diff options
Diffstat (limited to '')
| -rw-r--r-- | changelog.d/13205.feature | 1 | ||||
| -rw-r--r-- | synapse/handlers/federation_event.py | 49 | ||||
| -rw-r--r-- | synapse/handlers/room.py | 59 |
3 files changed, 94 insertions, 15 deletions
diff --git a/changelog.d/13205.feature b/changelog.d/13205.feature new file mode 100644 index 0000000000..d89aa9aa75 --- /dev/null +++ b/changelog.d/13205.feature @@ -0,0 +1 @@ +Allow pagination from remote event after discovering it from MSC3030 `/timestamp_to_event`. diff --git a/synapse/handlers/federation_event.py b/synapse/handlers/federation_event.py index 9d9f1696f2..16f20c8be7 100644 --- a/synapse/handlers/federation_event.py +++ b/synapse/handlers/federation_event.py @@ -793,7 +793,7 @@ class FederationEventHandler: if existing: if not existing.internal_metadata.is_outlier(): logger.info( - "Ignoring received event %s which we have already seen", + "_process_pulled_event: Ignoring received event %s which we have already seen", event_id, ) return @@ -1329,6 +1329,53 @@ class FederationEventHandler: marker_event, ) + async def backfill_event_id( + self, destination: str, room_id: str, event_id: str + ) -> EventBase: + """Backfill a single event and persist it as a non-outlier which means + we also pull in all of the state and auth events necessary for it. + + Args: + destination: The homeserver to pull the given event_id from. + room_id: The room where the event is from. + event_id: The event ID to backfill. + + Raises: + FederationError if we are unable to find the event from the destination + """ + logger.info( + "backfill_event_id: event_id=%s from destination=%s", event_id, destination + ) + + room_version = await self._store.get_room_version(room_id) + + event_from_response = await self._federation_client.get_pdu( + [destination], + event_id, + room_version, + ) + + if not event_from_response: + raise FederationError( + "ERROR", + 404, + "Unable to find event_id=%s from destination=%s to backfill." + % (event_id, destination), + affected=event_id, + ) + + # Persist the event we just fetched, including pulling all of the state + # and auth events to de-outlier it. This also sets up the necessary + # `state_groups` for the event. + await self._process_pulled_events( + destination, + [event_from_response], + # Prevent notifications going to clients + backfilled=True, + ) + + return event_from_response + async def _get_events_and_persist( self, destination: str, room_id: str, event_ids: Collection[str] ) -> None: diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py index 978d3ee39f..55395457c3 100644 --- a/synapse/handlers/room.py +++ b/synapse/handlers/room.py @@ -1384,6 +1384,7 @@ class TimestampLookupHandler: self.store = hs.get_datastores().main self.state_handler = hs.get_state_handler() self.federation_client = hs.get_federation_client() + self.federation_event_handler = hs.get_federation_event_handler() self._storage_controllers = hs.get_storage_controllers() async def get_event_for_timestamp( @@ -1479,38 +1480,68 @@ class TimestampLookupHandler: remote_response, ) - # TODO: Do we want to persist this as an extremity? - # TODO: I think ideally, we would try to backfill from - # this event and run this whole - # `get_event_for_timestamp` function again to make sure - # they didn't give us an event from their gappy history. remote_event_id = remote_response.event_id - origin_server_ts = remote_response.origin_server_ts + remote_origin_server_ts = remote_response.origin_server_ts + + # Backfill this event so we can get a pagination token for + # it with `/context` and paginate `/messages` from this + # point. + # + # TODO: The requested timestamp may lie in a part of the + # event graph that the remote server *also* didn't have, + # in which case they will have returned another event + # which may be nowhere near the requested timestamp. In + # the future, we may need to reconcile that gap and ask + # other homeservers, and/or extend `/timestamp_to_event` + # to return events on *both* sides of the timestamp to + # help reconcile the gap faster. + remote_event = ( + await self.federation_event_handler.backfill_event_id( + domain, room_id, remote_event_id + ) + ) + + # XXX: When we see that the remote server is not trustworthy, + # maybe we should not ask them first in the future. + if remote_origin_server_ts != remote_event.origin_server_ts: + logger.info( + "get_event_for_timestamp: Remote server (%s) claimed that remote_event_id=%s occured at remote_origin_server_ts=%s but that isn't true (actually occured at %s). Their claims are dubious and we should consider not trusting them.", + domain, + remote_event_id, + remote_origin_server_ts, + remote_event.origin_server_ts, + ) # Only return the remote event if it's closer than the local event if not local_event or ( - abs(origin_server_ts - timestamp) + abs(remote_event.origin_server_ts - timestamp) < abs(local_event.origin_server_ts - timestamp) ): - return remote_event_id, origin_server_ts + logger.info( + "get_event_for_timestamp: returning remote_event_id=%s (%s) since it's closer to timestamp=%s than local_event=%s (%s)", + remote_event_id, + remote_event.origin_server_ts, + timestamp, + local_event.event_id if local_event else None, + local_event.origin_server_ts if local_event else None, + ) + return remote_event_id, remote_origin_server_ts except (HttpResponseException, InvalidResponseError) as ex: # Let's not put a high priority on some other homeserver # failing to respond or giving a random response logger.debug( - "Failed to fetch /timestamp_to_event from %s because of exception(%s) %s args=%s", + "get_event_for_timestamp: Failed to fetch /timestamp_to_event from %s because of exception(%s) %s args=%s", domain, type(ex).__name__, ex, ex.args, ) - except Exception as ex: + except Exception: # But we do want to see some exceptions in our code logger.warning( - "Failed to fetch /timestamp_to_event from %s because of exception(%s) %s args=%s", + "get_event_for_timestamp: Failed to fetch /timestamp_to_event from %s because of exception", domain, - type(ex).__name__, - ex, - ex.args, + exc_info=True, ) # To appease mypy, we have to add both of these conditions to check for |