libcxx/src/thread.cpp

   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
  37 thread::~thread()
  38 {
  39     if (!__libcpp_thread_isnull(&__t_))
  40         terminate();
  41 }
  42
  43 void
  44 thread::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
  58 void
  59 thread::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
  73 unsigned
  74 thread::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
 101 namespace this_thread
 102 {
 103
 104 void
 105 sleep_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
 129 template <class T>
 130 class _LIBCPP_HIDDEN __hidden_allocator
 131 {
 132 public:
 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
 142 class _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&);
 154 public:
 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->second->unlock();
 168         i->first->notify_all();
 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
 178 void
 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
 184 void
 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
 203 void
 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
 209 void
 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