Method init

net/kernel_socket.cpp:826–832

    EventLoop* loop = nullptr;

    int init() {
        epfd = epoll_create(1);
        loop = new_event_loop({this, &ETPoller::waiter},
                              {this, &ETPoller::notify});
        loop->async_run();
        return epfd;
    }

    int fini() {
        loop->stop();