# -*- 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.util.logcontext 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 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})