//-----------------------------------------------
// turnstile.h: shared.h + turnstile
//-----------------------------------------------

#ifndef turnstile_h
#define turnstile_h

//-----------------------------------------------

#include <cstddef>      // std::size_t
#include <semaphore>    // std::binary_semaphore
#include <shared_mutex> // std::shared_mutex

//-----------------------------------------------

class turnstile_lock
{
public:
    turnstile_lock(std::size_t) {}

    void reader_lock()
    {
        turnstile.acquire();
        turnstile.release();
        sm.lock_shared();
    }

    void reader_unlock() { sm.unlock_shared(); }

    void writer_lock()
    {
        turnstile.acquire();
        sm.lock();
    }

    void writer_unlock()
    {
        turnstile.release();
        sm.unlock();
    }

private:
    std::binary_semaphore turnstile{1};
    std::shared_mutex sm;
};

//-----------------------------------------------

#endif // turnstile_h