mirror of
https://github.com/element-hq/synapse.git
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333 lines
11 KiB
Python
333 lines
11 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2014 OpenMarket Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from twisted.internet import defer
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from synapse.util.logutils import log_function
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from synapse.util.async import run_on_reactor
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from synapse.api.constants import EventTypes
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from collections import namedtuple
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import copy
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import logging
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import hashlib
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logger = logging.getLogger(__name__)
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def _get_state_key_from_event(event):
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return event.state_key
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KeyStateTuple = namedtuple("KeyStateTuple", ("context", "type", "state_key"))
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class StateHandler(object):
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""" Responsible for doing state conflict resolution.
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"""
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def __init__(self, hs):
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self.store = hs.get_datastore()
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@defer.inlineCallbacks
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@log_function
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def annotate_event_with_state(self, event, old_state=None):
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""" Annotates the event with the current state events as of that event.
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This method adds three new attributes to the event:
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* `state_events`: The state up to and including the event. Encoded
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as a dict mapping tuple (type, state_key) -> event.
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* `old_state_events`: The state up to, but excluding, the event.
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Encoded similarly as `state_events`.
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* `state_group`: If there is an existing state group that can be
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used, then return that. Otherwise return `None`. See state
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storage for more information.
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If the argument `old_state` is given (in the form of a list of
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events), then they are used as a the values for `old_state_events` and
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the value for `state_events` is generated from it. `state_group` is
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set to None.
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This needs to be called before persisting the event.
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"""
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yield run_on_reactor()
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if old_state:
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event.state_group = None
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event.old_state_events = {
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(s.type, s.state_key): s for s in old_state
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}
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event.state_events = event.old_state_events
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if hasattr(event, "state_key"):
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event.state_events[(event.type, event.state_key)] = event
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defer.returnValue(False)
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return
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if hasattr(event, "outlier") and event.outlier:
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event.state_group = None
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event.old_state_events = None
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event.state_events = None
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defer.returnValue(False)
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return
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ids = [e for e, _ in event.prev_events]
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ret = yield self.resolve_state_groups(ids)
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state_group, new_state, _ = ret
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event.old_state_events = copy.deepcopy(new_state)
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if hasattr(event, "state_key"):
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key = (event.type, event.state_key)
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if key in new_state:
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event.replaces_state = new_state[key].event_id
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new_state[key] = event
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elif state_group:
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event.state_group = state_group
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event.state_events = new_state
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defer.returnValue(False)
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event.state_group = None
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event.state_events = new_state
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defer.returnValue(hasattr(event, "state_key"))
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@defer.inlineCallbacks
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def get_current_state(self, room_id, event_type=None, state_key=""):
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""" Returns the current state for the room as a list. This is done by
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calling `get_latest_events_in_room` to get the leading edges of the
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event graph and then resolving any of the state conflicts.
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This is equivalent to getting the state of an event that were to send
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next before receiving any new events.
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If `event_type` is specified, then the method returns only the one
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event (or None) with that `event_type` and `state_key`.
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"""
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events = yield self.store.get_latest_events_in_room(room_id)
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event_ids = [
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e_id
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for e_id, _, _ in events
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]
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res = yield self.resolve_state_groups(event_ids)
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if event_type:
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defer.returnValue(res[1].get((event_type, state_key)))
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return
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defer.returnValue(res[1].values())
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@defer.inlineCallbacks
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def annotate_context_with_state(self, event, context, old_state=None):
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""" Fills out the context with the `current state` of the graph. The
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`current state` here is defined to be the state of the event graph
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just before the event - i.e. it never includes `event`
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If `event` has `auth_events` then this will also fill out the
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`auth_events` field on `context` from the `current_state`.
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Args:
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event (EventBase)
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context (EventContext)
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"""
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yield run_on_reactor()
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if old_state:
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context.current_state = {
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(s.type, s.state_key): s for s in old_state
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}
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context.state_group = None
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if hasattr(event, "auth_events") and event.auth_events:
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auth_ids = zip(*event.auth_events)[0]
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context.auth_events = {
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k: v
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for k, v in context.current_state.items()
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if v.event_id in auth_ids
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}
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else:
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context.auth_events = {}
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if event.is_state():
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key = (event.type, event.state_key)
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if key in context.current_state:
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replaces = context.current_state[key]
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if replaces.event_id != event.event_id: # Paranoia check
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event.unsigned["replaces_state"] = replaces.event_id
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defer.returnValue([])
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if event.is_state():
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ret = yield self.resolve_state_groups(
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[e for e, _ in event.prev_events],
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event_type=event.type,
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state_key=event.state_key,
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)
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else:
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ret = yield self.resolve_state_groups(
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[e for e, _ in event.prev_events],
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)
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group, curr_state, prev_state = ret
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context.current_state = curr_state
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context.state_group = group if not event.is_state() else None
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prev_state = yield self.store.add_event_hashes(
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prev_state
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)
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if event.is_state():
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key = (event.type, event.state_key)
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if key in context.current_state:
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replaces = context.current_state[key]
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event.unsigned["replaces_state"] = replaces.event_id
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if hasattr(event, "auth_events") and event.auth_events:
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auth_ids = zip(*event.auth_events)[0]
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context.auth_events = {
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k: v
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for k, v in context.current_state.items()
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if v.event_id in auth_ids
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}
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else:
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context.auth_events = {}
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defer.returnValue(prev_state)
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@defer.inlineCallbacks
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@log_function
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def resolve_state_groups(self, event_ids, event_type=None, state_key=""):
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""" Given a list of event_ids this method fetches the state at each
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event, resolves conflicts between them and returns them.
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Return format is a tuple: (`state_group`, `state_events`), where the
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first is the name of a state group if one and only one is involved,
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otherwise `None`.
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"""
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state_groups = yield self.store.get_state_groups(
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event_ids
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)
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group_names = set(state_groups.keys())
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if len(group_names) == 1:
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name, state_list = state_groups.items().pop()
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state = {
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(e.type, e.state_key): e
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for e in state_list
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}
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prev_state = state.get((event_type, state_key), None)
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if prev_state:
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prev_state = prev_state.event_id
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prev_states = [prev_state]
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else:
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prev_states = []
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defer.returnValue((name, state, prev_states))
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state = {}
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for group, g_state in state_groups.items():
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for s in g_state:
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state.setdefault(
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(s.type, s.state_key),
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{}
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)[s.event_id] = s
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unconflicted_state = {
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k: v.values()[0] for k, v in state.items()
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if len(v.values()) == 1
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}
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conflicted_state = {
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k: v.values()
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for k, v in state.items()
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if len(v.values()) > 1
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}
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if event_type:
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prev_states_events = conflicted_state.get(
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(event_type, state_key), []
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)
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prev_states = [s.event_id for s in prev_states_events]
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else:
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prev_states = []
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try:
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new_state = {}
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new_state.update(unconflicted_state)
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for key, events in conflicted_state.items():
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new_state[key] = self._resolve_state_events(events)
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except:
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logger.exception("Failed to resolve state")
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raise
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defer.returnValue((None, new_state, prev_states))
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def _get_power_level_from_event_state(self, event, user_id):
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if hasattr(event, "old_state_events") and event.old_state_events:
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key = (EventTypes.PowerLevels, "", )
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power_level_event = event.old_state_events.get(key)
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level = None
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if power_level_event:
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level = power_level_event.content.get("users", {}).get(
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user_id
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)
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if not level:
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level = power_level_event.content.get("users_default", 0)
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return level
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else:
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return 0
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@log_function
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def _resolve_state_events(self, events):
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curr_events = events
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new_powers = [
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self._get_power_level_from_event_state(e, e.user_id)
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for e in curr_events
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]
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new_powers = [
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int(p) if p else 0 for p in new_powers
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]
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max_power = max(new_powers)
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curr_events = [
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z[0] for z in zip(curr_events, new_powers)
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if z[1] == max_power
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]
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if not curr_events:
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raise RuntimeError("Max didn't get a max?")
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elif len(curr_events) == 1:
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return curr_events[0]
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# TODO: For now, just choose the one with the largest event_id.
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return (
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sorted(
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curr_events,
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key=lambda e: hashlib.sha1(
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e.event_id + e.user_id + e.room_id + e.type
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).hexdigest()
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)[0]
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)
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