xref: /llvm-project-15.0.7/libcxx/src/thread.cpp (revision 6b0101ac)

//===------------------------- thread.cpp----------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "thread"
#include "exception"
#include "vector"
#include "future"
#include "limits"
#include <sys/types.h>
#if !_WIN32
#if !__sun__ && !__linux__
#include <sys/sysctl.h>
#else
#include <unistd.h>
#endif // !__sun__ && !__linux__
#endif // !_WIN32

_LIBCPP_BEGIN_NAMESPACE_STD

thread::~thread()
{
    if (__t_ != 0)
        terminate();
}

void
thread::join()
{
    int ec = pthread_join(__t_, 0);
#ifndef _LIBCPP_NO_EXCEPTIONS
    if (ec)
        throw system_error(error_code(ec, system_category()), "thread::join failed");
#endif  // _LIBCPP_NO_EXCEPTIONS
    __t_ = 0;
}

void
thread::detach()
{
    int ec = EINVAL;
    if (__t_ != 0)
    {
        ec = pthread_detach(__t_);
        if (ec == 0)
            __t_ = 0;
    }
#ifndef _LIBCPP_NO_EXCEPTIONS
    if (ec)
        throw system_error(error_code(ec, system_category()), "thread::detach failed");
#endif  // _LIBCPP_NO_EXCEPTIONS
}

unsigned
thread::hardware_concurrency() _NOEXCEPT
{
#if defined(CTL_HW) && defined(HW_NCPU)
    unsigned n;
    int mib[2] = {CTL_HW, HW_NCPU};
    std::size_t s = sizeof(n);
    sysctl(mib, 2, &n, &s, 0, 0);
    return n;
#elif defined(_POSIX_C_SOURCE) && (_POSIX_C_SOURCE >= 200112L) && defined(_SC_NPROCESSORS_ONLN)
    long result = sysconf(_SC_NPROCESSORS_ONLN);
    // sysconf returns -1 if the name is invalid, the option does not exist or
    // does not have a definite limit.
    if (result == -1)
        return 0;
    return result;
#else  // defined(CTL_HW) && defined(HW_NCPU)
    // TODO: grovel through /proc or check cpuid on x86 and similar
    // instructions on other architectures.
    return 0;  // Means not computable [thread.thread.static]
#endif  // defined(CTL_HW) && defined(HW_NCPU)
}

namespace this_thread
{

void
sleep_for(const chrono::nanoseconds& ns)
{
    using namespace chrono;
    if (ns > nanoseconds::zero())
    {
        seconds s = duration_cast<seconds>(ns);
        timespec ts;
        typedef decltype(ts.tv_sec) ts_sec;
        _LIBCPP_CONSTEXPR ts_sec ts_sec_max = numeric_limits<ts_sec>::max();
        if (s.count() < ts_sec_max)
        {
            ts.tv_sec = static_cast<ts_sec>(s.count());
            ts.tv_nsec = static_cast<decltype(ts.tv_nsec)>((ns-s).count());
        }
        else
        {
            ts.tv_sec = ts_sec_max;
            ts.tv_nsec = giga::num - 1;
        }
        nanosleep(&ts, 0);
    }
}

}  // this_thread

__thread_specific_ptr<__thread_struct>&
__thread_local_data()
{
    static __thread_specific_ptr<__thread_struct> __p;
    return __p;
}

// __thread_struct_imp

template <class T>
class _LIBCPP_HIDDEN __hidden_allocator
{
public:
    typedef T  value_type;

    T* allocate(size_t __n)
        {return static_cast<T*>(::operator new(__n * sizeof(T)));}
    void deallocate(T* __p, size_t) {::operator delete((void*)__p);}

    size_t max_size() const {return size_t(~0) / sizeof(T);}
};

class _LIBCPP_HIDDEN __thread_struct_imp
{
    typedef vector<__assoc_sub_state*,
                          __hidden_allocator<__assoc_sub_state*> > _AsyncStates;
    typedef vector<pair<condition_variable*, mutex*>,
               __hidden_allocator<pair<condition_variable*, mutex*> > > _Notify;

    _AsyncStates async_states_;
    _Notify notify_;

    __thread_struct_imp(const __thread_struct_imp&);
    __thread_struct_imp& operator=(const __thread_struct_imp&);
public:
    __thread_struct_imp() {}
    ~__thread_struct_imp();

    void notify_all_at_thread_exit(condition_variable* cv, mutex* m);
    void __make_ready_at_thread_exit(__assoc_sub_state* __s);
};

__thread_struct_imp::~__thread_struct_imp()
{
    for (_Notify::iterator i = notify_.begin(), e = notify_.end();
            i != e; ++i)
    {
        i->second->unlock();
        i->first->notify_all();
    }
    for (_AsyncStates::iterator i = async_states_.begin(), e = async_states_.end();
            i != e; ++i)
    {
        (*i)->__make_ready();
        (*i)->__release_shared();
    }
}

void
__thread_struct_imp::notify_all_at_thread_exit(condition_variable* cv, mutex* m)
{
    notify_.push_back(pair<condition_variable*, mutex*>(cv, m));
}

void
__thread_struct_imp::__make_ready_at_thread_exit(__assoc_sub_state* __s)
{
    async_states_.push_back(__s);
    __s->__add_shared();
}

// __thread_struct

__thread_struct::__thread_struct()
    : __p_(new __thread_struct_imp)
{
}

__thread_struct::~__thread_struct()
{
    delete __p_;
}

void
__thread_struct::notify_all_at_thread_exit(condition_variable* cv, mutex* m)
{
    __p_->notify_all_at_thread_exit(cv, m);
}

void
__thread_struct::__make_ready_at_thread_exit(__assoc_sub_state* __s)
{
    __p_->__make_ready_at_thread_exit(__s);
}

_LIBCPP_END_NAMESPACE_STD