bvandeusen
9cbdb70e13
Two coupled problems, operator-flagged 2026-06-01: "missing thumbnails
but triggering backfill found nothing."
1. **Backfill UI was a black box.** `POST /api/thumbnails/backfill`
returned just `{celery_task_id}` and the admin card said
"Enqueued." with no counts. There was no way to tell whether the
scan found 0 candidates, 5000 candidates, or whether the worker
even picked up the task. "Found nothing" was indistinguishable
from a broken queue.
Fix: refactor the scan into a sync helper (`_run_backfill_scan`)
shared by the Celery task and the API endpoint. The API now runs
the scan in an executor and returns `{scanned, enqueued, ok,
regenerated}`. The actual thumbnail generation work still goes
to the thumbnail Celery queue per row via
`generate_thumbnail.delay()` — the scan itself is fast
(SELECT id+thumbnail_path + a file.stat() per row).
2. **`_thumb_is_valid` accepted header-only corrupt files.** The
magic-byte check passed for any 8-byte file starting with a JPEG
or PNG header, including empty/truncated/zero-pad files that
browsers render as broken. Backfill counted these as `ok` and
never regenerated.
Fix: also require file size ≥ MIN_THUMB_BYTES (256). Real
thumbnails are minimum ~2KB even on solid-color sources; header-
only corrupt files top out around 12 bytes. 256 is well above
the corrupt floor and well below any legitimate thumbnail.
Plus the admin card now shows the per-run counts instead of
"Enqueued.":
Scanned 5,432 · enqueued 3 (2 regenerated) · 5,429 ok
29 lines
991 B
Python
29 lines
991 B
Python
import pytest
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from backend.app.celery_app import celery
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pytestmark = pytest.mark.integration
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@pytest.fixture(autouse=True)
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def eager():
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celery.conf.task_always_eager = True
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yield
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celery.conf.task_always_eager = False
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@pytest.mark.asyncio
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async def test_trigger_thumbnail_backfill_returns_counts(client):
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"""The API runs the scan synchronously now and returns
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{scanned, enqueued, ok, regenerated} — operator-flagged 2026-06-01:
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the previous fire-and-forget shape returned only a celery_task_id,
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so the admin UI couldn't show whether backfill found 0 or 5000
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candidates. \"Found nothing\" was indistinguishable from \"the
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worker isn't picking up the task.\""""
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r = await client.post("/api/thumbnails/backfill")
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assert r.status_code == 200
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body = await r.get_json()
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assert set(body) == {"scanned", "enqueued", "ok", "regenerated"}
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for key in ("scanned", "enqueued", "ok", "regenerated"):
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assert isinstance(body[key], int)
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