xref: /llvm-project-15.0.7/libcxx/include/__mutex_base (revision 4887d047)

// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP___MUTEX_BASE
#define _LIBCPP___MUTEX_BASE

#include <__chrono/duration.h>
#include <__chrono/steady_clock.h>
#include <__chrono/system_clock.h>
#include <__chrono/time_point.h>
#include <__config>
#include <__threading_support>
#include <ratio>
#include <system_error>
#include <time.h>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

_LIBCPP_PUSH_MACROS
#include <__undef_macros>


_LIBCPP_BEGIN_NAMESPACE_STD

#ifndef _LIBCPP_HAS_NO_THREADS

class _LIBCPP_TYPE_VIS _LIBCPP_THREAD_SAFETY_ANNOTATION(capability("mutex")) mutex
{
    __libcpp_mutex_t __m_ = _LIBCPP_MUTEX_INITIALIZER;

public:
    _LIBCPP_INLINE_VISIBILITY
    _LIBCPP_CONSTEXPR mutex() = default;

    mutex(const mutex&) = delete;
    mutex& operator=(const mutex&) = delete;

#if defined(_LIBCPP_HAS_TRIVIAL_MUTEX_DESTRUCTION)
    ~mutex() = default;
#else
    ~mutex() _NOEXCEPT;
#endif

    void lock() _LIBCPP_THREAD_SAFETY_ANNOTATION(acquire_capability());
    bool try_lock() _NOEXCEPT _LIBCPP_THREAD_SAFETY_ANNOTATION(try_acquire_capability(true));
    void unlock() _NOEXCEPT _LIBCPP_THREAD_SAFETY_ANNOTATION(release_capability());

    typedef __libcpp_mutex_t* native_handle_type;
    _LIBCPP_INLINE_VISIBILITY native_handle_type native_handle() {return &__m_;}
};

static_assert(is_nothrow_default_constructible<mutex>::value,
              "the default constructor for std::mutex must be nothrow");

struct _LIBCPP_TYPE_VIS defer_lock_t { explicit defer_lock_t() = default; };
struct _LIBCPP_TYPE_VIS try_to_lock_t { explicit try_to_lock_t() = default; };
struct _LIBCPP_TYPE_VIS adopt_lock_t { explicit adopt_lock_t() = default; };

#if defined(_LIBCPP_CXX03_LANG) || defined(_LIBCPP_BUILDING_LIBRARY)

extern _LIBCPP_EXPORTED_FROM_ABI const defer_lock_t  defer_lock;
extern _LIBCPP_EXPORTED_FROM_ABI const try_to_lock_t try_to_lock;
extern _LIBCPP_EXPORTED_FROM_ABI const adopt_lock_t  adopt_lock;

#else

/* inline */ constexpr defer_lock_t  defer_lock  = defer_lock_t();
/* inline */ constexpr try_to_lock_t try_to_lock = try_to_lock_t();
/* inline */ constexpr adopt_lock_t  adopt_lock  = adopt_lock_t();

#endif

template <class _Mutex>
class _LIBCPP_TEMPLATE_VIS _LIBCPP_THREAD_SAFETY_ANNOTATION(scoped_lockable)
lock_guard
{
public:
    typedef _Mutex mutex_type;

private:
    mutex_type& __m_;
public:

    _LIBCPP_NODISCARD_EXT _LIBCPP_INLINE_VISIBILITY
    explicit lock_guard(mutex_type& __m) _LIBCPP_THREAD_SAFETY_ANNOTATION(acquire_capability(__m))
        : __m_(__m) {__m_.lock();}

    _LIBCPP_NODISCARD_EXT _LIBCPP_INLINE_VISIBILITY
    lock_guard(mutex_type& __m, adopt_lock_t) _LIBCPP_THREAD_SAFETY_ANNOTATION(requires_capability(__m))
        : __m_(__m) {}
    _LIBCPP_INLINE_VISIBILITY
    ~lock_guard() _LIBCPP_THREAD_SAFETY_ANNOTATION(release_capability()) {__m_.unlock();}

private:
    lock_guard(lock_guard const&) = delete;
    lock_guard& operator=(lock_guard const&) = delete;
};

template <class _Mutex>
class _LIBCPP_TEMPLATE_VIS unique_lock
{
public:
    typedef _Mutex mutex_type;

private:
    mutex_type* __m_;
    bool __owns_;

public:
    _LIBCPP_INLINE_VISIBILITY
    unique_lock() _NOEXCEPT : __m_(nullptr), __owns_(false) {}
    _LIBCPP_INLINE_VISIBILITY
    explicit unique_lock(mutex_type& __m)
        : __m_(_VSTD::addressof(__m)), __owns_(true) {__m_->lock();}
    _LIBCPP_INLINE_VISIBILITY
    unique_lock(mutex_type& __m, defer_lock_t) _NOEXCEPT
        : __m_(_VSTD::addressof(__m)), __owns_(false) {}
    _LIBCPP_INLINE_VISIBILITY
    unique_lock(mutex_type& __m, try_to_lock_t)
        : __m_(_VSTD::addressof(__m)), __owns_(__m.try_lock()) {}
    _LIBCPP_INLINE_VISIBILITY
    unique_lock(mutex_type& __m, adopt_lock_t)
        : __m_(_VSTD::addressof(__m)), __owns_(true) {}
    template <class _Clock, class _Duration>
    _LIBCPP_INLINE_VISIBILITY
        unique_lock(mutex_type& __m, const chrono::time_point<_Clock, _Duration>& __t)
            : __m_(_VSTD::addressof(__m)), __owns_(__m.try_lock_until(__t)) {}
    template <class _Rep, class _Period>
    _LIBCPP_INLINE_VISIBILITY
        unique_lock(mutex_type& __m, const chrono::duration<_Rep, _Period>& __d)
            : __m_(_VSTD::addressof(__m)), __owns_(__m.try_lock_for(__d)) {}
    _LIBCPP_INLINE_VISIBILITY
    ~unique_lock()
    {
        if (__owns_)
            __m_->unlock();
    }

    unique_lock(unique_lock const&) = delete;
    unique_lock& operator=(unique_lock const&) = delete;

    _LIBCPP_INLINE_VISIBILITY
    unique_lock(unique_lock&& __u) _NOEXCEPT
        : __m_(__u.__m_), __owns_(__u.__owns_)
        {__u.__m_ = nullptr; __u.__owns_ = false;}
    _LIBCPP_INLINE_VISIBILITY
    unique_lock& operator=(unique_lock&& __u) _NOEXCEPT
        {
            if (__owns_)
                __m_->unlock();
            __m_ = __u.__m_;
            __owns_ = __u.__owns_;
            __u.__m_ = nullptr;
            __u.__owns_ = false;
            return *this;
        }

    void lock();
    bool try_lock();

    template <class _Rep, class _Period>
        bool try_lock_for(const chrono::duration<_Rep, _Period>& __d);
    template <class _Clock, class _Duration>
        bool try_lock_until(const chrono::time_point<_Clock, _Duration>& __t);

    void unlock();

    _LIBCPP_INLINE_VISIBILITY
    void swap(unique_lock& __u) _NOEXCEPT
    {
        _VSTD::swap(__m_, __u.__m_);
        _VSTD::swap(__owns_, __u.__owns_);
    }
    _LIBCPP_INLINE_VISIBILITY
    mutex_type* release() _NOEXCEPT
    {
        mutex_type* __m = __m_;
        __m_ = nullptr;
        __owns_ = false;
        return __m;
    }

    _LIBCPP_INLINE_VISIBILITY
    bool owns_lock() const _NOEXCEPT {return __owns_;}
    _LIBCPP_INLINE_VISIBILITY
    explicit operator bool() const _NOEXCEPT {return __owns_;}
    _LIBCPP_INLINE_VISIBILITY
    mutex_type* mutex() const _NOEXCEPT {return __m_;}
};

template <class _Mutex>
void
unique_lock<_Mutex>::lock()
{
    if (__m_ == nullptr)
        __throw_system_error(EPERM, "unique_lock::lock: references null mutex");
    if (__owns_)
        __throw_system_error(EDEADLK, "unique_lock::lock: already locked");
    __m_->lock();
    __owns_ = true;
}

template <class _Mutex>
bool
unique_lock<_Mutex>::try_lock()
{
    if (__m_ == nullptr)
        __throw_system_error(EPERM, "unique_lock::try_lock: references null mutex");
    if (__owns_)
        __throw_system_error(EDEADLK, "unique_lock::try_lock: already locked");
    __owns_ = __m_->try_lock();
    return __owns_;
}

template <class _Mutex>
template <class _Rep, class _Period>
bool
unique_lock<_Mutex>::try_lock_for(const chrono::duration<_Rep, _Period>& __d)
{
    if (__m_ == nullptr)
        __throw_system_error(EPERM, "unique_lock::try_lock_for: references null mutex");
    if (__owns_)
        __throw_system_error(EDEADLK, "unique_lock::try_lock_for: already locked");
    __owns_ = __m_->try_lock_for(__d);
    return __owns_;
}

template <class _Mutex>
template <class _Clock, class _Duration>
bool
unique_lock<_Mutex>::try_lock_until(const chrono::time_point<_Clock, _Duration>& __t)
{
    if (__m_ == nullptr)
        __throw_system_error(EPERM, "unique_lock::try_lock_until: references null mutex");
    if (__owns_)
        __throw_system_error(EDEADLK, "unique_lock::try_lock_until: already locked");
    __owns_ = __m_->try_lock_until(__t);
    return __owns_;
}

template <class _Mutex>
void
unique_lock<_Mutex>::unlock()
{
    if (!__owns_)
        __throw_system_error(EPERM, "unique_lock::unlock: not locked");
    __m_->unlock();
    __owns_ = false;
}

template <class _Mutex>
inline _LIBCPP_INLINE_VISIBILITY
void
swap(unique_lock<_Mutex>& __x, unique_lock<_Mutex>& __y) _NOEXCEPT
    {__x.swap(__y);}

//enum class cv_status
_LIBCPP_DECLARE_STRONG_ENUM(cv_status)
{
    no_timeout,
    timeout
};
_LIBCPP_DECLARE_STRONG_ENUM_EPILOG(cv_status)

class _LIBCPP_TYPE_VIS condition_variable
{
    __libcpp_condvar_t __cv_ = _LIBCPP_CONDVAR_INITIALIZER;
public:
    _LIBCPP_INLINE_VISIBILITY
    _LIBCPP_CONSTEXPR condition_variable() _NOEXCEPT = default;

#ifdef _LIBCPP_HAS_TRIVIAL_CONDVAR_DESTRUCTION
    ~condition_variable() = default;
#else
    ~condition_variable();
#endif

    condition_variable(const condition_variable&) = delete;
    condition_variable& operator=(const condition_variable&) = delete;

    void notify_one() _NOEXCEPT;
    void notify_all() _NOEXCEPT;

    void wait(unique_lock<mutex>& __lk) _NOEXCEPT;
    template <class _Predicate>
        _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
        void wait(unique_lock<mutex>& __lk, _Predicate __pred);

    template <class _Clock, class _Duration>
        _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
        cv_status
        wait_until(unique_lock<mutex>& __lk,
                   const chrono::time_point<_Clock, _Duration>& __t);

    template <class _Clock, class _Duration, class _Predicate>
        _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
        bool
        wait_until(unique_lock<mutex>& __lk,
                   const chrono::time_point<_Clock, _Duration>& __t,
                   _Predicate __pred);

    template <class _Rep, class _Period>
        _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
        cv_status
        wait_for(unique_lock<mutex>& __lk,
                 const chrono::duration<_Rep, _Period>& __d);

    template <class _Rep, class _Period, class _Predicate>
        bool
        _LIBCPP_INLINE_VISIBILITY
        wait_for(unique_lock<mutex>& __lk,
                 const chrono::duration<_Rep, _Period>& __d,
                 _Predicate __pred);

    typedef __libcpp_condvar_t* native_handle_type;
    _LIBCPP_INLINE_VISIBILITY native_handle_type native_handle() {return &__cv_;}

private:
    void __do_timed_wait(unique_lock<mutex>& __lk,
       chrono::time_point<chrono::system_clock, chrono::nanoseconds>) _NOEXCEPT;
#if defined(_LIBCPP_HAS_COND_CLOCKWAIT)
    void __do_timed_wait(unique_lock<mutex>& __lk,
       chrono::time_point<chrono::steady_clock, chrono::nanoseconds>) _NOEXCEPT;
#endif
    template <class _Clock>
    void __do_timed_wait(unique_lock<mutex>& __lk,
       chrono::time_point<_Clock, chrono::nanoseconds>) _NOEXCEPT;
};
#endif // !_LIBCPP_HAS_NO_THREADS

template <class _Rep, class _Period>
inline _LIBCPP_INLINE_VISIBILITY
__enable_if_t<is_floating_point<_Rep>::value, chrono::nanoseconds>
__safe_nanosecond_cast(chrono::duration<_Rep, _Period> __d)
{
    using namespace chrono;
    using __ratio = ratio_divide<_Period, nano>;
    using __ns_rep = nanoseconds::rep;
    _Rep __result_float = __d.count() * __ratio::num / __ratio::den;

    _Rep __result_max = numeric_limits<__ns_rep>::max();
    if (__result_float >= __result_max) {
        return nanoseconds::max();
    }

    _Rep __result_min = numeric_limits<__ns_rep>::min();
    if (__result_float <= __result_min) {
        return nanoseconds::min();
    }

    return nanoseconds(static_cast<__ns_rep>(__result_float));
}

template <class _Rep, class _Period>
inline _LIBCPP_INLINE_VISIBILITY
__enable_if_t<!is_floating_point<_Rep>::value, chrono::nanoseconds>
__safe_nanosecond_cast(chrono::duration<_Rep, _Period> __d)
{
    using namespace chrono;
    if (__d.count() == 0) {
        return nanoseconds(0);
    }

    using __ratio = ratio_divide<_Period, nano>;
    using __ns_rep = nanoseconds::rep;
    __ns_rep __result_max = numeric_limits<__ns_rep>::max();
    if (__d.count() > 0 && __d.count() > __result_max / __ratio::num) {
        return nanoseconds::max();
    }

    __ns_rep __result_min = numeric_limits<__ns_rep>::min();
    if (__d.count() < 0 && __d.count() < __result_min / __ratio::num) {
        return nanoseconds::min();
    }

    __ns_rep __result = __d.count() * __ratio::num / __ratio::den;
    if (__result == 0) {
        return nanoseconds(1);
    }

    return nanoseconds(__result);
}

#ifndef _LIBCPP_HAS_NO_THREADS
template <class _Predicate>
void
condition_variable::wait(unique_lock<mutex>& __lk, _Predicate __pred)
{
    while (!__pred())
        wait(__lk);
}

template <class _Clock, class _Duration>
cv_status
condition_variable::wait_until(unique_lock<mutex>& __lk,
                               const chrono::time_point<_Clock, _Duration>& __t)
{
    using namespace chrono;
    using __clock_tp_ns = time_point<_Clock, nanoseconds>;

    typename _Clock::time_point __now = _Clock::now();
    if (__t <= __now)
        return cv_status::timeout;

    __clock_tp_ns __t_ns = __clock_tp_ns(_VSTD::__safe_nanosecond_cast(__t.time_since_epoch()));

    __do_timed_wait(__lk, __t_ns);
    return _Clock::now() < __t ? cv_status::no_timeout : cv_status::timeout;
}

template <class _Clock, class _Duration, class _Predicate>
bool
condition_variable::wait_until(unique_lock<mutex>& __lk,
                   const chrono::time_point<_Clock, _Duration>& __t,
                   _Predicate __pred)
{
    while (!__pred())
    {
        if (wait_until(__lk, __t) == cv_status::timeout)
            return __pred();
    }
    return true;
}

template <class _Rep, class _Period>
cv_status
condition_variable::wait_for(unique_lock<mutex>& __lk,
                             const chrono::duration<_Rep, _Period>& __d)
{
    using namespace chrono;
    if (__d <= __d.zero())
        return cv_status::timeout;
    using __ns_rep = nanoseconds::rep;
    steady_clock::time_point __c_now = steady_clock::now();

#if defined(_LIBCPP_HAS_COND_CLOCKWAIT)
    using __clock_tp_ns = time_point<steady_clock, nanoseconds>;
    __ns_rep __now_count_ns = _VSTD::__safe_nanosecond_cast(__c_now.time_since_epoch()).count();
#else
    using __clock_tp_ns = time_point<system_clock, nanoseconds>;
    __ns_rep __now_count_ns = _VSTD::__safe_nanosecond_cast(system_clock::now().time_since_epoch()).count();
#endif

    __ns_rep __d_ns_count = _VSTD::__safe_nanosecond_cast(__d).count();

    if (__now_count_ns > numeric_limits<__ns_rep>::max() - __d_ns_count) {
        __do_timed_wait(__lk, __clock_tp_ns::max());
    } else {
        __do_timed_wait(__lk, __clock_tp_ns(nanoseconds(__now_count_ns + __d_ns_count)));
    }

    return steady_clock::now() - __c_now < __d ? cv_status::no_timeout :
                                                 cv_status::timeout;
}

template <class _Rep, class _Period, class _Predicate>
inline
bool
condition_variable::wait_for(unique_lock<mutex>& __lk,
                             const chrono::duration<_Rep, _Period>& __d,
                             _Predicate __pred)
{
    return wait_until(__lk, chrono::steady_clock::now() + __d,
                      _VSTD::move(__pred));
}

#if defined(_LIBCPP_HAS_COND_CLOCKWAIT)
inline
void
condition_variable::__do_timed_wait(unique_lock<mutex>& __lk,
     chrono::time_point<chrono::steady_clock, chrono::nanoseconds> __tp) _NOEXCEPT
{
    using namespace chrono;
    if (!__lk.owns_lock())
        __throw_system_error(EPERM,
                            "condition_variable::timed wait: mutex not locked");
    nanoseconds __d = __tp.time_since_epoch();
    timespec __ts;
    seconds __s = duration_cast<seconds>(__d);
    using __ts_sec = decltype(__ts.tv_sec);
    const __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 = (__d - __s).count();
    }
    else
    {
        __ts.tv_sec = __ts_sec_max;
        __ts.tv_nsec = giga::num - 1;
    }
    int __ec = pthread_cond_clockwait(&__cv_, __lk.mutex()->native_handle(), CLOCK_MONOTONIC, &__ts);
    if (__ec != 0 && __ec != ETIMEDOUT)
        __throw_system_error(__ec, "condition_variable timed_wait failed");
}
#endif // _LIBCPP_HAS_COND_CLOCKWAIT

template <class _Clock>
inline
void
condition_variable::__do_timed_wait(unique_lock<mutex>& __lk,
     chrono::time_point<_Clock, chrono::nanoseconds> __tp) _NOEXCEPT
{
    wait_for(__lk, __tp - _Clock::now());
}

#endif // !_LIBCPP_HAS_NO_THREADS

_LIBCPP_END_NAMESPACE_STD

_LIBCPP_POP_MACROS

#endif // _LIBCPP___MUTEX_BASE