diff --git a/synapse/handlers/federation_event.py b/synapse/handlers/federation_event.py
index 16f20c8be7..fc1254d2ad 100644
--- a/synapse/handlers/federation_event.py
+++ b/synapse/handlers/federation_event.py
@@ -278,7 +278,9 @@ class FederationEventHandler:
)
try:
- await self._process_received_pdu(origin, pdu, state_ids=None)
+ await self._process_received_pdu(
+ origin, pdu, state_ids=None, partial_state=None
+ )
except PartialStateConflictError:
# The room was un-partial stated while we were processing the PDU.
# Try once more, with full state this time.
@@ -286,7 +288,9 @@ class FederationEventHandler:
"Room %s was un-partial stated while processing the PDU, trying again.",
room_id,
)
- await self._process_received_pdu(origin, pdu, state_ids=None)
+ await self._process_received_pdu(
+ origin, pdu, state_ids=None, partial_state=None
+ )
async def on_send_membership_event(
self, origin: str, event: EventBase
@@ -534,14 +538,36 @@ class FederationEventHandler:
#
# This is the same operation as we do when we receive a regular event
# over federation.
- state_ids = await self._resolve_state_at_missing_prevs(destination, event)
-
- # build a new state group for it if need be
- context = await self._state_handler.compute_event_context(
- event,
- state_ids_before_event=state_ids,
+ state_ids, partial_state = await self._resolve_state_at_missing_prevs(
+ destination, event
)
- if context.partial_state:
+
+ # There are three possible cases for (state_ids, partial_state):
+ # * `state_ids` and `partial_state` are both `None` if we had all the
+ # prev_events. The prev_events may or may not have partial state and
+ # we won't know until we compute the event context.
+ # * `state_ids` is not `None` and `partial_state` is `False` if we were
+ # missing some prev_events (but we have full state for any we did
+ # have). We calculated the full state after the prev_events.
+ # * `state_ids` is not `None` and `partial_state` is `True` if we were
+ # missing some, but not all, prev_events. At least one of the
+ # prev_events we did have had partial state, so we calculated a partial
+ # state after the prev_events.
+
+ context = None
+ if state_ids is not None and partial_state:
+ # the state after the prev events is still partial. We can't de-partial
+ # state the event, so don't bother building the event context.
+ pass
+ else:
+ # build a new state group for it if need be
+ context = await self._state_handler.compute_event_context(
+ event,
+ state_ids_before_event=state_ids,
+ partial_state=partial_state,
+ )
+
+ if context is None or context.partial_state:
# this can happen if some or all of the event's prev_events still have
# partial state - ie, an event has an earlier stream_ordering than one
# or more of its prev_events, so we de-partial-state it before its
@@ -806,14 +832,39 @@ class FederationEventHandler:
return
try:
- state_ids = await self._resolve_state_at_missing_prevs(origin, event)
- # TODO(faster_joins): make sure that _resolve_state_at_missing_prevs does
- # not return partial state
- # https://github.com/matrix-org/synapse/issues/13002
+ try:
+ state_ids, partial_state = await self._resolve_state_at_missing_prevs(
+ origin, event
+ )
+ await self._process_received_pdu(
+ origin,
+ event,
+ state_ids=state_ids,
+ partial_state=partial_state,
+ backfilled=backfilled,
+ )
+ except PartialStateConflictError:
+ # The room was un-partial stated while we were processing the event.
+ # Try once more, with full state this time.
+ state_ids, partial_state = await self._resolve_state_at_missing_prevs(
+ origin, event
+ )
- await self._process_received_pdu(
- origin, event, state_ids=state_ids, backfilled=backfilled
- )
+ # We ought to have full state now, barring some unlikely race where we left and
+ # rejoned the room in the background.
+ if state_ids is not None and partial_state:
+ raise AssertionError(
+ f"Event {event.event_id} still has a partial resolved state "
+ f"after room {event.room_id} was un-partial stated"
+ )
+
+ await self._process_received_pdu(
+ origin,
+ event,
+ state_ids=state_ids,
+ partial_state=partial_state,
+ backfilled=backfilled,
+ )
except FederationError as e:
if e.code == 403:
logger.warning("Pulled event %s failed history check.", event_id)
@@ -822,7 +873,7 @@ class FederationEventHandler:
async def _resolve_state_at_missing_prevs(
self, dest: str, event: EventBase
- ) -> Optional[StateMap[str]]:
+ ) -> Tuple[Optional[StateMap[str]], Optional[bool]]:
"""Calculate the state at an event with missing prev_events.
This is used when we have pulled a batch of events from a remote server, and
@@ -849,8 +900,10 @@ class FederationEventHandler:
event: an event to check for missing prevs.
Returns:
- if we already had all the prev events, `None`. Otherwise, returns
- the event ids of the state at `event`.
+ if we already had all the prev events, `None, None`. Otherwise, returns a
+ tuple containing:
+ * the event ids of the state at `event`.
+ * a boolean indicating whether the state may be partial.
Raises:
FederationError if we fail to get the state from the remote server after any
@@ -864,7 +917,7 @@ class FederationEventHandler:
missing_prevs = prevs - seen
if not missing_prevs:
- return None
+ return None, None
logger.info(
"Event %s is missing prev_events %s: calculating state for a "
@@ -876,9 +929,15 @@ class FederationEventHandler:
# resolve them to find the correct state at the current event.
try:
+ # Determine whether we may be about to retrieve partial state
+ # Events may be un-partial stated right after we compute the partial state
+ # flag, but that's okay, as long as the flag errs on the conservative side.
+ partial_state_flags = await self._store.get_partial_state_events(seen)
+ partial_state = any(partial_state_flags.values())
+
# Get the state of the events we know about
ours = await self._state_storage_controller.get_state_groups_ids(
- room_id, seen
+ room_id, seen, await_full_state=False
)
# state_maps is a list of mappings from (type, state_key) to event_id
@@ -924,7 +983,7 @@ class FederationEventHandler:
"We can't get valid state history.",
affected=event_id,
)
- return state_map
+ return state_map, partial_state
async def _get_state_ids_after_missing_prev_event(
self,
@@ -1094,6 +1153,7 @@ class FederationEventHandler:
origin: str,
event: EventBase,
state_ids: Optional[StateMap[str]],
+ partial_state: Optional[bool],
backfilled: bool = False,
) -> None:
"""Called when we have a new non-outlier event.
@@ -1117,14 +1177,21 @@ class FederationEventHandler:
state_ids: Normally None, but if we are handling a gap in the graph
(ie, we are missing one or more prev_events), the resolved state at the
- event. Must not be partial state.
+ event
+
+ partial_state:
+ `True` if `state_ids` is partial and omits non-critical membership
+ events.
+ `False` if `state_ids` is the full state.
+ `None` if `state_ids` is not provided. In this case, the flag will be
+ calculated based on `event`'s prev events.
backfilled: True if this is part of a historical batch of events (inhibits
notification to clients, and validation of device keys.)
PartialStateConflictError: if the room was un-partial stated in between
computing the state at the event and persisting it. The caller should retry
- exactly once in this case. Will never be raised if `state_ids` is provided.
+ exactly once in this case.
"""
logger.debug("Processing event: %s", event)
assert not event.internal_metadata.outlier
@@ -1132,6 +1199,7 @@ class FederationEventHandler:
context = await self._state_handler.compute_event_context(
event,
state_ids_before_event=state_ids,
+ partial_state=partial_state,
)
try:
await self._check_event_auth(origin, event, context)
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