Function read_value 

pub fn read_value<R, T>(
    reader: &mut R,
    codec: &dyn Codec,
    max_bytes: usize,
) -> AppResult<Option<T>>
where
    R: Read,
    T: DeserializeOwned,

Read one frame and decode it into T through codec.

Returns Ok(None) on a clean end-of-stream between frames.

Errors

Returns a typed AppError (cause preserved) on a transport failure or a payload that does not decode into T.