Files
siftlode/backend/tests/test_playlist_sync_claim.py
T
peter 26697472cf fix(playlists): every sync path locks the list before its items, and holds it to the write
The mirror refresh re-ingested inside its row lock, and that ingest's commit let go of the lock
before the replace: a remove made then was undone and the list read as synced. Push, re-pull and a
delete touched items before the list row, a deadlock beside the playlist-first route edits. A push
now re-plans from the items under the lock and derives dirty after its YouTube writes.
lock_playlists moves to the sync package. Tests pin both ids of a move's lock and the claim's
own connection.
2026-09-27 21:56:23 +02:00

206 lines
7.9 KiB
Python

"""E28 review C1 — one YouTube sync of a playlist at a time, whoever starts it.
A push reads YouTube and then writes both sides for seconds, committing step by step, so the
client's in-flight flag (one page's menus) and a row lock (gone at the first commit) both leave two
tabs, or a push and the scheduled mirror refresh, free to interleave. The claim is an advisory lock
on a connection of its own; the test holds it from outside, the way a second request would.
"""
from sqlalchemy import text
from app.auth import require_write_scope
from app.db import SessionLocal
from app.models import Playlist
from app.routes import playlists as plroutes
from app.sync import playlists as plsync
def _linked(db, user, *, source="local"):
pl = Playlist(user_id=user.id, name="L", source=source, yt_playlist_id="PL123")
db.add(pl)
db.commit()
return pl
class FakeYT:
"""YouTube as far as these routes read it: two playlists, none with items."""
def __init__(self, *_):
pass
def __enter__(self):
return self
def __exit__(self, *_):
return False
def iter_my_playlists(self):
return [{"id": "PL123", "title": "Renamed"}, {"id": "PL999", "title": "New"}]
def iter_my_playlist_video_ids(self, _ytid):
return []
def iter_playlist_items_with_ids(self, _ytid):
return []
def get_playlist_snippet(self, _ytid):
return {}
def test_push_and_revert_refuse_while_the_list_is_claimed(
db, as_user, make_user, override_dep, monkeypatch
):
user = make_user()
pl = _linked(db, user)
override_dep(require_write_scope, lambda: user)
monkeypatch.setattr(plroutes, "has_read_scope", lambda u: True)
ran: list[str] = []
monkeypatch.setattr(plroutes, "YouTubeClient", FakeYT)
monkeypatch.setattr(plroutes, "plan_merge", lambda d, u, p, live: {"units_estimate": 0})
monkeypatch.setattr(plroutes, "merge_playlist", lambda d, u, p, live: ran.append("push") or {})
monkeypatch.setattr(plroutes, "repull_playlist", lambda d, u, p: ran.append("revert") or {})
c = as_user(user)
with plsync.sync_claim(db, pl.id) as free:
assert free
for path in ("push", "revert-youtube"):
r = c.post(f"/api/playlists/{pl.id}/{path}")
assert r.status_code == 409
assert r.json()["detail"] == {"code": "playlist", "reason": "sync_busy"}
assert ran == []
# Released on the way out: the same list syncs again, and a claim is per list.
assert c.post(f"/api/playlists/{pl.id}/push").status_code == 200
assert c.post(f"/api/playlists/{pl.id}/revert-youtube").status_code == 200
assert ran == ["push", "revert"]
def test_a_claim_is_released_when_its_block_raises(db, make_user):
pl = _linked(db, make_user())
try:
with plsync.sync_claim(db, pl.id) as free:
assert free
raise RuntimeError("boom")
except RuntimeError:
pass
# Asked of pg_locks, not by claiming again: a lock leaked on a pooled connection would be granted
# again to that same connection (advisory locks are re-entrant per session).
held = db.scalar(
text("SELECT count(*) FROM pg_locks WHERE locktype = 'advisory' AND objid = :id"),
{"id": pl.id},
)
assert held == 0
def test_a_claim_draws_no_connection_from_the_app_pool(db, make_user):
"""A claim is held for a whole push beside the request's pooled session; drawn from the pool
too, a burst of pushes ran it dry and stalled every other request for pool_timeout."""
from app.db import engine
pl = _linked(db, make_user())
before = engine.pool.checkedout()
with plsync.sync_claim(db, pl.id) as free:
assert free
assert engine.pool.checkedout() == before
def test_the_scheduled_refresh_skips_a_mirror_being_synced(db, make_user, monkeypatch):
user = make_user()
busy = _linked(db, user, source="youtube")
replaced: list[int] = []
monkeypatch.setattr(plsync, "has_read_scope", lambda u: True)
monkeypatch.setattr(plsync, "YouTubeClient", FakeYT)
monkeypatch.setattr(
plsync, "_replace_items_from_youtube", lambda d, p, ids: replaced.append(p.id)
)
with plsync.sync_claim(db, busy.id):
out = plsync.sync_user_playlists(db, user)
assert out == {"synced": 1}
assert busy.id not in replaced and len(replaced) == 1
db.refresh(busy)
assert busy.name == "L"
def test_refused_reverts_do_not_spend_the_pull_cooldown(
db, as_user, make_user, override_dep, monkeypatch
):
"""Round 2: the cooldown (three pulls per ten minutes) is checked after the claim, so clicking
Revert while a push runs is refused as busy without using up a pull."""
user = make_user()
pl = _linked(db, user)
monkeypatch.setattr(plroutes, "has_read_scope", lambda u: True)
monkeypatch.setattr(plroutes, "repull_playlist", lambda d, u, p: {})
c = as_user(user)
with plsync.sync_claim(db, pl.id):
for _ in range(4):
assert c.post(f"/api/playlists/{pl.id}/revert-youtube").status_code == 409
assert c.post(f"/api/playlists/{pl.id}/revert-youtube").status_code == 200
def test_a_bulk_pull_runs_once_per_user_at_a_time(db, as_user, make_user, monkeypatch):
"""Two bulk pulls at once both saw a YouTube list unmirrored and each created its mirror."""
user = make_user()
monkeypatch.setattr(plsync, "has_read_scope", lambda u: True)
monkeypatch.setattr(plroutes, "has_read_scope", lambda u: True)
monkeypatch.setattr(plsync, "YouTubeClient", FakeYT)
monkeypatch.setattr(plsync, "_replace_items_from_youtube", lambda d, p, ids: None)
c = as_user(user)
with plsync.user_sync_claim(db, user.id):
assert plsync.sync_user_playlists(db, user) == {"synced": 0, "reason": "busy"}
for _ in range(4):
r = c.post("/api/playlists/sync-youtube")
assert r.status_code == 409
assert r.json()["detail"] == {"code": "playlist", "reason": "sync_all_busy"}
assert c.post("/api/playlists/sync-youtube").json() == {"ok": True, "synced": 2}
def test_a_gone_mirror_is_deleted_even_when_no_list_refreshes(db, make_user, monkeypatch):
"""Every remaining mirror has unpushed edits, so nothing below the deletion commits."""
user = make_user()
gone = Playlist(user_id=user.id, name="Gone", source="youtube", yt_playlist_id="PLgone")
kept = Playlist(user_id=user.id, name="K", source="youtube", yt_playlist_id="PL123", dirty=True)
other = Playlist(
user_id=user.id, name="O", source="youtube", yt_playlist_id="PL999", dirty=True
)
db.add_all([gone, kept, other])
db.commit()
gone_id = gone.id
monkeypatch.setattr(plsync, "has_read_scope", lambda u: True)
monkeypatch.setattr(plsync, "YouTubeClient", FakeYT)
assert plsync.sync_user_playlists(db, user) == {"synced": 0}
db.rollback() # what the request's session close does to an uncommitted deletion
assert db.get(Playlist, gone_id) is None
def test_a_mirror_edited_during_the_pull_is_not_replaced(db, make_user, monkeypatch):
"""The loop's `dirty` is a snapshot from before the YouTube calls; a remove committed by another
request meanwhile must win over YouTube's order."""
user = make_user()
pl = _linked(db, user, source="youtube")
replaced: list[int] = []
class EditedMeanwhile(FakeYT):
def iter_my_playlists(self):
return [{"id": "PL123", "title": "Renamed"}]
def iter_my_playlist_video_ids(self, _ytid):
with SessionLocal() as other:
other.get(Playlist, pl.id).dirty = True
other.commit()
return []
monkeypatch.setattr(plsync, "has_read_scope", lambda u: True)
monkeypatch.setattr(plsync, "YouTubeClient", EditedMeanwhile)
monkeypatch.setattr(
plsync, "_replace_items_from_youtube", lambda d, p, ids: replaced.append(p.id)
)
assert plsync.sync_user_playlists(db, user) == {"synced": 0}
assert replaced == []
db.expire_all()
assert db.get(Playlist, pl.id).name == "L"