Add type hints to synapse/storage/databases/main (#11984)

synapse/handlers/presence.py

@@ -204,25 +204,27 @@ class BasePresenceHandler(abc.ABC):
         Returns:
             dict: `user_id` -> `UserPresenceState`
         """
-        states = {
-            user_id: self.user_to_current_state.get(user_id, None)
-            for user_id in user_ids
-        }
+        states = {}
+        missing = []
+        for user_id in user_ids:
+            state = self.user_to_current_state.get(user_id, None)
+            if state:
+                states[user_id] = state
+            else:
+                missing.append(user_id)
 
-        missing = [user_id for user_id, state in states.items() if not state]
         if missing:
             # There are things not in our in memory cache. Lets pull them out of
             # the database.
             res = await self.store.get_presence_for_users(missing)
             states.update(res)
 
-            missing = [user_id for user_id, state in states.items() if not state]
-            if missing:
-                new = {
-                    user_id: UserPresenceState.default(user_id) for user_id in missing
-                }
-                states.update(new)
-                self.user_to_current_state.update(new)
+            for user_id in missing:
+                # if user has no state in database, create the state
+                if not res.get(user_id, None):
+                    new_state = UserPresenceState.default(user_id)
+                    states[user_id] = new_state
+                    self.user_to_current_state[user_id] = new_state
 
         return states