A cached source and its variants were served until eviction, so a
changed image at the same URL was never picked up.
After 24 hours a request checks the source with upstream, sending its
stored ETag and Last-Modified. A 304 renews the source with no download
or conversion. New bytes replace the source, and older variants are
converted again. A failed check serves the cached image and puts the
URL in the negative cache. This includes the full fetch made for a
variant whose source was evicted. Images not checked for 30 days are
evicted.
A variant file's modification time is its source's check time, so a
hit still makes no database call.
Model: opus-5-5
magic.DetectFormat returns an imagerequest.Format. ValidateMagicBytes
returns the format it checked against the upstream Content-Type. The
cache reads a cached source's format from its file's first bytes, as it
reads a variant's. The proxy hands the format to Process. Process
refuses a format that is not a source format, and input libvips would
load with another loader, such as an SVG passing as AVIF.
Format.MIMEType declares each MIME string once, and the fetcher, the
cache's variant read and the Accept matching use it. magic.MIMEType,
magic.ImageFormat, MIMEToImageFormat, magic's SVG detection,
detectFormat, formatFromString, FormatToMIME and Result.InputFormat are
gone.
Model: opus-5-5
The new package internal/imageproxy holds Proxy, which was imgcache.Service,
with its Config, ImageResponse, CacheStatus and errors. imageproxy.New makes
and registers the counters of upstream fetches and transforms.
internal/imgcache holds the cache only, with its hit and miss counters, and
imgcache.CacheConfig is imgcache.Config. The cache reads and writes each kind
it keeps with one pair of methods: Variant and PutVariant, Source and
PutSource, Failure and PutFailure. Source replaces LookupSource followed by
GetSourceContent. imgcache.go and module.go are gone. The proxy's tests moved
with it. The cache's tests check that the reconciliation pass removes an empty
or cut file and its row. The proxy's tests remove them by hand, then check
that Get fetches or converts again.
Model: opus-5-5