Function serve_connection 

pub async fn serve_connection<S, H>(
    scheduler: &S,
    socket: S::Socket,
    handler: &H,
    options: &Options,
    cancellation: &Cancellation,
) -> Result<u64, Error>
where
    S: SocketStreamReading + SocketStreamWriting + SocketClose,
    S::Socket: 'static,
    H: Handler,

Own one accepted socket through request admission, handler execution, output, uncancellable lane retirement, and finally exclusive socket closure. Await completion after cooperative cancellation; dropping this future is not a join.