Function recv_loop 

async fn recv_loop<R, K>(
    name: &'static str,
    id: K,
    reader: R,
    state: Arc<Mutex<TransportState>>,
    to_deliver: Sender<(K, Bytes, Option<OwnedSemaphorePermit>)>,
    to_writer: Sender<Message>,
    metrics: Arc<NetworkMetrics<K>>,
    budget: Arc<Semaphore>,
    countdown: Countdown,
    max_message_size: usize,
) -> Result<(), NetworkError>
where
    R: AsyncRead + Unpin,
    K: Eq + Hash + Display + Clone,

Read messages from the remote by assembling frames together.

Once complete the message will be handed over to the given MPSC sender.