Cache-Control: stale-while-revalidate

[the-leonat]

Does souin implement asynchronous background fetching similar to varnish grace setting?
I could not find anything about it in the docs and it seems to ignore my cache-control response header of my upstream webserver.
public, max-age=120, stale-while-revalidate=3600.
after the content turns stale souin replies once with:
Cache-Status: Souin; fwd=uri-miss; key={{key}}-/; detail=UNCACHEABLE-STATUS-CODE

server responds with code 304.

func isCacheableCode(code int) bool {
	switch code {
	case 200, 203, 204, 206, 300, 301, 404, 405, 410, 414, 501:
		return true
	}

	return false
}

but 304 is not a cacheable status code by implementation. is this a bug?

[darkweak]

Hello @the-leonat sorry for the delay, I was on other subjects.

In theory the stale while revalidate is working but seeing your issue, there is probably a bug.
After reading your issue, it seems the revalidation doesn't work, because it tries to store the given response that has a 304 status code. the revalidation block is the following:

		err := next(customWriter, rq)
		s.SurrogateKeyStorer.Invalidate(rq.Method, customWriter.Header())

		statusCode := customWriter.GetStatusCode()
		if err == nil {
			if validator.IfUnmodifiedSincePresent && statusCode != http.StatusNotModified {
				customWriter.Buf.Reset()
				customWriter.Rw.WriteHeader(http.StatusPreconditionFailed)

				return nil, errors.New("")
			}

			if statusCode != http.StatusNotModified {
				err = s.Store(customWriter, rq, requestCc, cachedKey)
			}
		}

If it returns a detail=UNCACHEABLE-STATUS-CODE that means you're going through the Store function and your http status code is not a not modified.