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- # -*- coding: utf-8 -*-
- # Copyright 2014-2016 OpenMarket Ltd
- #
- # Licensed under the Apache License, Version 2.0 (the "License");
- # you may not use this file except in compliance with the License.
- # You may obtain a copy of the License at
- #
- # http://www.apache.org/licenses/LICENSE-2.0
- #
- # Unless required by applicable law or agreed to in writing, software
- # distributed under the License is distributed on an "AS IS" BASIS,
- # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- # 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.logging.context import make_deferred_yieldable, run_in_background
- class EventContext(object):
- """
- Attributes:
- 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
- push_actions (list[(str, list[object])]): list of (user_id, actions)
- tuples
- prev_group (int): Previously persisted state group. ``None`` for an
- outlier.
- delta_ids (dict[(str, str), str]): Delta from ``prev_group``.
- (type, state_key) -> event_id. ``None`` for an outlier.
- 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__ = [
- "state_group",
- "rejected",
- "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
- context._current_state_ids = current_state_ids
- # The current state excluding the current event
- context._prev_state_ids = prev_state_ids
- context.state_group = state_group
- 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.
- context.prev_group = prev_group
- context.delta_ids = delta_ids
- return context
- @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
- return {
- "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.
- Maps a (type, state_key) to the event ID of the state event matching
- this tuple.
- """
- 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)
- return 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.
- Maps a (type, state_key) to the event ID of the state event matching
- this tuple.
- """
- 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)
- return 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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