feat(proxy-cache): honor Vary header for memory strategy#13376
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shreemaan-abhishek wants to merge 2 commits into
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feat(proxy-cache): honor Vary header for memory strategy#13376shreemaan-abhishek wants to merge 2 commits into
shreemaan-abhishek wants to merge 2 commits into
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Implement RFC 9111 §4.1 secondary cache key handling for the in-memory
cache. Cache entries are now partitioned by the request's values for
each header listed in the upstream Vary response, so a response cached
under one set of Vary header values is not returned to a request with
different values. Responses carrying `Vary: *` are treated as not
reusable and are not cached.
Storage layout:
- `<base_key>::__vary` holds the variant index `{vary, variants, version}`.
- `<base_key>::<md5(values)>` holds each variant body+headers.
PURGE walks every variant under a base key. CACHE_VERSION is bumped to
2 so any in-flight v1 entries are purged on read via the existing
version-mismatch path. The disk strategy is unchanged: NGINX's native
`proxy_cache` already honors Vary.
- Bound the per-base-key `variants` list to MAX_VARIANTS (64) with FIFO eviction. Without this, a Vary on a high-cardinality header would grow the index until it exceeds the shdict slot capacity and writes start failing with "no memory". - Make the `Vary: *` test deterministic: call `ngx.update_time()` in the fixture and sleep briefly between requests so the body comparison cannot tie on a single nginx time tick. - Trim two over-detailed comments in the handler.
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Description
The memory cache strategy previously ignored the upstream
Varyresponse header, so requests that differed only in a Vary'd header (e.g.Accept-Encoding) collided on the same cache entry. The disk strategy already inherits Vary handling from NGINX's nativeproxy_cache; this PR brings the memory strategy in line.What changes:
Varyheader into a canonical sorted list of lowercased header names.<base_key>::__varydescribing the Vary headers and known variants for that base key.<base_key>::<md5(request values)>.Vary: *is treated as not reusable per RFC 9111 §4.1 and is not cached.PURGEwalks every variant under a base key.CACHE_VERSIONis bumped from 1 to 2 so any pre-Vary entries get purged on read via the existing version-mismatch path.The disk handler is intentionally unchanged.
Which issue(s) this PR fixes:
Fixes #
Checklist
Notes
t/plugin/proxy-cache/memory.twere added (TEST 41–44) but I have not run the suite locally on this branch.proxy_cachealready handlesVary.