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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
import attr
from frozendict import frozendict
from twisted.internet import defer
from synapse.logging.context import make_deferred_yieldable, run_in_background
@attr.s(slots=True)
class EventContext:
"""
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
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.
app_service: FIXME
_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
"""
state_group = attr.ib(default=None)
rejected = attr.ib(default=False)
prev_group = attr.ib(default=None)
delta_ids = attr.ib(default=None)
app_service = attr.ib(default=None)
_prev_state_ids = attr.ib(default=None)
_current_state_ids = attr.ib(default=None)
@staticmethod
def with_state(
state_group, 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,
prev_group=prev_group,
delta_ids=delta_ids,
)
@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),
"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 = _AsyncEventContextImpl(
# 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.
prev_state_id=input["prev_state_id"],
event_type=input["event_type"],
event_state_key=input["event_state_key"],
state_group=input["state_group"],
prev_group=input["prev_group"],
delta_ids=_decode_state_dict(input["delta_ids"]),
rejected=input["rejected"],
)
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.
"""
yield self._ensure_fetched(store)
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.
"""
yield self._ensure_fetched(store)
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
def _ensure_fetched(self, store):
return defer.succeed(None)
@attr.s(slots=True)
class _AsyncEventContextImpl(EventContext):
"""
An implementation of EventContext which fetches _current_state_ids and
_prev_state_ids from the database on demand.
Attributes:
_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.
_event_state_key (str): The state_key of the event the context is
associated with.
_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.
"""
_prev_state_id = attr.ib(default=None)
_event_type = attr.ib(default=None)
_event_state_key = attr.ib(default=None)
_fetching_state_deferred = attr.ib(default=None)
def _ensure_fetched(self, store):
if not self._fetching_state_deferred:
self._fetching_state_deferred = run_in_background(
self._fill_out_state, store
)
return make_deferred_yieldable(self._fetching_state_deferred)
@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
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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