1 files changed, 9 insertions, 6 deletions
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index b73ad62147..82c8cb5f0c 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -16,7 +16,7 @@
from twisted.internet import defer
from synapse.api.constants import EventTypes, Membership
-from synapse.api.errors import SynapseError, AuthError, Codes
+from synapse.api.errors import AuthError, Codes
from synapse.streams.config import PaginationConfig
from synapse.events.utils import serialize_event
from synapse.events.validator import EventValidator
@@ -119,9 +119,12 @@ class MessageHandler(BaseHandler):
if source_config.direction == 'b':
# if we're going backwards, we might need to backfill. This
# requires that we have a topo token.
- if room_token.topological is None:
- raise SynapseError(400, "Invalid token: cannot paginate "
- "backwards from a stream token")
+ if room_token.topological:
+ max_topo = room_token.topological
+ else:
+ max_topo = yield self.store.get_max_topological_token_for_stream_and_room(
+ room_id, room_token.stream
+ )
if membership == Membership.LEAVE:
# If they have left the room then clamp the token to be before
@@ -131,11 +134,11 @@ class MessageHandler(BaseHandler):
member_event_id
)
leave_token = RoomStreamToken.parse(leave_token)
- if leave_token.topological < room_token.topological:
+ if leave_token.topological < max_topo:
source_config.from_key = str(leave_token)
yield self.hs.get_handlers().federation_handler.maybe_backfill(
- room_id, room_token.topological
+ room_id, max_topo
)
events, next_key = yield data_source.get_pagination_rows(
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