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 <__config>
10
11#ifndef _LIBCPP_HAS_NO_THREADS
12
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{
39    if (!__libcpp_thread_isnull(&__t_))
40        terminate();
41}
42
43void
44thread::join()
45{
46    int ec = EINVAL;
47    if (!__libcpp_thread_isnull(&__t_))
48    {
49        ec = __libcpp_thread_join(&__t_);
50        if (ec == 0)
51            __t_ = _LIBCPP_NULL_THREAD;
52    }
53
54    if (ec)
55        __throw_system_error(ec, "thread::join failed");
56}
57
58void
59thread::detach()
60{
61    int ec = EINVAL;
62    if (!__libcpp_thread_isnull(&__t_))
63    {
64        ec = __libcpp_thread_detach(&__t_);
65        if (ec == 0)
66            __t_ = _LIBCPP_NULL_THREAD;
67    }
68
69    if (ec)
70        __throw_system_error(ec, "thread::detach failed");
71}
72
73unsigned
74thread::hardware_concurrency() noexcept
75{
76#if defined(_SC_NPROCESSORS_ONLN)
77    long result = sysconf(_SC_NPROCESSORS_ONLN);
78    // sysconf returns -1 if the name is invalid, the option does not exist or
79    // does not have a definite limit.
80    // if sysconf returns some other negative number, we have no idea
81    // what is going on. Default to something safe.
82    if (result < 0)
83        return 0;
84    return static_cast<unsigned>(result);
85#elif defined(_LIBCPP_WIN32API)
86    SYSTEM_INFO info;
87    GetSystemInfo(&info);
88    return info.dwNumberOfProcessors;
89#else  // defined(CTL_HW) && defined(HW_NCPU)
90    // TODO: grovel through /proc or check cpuid on x86 and similar
91    // instructions on other architectures.
92#   if defined(_LIBCPP_WARNING)
93        _LIBCPP_WARNING("hardware_concurrency not yet implemented")
94#   else
95#       warning hardware_concurrency not yet implemented
96#   endif
97    return 0;  // Means not computable [thread.thread.static]
98#endif // defined(CTL_HW) && defined(HW_NCPU)
99}
100
101namespace this_thread
102{
103
104void
105sleep_for(const chrono::nanoseconds& ns)
106{
107    if (ns > chrono::nanoseconds::zero())
108    {
109        __libcpp_thread_sleep_for(ns);
110    }
111}
112
113}  // this_thread
114
115__thread_specific_ptr<__thread_struct>&
116__thread_local_data()
117{
118  // Even though __thread_specific_ptr's destructor doesn't actually destroy
119  // anything (see comments there), we can't call it at all because threads may
120  // outlive the static variable and calling its destructor means accessing an
121  // object outside of its lifetime, which is UB.
122  alignas(__thread_specific_ptr<__thread_struct>) static char __b[sizeof(__thread_specific_ptr<__thread_struct>)];
123  static __thread_specific_ptr<__thread_struct>* __p = new (__b) __thread_specific_ptr<__thread_struct>();
124  return *__p;
125}
126
127// __thread_struct_imp
128
129template <class T>
130class _LIBCPP_HIDDEN __hidden_allocator
131{
132public:
133    typedef T  value_type;
134
135    T* allocate(size_t __n)
136        {return static_cast<T*>(::operator new(__n * sizeof(T)));}
137    void deallocate(T* __p, size_t) {::operator delete(static_cast<void*>(__p));}
138
139    size_t max_size() const {return size_t(~0) / sizeof(T);}
140};
141
142class _LIBCPP_HIDDEN __thread_struct_imp
143{
144    typedef vector<__assoc_sub_state*,
145                          __hidden_allocator<__assoc_sub_state*> > _AsyncStates;
146    typedef vector<pair<condition_variable*, mutex*>,
147               __hidden_allocator<pair<condition_variable*, mutex*> > > _Notify;
148
149    _AsyncStates async_states_;
150    _Notify notify_;
151
152    __thread_struct_imp(const __thread_struct_imp&);
153    __thread_struct_imp& operator=(const __thread_struct_imp&);
154public:
155    __thread_struct_imp() {}
156    ~__thread_struct_imp();
157
158    void notify_all_at_thread_exit(condition_variable* cv, mutex* m);
159    void __make_ready_at_thread_exit(__assoc_sub_state* __s);
160};
161
162__thread_struct_imp::~__thread_struct_imp()
163{
164    for (_Notify::iterator i = notify_.begin(), e = notify_.end();
165            i != e; ++i)
166    {
167        i->first->notify_all();
168        i->second->unlock();
169    }
170    for (_AsyncStates::iterator i = async_states_.begin(), e = async_states_.end();
171            i != e; ++i)
172    {
173        (*i)->__make_ready();
174        (*i)->__release_shared();
175    }
176}
177
178void
179__thread_struct_imp::notify_all_at_thread_exit(condition_variable* cv, mutex* m)
180{
181    notify_.push_back(pair<condition_variable*, mutex*>(cv, m));
182}
183
184void
185__thread_struct_imp::__make_ready_at_thread_exit(__assoc_sub_state* __s)
186{
187    async_states_.push_back(__s);
188    __s->__add_shared();
189}
190
191// __thread_struct
192
193__thread_struct::__thread_struct()
194    : __p_(new __thread_struct_imp)
195{
196}
197
198__thread_struct::~__thread_struct()
199{
200    delete __p_;
201}
202
203void
204__thread_struct::notify_all_at_thread_exit(condition_variable* cv, mutex* m)
205{
206    __p_->notify_all_at_thread_exit(cv, m);
207}
208
209void
210__thread_struct::__make_ready_at_thread_exit(__assoc_sub_state* __s)
211{
212    __p_->__make_ready_at_thread_exit(__s);
213}
214
215_LIBCPP_END_NAMESPACE_STD
216
217#endif // !_LIBCPP_HAS_NO_THREADS
218