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#ifdef _WIN32
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_LIBCPP_BEGIN_EXPLICIT_ABI_ANNOTATIONS
37
38thread::~thread() {
39 if (!__libcpp_thread_isnull(t: &__t_))
40 terminate();
41}
42
43void thread::join() {
44 int ec = EINVAL;
45 if (!__libcpp_thread_isnull(t: &__t_)) {
46 ec = __libcpp_thread_join(t: &__t_);
47 if (ec == 0)
48 __t_ = _LIBCPP_NULL_THREAD;
49 }
50
51 if (ec)
52 std::__throw_system_error(ev: ec, what_arg: "thread::join failed");
53}
54
55void thread::detach() {
56 int ec = EINVAL;
57 if (!__libcpp_thread_isnull(t: &__t_)) {
58 ec = __libcpp_thread_detach(t: &__t_);
59 if (ec == 0)
60 __t_ = _LIBCPP_NULL_THREAD;
61 }
62
63 if (ec)
64 std::__throw_system_error(ev: ec, what_arg: "thread::detach failed");
65}
66
67// Defined here only for backwards compatibility.
68unsigned thread::hardware_concurrency() noexcept { return std::__thread_hardware_concurrency(); }
69
70namespace this_thread {
71
72void sleep_for(const chrono::nanoseconds& ns) {
73 if (ns > chrono::nanoseconds::zero()) {
74 __libcpp_thread_sleep_for(ns: ns);
75 }
76}
77
78} // namespace this_thread
79
80__thread_specific_ptr<__thread_struct>& __thread_local_data() {
81 // Even though __thread_specific_ptr's destructor doesn't actually destroy
82 // anything (see comments there), we can't call it at all because threads may
83 // outlive the static variable and calling its destructor means accessing an
84 // object outside of its lifetime, which is UB.
85 alignas(__thread_specific_ptr<__thread_struct>) static char __b[sizeof(__thread_specific_ptr<__thread_struct>)];
86 static __thread_specific_ptr<__thread_struct>* __p = new (__b) __thread_specific_ptr<__thread_struct>();
87 return *__p;
88}
89
90// __thread_struct_imp
91
92template <class T>
93class _LIBCPP_HIDDEN __hidden_allocator {
94public:
95 typedef T value_type;
96
97 T* allocate(size_t __n) { return static_cast<T*>(::operator new(__n * sizeof(T))); }
98 void deallocate(T* __p, size_t) { ::operator delete(static_cast<void*>(__p)); }
99
100 size_t max_size() const { return size_t(~0) / sizeof(T); }
101};
102
103class _LIBCPP_HIDDEN __thread_struct_imp {
104 typedef vector<__assoc_sub_state*, __hidden_allocator<__assoc_sub_state*> > _AsyncStates;
105 typedef vector<pair<condition_variable*, mutex*>, __hidden_allocator<pair<condition_variable*, mutex*> > > _Notify;
106
107 _AsyncStates async_states_;
108 _Notify notify_;
109
110 __thread_struct_imp(const __thread_struct_imp&);
111 __thread_struct_imp& operator=(const __thread_struct_imp&);
112
113public:
114 __thread_struct_imp() {}
115 ~__thread_struct_imp();
116
117 void notify_all_at_thread_exit(condition_variable* cv, mutex* m);
118 void __make_ready_at_thread_exit(__assoc_sub_state* __s);
119};
120
121__thread_struct_imp::~__thread_struct_imp() {
122 for (_Notify::iterator i = notify_.begin(), e = notify_.end(); i != e; ++i) {
123 i->first->notify_all();
124 i->second->unlock();
125 }
126 for (_AsyncStates::iterator i = async_states_.begin(), e = async_states_.end(); i != e; ++i) {
127 (*i)->__make_ready();
128 (*i)->__release_shared();
129 }
130}
131
132void __thread_struct_imp::notify_all_at_thread_exit(condition_variable* cv, mutex* m) {
133 notify_.push_back(x: pair<condition_variable*, mutex*>(cv, m));
134}
135
136void __thread_struct_imp::__make_ready_at_thread_exit(__assoc_sub_state* __s) {
137 async_states_.push_back(x: __s);
138 __s->__add_shared();
139}
140
141// __thread_struct
142
143__thread_struct::__thread_struct() : __p_(new __thread_struct_imp) {}
144
145__thread_struct::~__thread_struct() { delete __p_; }
146
147void __thread_struct::notify_all_at_thread_exit(condition_variable* cv, mutex* m) {
148 __p_->notify_all_at_thread_exit(cv, m);
149}
150
151void __thread_struct::__make_ready_at_thread_exit(__assoc_sub_state* __s) { __p_->__make_ready_at_thread_exit(__s); }
152
153unsigned __thread_hardware_concurrency() noexcept {
154#if defined(_SC_NPROCESSORS_ONLN)
155 long result = sysconf(_SC_NPROCESSORS_ONLN);
156 // sysconf returns -1 if the name is invalid, the option does not exist or
157 // does not have a definite limit.
158 // if sysconf returns some other negative number, we have no idea
159 // what is going on. Default to something safe.
160 if (result < 0)
161 return 0;
162 return static_cast<unsigned>(result);
163#elif defined(_WIN32)
164 return static_cast<unsigned>(GetActiveProcessorCount(ALL_PROCESSOR_GROUPS));
165#else // defined(CTL_HW) && defined(HW_NCPU)
166 // TODO: grovel through /proc or check cpuid on x86 and similar
167 // instructions on other architectures.
168# if defined(_LIBCPP_WARNING)
169 _LIBCPP_WARNING("hardware_concurrency not yet implemented")
170# else
171# warning hardware_concurrency not yet implemented
172# endif
173 return 0; // Means not computable [thread.thread.static]
174#endif // defined(CTL_HW) && defined(HW_NCPU)
175}
176
177_LIBCPP_END_EXPLICIT_ABI_ANNOTATIONS
178_LIBCPP_END_NAMESPACE_STD
179