store

class Store {
public:
    std::shared_ptr<Bread> GetBread() {
        mut.lock();
        ThreadChecker checker(count_);
        ++next_id_;
        mut.unlock();
        return std::make_shared<Bread>(next_id_);
    }

    std::shared_ptr<Sausage> GetSausage() {
        mut.lock();
        ThreadChecker checker(count_);
        ++next_id_;
        mut.unlock();
        return std::make_shared<Sausage>(next_id_);
    }

private:
    int next_id_ = 0;
    std::atomic_int count_ = 0;
    std::mutex mut;
}