(new __thread_struct), __fn_(__f) {}
324    unique_ptr<__thread_struct> __tsp_;
325    _Fp __fn_;
326};
327
328template <class _Fp>
329_LIBCPP_HIDE_FROM_ABI void* __thread_proxy_cxx03(void* __vp)
330{
331    unique_ptr<_Fp> __p(static_cast<_Fp*>(__vp));
332    __thread_local_data().set_pointer(__p->__tsp_.release());
333    (__p->__fn_)();
334    return nullptr;
335}
336
337template <class _Fp>
338thread::thread(_Fp __f)
339{
340
341    typedef __thread_invoke_pair<_Fp> _InvokePair;
342    typedef unique_ptr<_InvokePair> _PairPtr;
343    _PairPtr __pp(new _InvokePair(__f));
344    int __ec = _VSTD::__libcpp_thread_create(&__t_, &__thread_proxy_cxx03<_InvokePair>, __pp.get());
345    if (__ec == 0)
346        __pp.release();
347    else
348        __throw_system_error(__ec, "thread constructor failed");
349}
350
351#endif // _LIBCPP_CXX03_LANG
352
353inline _LIBCPP_INLINE_VISIBILITY
354void swap(thread& __x, thread& __y) _NOEXCEPT {__x.swap(__y);}
355
356namespace this_thread
357{
358
359_LIBCPP_FUNC_VIS void sleep_for(const chrono::nanoseconds& __ns);
360
361template <class _Rep, class _Period>
362_LIBCPP_HIDE_FROM_ABI void
363sleep_for(const chrono::duration<_Rep, _Period>& __d)
364{
365    if (__d > chrono::duration<_Rep, _Period>::zero())
366    {
367        // The standard guarantees a 64bit signed integer resolution for nanoseconds,
368        // so use INT64_MAX / 1e9 as cut-off point. Use a constant to avoid <climits>
369        // and issues with long double folding on PowerPC with GCC.
370        _LIBCPP_CONSTEXPR chrono::duration<long double> _Max =
371            chrono::duration<long double>(9223372036.0L);
372        chrono::nanoseconds __ns;
373        if (__d < _Max)
374        {
375            __ns = chrono::duration_cast<chrono::nanoseconds>(__d);
376            if (__ns < __d)
377                ++__ns;
378        }
379        else
380            __ns = chrono::nanoseconds::max();
381        this_thread::sleep_for(__ns);
382    }
383}
384
385template <class _Clock, class _Duration>
386_LIBCPP_HIDE_FROM_ABI void
387sleep_until(const chrono::time_point<_Clock, _Duration>& __t)
388{
389    mutex __mut;
390    condition_variable __cv;
391    unique_lock<mutex> __lk(__mut);
392    while (_Clock::now() < __t)
393        __cv.wait_until(__lk, __t);
394}
395
396template <class _Duration>
397inline _LIBCPP_INLINE_VISIBILITY
398void
399sleep_until(const chrono::time_point<chrono::steady_clock, _Duration>& __t)
400{
401    this_thread::sleep_for(__t - chrono::steady_clock::now());
402}
403
404inline _LIBCPP_INLINE_VISIBILITY
405void yield() _NOEXCEPT {__libcpp_thread_yield();}
406
407} // namespace this_thread
408
409_LIBCPP_END_NAMESPACE_STD
410
411_LIBCPP_POP_MACROS
412
413#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 17
414#  include <chrono>
415#endif
416
417#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
418#  include <functional>
419#endif
420
421#endif // _LIBCPP_THREAD
422