This is part of web-monitoring#168 — the goal here is to make our diff cache less important so we can shrink it or even remove it (in favor of just having CloudFront do the job).
CloudFront needs a Date header to go with the Last-Modified and ETag headers from the stale? method, and works better still if we give it an actual cache age. This adds the expires_in helper which sets all the headers. I've also taken the strategy of setting a relatively short cache time but a much longer revalidation window when a stale response can be used, to balance concerns about updating the diff algorithm and effective long-term caching.
This is part of web-monitoring#168 — the goal here is to make our diff cache less important so we can shrink it or even remove it (in favor of just having CloudFront do the job).
CloudFront needs a
Dateheader to go with theLast-ModifiedandETagheaders from thestale?method, and works better still if we give it an actual cache age. This adds theexpires_inhelper which sets all the headers. I've also taken the strategy of setting a relatively short cache time but a much longer revalidation window when a stale response can be used, to balance concerns about updating the diff algorithm and effective long-term caching.