Shared mutex discovery

shared_mutex.cpp

#include <mutex>
#include <shared_mutex>
#include <iostream>

template <typename M>
void test(M& mutex)
{
    bool exclusive = false;
    bool shared = false;

    if (mutex.try_lock())
    {
        mutex.unlock();
        exclusive = true;
    }

    if (mutex.try_lock_shared())
    {
        mutex.unlock_shared();
        shared = true;
    }

    auto stringify = [](bool s) { return s ? "free" : "busy"; };

    std::cout << "mutex status: X=" << stringify(exclusive) << ", S=" << stringify(shared) << "\n";
}

int main()
{
    std::shared_mutex mutex;

    test(mutex);
    mutex.lock_shared();
    test(mutex);
    mutex.unlock_shared();
    test(mutex);

    std::cout << "============================\n";

    test(mutex);
    mutex.lock();
    test(mutex);
    mutex.unlock();
    test(mutex);

    return 0;
}