KeelrLeek
ddf2840b78
Two failures that looked like nothing at all.
**A failed MusicBrainz page was indistinguishable from an empty one.**
`musicbrainz_first_release_dates` `break`s out of its paging loop when a
request fails and returns the map it has, so one transient blip produced an
empty map — exactly what an artist with no release groups produces. Everything
downstream then no-ops in silence: the album dates keep Deezer's reissue
values, every popular row keeps the pressing Deezer licensed, and the traces
read "0/47 corrected" and "0/10 re-attributed", which is also what a page looks
like when it was already perfect.
That is not hypothetical. It cost an hour last session chasing a regression in
Eagles' dates that turned out to be this machine having throttled its own IP
with probes, and it produced a false bug report that outlived it: My Bloody
Valentine was written up as "the supplement is failing to inject Loveless" when
the supplement was fine and MusicBrainz had simply not replied that once —
verified today, both Loveless and Isn't Anything inject correctly and always
did.
The third state is cheap to know, because a `None` here can only ever be a
failure: the mbid was resolved FROM MusicBrainz moments earlier, so the artist
provably exists there, and an artist it holds nothing for answers with an empty
`release-groups` ARRAY rather than with nothing. So the first page is now
retried twice behind a widening backoff — the failure this guards against is
overwhelmingly transient, and the pass is deferred, so nothing on screen is
waiting on it — and only then is the verdict recorded and carried to the
callers. Fault-injected against an unroutable host, the traces now read:
musicbrainz.first_release_dates 4430ms UNAVAILABLE
page.original_dates 0/47 corrected — MUSICBRAINZ UNAVAILABLE, dates are unverified
page.attribution 0/10 re-attributed — MUSICBRAINZ UNAVAILABLE, rows keep Deezer's attribution
A later page failing stays partial rather than unavailable: the dates already
collected are real, and the discography is date-sorted so the tail matters
least.
**Supplemented albums had no play counts, for a stale reason.** The comment
said a MusicBrainz or Apple album "simply carries no play counts" because the
scrobble pass resolved its anchor from a DEEZER artist id, which a record
Deezer never carried does not have. But the scrobble table is keyed on an
artist MBID, and a MusicBrainz-supplemented album was fetched BY that mbid — it
was in hand at registration and simply not kept. So the records the supplement
exists to rescue opened with no Plays column at all: Loveless, Isn't Anything,
Exmilitary.
Apple needs the same thing by the other route. It has no MusicBrainz id of its
own, but it does know which Deezer artist it was supplementing, so keeping that
id lets it reach the table the ordinary way. Weezer's "Hurley (Deluxe Edition)"
is an Apple row and had no Plays column while the plain Deezer edition beside
it had one.
Measured live: Loveless 79M album plays / 1.8M listeners with Only Shallow at
10,801,602; Hurley (Deluxe Edition) 1.9M / 93K with Memories at 1,219,036;
Exmilitary showing Guillotine at 3,363,409. 75 Rust tests and 85 JS tests pass.