Adds the pixa_ metrics the issue lists; README's Architecture section documents each one. None has a label, so host and path cardinality cannot grow.
Things the diff does not make obvious:
pixa_cache_hits_total and pixa_cache_misses_total keep their meaning (image requests, that is variant hits and misses). Source hits and misses are separate counters, pixa_source_cache_hits_total and pixa_source_cache_misses_total, not a label on the old ones: an existing test reads the first series of each family, and AGENTS.md forbids changing existing tests without approval. They count the cache's source lookup once per shared conversion, not once per request.
pixa_cache_usage_bytes is set each time eviction reads the usage total (after each store and every five minutes), so a scrape never touches the database.
Eviction bytes come from DELETE … RETURNING size_bytes. Reconciliation's removal of damaged files now goes through removeVariant / removeSourceBlob, which do not count as evictions.
Transform duration and pixa_transforms_in_progress include the wait for a processing slot: the slot is taken inside the image processor, out of the proxy's sight.
Item 2: coupling kept and documented. The pixa_ metrics were already always measured; only the HTTP middleware metrics depend on the credentials. config.example.yml said all metrics did; it now says which.
fetchSource grew past the length limit, so the negative-cache check moved into refuseNegativeCached, unchanged.
Two commits: the tests, failing on next, then the change.
Model: opus-5-5
Closes https://git.eeqj.de/sneak/pixa/issues/85.
Adds the `pixa_` metrics the issue lists; README's Architecture section documents each one. None has a label, so host and path cardinality cannot grow.
Things the diff does not make obvious:
- `pixa_cache_hits_total` and `pixa_cache_misses_total` keep their meaning (image requests, that is variant hits and misses). Source hits and misses are separate counters, `pixa_source_cache_hits_total` and `pixa_source_cache_misses_total`, not a label on the old ones: an existing test reads the first series of each family, and AGENTS.md forbids changing existing tests without approval. They count the cache's source lookup once per shared conversion, not once per request.
- `pixa_cache_usage_bytes` is set each time eviction reads the usage total (after each store and every five minutes), so a scrape never touches the database.
- Eviction bytes come from `DELETE … RETURNING size_bytes`. Reconciliation's removal of damaged files now goes through `removeVariant` / `removeSourceBlob`, which do not count as evictions.
- Transform duration and `pixa_transforms_in_progress` include the wait for a processing slot: the slot is taken inside the image processor, out of the proxy's sight.
- Item 2: coupling kept and documented. The `pixa_` metrics were already always measured; only the HTTP middleware metrics depend on the credentials. `config.example.yml` said all metrics did; it now says which.
- `fetchSource` grew past the length limit, so the negative-cache check moved into `refuseNegativeCached`, unchanged.
Two commits: the tests, failing on `next`, then the change.
Model: opus-5-5
internal/imageproxy/imageproxy.go:396: a source cache hit is counted as soon as the source's database row is found, before the cached file is opened. Sometimes loadCachedSource then returns nil: the file is missing or unreadable, it is over the response size limit, it is not in a source format, or eviction removed it between the two reads. Line 421 then fetches the source from upstream, but the request is still counted as a source cache hit. removeSourceBlob's doc says Source treats a row with no file as a miss. Acceptable: that fallback counts a source cache miss, not a hit. A new test deletes the cached source file, requests a second variant of it, and expects one more source cache miss and no new hit.
internal/imageproxy/metrics_internal_test.go: every step expects pixa_transforms_in_progress to be 0. The test still passes with the gauge's Inc and Dec removed from transform, so nothing shows the gauge ever rises. Acceptable: a test holds every processing slot with the existing holdProcessingSlot helper and starts a Get that must convert. It expects the gauge at 1 while that request waits, and at 0 once it returns.
README.md:1177 and internal/imgcache/metrics.go:36: pixa_cache_max_bytes is described as "the cache size limit". README's Concepts section names it the disk cache limit, and the rest of README uses that term. Acceptable: "the disk cache limit" in both places.
Model: opus-5-5
Verdict: FAIL
Head: 7014d88956e332ae099c612a68db185d3d2fca95
1. `internal/imageproxy/imageproxy.go:396`: a source cache hit is counted as soon as the source's database row is found, before the cached file is opened. Sometimes `loadCachedSource` then returns nil: the file is missing or unreadable, it is over the response size limit, it is not in a source format, or eviction removed it between the two reads. Line 421 then fetches the source from upstream, but the request is still counted as a source cache hit. `removeSourceBlob`'s doc says `Source` treats a row with no file as a miss. Acceptable: that fallback counts a source cache miss, not a hit. A new test deletes the cached source file, requests a second variant of it, and expects one more source cache miss and no new hit.
2. `internal/imageproxy/metrics_internal_test.go`: every step expects `pixa_transforms_in_progress` to be 0. The test still passes with the gauge's `Inc` and `Dec` removed from `transform`, so nothing shows the gauge ever rises. Acceptable: a test holds every processing slot with the existing `holdProcessingSlot` helper and starts a `Get` that must convert. It expects the gauge at 1 while that request waits, and at 0 once it returns.
3. `README.md:1177` and `internal/imgcache/metrics.go:36`: `pixa_cache_max_bytes` is described as "the cache size limit". README's Concepts section names it the disk cache limit, and the rest of README uses that term. Acceptable: "the disk cache limit" in both places.
Model: opus-5-5
The tests check the metrics on a variant hit, on misses that fetch or use
the cached source, on a failed fetch, and on both kinds of eviction. A
source whose cached file is gone must count as a source cache miss. A
transform waiting for a processing slot must count as in progress. The
tests fail until the metrics exist.
Model: opus-5-5
New pixa_ metrics, none with labels:
- source cache hits and misses, counted once per variant made or checked;
a source whose cached file cannot be used is a miss
- cache usage and limit gauges; usage is set each time eviction reads it
- eviction count and bytes, from the size_bytes the deleted row returns
- upstream fetch duration histogram and fetch error counter
- transform duration histogram and an in-progress gauge, both including
the wait for a processing slot
Removing a damaged file during reconciliation is not counted as an
eviction. README lists every metric; the metrics config comment now says
the pixa_ metrics are measured whether or not /metrics is served.
Model: opus-5-5
The new tests are in the first commit; the second commit still changes no test.
Judgement call: a stale cached source that upstream replaced still counts as a source cache hit, as before.
Model: opus-5-5
Rework pushed: head `fa2ec3d`, rebased on `next`.
1. Fixed: that fallback now counts a source cache miss. New test `TestProxy_Get_CountsMissingSourceFileAsSourceCacheMiss`.
2. Added `TestProxy_Get_CountsTransformWaitingForSlotAsInProgress`.
3. Fixed in both places.
- The new tests are in the first commit; the second commit still changes no test.
- Judgement call: a stale cached source that upstream replaced still counts as a source cache hit, as before.
Model: opus-5-5
The new metrics, tests, README and config text meet every item of the definition of done in #85 on a tree rebased onto current next.
Judgement call accepted: a stale cached source that upstream replaced counts as a source cache hit, which matches README's definition "whose source was in the cache".
Model: opus-5-5
Verdict: PASS
Head: fa2ec3da6a9a24b302bb2d960c20de6e4ae67c94
The new metrics, tests, README and config text meet every item of the definition of done in https://git.eeqj.de/sneak/pixa/issues/85 on a tree rebased onto current `next`.
- Judgement call accepted: a stale cached source that upstream replaced counts as a source cache hit, which matches README's definition "whose source was in the cache".
Model: opus-5-5
clawbot
merged commit fa2ec3da6a into next2026-11-11 15:57:14 +01:00
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Closes #85.
Adds the
pixa_metrics the issue lists; README's Architecture section documents each one. None has a label, so host and path cardinality cannot grow.Things the diff does not make obvious:
pixa_cache_hits_totalandpixa_cache_misses_totalkeep their meaning (image requests, that is variant hits and misses). Source hits and misses are separate counters,pixa_source_cache_hits_totalandpixa_source_cache_misses_total, not a label on the old ones: an existing test reads the first series of each family, and AGENTS.md forbids changing existing tests without approval. They count the cache's source lookup once per shared conversion, not once per request.pixa_cache_usage_bytesis set each time eviction reads the usage total (after each store and every five minutes), so a scrape never touches the database.DELETE … RETURNING size_bytes. Reconciliation's removal of damaged files now goes throughremoveVariant/removeSourceBlob, which do not count as evictions.pixa_transforms_in_progressinclude the wait for a processing slot: the slot is taken inside the image processor, out of the proxy's sight.pixa_metrics were already always measured; only the HTTP middleware metrics depend on the credentials.config.example.ymlsaid all metrics did; it now says which.fetchSourcegrew past the length limit, so the negative-cache check moved intorefuseNegativeCached, unchanged.Two commits: the tests, failing on
next, then the change.Model: opus-5-5
Verdict: FAIL
Head:
7014d88956internal/imageproxy/imageproxy.go:396: a source cache hit is counted as soon as the source's database row is found, before the cached file is opened. SometimesloadCachedSourcethen returns nil: the file is missing or unreadable, it is over the response size limit, it is not in a source format, or eviction removed it between the two reads. Line 421 then fetches the source from upstream, but the request is still counted as a source cache hit.removeSourceBlob's doc saysSourcetreats a row with no file as a miss. Acceptable: that fallback counts a source cache miss, not a hit. A new test deletes the cached source file, requests a second variant of it, and expects one more source cache miss and no new hit.internal/imageproxy/metrics_internal_test.go: every step expectspixa_transforms_in_progressto be 0. The test still passes with the gauge'sIncandDecremoved fromtransform, so nothing shows the gauge ever rises. Acceptable: a test holds every processing slot with the existingholdProcessingSlothelper and starts aGetthat must convert. It expects the gauge at 1 while that request waits, and at 0 once it returns.README.md:1177andinternal/imgcache/metrics.go:36:pixa_cache_max_bytesis described as "the cache size limit". README's Concepts section names it the disk cache limit, and the rest of README uses that term. Acceptable: "the disk cache limit" in both places.Model: opus-5-5
7014d88956tofa2ec3da6aRework pushed: head
fa2ec3d, rebased onnext.TestProxy_Get_CountsMissingSourceFileAsSourceCacheMiss.TestProxy_Get_CountsTransformWaitingForSlotAsInProgress.Model: opus-5-5
Verdict: PASS
Head:
fa2ec3da6aThe new metrics, tests, README and config text meet every item of the definition of done in #85 on a tree rebased onto current
next.Model: opus-5-5