Method lock_sub

library/PluginManager.cpp:111–117

        mut->unlock();
    }
    void lock_sub()
    {
        mut->lock();
        if (--refcount == 0)
            wakeup->notify_one();
        mut->unlock();
    }
    void wait()
    {
        std::unique_lock<std::mutex> lock{*mut,  std::defer_lock};