Module conditional 

ETags and conditional requests

• ETags middleware: tags GET responses with an ETag derived from the body and answers 304 Not Modified when the client’s If-None-Match still matches. Responses that already carry an ETag keep it.
• require_if_match: optimistic concurrency for updates. The client sends the ETag it last saw as If-Match; a stale one gets 412, a missing one 428, so concurrent edits cannot silently overwrite each other.

use ullun::conditional::{etag_for, if_none_match_hits};

let tag = etag_for(b"hello");
assert!(if_none_match_hits(&tag, &tag));
assert!(if_none_match_hits("\"other\", *", &tag));
assert!(!if_none_match_hits("\"other\"", &tag));

Structs

ETags

Middleware adding ETag and 304 Not Modified handling to GET responses

Functions

etag_for

Strong ETag for a body: 64-bit FNV-1a plus the length, e.g. "2f3c...-5". Stable across processes and releases (unlike DefaultHasher).

if_match_hits

If-Match evaluation: strong comparison, so weak tags never match

if_none_match_hits

If-None-Match evaluation: weak comparison, * matches anything

require_if_match

Precondition for updating a resource whose current tag is current_etag