Cache _queue to local variable in VideoRecorder

Cache self._queue to a local variable (q) and use it for subsequent operations to avoid races and repeated attribute access. Remove the redundant assert and simplify qsize lookup by relying on the cached reference. This makes queue checks and put/qsize calls consistent in a multithreaded context and prevents potential None/attribute changes between checks and use.

Author: C-Achard

dlclivegui/services/video_recorder.py

@@ -149,7 +149,9 @@ def write(self, frame: np.ndarray, timestamp: float | None = None) -> bool:
         error = self._current_error()
         if error is not None:
             raise RuntimeError(f"Video encoding failed: {error}") from error
-        if not self.is_running or self._queue is None:
+
+        q = self._queue
+        if not self.is_running or q is None:
             return False
         if self._stop_event.is_set():
             return False
@@ -192,12 +194,11 @@ def write(self, frame: np.ndarray, timestamp: float | None = None) -> bool:
                 return False
 
         try:
-            assert self._queue is not None
-            self._queue.put((frame, timestamp), block=False)
+            q.put((frame, timestamp), block=False)
         except queue.Full:
             with self._stats_lock:
                 self._dropped_frames += 1
-            queue_size = self._queue.qsize() if self._queue is not None else -1
+            queue_size = q.qsize()
             logger.warning(
                 "Video recorder queue full; dropping frame. queue=%d buffer=%d",
                 queue_size,