diff --git a/synapse/events/snapshot.py b/synapse/events/snapshot.py
index 5f07f6fe4b..64e898f40c 100644
--- a/synapse/events/snapshot.py
+++ b/synapse/events/snapshot.py
@@ -33,7 +33,7 @@ class EventContext:
Attributes:
rejected: A rejection reason if the event was rejected, else False
- state_group: The ID of the state group for this event. Note that state events
+ _state_group: The ID of the state group for this event. Note that state events
are persisted with a state group which includes the new event, so this is
effectively the state *after* the event in question.
@@ -45,10 +45,24 @@ class EventContext:
For an outlier, where we don't have the state at the event, this will be
None.
+ Note that this is a private attribute: it should be accessed via
+ the ``state_group`` property.
+
+ state_group_before_event: The ID of the state group representing the state
+ of the room before this event.
+
+ If this is a non-state event, this will be the same as ``state_group``. If
+ it's a state event, it will be the same as ``prev_group``.
+
+ If ``state_group`` is None (ie, the event is an outlier),
+ ``state_group_before_event`` will always also be ``None``.
+
prev_group: If it is known, ``state_group``'s prev_group. Note that this being
None does not necessarily mean that ``state_group`` does not have
a prev_group!
+ If the event is a state event, this is normally the same as ``prev_group``.
+
If ``state_group`` is None (ie, the event is an outlier), ``prev_group``
will always also be ``None``.
@@ -74,7 +88,8 @@ class EventContext:
``get_current_state_ids``. _AsyncEventContext impl calculates this
on-demand: it will be None until that happens.
- _prev_state_ids: The room state map, excluding this event. For a non-state
+ _prev_state_ids: The room state map, excluding this event - ie, the state
+ in ``state_group_before_event``. For a non-state
event, this will be the same as _current_state_events.
Note that it is a completely different thing to prev_group!
@@ -88,7 +103,8 @@ class EventContext:
"""
rejected = attr.ib(default=False, type=Union[bool, str])
- state_group = attr.ib(default=None, type=Optional[int])
+ _state_group = attr.ib(default=None, type=Optional[int])
+ state_group_before_event = attr.ib(default=None, type=Optional[int])
prev_group = attr.ib(default=None, type=Optional[int])
delta_ids = attr.ib(default=None, type=Optional[Dict[Tuple[str, str], str]])
app_service = attr.ib(default=None, type=Optional[ApplicationService])
@@ -100,12 +116,18 @@ class EventContext:
@staticmethod
def with_state(
- state_group, current_state_ids, prev_state_ids, prev_group=None, delta_ids=None
+ state_group,
+ state_group_before_event,
+ current_state_ids,
+ prev_state_ids,
+ prev_group=None,
+ delta_ids=None,
):
return EventContext(
current_state_ids=current_state_ids,
prev_state_ids=prev_state_ids,
state_group=state_group,
+ state_group_before_event=state_group_before_event,
prev_group=prev_group,
delta_ids=delta_ids,
)
@@ -136,7 +158,8 @@ class EventContext:
"prev_state_id": prev_state_id,
"event_type": event.type,
"event_state_key": event.state_key if event.is_state() else None,
- "state_group": self.state_group,
+ "state_group": self._state_group,
+ "state_group_before_event": self.state_group_before_event,
"rejected": self.rejected,
"prev_group": self.prev_group,
"delta_ids": _encode_state_dict(self.delta_ids),
@@ -162,6 +185,7 @@ class EventContext:
event_type=input["event_type"],
event_state_key=input["event_state_key"],
state_group=input["state_group"],
+ state_group_before_event=input["state_group_before_event"],
prev_group=input["prev_group"],
delta_ids=_decode_state_dict(input["delta_ids"]),
rejected=input["rejected"],
@@ -173,22 +197,52 @@ class EventContext:
return context
+ @property
+ def state_group(self) -> Optional[int]:
+ """The ID of the state group for this event.
+
+ Note that state events are persisted with a state group which includes the new
+ event, so this is effectively the state *after* the event in question.
+
+ For an outlier, where we don't have the state at the event, this will be None.
+
+ It is an error to access this for a rejected event, since rejected state should
+ not make it into the room state. Accessing this property will raise an exception
+ if ``rejected`` is set.
+ """
+ if self.rejected:
+ raise RuntimeError("Attempt to access state_group of rejected event")
+
+ return self._state_group
+
@defer.inlineCallbacks
def get_current_state_ids(self, store):
- """Gets the current state IDs
+ """
+ Gets the room state map, including this event - ie, the state in ``state_group``
+
+ It is an error to access this for a rejected event, since rejected state should
+ not make it into the room state. This method will raise an exception if
+ ``rejected`` is set.
Returns:
Deferred[dict[(str, str), str]|None]: Returns None if state_group
is None, which happens when the associated event is an outlier.
+
Maps a (type, state_key) to the event ID of the state event matching
this tuple.
"""
+ if self.rejected:
+ raise RuntimeError("Attempt to access state_ids of rejected event")
+
yield self._ensure_fetched(store)
return self._current_state_ids
@defer.inlineCallbacks
def get_prev_state_ids(self, store):
- """Gets the prev state IDs
+ """
+ Gets the room state map, excluding this event.
+
+ For a non-state event, this will be the same as get_current_state_ids().
Returns:
Deferred[dict[(str, str), str]|None]: Returns None if state_group
@@ -202,11 +256,17 @@ class EventContext:
def get_cached_current_state_ids(self):
"""Gets the current state IDs if we have them already cached.
+ It is an error to access this for a rejected event, since rejected state should
+ not make it into the room state. This method will raise an exception if
+ ``rejected`` is set.
+
Returns:
dict[(str, str), str]|None: Returns None if we haven't cached the
state or if state_group is None, which happens when the associated
event is an outlier.
"""
+ if self.rejected:
+ raise RuntimeError("Attempt to access state_ids of rejected event")
return self._current_state_ids
|
