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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
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|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?
"""
__slots__ = [
"current_state_ids",
"prev_state_ids",
"state_group",
"rejected",
"prev_group",
"delta_ids",
"prev_state_events",
"app_service",
]
def __init__(self, state_group, current_state_ids, prev_state_ids,
prev_group=None, delta_ids=None):
# The current state including the current event
self.current_state_ids = current_state_ids
# The current state excluding the current event
self.prev_state_ids = prev_state_ids
self.state_group = state_group
# A previously persisted state group and a delta between that
# and this state.
self.prev_group = prev_group
self.delta_ids = delta_ids
self.prev_state_events = []
self.rejected = False
self.app_service = None
def serialize(self, event):
"""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_id = self.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
@defer.inlineCallbacks
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
"""
# 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"]
current_state_ids = yield store.get_state_ids_for_group(
state_group,
)
if prev_state_id and event_state_key:
prev_state_ids = dict(current_state_ids)
prev_state_ids[(event_type, event_state_key)] = prev_state_id
else:
prev_state_ids = current_state_ids
context = EventContext(
state_group=state_group,
current_state_ids=current_state_ids,
prev_state_ids=prev_state_ids,
prev_group=input["prev_group"],
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)
defer.returnValue(context)
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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