Proper usage of messagebox in update handling loop

telethon/_client/updates.py

@@ -7,6 +7,7 @@ import time
 import traceback
 import typing
 import logging
+from collections import deque
 
 from ..errors._rpcbase import RpcError
 from .._events.common import EventBuilder, EventCommon
@@ -82,6 +83,42 @@ async def catch_up(self: 'TelegramClient'):
     pass
 
 async def _update_loop(self: 'TelegramClient'):
-    while self.is_connected():
-        updates = await self._updates_queue.get()
-        updates, users, chats = self._message_box.process_updates(updates, self._entity_cache)
+    try:
+        updates_to_dispatch = deque()
+        while self.is_connected():
+            if updates_to_dispatch:
+                # TODO dispatch
+                updates_to_dispatch.popleft()
+                continue
+
+            get_diff = self._message_box.get_difference()
+            if get_diff:
+                self._log[__name__].info('Getting difference for account updates')
+                diff = await self(get_diff)
+                updates, users, chats = self._message_box.apply_difference(diff, self._entity_cache)
+                updates_to_dispatch.extend(updates)
+                continue
+
+            get_diff = self._message_box.get_channel_difference(self._entity_cache)
+            if get_diff:
+                self._log[__name__].info('Getting difference for channel updates')
+                diff = await self(get_diff)
+                updates, users, chats = self._message_box.apply_channel_difference(diff, self._entity_cache)
+                updates_to_dispatch.extend(updates)
+                continue
+
+            deadline = self._message_box.check_deadlines()
+            try:
+                updates = await asyncio.wait_for(
+                    self._updates_queue.get(),
+                    deadline - asyncio.get_running_loop().time()
+                )
+            except asyncio.TimeoutError:
+                self._log[__name__].info('Timeout waiting for updates expired')
+                continue
+
+            processed = []
+            users, chats = self._message_box.process_updates(updates, self._entity_cache, processed)
+            updates_to_dispatch.extend(processed)
+    except Exception:
+        self._log[__name__].exception('Fatal error handling updates (this is a bug in Telethon, please report it)')