diff options
Diffstat (limited to 'synapse/handlers/room.py')
| -rw-r--r-- | synapse/handlers/room.py | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py index 88053f9869..2bcdf32dcc 100644 --- a/synapse/handlers/room.py +++ b/synapse/handlers/room.py @@ -46,6 +46,7 @@ from synapse.api.constants import ( from synapse.api.errors import ( AuthError, Codes, + HttpResponseException, LimitExceededError, NotFoundError, StoreError, @@ -56,6 +57,8 @@ from synapse.api.room_versions import KNOWN_ROOM_VERSIONS, RoomVersion from synapse.event_auth import validate_event_for_room_version from synapse.events import EventBase from synapse.events.utils import copy_power_levels_contents +from synapse.federation.federation_client import InvalidResponseError +from synapse.handlers.federation import get_domains_from_state from synapse.rest.admin._base import assert_user_is_admin from synapse.storage.state import StateFilter from synapse.streams import EventSource @@ -1220,6 +1223,147 @@ class RoomContextHandler: return results +class TimestampLookupHandler: + def __init__(self, hs: "HomeServer"): + self.server_name = hs.hostname + self.store = hs.get_datastore() + self.state_handler = hs.get_state_handler() + self.federation_client = hs.get_federation_client() + + async def get_event_for_timestamp( + self, + requester: Requester, + room_id: str, + timestamp: int, + direction: str, + ) -> Tuple[str, int]: + """Find the closest event to the given timestamp in the given direction. + If we can't find an event locally or the event we have locally is next to a gap, + it will ask other federated homeservers for an event. + + Args: + requester: The user making the request according to the access token + room_id: Room to fetch the event from + timestamp: The point in time (inclusive) we should navigate from in + the given direction to find the closest event. + direction: ["f"|"b"] to indicate whether we should navigate forward + or backward from the given timestamp to find the closest event. + + Returns: + A tuple containing the `event_id` closest to the given timestamp in + the given direction and the `origin_server_ts`. + + Raises: + SynapseError if unable to find any event locally in the given direction + """ + + local_event_id = await self.store.get_event_id_for_timestamp( + room_id, timestamp, direction + ) + logger.debug( + "get_event_for_timestamp: locally, we found event_id=%s closest to timestamp=%s", + local_event_id, + timestamp, + ) + + # Check for gaps in the history where events could be hiding in between + # the timestamp given and the event we were able to find locally + is_event_next_to_backward_gap = False + is_event_next_to_forward_gap = False + if local_event_id: + local_event = await self.store.get_event( + local_event_id, allow_none=False, allow_rejected=False + ) + + if direction == "f": + # We only need to check for a backward gap if we're looking forwards + # to ensure there is nothing in between. + is_event_next_to_backward_gap = ( + await self.store.is_event_next_to_backward_gap(local_event) + ) + elif direction == "b": + # We only need to check for a forward gap if we're looking backwards + # to ensure there is nothing in between + is_event_next_to_forward_gap = ( + await self.store.is_event_next_to_forward_gap(local_event) + ) + + # If we found a gap, we should probably ask another homeserver first + # about more history in between + if ( + not local_event_id + or is_event_next_to_backward_gap + or is_event_next_to_forward_gap + ): + logger.debug( + "get_event_for_timestamp: locally, we found event_id=%s closest to timestamp=%s which is next to a gap in event history so we're asking other homeservers first", + local_event_id, + timestamp, + ) + + # Find other homeservers from the given state in the room + curr_state = await self.state_handler.get_current_state(room_id) + curr_domains = get_domains_from_state(curr_state) + likely_domains = [ + domain for domain, depth in curr_domains if domain != self.server_name + ] + + # Loop through each homeserver candidate until we get a succesful response + for domain in likely_domains: + try: + remote_response = await self.federation_client.timestamp_to_event( + domain, room_id, timestamp, direction + ) + logger.debug( + "get_event_for_timestamp: response from domain(%s)=%s", + domain, + 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 + + # Only return the remote event if it's closer than the local event + if not local_event or ( + abs(origin_server_ts - timestamp) + < abs(local_event.origin_server_ts - timestamp) + ): + return remote_event_id, 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", + domain, + type(ex).__name__, + ex, + ex.args, + ) + except Exception as ex: + # 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", + domain, + type(ex).__name__, + ex, + ex.args, + ) + + if not local_event_id: + raise SynapseError( + 404, + "Unable to find event from %s in direction %s" % (timestamp, direction), + errcode=Codes.NOT_FOUND, + ) + + return local_event_id, local_event.origin_server_ts + + class RoomEventSource(EventSource[RoomStreamToken, EventBase]): def __init__(self, hs: "HomeServer"): self.store = hs.get_datastore() |