refactor: track imdb retry queue persistence (#61)

* refactor(loader): track imdb retry queue for persistence

* Update mcp_plex/loader.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update mcp_plex/loader.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Apply suggestions from code review

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Apply suggestions from code review

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: Teagan42

mcp_plex/loader.py

@@ -5,8 +5,9 @@
 import json
 import logging
 import sys
+from collections import deque
 from pathlib import Path
-from typing import Awaitable, List, Optional, Sequence, TypeVar
+from typing import Awaitable, Iterable, List, Optional, Sequence, TypeVar
 
 import click
 import httpx
@@ -43,10 +44,42 @@
 _imdb_cache: IMDbCache | None = None
 _imdb_max_retries: int = 3
 _imdb_backoff: float = 1.0
-_imdb_retry_queue: asyncio.Queue[str] | None = None
+_imdb_retry_queue: "_IMDbRetryQueue" | None = None
 _imdb_batch_limit: int = 5
 _qdrant_batch_size: int = 1000
 
+
+class _IMDbRetryQueue(asyncio.Queue[str]):
+    """Queue that tracks items in a deque for safe serialization."""
+
+    def __init__(self, initial: Iterable[str] | None = None):
+        super().__init__()
+        self._items: deque[str] = deque()
+        if initial:
+            for imdb_id in initial:
+                imdb_id_str = str(imdb_id)
+                super().put_nowait(imdb_id_str)
+                self._items.append(imdb_id_str)
+
+    def put_nowait(self, item: str) -> None:  # type: ignore[override]
+        super().put_nowait(item)
+        self._items.append(item)
+
+    def get_nowait(self) -> str:  # type: ignore[override]
+        if not self._items:
+            raise RuntimeError("Desynchronization: Queue is not empty but self._items is empty.")
+        try:
+            item = super().get_nowait()
+        except asyncio.QueueEmpty:
+            raise RuntimeError("Desynchronization: self._items is not empty but asyncio.Queue is empty.")
+        self._items.popleft()
+        return item
+
+    def snapshot(self) -> list[str]:
+        """Return a list of the current queue contents."""
+
+        return list(self._items)
+
 # Known Qdrant-managed dense embedding models with their dimensionality and
 # similarity metric. To support a new server-side embedding model, add an entry
 # here with the appropriate vector size and `models.Distance` value.
@@ -182,14 +215,20 @@ def _load_imdb_retry_queue(path: Path) -> None:
     """Populate the retry queue from a JSON file if it exists."""
 
     global _imdb_retry_queue
-    _imdb_retry_queue = asyncio.Queue()
+    ids: list[str] = []
     if path.exists():
         try:
-            ids = json.loads(path.read_text())
-            for imdb_id in ids:
-                _imdb_retry_queue.put_nowait(str(imdb_id))
+            data = json.loads(path.read_text())
+            if isinstance(data, list):
+                ids = [str(imdb_id) for imdb_id in data]
+            else:
+                logger.warning(
+                    "IMDb retry queue file %s did not contain a list; ignoring its contents",
+                    path,
+                )
         except Exception:
             logger.exception("Failed to load IMDb retry queue from %s", path)
+    _imdb_retry_queue = _IMDbRetryQueue(ids)
 
 
 async def _process_imdb_retry_queue(client: httpx.AsyncClient) -> None:
@@ -210,8 +249,7 @@ def _persist_imdb_retry_queue(path: Path) -> None:
 
     if _imdb_retry_queue is None:
         return
-    ids = list(_imdb_retry_queue._queue)  # type: ignore[attr-defined]
-    path.write_text(json.dumps(ids))
+    path.write_text(json.dumps(_imdb_retry_queue.snapshot()))
 
 
 async def _upsert_in_batches(
@@ -598,7 +636,7 @@ async def run(
         async with httpx.AsyncClient(timeout=30) as client:
             await _process_imdb_retry_queue(client)
     else:
-        _imdb_retry_queue = asyncio.Queue()
+        _imdb_retry_queue = _IMDbRetryQueue()
 
     items: List[AggregatedItem]
     if sample_dir is not None:

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "mcp-plex"
-version = "0.26.28"
+version = "0.26.29"
 
 description = "Plex-Oriented Model Context Protocol Server"
 requires-python = ">=3.11,<3.13"

tests/test_loader_unit.py

@@ -370,6 +370,9 @@ async def first_run():
 
     async def second_run():
         _load_imdb_retry_queue(queue_path)
+        assert loader._imdb_retry_queue is not None
+        assert loader._imdb_retry_queue.qsize() == 1
+        assert loader._imdb_retry_queue.snapshot() == ["tt0111161"]
         async with httpx.AsyncClient(transport=httpx.MockTransport(second_transport)) as client:
             await _process_imdb_retry_queue(client)
         _persist_imdb_retry_queue(queue_path)
@@ -388,8 +391,7 @@ def test_load_imdb_retry_queue_invalid_json(tmp_path):
 
 
 def test_process_imdb_retry_queue_requeues(monkeypatch):
-    queue: asyncio.Queue[str] = asyncio.Queue()
-    queue.put_nowait("tt0111161")
+    queue = loader._IMDbRetryQueue(["tt0111161"])
     monkeypatch.setattr(loader, "_imdb_retry_queue", queue)
 
     async def fake_fetch(client, imdb_id):
@@ -403,6 +405,7 @@ async def run_test():
 
     asyncio.run(run_test())
     assert queue.qsize() == 1
+    assert queue.snapshot() == ["tt0111161"]
 
 
 def test_resolve_tmdb_season_number_matches_name():