diff options
Diffstat (limited to 'synapse/handlers/sync.py')
| -rw-r--r-- | synapse/handlers/sync.py | 121 |
1 files changed, 107 insertions, 14 deletions
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py index 3aa2e2b7ba..7fcd54ac55 100644 --- a/synapse/handlers/sync.py +++ b/synapse/handlers/sync.py @@ -953,7 +953,7 @@ class SyncHandler: batch: TimelineBatch, sync_config: SyncConfig, since_token: Optional[StreamToken], - now_token: StreamToken, + end_token: StreamToken, full_state: bool, ) -> MutableStateMap[EventBase]: """Works out the difference in state between the end of the previous sync and @@ -964,7 +964,9 @@ class SyncHandler: batch: The timeline batch for the room that will be sent to the user. sync_config: since_token: Token of the end of the previous batch. May be `None`. - now_token: Token of the end of the current batch. + end_token: Token of the end of the current batch. Normally this will be + the same as the global "now_token", but if the user has left the room, + the point just after their leave event. full_state: Whether to force returning the full state. `lazy_load_members` still applies when `full_state` is `True`. @@ -1044,7 +1046,7 @@ class SyncHandler: room_id, sync_config.user, batch, - now_token, + end_token, members_to_fetch, timeline_state, ) @@ -1058,7 +1060,7 @@ class SyncHandler: room_id, batch, since_token, - now_token, + end_token, members_to_fetch, timeline_state, ) @@ -1130,7 +1132,7 @@ class SyncHandler: room_id: str, syncing_user: UserID, batch: TimelineBatch, - now_token: StreamToken, + end_token: StreamToken, members_to_fetch: Optional[Set[str]], timeline_state: StateMap[str], ) -> StateMap[str]: @@ -1143,7 +1145,9 @@ class SyncHandler: room_id: The room we are calculating for. syncing_user: The user that is calling `/sync`. batch: The timeline batch for the room that will be sent to the user. - now_token: Token of the end of the current batch. + end_token: Token of the end of the current batch. Normally this will be + the same as the global "now_token", but if the user has left the room, + the point just after their leave event. members_to_fetch: If lazy-loading is enabled, the memberships needed for events in the timeline. timeline_state: The contribution to the room state from state events in @@ -1202,7 +1206,7 @@ class SyncHandler: else: state_at_timeline_end = await self.get_state_at( room_id, - stream_position=now_token, + stream_position=end_token, state_filter=state_filter, await_full_state=await_full_state, ) @@ -1223,7 +1227,7 @@ class SyncHandler: room_id: str, batch: TimelineBatch, since_token: StreamToken, - now_token: StreamToken, + end_token: StreamToken, members_to_fetch: Optional[Set[str]], timeline_state: StateMap[str], ) -> StateMap[str]: @@ -1239,7 +1243,9 @@ class SyncHandler: room_id: The room we are calculating for. batch: The timeline batch for the room that will be sent to the user. since_token: Token of the end of the previous batch. - now_token: Token of the end of the current batch. + end_token: Token of the end of the current batch. Normally this will be + the same as the global "now_token", but if the user has left the room, + the point just after their leave event. members_to_fetch: If lazy-loading is enabled, the memberships needed for events in the timeline. Otherwise, `None`. timeline_state: The contribution to the room state from state events in @@ -1273,7 +1279,7 @@ class SyncHandler: # the recent events. state_at_timeline_start = await self.get_state_at( room_id, - stream_position=now_token, + stream_position=end_token, state_filter=state_filter, await_full_state=await_full_state, ) @@ -1312,7 +1318,7 @@ class SyncHandler: # the recent events. state_at_timeline_end = await self.get_state_at( room_id, - stream_position=now_token, + stream_position=end_token, state_filter=state_filter, await_full_state=await_full_state, ) @@ -2344,6 +2350,7 @@ class SyncHandler: full_state=False, since_token=since_token, upto_token=leave_token, + end_token=leave_token, out_of_band=leave_event.internal_metadata.is_out_of_band_membership(), ) ) @@ -2381,6 +2388,7 @@ class SyncHandler: full_state=False, since_token=None if newly_joined else since_token, upto_token=prev_batch_token, + end_token=now_token, ) else: entry = RoomSyncResultBuilder( @@ -2391,6 +2399,7 @@ class SyncHandler: full_state=False, since_token=since_token, upto_token=since_token, + end_token=now_token, ) room_entries.append(entry) @@ -2449,6 +2458,7 @@ class SyncHandler: full_state=True, since_token=since_token, upto_token=now_token, + end_token=now_token, ) ) elif event.membership == Membership.INVITE: @@ -2478,6 +2488,7 @@ class SyncHandler: full_state=True, since_token=since_token, upto_token=leave_token, + end_token=leave_token, ) ) @@ -2548,6 +2559,7 @@ class SyncHandler: { "since_token": since_token, "upto_token": upto_token, + "end_token": room_builder.end_token, } ) @@ -2621,7 +2633,7 @@ class SyncHandler: batch, sync_config, since_token, - now_token, + room_builder.end_token, full_state=full_state, ) else: @@ -2781,6 +2793,70 @@ def _calculate_state( e for t, e in timeline_start.items() if t[0] == EventTypes.Member ) + # Naively, we would just return the difference between the state at the start + # of the timeline (`timeline_start_ids`) and that at the end of the previous sync + # (`previous_timeline_end_ids`). However, that fails in the presence of forks in + # the DAG. + # + # For example, consider a DAG such as the following: + # + # E1 + # ↗ ↖ + # | S2 + # | ↑ + # --|------|---- + # | | + # E3 | + # ↖ / + # E4 + # + # ... and a filter that means we only return 2 events, represented by the dashed + # horizontal line. Assuming S2 was *not* included in the previous sync, we need to + # include it in the `state` section. + # + # Note that the state at the start of the timeline (E3) does not include S2. So, + # to make sure it gets included in the calculation here, we actually look at + # the state at the *end* of the timeline, and subtract any events that are present + # in the timeline. + # + # ---------- + # + # Aside 1: You may then wonder if we need to include `timeline_start` in the + # calculation. Consider a linear DAG: + # + # E1 + # ↑ + # S2 + # ↑ + # ----|------ + # | + # E3 + # ↑ + # S4 + # ↑ + # E5 + # + # ... where S2 and S4 change the same piece of state; and where we have a filter + # that returns 3 events (E3, S4, E5). We still need to tell the client about S2, + # because it might affect the display of E3. However, the state at the end of the + # timeline only tells us about S4; if we don't inspect `timeline_start` we won't + # find out about S2. + # + # (There are yet more complicated cases in which a state event is excluded from the + # timeline, but whose effect actually lands in the DAG in the *middle* of the + # timeline. We have no way to represent that in the /sync response, and we don't + # even try; it is ether omitted or plonked into `state` as if it were at the start + # of the timeline, depending on what else is in the timeline.) + # + # ---------- + # + # Aside 2: it's worth noting that `timeline_end`, as provided to us, is actually + # the state *before* the final event in the timeline. In other words: if the final + # event in the timeline is a state event, it won't be included in `timeline_end`. + # However, that doesn't matter here, because the only difference can be in that + # one piece of state, and by definition that event is in the timeline, so we + # don't need to include it in the `state` section. + state_ids = ( (timeline_end_ids | timeline_start_ids) - previous_timeline_end_ids @@ -2883,13 +2959,30 @@ class RoomSyncResultBuilder: Attributes: room_id + rtype: One of `"joined"` or `"archived"` + events: List of events to include in the room (more events may be added when generating result). + newly_joined: If the user has newly joined the room + full_state: Whether the full state should be sent in result + since_token: Earliest point to return events from, or None - upto_token: Latest point to return events from. + + upto_token: Latest point to return events from. If `events` is populated, + this is set to the token at the start of `events` + + end_token: The last point in the timeline that the client should see events + from. Normally this will be the same as the global `now_token`, but in + the case of rooms where the user has left the room, this will be the point + just after their leave event. + + This is used in the calculation of the state which is returned in `state`: + any state changes *up to* `end_token` (and not beyond!) which are not + reflected in the timeline need to be returned in `state`. + out_of_band: whether the events in the room are "out of band" events and the server isn't in the room. """ @@ -2901,5 +2994,5 @@ class RoomSyncResultBuilder: full_state: bool since_token: Optional[StreamToken] upto_token: StreamToken - + end_token: StreamToken out_of_band: bool = False |