Add 'is_interested_in_user' and 'is_interested_in_room'

...that make use of the simpler helper methods we just renamed.

This commit adds the equivalent methods of is_interested_in_event for
both users and rooms. These implementations include more comprehensive
checks then the older methods with the same names.

synapse/appservice/__init__.py

@@ -214,6 +214,68 @@ async def matches_user_in_member_list(
                 return True
         return False
 
+    def is_interested_in_user(
+        self,
+        user_id: str,
+    ) -> bool:
+        """
+        Returns whether the application is interested in a given user ID.
+
+        The appservice is considered to be interested in a user if either: the
+        user ID is in the appservice's user namespace, or if the user is the
+        appservice's configured sender_localpart.
+
+        Args:
+            user_id: The ID of the user to check.
+
+        Returns:
+            True if the application service is interested in the user, False if not.
+        """
+        return (
+            # User is the appservice's sender_localpart user
+            user_id == self.sender
+            # User is in the appservice's user namespace
+            or self.is_user_in_namespace(user_id)
+        )
+
+    @cached(num_args=1, cache_context=True)
+    async def is_interested_in_room(
+        self,
+        room_id: str,
+        store: "DataStore",
+        cache_context: _CacheContext,
+    ) -> bool:
+        """
+        Returns whether the application service is interested in a given room ID.
+
+        The appservice is considered to be interested in the room if either: the ID or one
+        of the aliases of the room is in the appservice's room ID or alias namespace
+        respectively, or if one of the members of the room fall into the appservice's user
+        namespace.
+
+        Args:
+            room_id: The ID of the room to check.
+            store: The homeserver's datastore class.
+
+        Returns:
+            True if the application service is interested in the room, False if not.
+        """
+        # Check if this room ID matches the appservice's room ID namespace
+        if self.is_room_id_in_namespace(room_id):
+            return True
+
+        # likewise with the room's aliases (if it has any)
+        alias_list = await store.get_aliases_for_room(room_id)
+        for alias in alias_list:
+            if self.is_room_alias_in_namespace(alias):
+                return True
+
+        # And finally, perform an expensive check on whether any of the
+        # users in the room match the appservice's user namespace
+        return await self.matches_user_in_member_list(
+            room_id, store, on_invalidate=cache_context.invalidate
+        )
+
     def _matches_room_id(self, event: EventBase) -> bool:
         if hasattr(event, "room_id"):
             return self.is_room_id_in_namespace(event.room_id)
@@ -239,17 +301,20 @@ async def is_interested_in_event(
         Returns:
             True if this service would like to know about this event.
         """
-        # Do cheap checks first
-        if self._matches_room_id(event):
+        # Check if we're interested in this event's sender by namespace (or if they're the
+        # sender_localpart user)
+        if self.is_interested_in_user(event.sender):
             return True
 
-        # This will check the namespaces first before
-        # checking the store, so should be run before _matches_aliases
-        if await self._matches_user(event, store):
+        # additionally, if this is a membership event, perform the same checks on
+        # the user it references
+        if event.type == EventTypes.Member and self.is_interested_in_user(
+            event.state_key
+        ):
             return True
 
-        # This will check the store, so should be run last
-        if await self._matches_aliases(event, store):
+        # This will check the datastore, so should be run last
+        if await self.is_interested_in_room(event.room_id, store):
             return True
 
         return False