diff --git a/synapse/events/snapshot.py b/synapse/events/snapshot.py
index e9a732ff03..368b5f6ae4 100644
--- a/synapse/events/snapshot.py
+++ b/synapse/events/snapshot.py
@@ -13,19 +13,21 @@
# See the License for the specific language governing permissions and
# limitations under the License.
+from six import iteritems
+
+from frozendict import frozendict
+
+from twisted.internet import defer
+
+from synapse.util.logcontext import make_deferred_yieldable, run_in_background
+
class EventContext(object):
"""
Attributes:
- current_state_ids (dict[(str, str), str]):
- The current state map including the current event.
- (type, state_key) -> event_id
-
- prev_state_ids (dict[(str, str), str]):
- The current state map excluding the current event.
- (type, state_key) -> event_id
-
- state_group (int): state group id
+ state_group (int|None): state group id, if the state has been stored
+ as a state group. This is usually only None if e.g. the event is
+ an outlier.
rejected (bool|str): A rejection reason if the event was rejected, else
False
@@ -39,35 +41,250 @@ class EventContext(object):
prev_state_events (?): XXX: is this ever set to anything other than
the empty list?
+
+ _current_state_ids (dict[(str, str), str]|None):
+ The current state map including the current event. None if outlier
+ or we haven't fetched the state from DB yet.
+ (type, state_key) -> event_id
+
+ _prev_state_ids (dict[(str, str), str]|None):
+ The current state map excluding the current event. None if outlier
+ or we haven't fetched the state from DB yet.
+ (type, state_key) -> event_id
+
+ _fetching_state_deferred (Deferred|None): Resolves when *_state_ids have
+ been calculated. None if we haven't started calculating yet
+
+ _event_type (str): The type of the event the context is associated with.
+ Only set when state has not been fetched yet.
+
+ _event_state_key (str|None): The state_key of the event the context is
+ associated with. Only set when state has not been fetched yet.
+
+ _prev_state_id (str|None): If the event associated with the context is
+ a state event, then `_prev_state_id` is the event_id of the state
+ that was replaced.
+ Only set when state has not been fetched yet.
"""
__slots__ = [
- "current_state_ids",
- "prev_state_ids",
"state_group",
"rejected",
- "push_actions",
"prev_group",
"delta_ids",
"prev_state_events",
"app_service",
+ "_current_state_ids",
+ "_prev_state_ids",
+ "_prev_state_id",
+ "_event_type",
+ "_event_state_key",
+ "_fetching_state_deferred",
]
def __init__(self):
+ self.prev_state_events = []
+ self.rejected = False
+ self.app_service = None
+
+ @staticmethod
+ def with_state(state_group, current_state_ids, prev_state_ids,
+ prev_group=None, delta_ids=None):
+ context = EventContext()
+
# The current state including the current event
- self.current_state_ids = None
+ context._current_state_ids = current_state_ids
# The current state excluding the current event
- self.prev_state_ids = None
- self.state_group = None
+ context._prev_state_ids = prev_state_ids
+ context.state_group = state_group
- self.rejected = False
- self.push_actions = []
+ context._prev_state_id = None
+ context._event_type = None
+ context._event_state_key = None
+ context._fetching_state_deferred = defer.succeed(None)
# A previously persisted state group and a delta between that
# and this state.
- self.prev_group = None
- self.delta_ids = None
+ context.prev_group = prev_group
+ context.delta_ids = delta_ids
- self.prev_state_events = None
+ return context
- self.app_service = None
+ @defer.inlineCallbacks
+ def serialize(self, event, store):
+ """Converts self to a type that can be serialized as JSON, and then
+ deserialized by `deserialize`
+
+ Args:
+ event (FrozenEvent): The event that this context relates to
+
+ Returns:
+ dict
+ """
+
+ # We don't serialize the full state dicts, instead they get pulled out
+ # of the DB on the other side. However, the other side can't figure out
+ # the prev_state_ids, so if we're a state event we include the event
+ # id that we replaced in the state.
+ if event.is_state():
+ prev_state_ids = yield self.get_prev_state_ids(store)
+ prev_state_id = prev_state_ids.get((event.type, event.state_key))
+ else:
+ prev_state_id = None
+
+ defer.returnValue({
+ "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,
+ "rejected": self.rejected,
+ "prev_group": self.prev_group,
+ "delta_ids": _encode_state_dict(self.delta_ids),
+ "prev_state_events": self.prev_state_events,
+ "app_service_id": self.app_service.id if self.app_service else None
+ })
+
+ @staticmethod
+ def deserialize(store, input):
+ """Converts a dict that was produced by `serialize` back into a
+ EventContext.
+
+ Args:
+ store (DataStore): Used to convert AS ID to AS object
+ input (dict): A dict produced by `serialize`
+
+ Returns:
+ EventContext
+ """
+ context = EventContext()
+
+ # We use the state_group and prev_state_id stuff to pull the
+ # current_state_ids out of the DB and construct prev_state_ids.
+ context._prev_state_id = input["prev_state_id"]
+ context._event_type = input["event_type"]
+ context._event_state_key = input["event_state_key"]
+
+ context._current_state_ids = None
+ context._prev_state_ids = None
+ context._fetching_state_deferred = None
+
+ context.state_group = input["state_group"]
+ context.prev_group = input["prev_group"]
+ context.delta_ids = _decode_state_dict(input["delta_ids"])
+
+ context.rejected = input["rejected"]
+ context.prev_state_events = input["prev_state_events"]
+
+ app_service_id = input["app_service_id"]
+ if app_service_id:
+ context.app_service = store.get_app_service_by_id(app_service_id)
+
+ return context
+
+ @defer.inlineCallbacks
+ def get_current_state_ids(self, store):
+ """Gets the current state IDs
+
+ Returns:
+ Deferred[dict[(str, str), str]|None]: Returns None if state_group
+ is None, which happens when the associated event is an outlier.
+ """
+
+ if not self._fetching_state_deferred:
+ self._fetching_state_deferred = run_in_background(
+ self._fill_out_state, store,
+ )
+
+ yield make_deferred_yieldable(self._fetching_state_deferred)
+
+ defer.returnValue(self._current_state_ids)
+
+ @defer.inlineCallbacks
+ def get_prev_state_ids(self, store):
+ """Gets the prev state IDs
+
+ Returns:
+ Deferred[dict[(str, str), str]|None]: Returns None if state_group
+ is None, which happens when the associated event is an outlier.
+ """
+
+ if not self._fetching_state_deferred:
+ self._fetching_state_deferred = run_in_background(
+ self._fill_out_state, store,
+ )
+
+ yield make_deferred_yieldable(self._fetching_state_deferred)
+
+ defer.returnValue(self._prev_state_ids)
+
+ def get_cached_current_state_ids(self):
+ """Gets the current state IDs if we have them already cached.
+
+ 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.
+ """
+
+ return self._current_state_ids
+
+ @defer.inlineCallbacks
+ def _fill_out_state(self, store):
+ """Called to populate the _current_state_ids and _prev_state_ids
+ attributes by loading from the database.
+ """
+ if self.state_group is None:
+ return
+
+ self._current_state_ids = yield store.get_state_ids_for_group(
+ self.state_group,
+ )
+ if self._prev_state_id and self._event_state_key is not None:
+ self._prev_state_ids = dict(self._current_state_ids)
+
+ key = (self._event_type, self._event_state_key)
+ self._prev_state_ids[key] = self._prev_state_id
+ else:
+ self._prev_state_ids = self._current_state_ids
+
+ @defer.inlineCallbacks
+ def update_state(self, state_group, prev_state_ids, current_state_ids,
+ prev_group, delta_ids):
+ """Replace the state in the context
+ """
+
+ # We need to make sure we wait for any ongoing fetching of state
+ # to complete so that the updated state doesn't get clobbered
+ if self._fetching_state_deferred:
+ yield make_deferred_yieldable(self._fetching_state_deferred)
+
+ self.state_group = state_group
+ self._prev_state_ids = prev_state_ids
+ self.prev_group = prev_group
+ self._current_state_ids = current_state_ids
+ self.delta_ids = delta_ids
+
+ # We need to ensure that that we've marked as having fetched the state
+ self._fetching_state_deferred = defer.succeed(None)
+
+
+def _encode_state_dict(state_dict):
+ """Since dicts of (type, state_key) -> event_id cannot be serialized in
+ JSON we need to convert them to a form that can.
+ """
+ if state_dict is None:
+ return None
+
+ return [
+ (etype, state_key, v)
+ for (etype, state_key), v in iteritems(state_dict)
+ ]
+
+
+def _decode_state_dict(input):
+ """Decodes a state dict encoded using `_encode_state_dict` above
+ """
+ if input is None:
+ return None
+
+ return frozendict({(etype, state_key,): v for etype, state_key, v in input})
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