536 lines
		
	
	
		
			19 KiB
		
	
	
	
		
			Python
		
	
	
			
		
		
	
	
			536 lines
		
	
	
		
			19 KiB
		
	
	
	
		
			Python
		
	
	
# -*- coding: utf-8 -*-
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# Copyright 2014-2016 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.caches.expiringcache import ExpiringCache
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from synapse.util.metrics import Measure
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from synapse.api.constants import EventTypes
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from synapse.api.errors import AuthError
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from synapse.api.auth import AuthEventTypes
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from synapse.events.snapshot import EventContext
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from synapse.util.async import Linearizer
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from collections import namedtuple
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from frozendict import frozendict
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import logging
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import hashlib
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import os
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logger = logging.getLogger(__name__)
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KeyStateTuple = namedtuple("KeyStateTuple", ("context", "type", "state_key"))
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CACHE_SIZE_FACTOR = float(os.environ.get("SYNAPSE_CACHE_FACTOR", 0.1))
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SIZE_OF_CACHE = int(1000 * CACHE_SIZE_FACTOR)
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EVICTION_TIMEOUT_SECONDS = 60 * 60
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_NEXT_STATE_ID = 1
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def _gen_state_id():
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    global _NEXT_STATE_ID
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    s = "X%d" % (_NEXT_STATE_ID,)
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    _NEXT_STATE_ID += 1
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    return s
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class _StateCacheEntry(object):
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    __slots__ = ["state", "state_group", "state_id", "prev_group", "delta_ids"]
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    def __init__(self, state, state_group, prev_group=None, delta_ids=None):
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        self.state = frozendict(state)
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        self.state_group = state_group
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        self.prev_group = prev_group
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        self.delta_ids = frozendict(delta_ids) if delta_ids is not None else None
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        # The `state_id` is a unique ID we generate that can be used as ID for
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        # this collection of state. Usually this would be the same as the
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        # state group, but on worker instances we can't generate a new state
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        # group each time we resolve state, so we generate a separate one that
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        # isn't persisted and is used solely for caches.
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        # `state_id` is either a state_group (and so an int) or a string. This
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        # ensures we don't accidentally persist a state_id as a stateg_group
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        if state_group:
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            self.state_id = state_group
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        else:
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            self.state_id = _gen_state_id()
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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.clock = hs.get_clock()
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        self.store = hs.get_datastore()
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        self.hs = hs
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        # dict of set of event_ids -> _StateCacheEntry.
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        self._state_cache = None
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        self.resolve_linearizer = Linearizer()
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    def start_caching(self):
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        logger.debug("start_caching")
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        self._state_cache = ExpiringCache(
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            cache_name="state_cache",
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            clock=self.clock,
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            max_len=SIZE_OF_CACHE,
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            expiry_ms=EVICTION_TIMEOUT_SECONDS * 1000,
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            reset_expiry_on_get=True,
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        )
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        self._state_cache.start()
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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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                          latest_event_ids=None):
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        """ Retrieves the current state for the room. 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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        Returns:
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            map from (type, state_key) to event
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        """
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        if not latest_event_ids:
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            latest_event_ids = yield self.store.get_latest_event_ids_in_room(room_id)
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        ret = yield self.resolve_state_groups(room_id, latest_event_ids)
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        state = ret.state
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        if event_type:
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            event_id = state.get((event_type, state_key))
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            event = None
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            if event_id:
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                event = yield self.store.get_event(event_id, allow_none=True)
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            defer.returnValue(event)
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            return
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        state_map = yield self.store.get_events(state.values(), get_prev_content=False)
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        state = {
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            key: state_map[e_id] for key, e_id in state.items() if e_id in state_map
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        }
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        defer.returnValue(state)
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    @defer.inlineCallbacks
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    def get_current_state_ids(self, room_id, event_type=None, state_key="",
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                              latest_event_ids=None):
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        if not latest_event_ids:
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            latest_event_ids = yield self.store.get_latest_event_ids_in_room(room_id)
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        ret = yield self.resolve_state_groups(room_id, latest_event_ids)
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        state = ret.state
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        if event_type:
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            defer.returnValue(state.get((event_type, state_key)))
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            return
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        defer.returnValue(state)
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    @defer.inlineCallbacks
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    def get_current_user_in_room(self, room_id, latest_event_ids=None):
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        if not latest_event_ids:
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            latest_event_ids = yield self.store.get_latest_event_ids_in_room(room_id)
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        entry = yield self.resolve_state_groups(room_id, latest_event_ids)
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        joined_users = yield self.store.get_joined_users_from_state(
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            room_id, entry.state_id, entry.state
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        )
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        defer.returnValue(joined_users)
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    @defer.inlineCallbacks
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    def compute_event_context(self, event, 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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        Returns:
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            an EventContext
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        """
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        context = EventContext()
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        if event.internal_metadata.is_outlier():
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            # If this is an outlier, then we know it shouldn't have any current
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            # state. Certainly store.get_current_state won't return any, and
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            # persisting the event won't store the state group.
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            if old_state:
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                context.prev_state_ids = {
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                    (s.type, s.state_key): s.event_id for s in old_state
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                }
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                if event.is_state():
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                    context.current_state_events = dict(context.prev_state_ids)
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                    key = (event.type, event.state_key)
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                    context.current_state_events[key] = event.event_id
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                else:
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                    context.current_state_events = context.prev_state_ids
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            else:
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                context.current_state_ids = {}
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                context.prev_state_ids = {}
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            context.prev_state_events = []
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            context.state_group = self.store.get_next_state_group()
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            defer.returnValue(context)
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        if old_state:
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            context.prev_state_ids = {
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                (s.type, s.state_key): s.event_id for s in old_state
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            }
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            context.state_group = self.store.get_next_state_group()
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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.prev_state_ids:
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                    replaces = context.prev_state_ids[key]
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                    if replaces != event.event_id:  # Paranoia check
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                        event.unsigned["replaces_state"] = replaces
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                context.current_state_ids = dict(context.prev_state_ids)
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                context.current_state_ids[key] = event.event_id
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            else:
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                context.current_state_ids = context.prev_state_ids
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            context.prev_state_events = []
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            defer.returnValue(context)
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        if event.is_state():
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            entry = yield self.resolve_state_groups(
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                event.room_id, [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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            entry = yield self.resolve_state_groups(
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                event.room_id, [e for e, _ in event.prev_events],
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            )
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        curr_state = entry.state
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        context.prev_state_ids = curr_state
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        if event.is_state():
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            context.state_group = self.store.get_next_state_group()
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            key = (event.type, event.state_key)
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            if key in context.prev_state_ids:
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                replaces = context.prev_state_ids[key]
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                event.unsigned["replaces_state"] = replaces
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            context.current_state_ids = dict(context.prev_state_ids)
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            context.current_state_ids[key] = event.event_id
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            context.prev_group = entry.prev_group
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            context.delta_ids = entry.delta_ids
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            if context.delta_ids is not None:
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                context.delta_ids = dict(context.delta_ids)
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                context.delta_ids[key] = event.event_id
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        else:
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            if entry.state_group is None:
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                entry.state_group = self.store.get_next_state_group()
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                entry.state_id = entry.state_group
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            context.state_group = entry.state_group
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            context.current_state_ids = context.prev_state_ids
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            context.prev_group = entry.prev_group
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            context.delta_ids = entry.delta_ids
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        context.prev_state_events = []
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        defer.returnValue(context)
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    @defer.inlineCallbacks
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    @log_function
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    def resolve_state_groups(self, room_id, 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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        Returns:
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            a Deferred tuple of (`state_group`, `state`, `prev_state`).
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            `state_group` is the name of a state group if one and only one is
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            involved. `state` is a map from (type, state_key) to event, and
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            `prev_state` is a list of event ids.
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        """
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        logger.debug("resolve_state_groups event_ids %s", event_ids)
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        state_groups_ids = yield self.store.get_state_groups_ids(
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            room_id, event_ids
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        )
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        logger.debug(
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            "resolve_state_groups state_groups %s",
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            state_groups_ids.keys()
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        )
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        group_names = frozenset(state_groups_ids.keys())
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        if len(group_names) == 1:
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            name, state_list = state_groups_ids.items().pop()
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            defer.returnValue(_StateCacheEntry(
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                state=state_list,
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                state_group=name,
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                prev_group=name,
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                delta_ids={},
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            ))
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        with (yield self.resolve_linearizer.queue(group_names)):
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            if self._state_cache is not None:
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                cache = self._state_cache.get(group_names, None)
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                if cache:
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                    defer.returnValue(cache)
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            logger.info(
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                "Resolving state for %s with %d groups", room_id, len(state_groups_ids)
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            )
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            state = {}
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            for st in state_groups_ids.values():
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                for key, e_id in st.items():
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                    state.setdefault(key, set()).add(e_id)
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            conflicted_state = {
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                k: list(v)
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                for k, v in state.items()
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                if len(v) > 1
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            }
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            if conflicted_state:
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                logger.info("Resolving conflicted state for %r", room_id)
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                state_map = yield self.store.get_events(
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                    [e_id for st in state_groups_ids.values() for e_id in st.values()],
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                    get_prev_content=False
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                )
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                state_sets = [
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                    [state_map[e_id] for key, e_id in st.items() if e_id in state_map]
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                    for st in state_groups_ids.values()
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                ]
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                new_state, _ = self._resolve_events(
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                    state_sets, event_type, state_key
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                )
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                new_state = {
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                    key: e.event_id for key, e in new_state.items()
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                }
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            else:
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                new_state = {
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                    key: e_ids.pop() for key, e_ids in state.items()
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                }
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            state_group = None
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            new_state_event_ids = frozenset(new_state.values())
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            for sg, events in state_groups_ids.items():
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                if new_state_event_ids == frozenset(e_id for e_id in events):
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                    state_group = sg
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                    break
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            if state_group is None:
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                # Worker instances don't have access to this method, but we want
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                # to set the state_group on the main instance to increase cache
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                # hits.
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                if hasattr(self.store, "get_next_state_group"):
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                    state_group = self.store.get_next_state_group()
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            prev_group = None
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            delta_ids = None
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            for old_group, old_ids in state_groups_ids.items():
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                if not set(new_state.iterkeys()) - set(old_ids.iterkeys()):
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                    n_delta_ids = {
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                        k: v
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                        for k, v in new_state.items()
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                        if old_ids.get(k) != v
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                    }
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                    if not delta_ids or len(n_delta_ids) < len(delta_ids):
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                        prev_group = old_group
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                        delta_ids = n_delta_ids
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            cache = _StateCacheEntry(
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                state=new_state,
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                state_group=state_group,
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                prev_group=prev_group,
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                delta_ids=delta_ids,
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            )
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            if self._state_cache is not None:
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                self._state_cache[group_names] = cache
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            defer.returnValue(cache)
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    def resolve_events(self, state_sets, event):
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        logger.info(
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            "Resolving state for %s with %d groups", event.room_id, len(state_sets)
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        )
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        if event.is_state():
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            return self._resolve_events(
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                state_sets, event.type, event.state_key
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            )
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        else:
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            return self._resolve_events(state_sets)
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    def _resolve_events(self, state_sets, event_type=None, state_key=""):
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        """
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        Returns
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            (dict[(str, str), synapse.events.FrozenEvent], list[str]): a tuple
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            (new_state, prev_states). new_state is a map from (type, state_key)
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            to event. prev_states is a list of event_ids.
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        """
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        with Measure(self.clock, "state._resolve_events"):
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            state = {}
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            for st in state_sets:
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                for e in st:
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                    state.setdefault(
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                        (e.type, e.state_key),
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                        {}
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                    )[e.event_id] = e
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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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            auth_events = {
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                k: e for k, e in unconflicted_state.items()
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                if k[0] in AuthEventTypes
 | 
						|
            }
 | 
						|
 | 
						|
            try:
 | 
						|
                resolved_state = self._resolve_state_events(
 | 
						|
                    conflicted_state, auth_events
 | 
						|
                )
 | 
						|
            except:
 | 
						|
                logger.exception("Failed to resolve state")
 | 
						|
                raise
 | 
						|
 | 
						|
            new_state = unconflicted_state
 | 
						|
            new_state.update(resolved_state)
 | 
						|
 | 
						|
        return new_state, prev_states
 | 
						|
 | 
						|
    @log_function
 | 
						|
    def _resolve_state_events(self, conflicted_state, auth_events):
 | 
						|
        """ This is where we actually decide which of the conflicted state to
 | 
						|
        use.
 | 
						|
 | 
						|
        We resolve conflicts in the following order:
 | 
						|
            1. power levels
 | 
						|
            2. join rules
 | 
						|
            3. memberships
 | 
						|
            4. other events.
 | 
						|
        """
 | 
						|
        resolved_state = {}
 | 
						|
        power_key = (EventTypes.PowerLevels, "")
 | 
						|
        if power_key in conflicted_state:
 | 
						|
            events = conflicted_state[power_key]
 | 
						|
            logger.debug("Resolving conflicted power levels %r", events)
 | 
						|
            resolved_state[power_key] = self._resolve_auth_events(
 | 
						|
                events, auth_events)
 | 
						|
 | 
						|
        auth_events.update(resolved_state)
 | 
						|
 | 
						|
        for key, events in conflicted_state.items():
 | 
						|
            if key[0] == EventTypes.JoinRules:
 | 
						|
                logger.debug("Resolving conflicted join rules %r", events)
 | 
						|
                resolved_state[key] = self._resolve_auth_events(
 | 
						|
                    events,
 | 
						|
                    auth_events
 | 
						|
                )
 | 
						|
 | 
						|
        auth_events.update(resolved_state)
 | 
						|
 | 
						|
        for key, events in conflicted_state.items():
 | 
						|
            if key[0] == EventTypes.Member:
 | 
						|
                logger.debug("Resolving conflicted member lists %r", events)
 | 
						|
                resolved_state[key] = self._resolve_auth_events(
 | 
						|
                    events,
 | 
						|
                    auth_events
 | 
						|
                )
 | 
						|
 | 
						|
        auth_events.update(resolved_state)
 | 
						|
 | 
						|
        for key, events in conflicted_state.items():
 | 
						|
            if key not in resolved_state:
 | 
						|
                logger.debug("Resolving conflicted state %r:%r", key, events)
 | 
						|
                resolved_state[key] = self._resolve_normal_events(
 | 
						|
                    events, auth_events
 | 
						|
                )
 | 
						|
 | 
						|
        return resolved_state
 | 
						|
 | 
						|
    def _resolve_auth_events(self, events, auth_events):
 | 
						|
        reverse = [i for i in reversed(self._ordered_events(events))]
 | 
						|
 | 
						|
        auth_events = dict(auth_events)
 | 
						|
 | 
						|
        prev_event = reverse[0]
 | 
						|
        for event in reverse[1:]:
 | 
						|
            auth_events[(prev_event.type, prev_event.state_key)] = prev_event
 | 
						|
            try:
 | 
						|
                # FIXME: hs.get_auth() is bad style, but we need to do it to
 | 
						|
                # get around circular deps.
 | 
						|
                # The signatures have already been checked at this point
 | 
						|
                self.hs.get_auth().check(event, auth_events, do_sig_check=False)
 | 
						|
                prev_event = event
 | 
						|
            except AuthError:
 | 
						|
                return prev_event
 | 
						|
 | 
						|
        return event
 | 
						|
 | 
						|
    def _resolve_normal_events(self, events, auth_events):
 | 
						|
        for event in self._ordered_events(events):
 | 
						|
            try:
 | 
						|
                # FIXME: hs.get_auth() is bad style, but we need to do it to
 | 
						|
                # get around circular deps.
 | 
						|
                # The signatures have already been checked at this point
 | 
						|
                self.hs.get_auth().check(event, auth_events, do_sig_check=False)
 | 
						|
                return event
 | 
						|
            except AuthError:
 | 
						|
                pass
 | 
						|
 | 
						|
        # Use the last event (the one with the least depth) if they all fail
 | 
						|
        # the auth check.
 | 
						|
        return event
 | 
						|
 | 
						|
    def _ordered_events(self, events):
 | 
						|
        def key_func(e):
 | 
						|
            return -int(e.depth), hashlib.sha1(e.event_id).hexdigest()
 | 
						|
 | 
						|
        return sorted(events, key=key_func)
 |