fix(plex): E30 review round 3 — a dead headshot breaks the Plex-failing streak, 410 held by a test

backend/app/plex/people.py

@@ -244,7 +244,8 @@ def warm_portraits(db: Session, limit: int) -> dict:
         ).tuples()
         if thumb
     }
-    done = dead = plex_failed = down = 0  # `down` counts in a row, `plex_failed` in all
+    # `down` counts Plex failing in a row (any answer from Plex breaks it), `plex_failed` in all
+    done = dead = plex_failed = down = 0
     with plex:
         for pid in people_by_credits(db, "portrait", None):
             if done + dead >= limit or down >= _PLEX_DOWN_AFTER:
@@ -264,7 +265,7 @@ def warm_portraits(db: Session, limit: int) -> dict:
                 # Plex failing, which must neither mark the file nor keep the run going.
                 cause = exc.__cause__
                 if isinstance(cause, httpx.HTTPStatusError) and cause.response.status_code in _DEAD:
-                    dead += 1
+                    dead, down = dead + 1, 0  # Plex answered: it is up, the streak is broken
                     imgcache.mark_miss(key)
                 else:
                     plex_failed, down = plex_failed + 1, down + 1

backend/tests/test_plex_people_enrich.py

@@ -117,13 +117,15 @@ def test_the_batch_stores_the_hungarian_biography(db):
 
 class _Plex:
     """A PlexClient stand-in. `down`: urls Plex does not answer for (True: none); `dead`: urls Plex
-    answers "not found" for (a dead CDN file); `status`: an error status Plex answers every url with."""
+    answers `gone` for (a dead CDN file: "not found"); `status`: an error status Plex answers every
+    other url with."""
 
-    def __init__(self, down=False, dead=(), status=None):
+    def __init__(self, down=False, dead=(), status=None, gone=404):
         self.asked: list[tuple[str, int | None]] = []
         self.down = down
         self.dead = set(dead)
         self.status = status
+        self.gone = gone
 
     def __enter__(self):
         return self
@@ -135,7 +137,7 @@ class _Plex:
         self.asked.append((url, width))
         if self.down is True or (self.down and url in self.down):
             raise plex_people.PlexError("down") from httpx.ConnectError("refused")
-        code = 404 if url in self.dead else self.status
+        code = self.gone if url in self.dead else self.status
         if code:
             req = httpx.Request("GET", url)
             status = httpx.HTTPStatusError(
@@ -236,13 +238,23 @@ def test_plex_failing_between_successes_does_not_end_the_run(db, cache_dir, plex
     assert plex_people.warm_portraits(db, 100) == {"cached": 4, "failed": 4}
 
 
-def test_dead_headshots_are_left_alone_and_the_rest_still_land(db, cache_dir, plex_on):
+def test_plex_failing_between_dead_files_does_not_end_the_run(db, cache_dir, plex_on):
+    _faces(db, 8)
+    plex_on["plex"] = _Plex(  # down, dead, down, dead, …: Plex answers in between
+        down={CDN + f"{i}.jpg" for i in (0, 2, 4, 6)}, dead={CDN + f"{i}.jpg" for i in (1, 3, 5, 7)}
+    )
+    assert plex_people.warm_portraits(db, 100) == {"cached": 0, "failed": 8}
+    assert len(plex_on["plex"].asked) == 8
+
+
+@pytest.mark.parametrize("gone", [404, 410])
+def test_dead_headshots_are_left_alone_and_the_rest_still_land(db, cache_dir, plex_on, gone):
     _faces(db, 8)
     dead = {CDN + f"{i}.jpg" for i in range(6)}  # more dead files than any failure limit
-    plex_on["plex"] = _Plex(dead=dead)
+    plex_on["plex"] = _Plex(dead=dead, gone=gone)
     assert plex_people.warm_portraits(db, 100) == {"cached": 2, "failed": 6}
 
-    plex_on["plex"] = again = _Plex(dead=dead)
+    plex_on["plex"] = again = _Plex(dead=dead, gone=gone)
     assert plex_people.warm_portraits(db, 100) == {"cached": 0}
     assert again.asked == []  # dead ones marked, live ones cached: nothing to ask for