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_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
67unsigned thread::hardware_concurrency() noexcept {
68#if defined(_SC_NPROCESSORS_ONLN)
69 long result = sysconf(_SC_NPROCESSORS_ONLN);
70 // sysconf returns -1 if the name is invalid, the option does not exist or
71 // does not have a definite limit.
72 // if sysconf returns some other negative number, we have no idea
73 // what is going on. Default to something safe.
74 if (result < 0)
75 return 0;
76 return static_cast<unsigned>(result);
77#elif defined(_LIBCPP_WIN32API)
78 return static_cast<unsigned>(GetActiveProcessorCount(ALL_PROCESSOR_GROUPS));
79#else // defined(CTL_HW) && defined(HW_NCPU)
80 // TODO: grovel through /proc or check cpuid on x86 and similar
81 // instructions on other architectures.
82# if defined(_LIBCPP_WARNING)
83 _LIBCPP_WARNING("hardware_concurrency not yet implemented")
84# else
85# warning hardware_concurrency not yet implemented
86# endif
87 return 0; // Means not computable [thread.thread.static]
88#endif // defined(CTL_HW) && defined(HW_NCPU)
89}
90
91namespace this_thread {
92
93void sleep_for(const chrono::nanoseconds& ns) {
94 if (ns > chrono::nanoseconds::zero()) {
95 __libcpp_thread_sleep_for(ns: ns);
96 }
97}
98
99} // namespace this_thread
100
101__thread_specific_ptr<__thread_struct>& __thread_local_data() {
102 // Even though __thread_specific_ptr's destructor doesn't actually destroy
103 // anything (see comments there), we can't call it at all because threads may
104 // outlive the static variable and calling its destructor means accessing an
105 // object outside of its lifetime, which is UB.
106 alignas(__thread_specific_ptr<__thread_struct>) static char __b[sizeof(__thread_specific_ptr<__thread_struct>)];
107 static __thread_specific_ptr<__thread_struct>* __p = new (__b) __thread_specific_ptr<__thread_struct>();
108 return *__p;
109}
110
111// __thread_struct_imp
112
113template <class T>
114class _LIBCPP_HIDDEN __hidden_allocator {
115public:
116 typedef T value_type;
117
118 T* allocate(size_t __n) { return static_cast<T*>(::operator new(__n * sizeof(T))); }
119 void deallocate(T* __p, size_t) { ::operator delete(static_cast<void*>(__p)); }
120
121 size_t max_size() const { return size_t(~0) / sizeof(T); }
122};
123
124class _LIBCPP_HIDDEN __thread_struct_imp {
125 typedef vector<__assoc_sub_state*, __hidden_allocator<__assoc_sub_state*> > _AsyncStates;
126 typedef vector<pair<condition_variable*, mutex*>, __hidden_allocator<pair<condition_variable*, mutex*> > > _Notify;
127
128 _AsyncStates async_states_;
129 _Notify notify_;
130
131 __thread_struct_imp(const __thread_struct_imp&);
132 __thread_struct_imp& operator=(const __thread_struct_imp&);
133
134public:
135 __thread_struct_imp() {}
136 ~__thread_struct_imp();
137
138 void notify_all_at_thread_exit(condition_variable* cv, mutex* m);
139 void __make_ready_at_thread_exit(__assoc_sub_state* __s);
140};
141
142__thread_struct_imp::~__thread_struct_imp() {
143 for (_Notify::iterator i = notify_.begin(), e = notify_.end(); i != e; ++i) {
144 i->first->notify_all();
145 i->second->unlock();
146 }
147 for (_AsyncStates::iterator i = async_states_.begin(), e = async_states_.end(); i != e; ++i) {
148 (*i)->__make_ready();
149 (*i)->__release_shared();
150 }
151}
152
153void __thread_struct_imp::notify_all_at_thread_exit(condition_variable* cv, mutex* m) {
154 notify_.push_back(x: pair<condition_variable*, mutex*>(cv, m));
155}
156
157void __thread_struct_imp::__make_ready_at_thread_exit(__assoc_sub_state* __s) {
158 async_states_.push_back(x: __s);
159 __s->__add_shared();
160}
161
162// __thread_struct
163
164__thread_struct::__thread_struct() : __p_(new __thread_struct_imp) {}
165
166__thread_struct::~__thread_struct() { delete __p_; }
167
168void __thread_struct::notify_all_at_thread_exit(condition_variable* cv, mutex* m) {
169 __p_->notify_all_at_thread_exit(cv, m);
170}
171
172void __thread_struct::__make_ready_at_thread_exit(__assoc_sub_state* __s) { __p_->__make_ready_at_thread_exit(__s); }
173
174_LIBCPP_END_EXPLICIT_ABI_ANNOTATIONS
175_LIBCPP_END_NAMESPACE_STD
176