Implement stale while revalidate

[mcollina]

Signed-off-by: Matteo Collina hello@matteocollina.com

33

[simone-sanfratello]

I'm not sure of the implementation, I think the stale should kind of extend the expiration of the cache entries as ttl+stale, so we can still serve the old cached values while running the refresh - I'm not sure, I may be wrong with that.

I've found this https://web.dev/stale-while-revalidate/#whats-it-mean maybe can help

[mcollina]

I'm not sure of the implementation, I think the stale should kind of extend the expiration of the cache entries as ttl+stale, so we can still serve the old cached values while running the refresh - I'm not sure, I may be wrong with that.

Good catch! I'll update the way the ttl and stale parameters compute the final expiration time.

[mcollina]

PTAL, updated.

[simone-sanfratello]

LGTM!