STL/stl/inc/mutex

// mutex standard header

// Copyright (c) Microsoft Corporation.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

#pragma once
#ifndef _MUTEX_
#define _MUTEX_
#include <yvals_core.h>
#if _STL_COMPILER_PREPROCESSOR

#ifdef _M_CEE_PURE
#error <mutex> is not supported when compiling with /clr:pure.
#endif // _M_CEE_PURE

#include <chrono>
#include <system_error>
#include <thread>
#include <tuple>
#include <utility>
#include <xcall_once.h>

#pragma pack(push, _CRT_PACKING)
#pragma warning(push, _STL_WARNING_LEVEL)
#pragma warning(disable : _STL_DISABLED_WARNINGS)
_STL_DISABLE_CLANG_WARNINGS
#pragma push_macro("new")
#undef new

_STD_BEGIN
// mutex and recursive_mutex are not supported under /clr
#ifndef _M_CEE
class condition_variable;
class condition_variable_any;

// MUTUAL EXCLUSION
class _Mutex_base { // base class for all mutex types
public:
    _Mutex_base(int _Flags = 0) noexcept {
        _Mtx_init_in_situ(_Mymtx(), _Flags | _Mtx_try);
    }

    ~_Mutex_base() noexcept {
        _Mtx_destroy_in_situ(_Mymtx());
    }

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

    void lock() {
        _Check_C_return(_Mtx_lock(_Mymtx()));
    }

    _NODISCARD bool try_lock() {
        const auto _Res = _Mtx_trylock(_Mymtx());
        switch (_Res) {
        case _Thrd_success:
            return true;
        case _Thrd_busy:
            return false;
        default:
            _Throw_C_error(_Res);
        }
    }

    void unlock() {
        _Check_C_return(_Mtx_unlock(_Mymtx()));
    }

    using native_handle_type = void*;

    _NODISCARD native_handle_type native_handle() {
        return _Mtx_getconcrtcs(_Mymtx());
    }

private:
    friend condition_variable;
    friend condition_variable_any;

    aligned_storage_t<_Mtx_internal_imp_size, _Mtx_internal_imp_alignment> _Mtx_storage;

    _Mtx_t _Mymtx() noexcept { // get pointer to _Mtx_internal_imp_t inside _Mtx_storage
        return reinterpret_cast<_Mtx_t>(&_Mtx_storage);
    }
};

class mutex : public _Mutex_base { // class for mutual exclusion
public:
    /* constexpr */ mutex() noexcept // TRANSITION, ABI
        : _Mutex_base() {}

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

class recursive_mutex : public _Mutex_base { // class for recursive mutual exclusion
public:
    recursive_mutex() : _Mutex_base(_Mtx_recursive) {}

    _NODISCARD bool try_lock() noexcept {
        return _Mutex_base::try_lock();
    }

    recursive_mutex(const recursive_mutex&) = delete;
    recursive_mutex& operator=(const recursive_mutex&) = delete;
};
#endif // _M_CEE

// LOCK PROPERTIES
struct adopt_lock_t { // indicates adopt lock
    explicit adopt_lock_t() = default;
};

struct defer_lock_t { // indicates defer lock
    explicit defer_lock_t() = default;
};

struct try_to_lock_t { // indicates try to lock
    explicit try_to_lock_t() = default;
};

_INLINE_VAR constexpr adopt_lock_t adopt_lock{};
_INLINE_VAR constexpr defer_lock_t defer_lock{};
_INLINE_VAR constexpr try_to_lock_t try_to_lock{};

// CLASS TEMPLATE unique_lock
template <class _Mutex>
class unique_lock { // whizzy class with destructor that unlocks mutex
public:
    using mutex_type = _Mutex;

    // CONSTRUCT, ASSIGN, AND DESTROY
    unique_lock() noexcept : _Pmtx(nullptr), _Owns(false) {}

    explicit unique_lock(_Mutex& _Mtx) : _Pmtx(_STD addressof(_Mtx)), _Owns(false) { // construct and lock
        _Pmtx->lock();
        _Owns = true;
    }

    unique_lock(_Mutex& _Mtx, adopt_lock_t)
        : _Pmtx(_STD addressof(_Mtx)), _Owns(true) { // construct and assume already locked
    }

    unique_lock(_Mutex& _Mtx, defer_lock_t) noexcept
        : _Pmtx(_STD addressof(_Mtx)), _Owns(false) { // construct but don't lock
    }

    unique_lock(_Mutex& _Mtx, try_to_lock_t)
        : _Pmtx(_STD addressof(_Mtx)), _Owns(_Pmtx->try_lock()) { // construct and try to lock
    }

    template <class _Rep, class _Period>
    unique_lock(_Mutex& _Mtx, const chrono::duration<_Rep, _Period>& _Rel_time)
        : _Pmtx(_STD addressof(_Mtx)), _Owns(_Pmtx->try_lock_for(_Rel_time)) { // construct and lock with timeout
    }

    template <class _Clock, class _Duration>
    unique_lock(_Mutex& _Mtx, const chrono::time_point<_Clock, _Duration>& _Abs_time)
        : _Pmtx(_STD addressof(_Mtx)), _Owns(_Pmtx->try_lock_until(_Abs_time)) { // construct and lock with timeout
    }

    unique_lock(_Mutex& _Mtx, const xtime* _Abs_time)
        : _Pmtx(_STD addressof(_Mtx)), _Owns(false) { // try to lock until _Abs_time
        _Owns = _Pmtx->try_lock_until(_Abs_time);
    }

    unique_lock(unique_lock&& _Other) noexcept : _Pmtx(_Other._Pmtx), _Owns(_Other._Owns) {
        _Other._Pmtx = nullptr;
        _Other._Owns = false;
    }

    unique_lock& operator=(unique_lock&& _Other) {
        if (this != _STD addressof(_Other)) {
            if (_Owns) {
                _Pmtx->unlock();
            }

            _Pmtx        = _Other._Pmtx;
            _Owns        = _Other._Owns;
            _Other._Pmtx = nullptr;
            _Other._Owns = false;
        }
        return *this;
    }

    ~unique_lock() noexcept {
        if (_Owns) {
            _Pmtx->unlock();
        }
    }

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

    void lock() { // lock the mutex
        _Validate();
        _Pmtx->lock();
        _Owns = true;
    }

    _NODISCARD bool try_lock() {
        _Validate();
        _Owns = _Pmtx->try_lock();
        return _Owns;
    }

    template <class _Rep, class _Period>
    _NODISCARD bool try_lock_for(const chrono::duration<_Rep, _Period>& _Rel_time) {
        _Validate();
        _Owns = _Pmtx->try_lock_for(_Rel_time);
        return _Owns;
    }

    template <class _Clock, class _Duration>
    _NODISCARD bool try_lock_until(const chrono::time_point<_Clock, _Duration>& _Abs_time) {
        _Validate();
        _Owns = _Pmtx->try_lock_until(_Abs_time);
        return _Owns;
    }

    _NODISCARD bool try_lock_until(const xtime* _Abs_time) {
        _Validate();
        _Owns = _Pmtx->try_lock_until(_Abs_time);
        return _Owns;
    }

    void unlock() {
        if (!_Pmtx || !_Owns) {
            _Throw_system_error(errc::operation_not_permitted);
        }

        _Pmtx->unlock();
        _Owns = false;
    }

    void swap(unique_lock& _Other) noexcept {
        _STD swap(_Pmtx, _Other._Pmtx);
        _STD swap(_Owns, _Other._Owns);
    }

    _Mutex* release() noexcept {
        _Mutex* _Res = _Pmtx;
        _Pmtx        = nullptr;
        _Owns        = false;
        return _Res;
    }

    _NODISCARD bool owns_lock() const noexcept {
        return _Owns;
    }

    explicit operator bool() const noexcept {
        return _Owns;
    }

    _NODISCARD _Mutex* mutex() const noexcept {
        return _Pmtx;
    }

private:
    _Mutex* _Pmtx;
    bool _Owns;

    void _Validate() const { // check if the mutex can be locked
        if (!_Pmtx) {
            _Throw_system_error(errc::operation_not_permitted);
        }

        if (_Owns) {
            _Throw_system_error(errc::resource_deadlock_would_occur);
        }
    }
};

// FUNCTION TEMPLATE swap FOR unique_lock
template <class _Mutex>
void swap(unique_lock<_Mutex>& _Left, unique_lock<_Mutex>& _Right) noexcept {
    _Left.swap(_Right);
}

// FUNCTION TEMPLATE _Lock_from_locks
template <size_t... _Indices, class... _LockN>
void _Lock_from_locks(const int _Target, index_sequence<_Indices...>, _LockN&... _LkN) { // lock _LkN[_Target]
    int _Ignored[] = {((static_cast<int>(_Indices) == _Target ? (void) _LkN.lock() : void()), 0)...};
    (void) _Ignored;
}

// FUNCTION TEMPLATE _Try_lock_from_locks
template <size_t... _Indices, class... _LockN>
bool _Try_lock_from_locks(
    const int _Target, index_sequence<_Indices...>, _LockN&... _LkN) { // try to lock _LkN[_Target]
    bool _Result{};
    int _Ignored[] = {((static_cast<int>(_Indices) == _Target ? (void) (_Result = _LkN.try_lock()) : void()), 0)...};
    (void) _Ignored;
    return _Result;
}

// FUNCTION TEMPLATE _Unlock_locks
template <size_t... _Indices, class... _LockN>
void _Unlock_locks(const int _First, const int _Last, index_sequence<_Indices...>, _LockN&... _LkN) noexcept
/* terminates */ {
    // unlock locks in _LkN[_First, _Last)
    int _Ignored[] = {
        ((_First <= static_cast<int>(_Indices) && static_cast<int>(_Indices) < _Last ? (void) _LkN.unlock() : void()),
            0)...};
    (void) _Ignored;
}

// FUNCTION TEMPLATE try_lock
template <class... _LockN>
int _Try_lock_range(const int _First, const int _Last, _LockN&... _LkN) {
    using _Indices = index_sequence_for<_LockN...>;
    int _Next      = _First;
    _TRY_BEGIN
    for (; _Next != _Last; ++_Next) {
        if (!_Try_lock_from_locks(_Next, _Indices{}, _LkN...)) { // try_lock failed, backout
            _Unlock_locks(_First, _Next, _Indices{}, _LkN...);
            return _Next;
        }
    }
    _CATCH_ALL
    _Unlock_locks(_First, _Next, _Indices{}, _LkN...);
    _RERAISE;
    _CATCH_END

    return -1;
}

template <class _Lock0, class _Lock1, class _Lock2, class... _LockN>
int _Try_lock1(_Lock0& _Lk0, _Lock1& _Lk1, _Lock2& _Lk2, _LockN&... _LkN) { // try to lock 3 or more locks
    return _Try_lock_range(0, sizeof...(_LockN) + 3, _Lk0, _Lk1, _Lk2, _LkN...);
}

template <class _Lock0, class _Lock1>
int _Try_lock1(_Lock0& _Lk0, _Lock1& _Lk1) {
    // try to lock 2 locks, special case for better codegen and reduced metaprogramming for common case
    if (!_Lk0.try_lock()) {
        return 0;
    }

    _TRY_BEGIN
    if (!_Lk1.try_lock()) {
        _Lk0.unlock();
        return 1;
    }
    _CATCH_ALL
    _Lk0.unlock();
    _RERAISE;
    _CATCH_END

    return -1;
}

template <class _Lock0, class _Lock1, class... _LockN>
_NODISCARD int try_lock(_Lock0& _Lk0, _Lock1& _Lk1, _LockN&... _LkN) { // try to lock multiple locks
    return _Try_lock1(_Lk0, _Lk1, _LkN...);
}


// FUNCTION TEMPLATE lock
template <class... _LockN>
int _Lock_attempt(const int _Hard_lock, _LockN&... _LkN) {
    // attempt to lock 3 or more locks, starting by locking _LkN[_Hard_lock] and trying to lock the rest
    using _Indices = index_sequence_for<_LockN...>;
    _Lock_from_locks(_Hard_lock, _Indices{}, _LkN...);
    int _Failed        = -1;
    int _Backout_start = _Hard_lock; // that is, unlock _Hard_lock

    _TRY_BEGIN
    _Failed = _Try_lock_range(0, _Hard_lock, _LkN...);
    if (_Failed == -1) {
        _Backout_start = 0; // that is, unlock [0, _Hard_lock] if the next throws
        _Failed        = _Try_lock_range(_Hard_lock + 1, sizeof...(_LockN), _LkN...);
        if (_Failed == -1) { // we got all the locks
            return -1;
        }
    }
    _CATCH_ALL
    _Unlock_locks(_Backout_start, _Hard_lock + 1, _Indices{}, _LkN...);
    _RERAISE;
    _CATCH_END

    // we didn't get all the locks, backout
    _Unlock_locks(_Backout_start, _Hard_lock + 1, _Indices{}, _LkN...);
    _STD this_thread::yield();
    return _Failed;
}

template <class _Lock0, class _Lock1, class _Lock2, class... _LockN>
void _Lock_nonmember1(_Lock0& _Lk0, _Lock1& _Lk1, _Lock2& _Lk2, _LockN&... _LkN) {
    // lock 3 or more locks, without deadlock
    int _Hard_lock = 0;
    while (_Hard_lock != -1) {
        _Hard_lock = _Lock_attempt(_Hard_lock, _Lk0, _Lk1, _Lk2, _LkN...);
    }
}

template <class _Lock0, class _Lock1>
bool _Lock_attempt_small(_Lock0& _Lk0, _Lock1& _Lk1) {
    // attempt to lock 2 locks, by first locking _Lk0, and then trying to lock _Lk1 returns whether to try again
    _Lk0.lock();
    _TRY_BEGIN
    if (_Lk1.try_lock()) {
        return false;
    }
    _CATCH_ALL
    _Lk0.unlock();
    _RERAISE;
    _CATCH_END

    _Lk0.unlock();
    _STD this_thread::yield();
    return true;
}

template <class _Lock0, class _Lock1>
void _Lock_nonmember1(_Lock0& _Lk0, _Lock1& _Lk1) {
    // lock 2 locks, without deadlock, special case for better codegen and reduced metaprogramming for common case
    while (_Lock_attempt_small(_Lk0, _Lk1) && _Lock_attempt_small(_Lk1, _Lk0)) { // keep trying
    }
}

template <class _Lock0, class _Lock1, class... _LockN>
void lock(_Lock0& _Lk0, _Lock1& _Lk1, _LockN&... _LkN) { // lock multiple locks, without deadlock
    _Lock_nonmember1(_Lk0, _Lk1, _LkN...);
}


// CLASS TEMPLATE lock_guard
template <class _Mutex>
class lock_guard { // class with destructor that unlocks a mutex
public:
    using mutex_type = _Mutex;

    explicit lock_guard(_Mutex& _Mtx) : _MyMutex(_Mtx) { // construct and lock
        _MyMutex.lock();
    }

    lock_guard(_Mutex& _Mtx, adopt_lock_t) : _MyMutex(_Mtx) { // construct but don't lock
    }

    ~lock_guard() noexcept {
        _MyMutex.unlock();
    }

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

private:
    _Mutex& _MyMutex;
};

#if _HAS_CXX17
// CLASS TEMPLATE scoped_lock
template <class... _Mutexes>
class scoped_lock { // class with destructor that unlocks mutexes
public:
    explicit scoped_lock(_Mutexes&... _Mtxes) : _MyMutexes(_Mtxes...) { // construct and lock
        _STD lock(_Mtxes...);
    }

    explicit scoped_lock(adopt_lock_t, _Mutexes&... _Mtxes) : _MyMutexes(_Mtxes...) { // construct but don't lock
    }

    ~scoped_lock() noexcept {
        _For_each_tuple_element(_MyMutexes, [](auto& _Mutex) noexcept { _Mutex.unlock(); });
    }

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

private:
    tuple<_Mutexes&...> _MyMutexes;
};

template <class _Mutex>
class scoped_lock<_Mutex> {
public:
    using mutex_type = _Mutex;

    explicit scoped_lock(_Mutex& _Mtx) : _MyMutex(_Mtx) { // construct and lock
        _MyMutex.lock();
    }

    explicit scoped_lock(adopt_lock_t, _Mutex& _Mtx) : _MyMutex(_Mtx) { // construct but don't lock
    }

    ~scoped_lock() noexcept {
        _MyMutex.unlock();
    }

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

private:
    _Mutex& _MyMutex;
};

template <>
class scoped_lock<> {
public:
    explicit scoped_lock() {}
    explicit scoped_lock(adopt_lock_t) {}
    ~scoped_lock() noexcept {}

    scoped_lock(const scoped_lock&) = delete;
    scoped_lock& operator=(const scoped_lock&) = delete;
};
#endif // _HAS_CXX17

// FUNCTION TEMPLATE _Invoke_stored_explicit
template <class... _Types, size_t... _Indices>
auto _Invoke_stored_explicit(tuple<_Types...>&& _Tuple, index_sequence<_Indices...>) -> decltype(
    _STD invoke(_STD get<_Indices>(_STD move(_Tuple))...)) { // invoke() a tuple with explicit parameter ordering
    return _STD invoke(_STD get<_Indices>(_STD move(_Tuple))...);
}

// FUNCTION TEMPLATE _Invoke_stored
template <class... _Types>
auto _Invoke_stored(tuple<_Types...>&& _Tuple)
    -> decltype(_Invoke_stored_explicit(_STD move(_Tuple), index_sequence_for<_Types...>())) { // invoke() a tuple
    return _Invoke_stored_explicit(_STD move(_Tuple), index_sequence_for<_Types...>());
}

// FUNCTION TEMPLATE call_once
[[noreturn]] _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL _XGetLastError();

template <class _Tuple, class _Seq, size_t _Idx>
int __stdcall _Callback_once(void*, void* _Pv, void**) { // adapt call_once() to callback API
    _Tuple* _Ptup = static_cast<_Tuple*>(_Pv);

    _TRY_BEGIN
    // Note explicit _Seq() selects every element from *_Ptup except the last,
    // which contains call_once's exception_ptr.
    _Invoke_stored_explicit(_STD move(*_Ptup), _Seq());
    _CATCH_ALL
    auto& _Ref = _STD get<_Idx>(*_Ptup);
    _Ref       = _STD current_exception();
    return 0;
    _CATCH_END

    return 1;
}

template <class _Fn, class... _Args>
void(call_once)(once_flag& _Flag, _Fn&& _Fx, _Args&&... _Ax) { // call _Fx(_Ax...) once
    using _Tuple = tuple<_Fn&&, _Args&&..., exception_ptr&>;
    using _Seq   = make_index_sequence<1 + sizeof...(_Args)>;

    exception_ptr _Exc;
    _Tuple _Tup(_STD forward<_Fn>(_Fx), _STD forward<_Args>(_Ax)..., _Exc);

    _Execute_once_fp_t _Fp = &_Callback_once<_Tuple, _Seq, 1 + sizeof...(_Args)>;

    if (_Execute_once(_Flag, _Fp, _STD addressof(_Tup)) != 0) {
        return;
    }

    if (_Exc) {
        _STD rethrow_exception(_Exc);
    }

    _XGetLastError();
}

// condition_variable, timed_mutex, and recursive_timed_mutex are not supported under /clr
#ifndef _M_CEE
enum class cv_status { // names for wait returns
    no_timeout,
    timeout
};

class condition_variable { // class for waiting for conditions
public:
    using native_handle_type = _Cnd_t;

    condition_variable() {
        _Cnd_init_in_situ(_Mycnd());
    }

    ~condition_variable() noexcept {
        _Cnd_destroy_in_situ(_Mycnd());
    }

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

    void notify_one() noexcept { // wake up one waiter
        _Check_C_return(_Cnd_signal(_Mycnd()));
    }

    void notify_all() noexcept { // wake up all waiters
        _Check_C_return(_Cnd_broadcast(_Mycnd()));
    }

    void wait(unique_lock<mutex>& _Lck) { // wait for signal
        // Nothing to do to comply with LWG-2135 because std::mutex lock/unlock are nothrow
        _Check_C_return(_Cnd_wait(_Mycnd(), _Lck.mutex()->_Mymtx()));
    }

    template <class _Predicate>
    void wait(unique_lock<mutex>& _Lck, _Predicate _Pred) { // wait for signal and test predicate
        while (!_Pred()) {
            wait(_Lck);
        }
    }

    template <class _Rep, class _Period>
    cv_status wait_for(unique_lock<mutex>& _Lck, const chrono::duration<_Rep, _Period>& _Rel_time) {
        // wait for duration
        if (_Rel_time <= chrono::duration<_Rep, _Period>::zero()) {
            return cv_status::timeout;
        }

        // TRANSITION, ABI: The standard says that we should use a steady clock,
        // but unfortunately our ABI speaks struct xtime, which is relative to the system clock.
        _CSTD xtime _Tgt;
        const bool _Clamped     = _To_xtime_10_day_clamped(_Tgt, _Rel_time);
        const cv_status _Result = wait_until(_Lck, &_Tgt);
        if (_Clamped) {
            return cv_status::no_timeout;
        }

        return _Result;
    }

    template <class _Rep, class _Period, class _Predicate>
    bool wait_for(unique_lock<mutex>& _Lck, const chrono::duration<_Rep, _Period>& _Rel_time, _Predicate _Pred) {
        // wait for signal with timeout and check predicate
        return _Wait_until1(_Lck, chrono::steady_clock::now() + _Rel_time, _Pred);
    }

    template <class _Clock, class _Duration>
    cv_status wait_until(unique_lock<mutex>& _Lck, const chrono::time_point<_Clock, _Duration>& _Abs_time) {
        // wait until time point
        for (;;) {
            const auto _Now = _Clock::now();
            if (_Abs_time <= _Now) {
                return cv_status::timeout;
            }

            _CSTD xtime _Tgt;
            (void) _To_xtime_10_day_clamped(_Tgt, _Abs_time - _Now);
            const cv_status _Result = wait_until(_Lck, &_Tgt);
            if (_Result == cv_status::no_timeout) {
                return cv_status::no_timeout;
            }
        }
    }

    template <class _Clock, class _Duration, class _Predicate>
    bool wait_until(
        unique_lock<mutex>& _Lck, const chrono::time_point<_Clock, _Duration>& _Abs_time, _Predicate _Pred) {
        // wait for signal with timeout and check predicate
        return _Wait_until1(_Lck, _Abs_time, _Pred);
    }

    cv_status wait_until(unique_lock<mutex>& _Lck, const xtime* _Abs_time) {
        // wait for signal with timeout
        if (!_Mtx_current_owns(_Lck.mutex()->_Mymtx())) {
            _Throw_Cpp_error(_OPERATION_NOT_PERMITTED);
        }

        // Nothing to do to comply with LWG-2135 because std::mutex lock/unlock are nothrow
        const int _Res = _Cnd_timedwait(_Mycnd(), _Lck.mutex()->_Mymtx(), _Abs_time);
        switch (_Res) {
        case _Thrd_success:
            return cv_status::no_timeout;
        case _Thrd_timedout:
            return cv_status::timeout;
        default:
            _Throw_C_error(_Res);
        }
    }

    template <class _Predicate>
    bool wait_until(unique_lock<mutex>& _Lck, const xtime* _Abs_time, _Predicate _Pred) {
        // wait for signal with timeout and check predicate
        return _Wait_until1(_Lck, _Abs_time, _Pred);
    }

    _NODISCARD native_handle_type native_handle() {
        return _Mycnd();
    }

    void _Register(unique_lock<mutex>& _Lck, int* _Ready) { // register this object for release at thread exit
        _Cnd_register_at_thread_exit(_Mycnd(), _Lck.release()->_Mymtx(), _Ready);
    }

    void _Unregister(mutex& _Mtx) { // unregister this object for release at thread exit
        _Cnd_unregister_at_thread_exit(_Mtx._Mymtx());
    }

private:
    aligned_storage_t<_Cnd_internal_imp_size, _Cnd_internal_imp_alignment> _Cnd_storage;

    _Cnd_t _Mycnd() noexcept { // get pointer to _Cnd_internal_imp_t inside _Cnd_storage
        return reinterpret_cast<_Cnd_t>(&_Cnd_storage);
    }

    template <class _Predicate>
    bool _Wait_until1(unique_lock<mutex>& _Lck, const xtime* _Abs_time, _Predicate& _Pred) {
        // wait for signal with timeout and check predicate
        while (!_Pred()) {
            if (wait_until(_Lck, _Abs_time) == cv_status::timeout) {
                return _Pred();
            }
        }

        return true;
    }

    template <class _Clock, class _Duration, class _Predicate>
    bool _Wait_until1(
        unique_lock<mutex>& _Lck, const chrono::time_point<_Clock, _Duration>& _Abs_time, _Predicate& _Pred) {
        while (!_Pred()) {
            const auto _Now = _Clock::now();
            if (_Abs_time <= _Now) {
                return false;
            }

            _CSTD xtime _Tgt;
            const bool _Clamped = _To_xtime_10_day_clamped(_Tgt, _Abs_time - _Now);
            if (wait_until(_Lck, &_Tgt) == cv_status::timeout && !_Clamped) {
                return _Pred();
            }
        }

        return true;
    }
};

struct _UInt_is_zero {
    const unsigned int& _UInt;

    _NODISCARD bool operator()() const {
        return _UInt == 0;
    }
};

class timed_mutex { // class for timed mutual exclusion
public:
    timed_mutex() noexcept : _My_locked(0) {}

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

    void lock() { // lock the mutex
        unique_lock<mutex> _Lock(_My_mutex);
        while (_My_locked != 0) {
            _My_cond.wait(_Lock);
        }

        _My_locked = UINT_MAX;
    }

    _NODISCARD bool try_lock() noexcept { // try to lock the mutex
        lock_guard<mutex> _Lock(_My_mutex);
        if (_My_locked != 0) {
            return false;
        } else {
            _My_locked = UINT_MAX;
            return true;
        }
    }

    void unlock() { // unlock the mutex
        {
            // The lock here is necessary
            lock_guard<mutex> _Lock(_My_mutex);
            _My_locked = 0;
        }
        _My_cond.notify_one();
    }

    template <class _Rep, class _Period>
    _NODISCARD bool try_lock_for(const chrono::duration<_Rep, _Period>& _Rel_time) { // try to lock for duration
        return try_lock_until(chrono::steady_clock::now() + _Rel_time);
    }

    template <class _Time>
    bool _Try_lock_until(_Time _Abs_time) { // try to lock the mutex with timeout
        unique_lock<mutex> _Lock(_My_mutex);
        if (!_My_cond.wait_until(_Lock, _Abs_time, _UInt_is_zero{_My_locked})) {
            return false;
        }

        _My_locked = UINT_MAX;
        return true;
    }

    template <class _Clock, class _Duration>
    _NODISCARD bool try_lock_until(
        const chrono::time_point<_Clock, _Duration>& _Abs_time) { // try to lock the mutex with timeout
        return _Try_lock_until(_Abs_time);
    }

    _NODISCARD bool try_lock_until(const xtime* _Abs_time) { // try to lock the mutex with timeout
        return _Try_lock_until(_Abs_time);
    }

private:
    mutex _My_mutex;
    condition_variable _My_cond;
    unsigned int _My_locked;
};

class recursive_timed_mutex { // class for recursive timed mutual exclusion
public:
    recursive_timed_mutex() noexcept : _My_locked(0) {}

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

    void lock() { // lock the mutex
        const thread::id _Tid = this_thread::get_id();

        unique_lock<mutex> _Lock(_My_mutex);

        if (_Tid == _My_owner) {
            if (_My_locked < UINT_MAX) {
                ++_My_locked;
            } else {
                _Throw_system_error(errc::device_or_resource_busy);
            }
        } else {
            while (_My_locked != 0) {
                _My_cond.wait(_Lock);
            }

            _My_locked = 1;
            _My_owner  = _Tid;
        }
    }

    _NODISCARD bool try_lock() noexcept { // try to lock the mutex
        const thread::id _Tid = this_thread::get_id();

        lock_guard<mutex> _Lock(_My_mutex);

        if (_Tid == _My_owner) {
            if (_My_locked < UINT_MAX) {
                ++_My_locked;
            } else {
                return false;
            }
        } else {
            if (_My_locked != 0) {
                return false;
            } else {
                _My_locked = 1;
                _My_owner  = _Tid;
            }
        }
        return true;
    }

    void unlock() { // unlock the mutex
        bool _Do_notify = false;

        {
            lock_guard<mutex> _Lock(_My_mutex);
            --_My_locked;
            if (_My_locked == 0) {
                _Do_notify = true;
                _My_owner  = thread::id();
            }
        }

        if (_Do_notify) {
            _My_cond.notify_one();
        }
    }

    template <class _Rep, class _Period>
    _NODISCARD bool try_lock_for(const chrono::duration<_Rep, _Period>& _Rel_time) { // try to lock for duration
        return try_lock_until(chrono::steady_clock::now() + _Rel_time);
    }

    template <class _Time>
    bool _Try_lock_until(_Time _Abs_time) { // try to lock the mutex with timeout
        const thread::id _Tid = this_thread::get_id();

        unique_lock<mutex> _Lock(_My_mutex);

        if (_Tid == _My_owner) {
            if (_My_locked < UINT_MAX) {
                ++_My_locked;
            } else {
                return false;
            }
        } else {
            if (!_My_cond.wait_until(_Lock, _Abs_time, _UInt_is_zero{_My_locked})) {
                return false;
            }

            _My_locked = 1;
            _My_owner  = _Tid;
        }
        return true;
    }

    template <class _Clock, class _Duration>
    _NODISCARD bool try_lock_until(
        const chrono::time_point<_Clock, _Duration>& _Abs_time) { // try to lock the mutex with timeout
        return _Try_lock_until(_Abs_time);
    }

    _NODISCARD bool try_lock_until(const xtime* _Abs_time) { // try to lock the mutex with timeout
        return _Try_lock_until(_Abs_time);
    }

private:
    mutex _My_mutex;
    condition_variable _My_cond;
    unsigned int _My_locked;
    thread::id _My_owner;
};
#endif // _M_CEE
_STD_END
#pragma pop_macro("new")
_STL_RESTORE_CLANG_WARNINGS
#pragma warning(pop)
#pragma pack(pop)
#endif // _STL_COMPILER_PREPROCESSOR
#endif // _MUTEX_