Function q_conn_attach 

pub unsafe extern "C" fn q_conn_attach(
    poll: *mut ray_poll_t,
    fd: c_int,
) -> i64

Put an already-connected, already-handshaken q_connect fd under poll’s rx machine. Returns a poll selector id (>= 0) — the handle for the two calls below — or -1. The fd is owned by the poll from here on; do not q_close it.