Function try_parse_request 

pub fn try_parse_request(buf: &[u8]) -> ParseResult<(Request<'_>, usize)>

Try to parse one complete request from buf.

Returns a ParseResult that distinguishes “need more data” (Incomplete), “unrecoverable framing error” (BadMagic), and “parseable header but invalid body layout” (MalformedFrame) from a successful parse (Ok).