Files
music-curator/tests/conftest.py
T
Emma Thorpe edebecc8ea
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fix: hold one connection to Lidarr open, and retry what deserves retrying
Indexing makes two requests per artist, and more when the album fallback fires.
urllib opens a new TCP connection and performs a new DNS lookup for every one of
them, so a large library becomes thousands of lookups inside a few minutes. That
is enough to exhaust a container's resolver, and the result is
"[Errno -3] Try again" on every artist at once -- a failure caused entirely by
how the requests were made rather than by anything wrong with Lidarr.

Add a transport that keeps one connection open per host, so the name is resolved
once and the socket is reused. It retries once on a connection the server has
already closed, since a stale keep-alive announces itself only on use.

Retries were previously declined on the grounds that Lidarr is on the same LAN.
That is not a safe assumption -- it may sit behind a public hostname and a
reverse proxy -- and a transient failure currently costs an artist their entire
entry for that pass. Transient failures are now retried with a backoff. HTTP 500
is deliberately excluded: it is an exception inside Lidarr's serialisation, not
a busy server, and three attempts only delay finding that out.

The same distinction gates the album probe added alongside this. Naming the
offending album costs one request per album of that artist, which is worth it
for a deterministic fault and actively harmful during a network-wide one, where
every artist fails and probing each of them multiplies the load responsible.

The keep-alive transport is tested against a real local HTTP server rather than
a fake, because connection reuse and status mapping are exactly the properties a
fake would assume rather than demonstrate.
2026-08-24 14:40:00 +01:00

296 lines
11 KiB
Python

import http.server
import io
import json
import os
import sys
import threading
import urllib.error
import urllib.parse
import pytest
# Ensure the project root is on sys.path when running tests.
ROOT = os.path.dirname(os.path.dirname(__file__))
if ROOT not in sys.path:
sys.path.insert(0, ROOT)
def make_tracks(count, start=1_600_000_000, step=300, artists=5):
"""Return a synthetic recent-tracks history, oldest first.
Mirrors the real payload's quirks: artist and album are sub-objects keyed
`#text`, MBIDs are present-but-empty rather than absent when unknown, and
only some entries carry one.
"""
return [
{
"artist": {"#text": f"Artist {index % artists}", "mbid": f"artist-{index % artists}"},
"album": {"#text": f"Album {index % 7}", "mbid": ""},
"name": f"Track {index}",
"mbid": f"recording-{index}" if index % 3 == 0 else "",
"date": {"uts": str(start + index * step), "#text": "whenever"},
}
for index in range(count)
]
def make_loved(names):
"""Return loved-track entries, which key the artist as `name` not `#text`."""
return [
{
"name": name,
"mbid": "",
"artist": {"name": "Artist 0", "mbid": "artist-0"},
"date": {"uts": "1600000000"},
}
for name in names
]
class FakeLastfm:
"""A transport serving a canned history, so the tests need no network.
Honours `from`, `to`, `limit` and `page` the way the real service does, and
reproduces the two shapes that catch clients out: a lone result comes back
as a bare object rather than a one-item list, and a currently-playing track
is prepended to the first page with no `date`.
"""
def __init__(self, tracks=(), loved=(), nowplaying=None, outcomes=()):
self.tracks = sorted(tracks, key=lambda track: int(track["date"]["uts"]), reverse=True)
self.loved = list(loved)
self.nowplaying = nowplaying
# Served in order before any real response; an Exception is raised.
self.outcomes = list(outcomes)
self.calls = []
def __call__(self, url, timeout=None):
query = {
key: value[0]
for key, value in urllib.parse.parse_qs(urllib.parse.urlparse(url).query).items()
}
self.calls.append(query)
if self.outcomes:
outcome = self.outcomes.pop(0)
if isinstance(outcome, Exception):
raise outcome
return json.dumps(outcome)
method = query["method"].lower()
if method == "user.getrecenttracks":
return json.dumps(self._recent(query))
if method == "user.getlovedtracks":
return json.dumps(self._loved(query))
raise AssertionError(f"unexpected method {method}")
def _recent(self, query):
selected = self.tracks
if "to" in query:
selected = [t for t in selected if int(t["date"]["uts"]) <= int(query["to"])]
if "from" in query:
selected = [t for t in selected if int(t["date"]["uts"]) >= int(query["from"])]
window = self._page(selected, query)
if int(query.get("page", 1)) == 1 and self.nowplaying is not None:
window = [self.nowplaying, *window]
return {"recenttracks": self._wrap(window, selected, query)}
def _loved(self, query):
window = self._page(self.loved, query)
return {"lovedtracks": self._wrap(window, self.loved, query)}
@staticmethod
def _page(items, query):
limit = int(query.get("limit", 50))
page = int(query.get("page", 1))
start = (page - 1) * limit
return items[start : start + limit]
@staticmethod
def _wrap(window, selected, query):
limit = int(query.get("limit", 50))
total = len(selected)
return {
# A single result is not wrapped in a list by the real service.
"track": window[0] if len(window) == 1 else window,
"@attr": {
"user": query.get("user", ""),
"page": query.get("page", "1"),
"perPage": str(limit),
"totalPages": str(max(1, -(-total // limit))),
"total": str(total),
},
}
class FakeLidarr:
"""A transport serving a canned library over the Lidarr v1 API surface.
Built from a nested description -- artist, album, tracks -- and split back
out across the four endpoints the indexer actually calls, so the tests
exercise the same stitching the real thing does.
"""
def __init__(self, artists=(), fail=()):
# (path, artistId) pairs the fake refuses to serve, standing in for the
# 500s Lidarr returns on data it cannot hydrate.
self.fail = set(fail)
self.artists, self.albums, self.tracks, self.files = [], [], [], []
for artist_index, entry in enumerate(artists, start=1):
artist_id = artist_index
self.artists.append(
{
"id": artist_id,
"artistName": entry["name"],
"foreignArtistId": entry.get("mbid", f"artist-mbid-{artist_id}"),
"path": f"/music/{entry['name']}",
"monitored": entry.get("monitored", True),
}
)
for album_index, album in enumerate(entry.get("albums", []), start=1):
album_id = artist_id * 100 + album_index
self.albums.append(
{
"id": album_id,
"artistId": artist_id,
"title": album["title"],
"foreignAlbumId": f"album-mbid-{album_id}",
"monitored": album.get("monitored", True),
"releaseDate": album.get("release_date", "2019-01-01T00:00:00Z"),
}
)
for track_index, track in enumerate(album.get("tracks", []), start=1):
track_id = album_id * 100 + track_index
has_file = track.get("has_file", True)
self.tracks.append(
{
"id": track_id,
"artistId": artist_id,
"albumId": album_id,
"title": track["title"],
"foreignRecordingId": track.get("recording_mbid", ""),
"trackFileId": track_id if has_file else 0,
"hasFile": has_file,
"duration": 210000,
}
)
if has_file:
self.files.append(
{
"id": track_id,
"artistId": artist_id,
"albumId": album_id,
"path": f"/music/{entry['name']}/{album['title']}/"
f"{track['title']}.flac",
"dateAdded": track.get("added", "2020-05-01T12:00:00Z"),
}
)
self.calls = []
def __call__(self, url, timeout=None, headers=None):
parsed = urllib.parse.urlparse(url)
assert (headers or {}).get("X-Api-Key"), "Lidarr requires the API key header"
path = parsed.path.rsplit("/", 1)[-1]
query = {
key: value[0] for key, value in urllib.parse.parse_qs(parsed.query).items()
}
self.calls.append((path, query))
artist_id = int(query.get("artistId", 0))
if (path, artist_id) in self.fail:
raise urllib.error.HTTPError(
url, 500, "Internal Server Error", {}, io.BytesIO(b'{"message": "boom"}')
)
album_ids = query.get("albumIds")
if path == "album" and album_ids:
album_id = int(album_ids)
if ("albumid", album_id) in self.fail:
raise urllib.error.HTTPError(
url,
500,
"Internal Server Error",
{},
io.BytesIO(b'{"message": "Sequence contains more than one element"}'),
)
return json.dumps([row for row in self.albums if row["id"] == album_id])
if path == "artist":
return json.dumps(self.artists)
source = {"album": self.albums, "track": self.tracks, "trackfile": self.files}[path]
if path == "album" and not artist_id:
# Lidarr's unfiltered album endpoint returns the lot.
return json.dumps(source)
if not artist_id:
raise urllib.error.HTTPError(
url,
400,
"Bad Request",
{},
io.BytesIO(b'{"message": "artistId must be provided"}'),
)
return json.dumps([row for row in source if row["artistId"] == artist_id])
@pytest.fixture
def now_playing():
"""The entry Last.fm prepends for a track in progress: no `date` at all."""
return {
"artist": {"#text": "Artist 0", "mbid": "artist-0"},
"album": {"#text": "Album 0", "mbid": ""},
"name": "Currently Playing",
"mbid": "",
"@attr": {"nowplaying": "true"},
}
class _CountingServer(http.server.ThreadingHTTPServer):
"""Counts accepted connections, which is what connection reuse is about."""
daemon_threads = True
def __init__(self, *args, **kwargs):
self.connections = 0
super().__init__(*args, **kwargs)
def process_request(self, request, client_address):
self.connections += 1
super().process_request(request, client_address)
class _Handler(http.server.BaseHTTPRequestHandler):
# Without HTTP/1.1 the server closes after every response and no client
# could reuse anything, which would make the test prove nothing.
protocol_version = "HTTP/1.1"
def do_GET(self):
if self.path.startswith("/boom"):
body, status = b'{"message": "boom"}', 500
else:
body = json.dumps(
{"path": self.path, "key": self.headers.get("X-Api-Key")}
).encode()
status = 200
self.send_response(status)
self.send_header("Content-Type", "application/json")
self.send_header("Content-Length", str(len(body)))
self.end_headers()
self.wfile.write(body)
def log_message(self, *args):
pass
@pytest.fixture
def http_server():
"""A real local HTTP server, for the one component that talks sockets."""
server = _CountingServer(("127.0.0.1", 0), _Handler)
thread = threading.Thread(target=server.serve_forever, daemon=True)
thread.start()
try:
yield server, f"http://127.0.0.1:{server.server_port}"
finally:
server.shutdown()
server.server_close()