xref: /freebsd/contrib/llvm-project/libcxx/include/thread (revision 4d846d260e2b9a3d4d0a701462568268cbfe7a5b) 
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#ifndef _LIBCPP_REMOVE_TRANSITIVE_INCLUDES
102#  include <chrono>
103#  include <functional>
104#endif
105
106// standard-mandated includes
107#include <compare>
108
109#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
110#  pragma GCC system_header
111#endif
112
113_LIBCPP_PUSH_MACROS
114#include <__undef_macros>
115
116#ifdef _LIBCPP_HAS_NO_THREADS
117# error "<thread> is not supported since libc++ has been configured without support for threads."
118#endif
119
120_LIBCPP_BEGIN_NAMESPACE_STD
121
122template <class _Tp> class __thread_specific_ptr;
123class _LIBCPP_TYPE_VIS __thread_struct;
124class _LIBCPP_HIDDEN __thread_struct_imp;
125class __assoc_sub_state;
126
127_LIBCPP_FUNC_VIS __thread_specific_ptr<__thread_struct>& __thread_local_data();
128
129class _LIBCPP_TYPE_VIS __thread_struct
130{
131    __thread_struct_imp* __p_;
132
133    __thread_struct(const __thread_struct&);
134    __thread_struct& operator=(const __thread_struct&);
135public:
136    __thread_struct();
137    ~__thread_struct();
138
139    void notify_all_at_thread_exit(condition_variable*, mutex*);
140    void __make_ready_at_thread_exit(__assoc_sub_state*);
141};
142
143template <class _Tp>
144class __thread_specific_ptr
145{
146    __libcpp_tls_key __key_;
147
148     // Only __thread_local_data() may construct a __thread_specific_ptr
149     // and only with _Tp == __thread_struct.
150    static_assert((is_same<_Tp, __thread_struct>::value), "");
151    __thread_specific_ptr();
152    friend _LIBCPP_FUNC_VIS __thread_specific_ptr<__thread_struct>& __thread_local_data();
153
154    __thread_specific_ptr(const __thread_specific_ptr&);
155    __thread_specific_ptr& operator=(const __thread_specific_ptr&);
156
157    _LIBCPP_HIDDEN static void _LIBCPP_TLS_DESTRUCTOR_CC __at_thread_exit(void*);
158
159public:
160    typedef _Tp* pointer;
161
162    ~__thread_specific_ptr();
163
164    _LIBCPP_INLINE_VISIBILITY
165    pointer get() const {return static_cast<_Tp*>(__libcpp_tls_get(__key_));}
166    _LIBCPP_INLINE_VISIBILITY
167    pointer operator*() const {return *get();}
168    _LIBCPP_INLINE_VISIBILITY
169    pointer operator->() const {return get();}
170    void set_pointer(pointer __p);
171};
172
173template <class _Tp>
174void _LIBCPP_TLS_DESTRUCTOR_CC
175__thread_specific_ptr<_Tp>::__at_thread_exit(void* __p)
176{
177    delete static_cast<pointer>(__p);
178}
179
180template <class _Tp>
181__thread_specific_ptr<_Tp>::__thread_specific_ptr()
182{
183  int __ec =
184      __libcpp_tls_create(&__key_, &__thread_specific_ptr::__at_thread_exit);
185  if (__ec)
186    __throw_system_error(__ec, "__thread_specific_ptr construction failed");
187}
188
189template <class _Tp>
190__thread_specific_ptr<_Tp>::~__thread_specific_ptr()
191{
192    // __thread_specific_ptr is only created with a static storage duration
193    // so this destructor is only invoked during program termination. Invoking
194    // pthread_key_delete(__key_) may prevent other threads from deleting their
195    // thread local data. For this reason we leak the key.
196}
197
198template <class _Tp>
199void
200__thread_specific_ptr<_Tp>::set_pointer(pointer __p)
201{
202    _LIBCPP_ASSERT(get() == nullptr,
203                   "Attempting to overwrite thread local data");
204    __libcpp_tls_set(__key_, __p);
205}
206
207template<>
208struct _LIBCPP_TEMPLATE_VIS hash<__thread_id>
209    : public __unary_function<__thread_id, size_t>
210{
211    _LIBCPP_INLINE_VISIBILITY
212    size_t operator()(__thread_id __v) const _NOEXCEPT
213    {
214        return hash<__libcpp_thread_id>()(__v.__id_);
215    }
216};
217
218template<class _CharT, class _Traits>
219_LIBCPP_INLINE_VISIBILITY
220basic_ostream<_CharT, _Traits>&
221operator<<(basic_ostream<_CharT, _Traits>& __os, __thread_id __id)
222{return __os << __id.__id_;}
223
224class _LIBCPP_TYPE_VIS thread
225{
226    __libcpp_thread_t __t_;
227
228    thread(const thread&);
229    thread& operator=(const thread&);
230public:
231    typedef __thread_id id;
232    typedef __libcpp_thread_t native_handle_type;
233
234    _LIBCPP_INLINE_VISIBILITY
235    thread() _NOEXCEPT : __t_(_LIBCPP_NULL_THREAD) {}
236#ifndef _LIBCPP_CXX03_LANG
237    template <class _Fp, class ..._Args,
238              class = __enable_if_t<!is_same<__uncvref_t<_Fp>, thread>::value> >
239        _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
240        explicit thread(_Fp&& __f, _Args&&... __args);
241#else  // _LIBCPP_CXX03_LANG
242    template <class _Fp>
243    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
244    explicit thread(_Fp __f);
245#endif
246    ~thread();
247
248    _LIBCPP_INLINE_VISIBILITY
249    thread(thread&& __t) _NOEXCEPT : __t_(__t.__t_) {
250        __t.__t_ = _LIBCPP_NULL_THREAD;
251    }
252
253    _LIBCPP_INLINE_VISIBILITY
254    thread& operator=(thread&& __t) _NOEXCEPT {
255        if (!__libcpp_thread_isnull(&__t_))
256            terminate();
257        __t_ = __t.__t_;
258        __t.__t_ = _LIBCPP_NULL_THREAD;
259        return *this;
260    }
261
262    _LIBCPP_INLINE_VISIBILITY
263    void swap(thread& __t) _NOEXCEPT {_VSTD::swap(__t_, __t.__t_);}
264
265    _LIBCPP_INLINE_VISIBILITY
266    bool joinable() const _NOEXCEPT {return !__libcpp_thread_isnull(&__t_);}
267    void join();
268    void detach();
269    _LIBCPP_INLINE_VISIBILITY
270    id get_id() const _NOEXCEPT {return __libcpp_thread_get_id(&__t_);}
271    _LIBCPP_INLINE_VISIBILITY
272    native_handle_type native_handle() _NOEXCEPT {return __t_;}
273
274    static unsigned hardware_concurrency() _NOEXCEPT;
275};
276
277#ifndef _LIBCPP_CXX03_LANG
278
279template <class _TSp, class _Fp, class ..._Args, size_t ..._Indices>
280inline _LIBCPP_INLINE_VISIBILITY
281void
282__thread_execute(tuple<_TSp, _Fp, _Args...>& __t, __tuple_indices<_Indices...>)
283{
284    _VSTD::__invoke(_VSTD::move(_VSTD::get<1>(__t)), _VSTD::move(_VSTD::get<_Indices>(__t))...);
285}
286
287template <class _Fp>
288_LIBCPP_INLINE_VISIBILITY
289void* __thread_proxy(void* __vp)
290{
291    // _Fp = tuple< unique_ptr<__thread_struct>, Functor, Args...>
292    unique_ptr<_Fp> __p(static_cast<_Fp*>(__vp));
293    __thread_local_data().set_pointer(_VSTD::get<0>(*__p.get()).release());
294    typedef typename __make_tuple_indices<tuple_size<_Fp>::value, 2>::type _Index;
295    _VSTD::__thread_execute(*__p.get(), _Index());
296    return nullptr;
297}
298
299template <class _Fp, class ..._Args,
300          class
301         >
302thread::thread(_Fp&& __f, _Args&&... __args)
303{
304    typedef unique_ptr<__thread_struct> _TSPtr;
305    _TSPtr __tsp(new __thread_struct);
306    typedef tuple<_TSPtr, typename decay<_Fp>::type, typename decay<_Args>::type...> _Gp;
307    unique_ptr<_Gp> __p(
308            new _Gp(_VSTD::move(__tsp),
309                    _VSTD::forward<_Fp>(__f),
310                    _VSTD::forward<_Args>(__args)...));
311    int __ec = _VSTD::__libcpp_thread_create(&__t_, &__thread_proxy<_Gp>, __p.get());
312    if (__ec == 0)
313        __p.release();
314    else
315        __throw_system_error(__ec, "thread constructor failed");
316}
317
318#else  // _LIBCPP_CXX03_LANG
319
320template <class _Fp>
321struct __thread_invoke_pair {
322    // This type is used to pass memory for thread local storage and a functor
323    // to a newly created thread because std::pair doesn't work with
324    // std::unique_ptr in C++03.
325    __thread_invoke_pair(_Fp& __f) : __tsp_(new __thread_struct), __fn_(__f) {}
326    unique_ptr<__thread_struct> __tsp_;
327    _Fp __fn_;
328};
329
330template <class _Fp>
331void* __thread_proxy_cxx03(void* __vp)
332{
333    unique_ptr<_Fp> __p(static_cast<_Fp*>(__vp));
334    __thread_local_data().set_pointer(__p->__tsp_.release());
335    (__p->__fn_)();
336    return nullptr;
337}
338
339template <class _Fp>
340thread::thread(_Fp __f)
341{
342
343    typedef __thread_invoke_pair<_Fp> _InvokePair;
344    typedef unique_ptr<_InvokePair> _PairPtr;
345    _PairPtr __pp(new _InvokePair(__f));
346    int __ec = _VSTD::__libcpp_thread_create(&__t_, &__thread_proxy_cxx03<_InvokePair>, __pp.get());
347    if (__ec == 0)
348        __pp.release();
349    else
350        __throw_system_error(__ec, "thread constructor failed");
351}
352
353#endif // _LIBCPP_CXX03_LANG
354
355inline _LIBCPP_INLINE_VISIBILITY
356void swap(thread& __x, thread& __y) _NOEXCEPT {__x.swap(__y);}
357
358namespace this_thread
359{
360
361_LIBCPP_FUNC_VIS void sleep_for(const chrono::nanoseconds& __ns);
362
363template <class _Rep, class _Period>
364void
365sleep_for(const chrono::duration<_Rep, _Period>& __d)
366{
367    if (__d > chrono::duration<_Rep, _Period>::zero())
368    {
369        // The standard guarantees a 64bit signed integer resolution for nanoseconds,
370        // so use INT64_MAX / 1e9 as cut-off point. Use a constant to avoid <climits>
371        // and issues with long double folding on PowerPC with GCC.
372        _LIBCPP_CONSTEXPR chrono::duration<long double> _Max =
373            chrono::duration<long double>(9223372036.0L);
374        chrono::nanoseconds __ns;
375        if (__d < _Max)
376        {
377            __ns = chrono::duration_cast<chrono::nanoseconds>(__d);
378            if (__ns < __d)
379                ++__ns;
380        }
381        else
382            __ns = chrono::nanoseconds::max();
383        this_thread::sleep_for(__ns);
384    }
385}
386
387template <class _Clock, class _Duration>
388void
389sleep_until(const chrono::time_point<_Clock, _Duration>& __t)
390{
391    mutex __mut;
392    condition_variable __cv;
393    unique_lock<mutex> __lk(__mut);
394    while (_Clock::now() < __t)
395        __cv.wait_until(__lk, __t);
396}
397
398template <class _Duration>
399inline _LIBCPP_INLINE_VISIBILITY
400void
401sleep_until(const chrono::time_point<chrono::steady_clock, _Duration>& __t)
402{
403    this_thread::sleep_for(__t - chrono::steady_clock::now());
404}
405
406inline _LIBCPP_INLINE_VISIBILITY
407void yield() _NOEXCEPT {__libcpp_thread_yield();}
408
409} // namespace this_thread
410
411_LIBCPP_END_NAMESPACE_STD
412
413_LIBCPP_POP_MACROS
414
415#endif // _LIBCPP_THREAD
416