feat: add TTL to MemoryMediaGroupAggregator

aiogram/dispatcher/middlewares/media_group.py

@@ -91,7 +91,9 @@ class RedisMediaGroupAggregator(BaseMediaGroupAggregator):
         await self.redis.delete(self.get_group_lock_key(media_group_id))
 
     async def get_group(self, media_group_id: str) -> list[Message]:
-        result = await self.redis.lrange(self.get_group_key(media_group_id), 0, -1)
+        result = await cast(
+            Awaitable[list[str]], self.redis.lrange(self.get_group_key(media_group_id), 0, -1)
+        )
         return self.deduplicate_messages([Message.model_validate_json(msg) for msg in result])
 
     async def delete_group(self, media_group_id: str) -> None:
@@ -113,9 +115,25 @@ class MemoryMediaGroupAggregator(BaseMediaGroupAggregator):
         self.last_message_timers: dict[str, float] = {}
         self.locks: dict[str, bool] = {}
 
+    def remove_expired_objects(self) -> None:
+        expired_group_ids = []
+        current_time = time.time()
+        for group_id, last_message_time in self.last_message_timers.items():
+            if current_time - last_message_time > TTL_SEC:
+                expired_group_ids.append(group_id)
+            else:
+                break  # the list is sorted in ascending order
+                # because python 3.7+ save dict in insertion order
+        for group_id in expired_group_ids:
+            self.groups.pop(group_id, None)
+            self.last_message_timers.pop(group_id, None)
+            self.locks.pop(group_id, None)
+
     async def add_into_group(self, media_group_id: str, media: Message) -> int:
+        self.remove_expired_objects()
         if media.message_id not in (msg.message_id for msg in self.groups[media_group_id]):
             self.groups[media_group_id].append(media)
+        self.last_message_timers.pop(media_group_id, None)
         self.last_message_timers[media_group_id] = time.time()
         return len(self.groups[media_group_id])
 
@@ -145,6 +163,9 @@ class MediaGroupAggregatorMiddleware(BaseMiddleware):
         media_group_aggregator: BaseMediaGroupAggregator | None = None,
         delay: float = DELAY_SEC,
     ) -> None:
+        """
+        :param delay: delay between last received message in media group and processing it
+        """
         self.media_group_aggregator = media_group_aggregator or MemoryMediaGroupAggregator()
         self.delay = delay