check / check (push) Canceled after 0s
Cached images were served until eviction, so upstream changes were missed. After 24 hours a request checks the source with upstream, sending its stored ETag and Last-Modified. A 304 renews it with no download or conversion. New bytes replace it; older variants are converted again. A failed check serves the cached image and puts the URL in the negative cache. Images not checked for 30 days are evicted. Variant rows keep the source's ETag and Last-Modified for checking a variant of an evicted source. A variant file's modification time is its source's check time when it was made or renewed. Hits read it without a database call. The ETag includes it, so new bytes get a new ETag. Model: opus-5-5