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1//===------------------------- thread.cpp----------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include <__system_error/throw_system_error.h>
10#include <__thread/poll_with_backoff.h>
11#include <__thread/timed_backoff_policy.h>
12#include <__utility/pair.h>
13#include <exception>
14#include <future>
15#include <limits>
16#include <thread>
17#include <vector>
18
19#if __has_include(<unistd.h>)
20# include <unistd.h> // for sysconf
21#endif
22
23#if defined(__NetBSD__)
24# pragma weak pthread_create // Do not create libpthread dependency
25#endif
26
27#if defined(_LIBCPP_WIN32API)
28# include <windows.h>
29#endif
30
31#if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
32# pragma comment(lib, "pthread")
33#endif
34
35_LIBCPP_BEGIN_NAMESPACE_STD
36
37thread::~thread() {
38 if (!__libcpp_thread_isnull(&__t_))
39 terminate();
40}
41
42void thread::join() {
43 int ec = EINVAL;
44 if (!__libcpp_thread_isnull(&__t_)) {
45 ec = __libcpp_thread_join(&__t_);
46 if (ec == 0)
47 __t_ = _LIBCPP_NULL_THREAD;
48 }
49
50 if (ec)
51 std::__throw_system_error(ec, "thread::join failed");
52}
53
54void thread::detach() {
55 int ec = EINVAL;
56 if (!__libcpp_thread_isnull(&__t_)) {
57 ec = __libcpp_thread_detach(&__t_);
58 if (ec == 0)
59 __t_ = _LIBCPP_NULL_THREAD;
60 }
61
62 if (ec)
63 std::__throw_system_error(ec, "thread::detach failed");
64}
65
66unsigned thread::hardware_concurrency() noexcept {
67#if defined(_SC_NPROCESSORS_ONLN)
68 long result = sysconf(_SC_NPROCESSORS_ONLN);
69 // sysconf returns -1 if the name is invalid, the option does not exist or
70 // does not have a definite limit.
71 // if sysconf returns some other negative number, we have no idea
72 // what is going on. Default to something safe.
73 if (result < 0)
74 return 0;
75 return static_cast<unsigned>(result);
76#elif defined(_LIBCPP_WIN32API)
77 SYSTEM_INFO info;
78 GetSystemInfo(&info);
79 return info.dwNumberOfProcessors;
80#else // defined(CTL_HW) && defined(HW_NCPU)
81 // TODO: grovel through /proc or check cpuid on x86 and similar
82 // instructions on other architectures.
83# if defined(_LIBCPP_WARNING)
84 _LIBCPP_WARNING("hardware_concurrency not yet implemented")
85# else
86# warning hardware_concurrency not yet implemented
87# endif
88 return 0; // Means not computable [thread.thread.static]
89#endif // defined(CTL_HW) && defined(HW_NCPU)
90}
91
92namespace this_thread {
93
94void sleep_for(const chrono::nanoseconds& ns) {
95 if (ns > chrono::nanoseconds::zero()) {
96 __libcpp_thread_sleep_for(ns);
97 }
98}
99
100} // namespace this_thread
101
102__thread_specific_ptr<__thread_struct>& __thread_local_data() {
103 // Even though __thread_specific_ptr's destructor doesn't actually destroy
104 // anything (see comments there), we can't call it at all because threads may
105 // outlive the static variable and calling its destructor means accessing an
106 // object outside of its lifetime, which is UB.
107 alignas(__thread_specific_ptr<__thread_struct>) static char __b[sizeof(__thread_specific_ptr<__thread_struct>)];
108 static __thread_specific_ptr<__thread_struct>* __p = new (__b) __thread_specific_ptr<__thread_struct>();
109 return *__p;
110}
111
112// __thread_struct_imp
113
114template <class T>
115class _LIBCPP_HIDDEN __hidden_allocator {
116public:
117 typedef T value_type;
118
119 T* allocate(size_t __n) { return static_cast<T*>(::operator new(__n * sizeof(T))); }
120 void deallocate(T* __p, size_t) { ::operator delete(static_cast<void*>(__p)); }
121
122 size_t max_size() const { return size_t(~0) / sizeof(T); }
123};
124
125class _LIBCPP_HIDDEN __thread_struct_imp {
126 typedef vector<__assoc_sub_state*, __hidden_allocator<__assoc_sub_state*> > _AsyncStates;
127 typedef vector<pair<condition_variable*, mutex*>, __hidden_allocator<pair<condition_variable*, mutex*> > > _Notify;
128
129 _AsyncStates async_states_;
130 _Notify notify_;
131
132 __thread_struct_imp(const __thread_struct_imp&);
133 __thread_struct_imp& operator=(const __thread_struct_imp&);
134
135public:
136 __thread_struct_imp() {}
137 ~__thread_struct_imp();
138
139 void notify_all_at_thread_exit(condition_variable* cv, mutex* m);
140 void __make_ready_at_thread_exit(__assoc_sub_state* __s);
141};
142
143__thread_struct_imp::~__thread_struct_imp() {
144 for (_Notify::iterator i = notify_.begin(), e = notify_.end(); i != e; ++i) {
145 i->first->notify_all();
146 i->second->unlock();
147 }
148 for (_AsyncStates::iterator i = async_states_.begin(), e = async_states_.end(); i != e; ++i) {
149 (*i)->__make_ready();
150 (*i)->__release_shared();
151 }
152}
153
154void __thread_struct_imp::notify_all_at_thread_exit(condition_variable* cv, mutex* m) {
155 notify_.push_back(pair<condition_variable*, mutex*>(cv, m));
156}
157
158void __thread_struct_imp::__make_ready_at_thread_exit(__assoc_sub_state* __s) {
159 async_states_.push_back(__s);
160 __s->__add_shared();
161}
162
163// __thread_struct
164
165__thread_struct::__thread_struct() : __p_(new __thread_struct_imp) {}
166
167__thread_struct::~__thread_struct() { delete __p_; }
168
169void __thread_struct::notify_all_at_thread_exit(condition_variable* cv, mutex* m) {
170 __p_->notify_all_at_thread_exit(cv, m);
171}
172
173void __thread_struct::__make_ready_at_thread_exit(__assoc_sub_state* __s) { __p_->__make_ready_at_thread_exit(__s); }
174
175_LIBCPP_END_NAMESPACE_STD