// Put client to sleep, since there is no more data for it; we will on
// longer listen on POLLOUT until we get more data. Also, it will be put
// in the list of clients to wake up when we do.
// Put client to sleep, since there is no more data for it; we will on
// longer listen on POLLOUT until we get more data. Also, it will be put
// in the list of clients to wake up when we do.