Method encode_inner

src/balancerd/src/codec.rs:163–228

This is the meat of the encoding logic. It's a separate function so that errors returned by `?` can be handled in the outer `encode` function.

(&self, msg: BackendMessage, dst: &mut BytesMut)

    /// This is the meat of the encoding logic. It's a separate function so that errors returned by
    /// `?` can be handled in the outer `encode` function.
    fn encode_inner(&self, msg: BackendMessage, dst: &mut BytesMut) -> Result<(), io::Error> {
        // Write type byte.
        let byte = match &msg {
            BackendMessage::AuthenticationCleartextPassword => b'R',
            BackendMessage::ErrorResponse(r) => {
                if r.severity.is_error() {
                    b'E'
                } else {
                    b'N'
                }
            }
        };
        dst.put_u8(byte);

        // Write message length placeholder. The true length is filled in later.
        let base = dst.len();
        dst.put_u32(0);

        // Write message contents.
        match msg {
            BackendMessage::AuthenticationCleartextPassword => {
                dst.put_u32(3);
            }
            BackendMessage::ErrorResponse(ErrorResponse {
                severity,
                code,
                message,
                detail,
                hint,
                position,
            }) => {
                dst.put_u8(b'S');
                dst.put_string(severity.as_str());
                dst.put_u8(b'C');
                dst.put_string(code.code());
                dst.put_u8(b'M');
                dst.put_string(&message);
                if let Some(detail) = &detail {
                    dst.put_u8(b'D');
                    dst.put_string(detail);
                }
                if let Some(hint) = &hint {
                    dst.put_u8(b'H');
                    dst.put_string(hint);
                }
                if let Some(position) = &position {
                    dst.put_u8(b'P');
                    dst.put_string(&position.to_string());
                }
                dst.put_u8(b'\0');
            }
        }

        let len = dst.len() - base;

        // Overwrite length placeholder with true length.
        let len = i32::try_from(len).map_err(|_| {
            io::Error::new(