661 lines
		
	
	
		
			24 KiB
		
	
	
	
		
			Python
		
	
	
			
		
		
	
	
			661 lines
		
	
	
		
			24 KiB
		
	
	
	
		
			Python
		
	
	
| # -*- coding: utf-8 -*-
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| # Copyright 2014-2016 OpenMarket Ltd
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| # Copyright 2018 New Vector 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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| 
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| import logging
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| from collections import namedtuple
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| 
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| from six import iteritems, itervalues
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| 
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| import attr
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| from frozendict import frozendict
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| from prometheus_client import Histogram
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| 
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| from twisted.internet import defer
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| 
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| from synapse.api.constants import EventTypes
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| from synapse.api.room_versions import KNOWN_ROOM_VERSIONS, StateResolutionVersions
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| from synapse.events.snapshot import EventContext
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| from synapse.logging.utils import log_function
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| from synapse.state import v1, v2
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| from synapse.util.async_helpers import Linearizer
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| from synapse.util.caches import get_cache_factor_for
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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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| 
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| logger = logging.getLogger(__name__)
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| 
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| 
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| # Metrics for number of state groups involved in a resolution.
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| state_groups_histogram = Histogram(
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|     "synapse_state_number_state_groups_in_resolution",
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|     "Number of state groups used when performing a state resolution",
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|     buckets=(1, 2, 3, 5, 7, 10, 15, 20, 50, 100, 200, 500, "+Inf"),
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| )
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| 
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| 
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| KeyStateTuple = namedtuple("KeyStateTuple", ("context", "type", "state_key"))
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| 
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| 
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| SIZE_OF_CACHE = 100000 * get_cache_factor_for("state_cache")
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| EVICTION_TIMEOUT_SECONDS = 60 * 60
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| 
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| 
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| _NEXT_STATE_ID = 1
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| 
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| POWER_KEY = (EventTypes.PowerLevels, "")
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| 
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| 
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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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| 
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| 
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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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| 
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|     def __init__(self, state, state_group, prev_group=None, delta_ids=None):
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|         # dict[(str, str), str] map  from (type, state_key) to event_id
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|         self.state = frozendict(state)
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| 
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|         # the ID of a state group if one and only one is involved.
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|         # otherwise, None otherwise?
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|         self.state_group = state_group
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| 
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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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| 
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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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| 
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|     def __len__(self):
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|         return len(self.state)
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| 
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| 
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| class StateHandler(object):
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|     """Fetches bits of state from the stores, and does state resolution
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|     where necessary
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|     """
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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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|         self._state_resolution_handler = hs.get_state_resolution_handler()
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| 
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|     @defer.inlineCallbacks
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|     def get_current_state(
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|         self, room_id, event_type=None, state_key="", latest_event_ids=None
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|     ):
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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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| 
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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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| 
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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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|         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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| 
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|         logger.debug("calling resolve_state_groups from get_current_state")
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|         ret = yield self.resolve_state_groups_for_events(room_id, latest_event_ids)
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|         state = ret.state
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| 
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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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|             return event
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| 
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|         state_map = yield self.store.get_events(
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|             list(state.values()), get_prev_content=False
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|         )
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|         state = {
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|             key: state_map[e_id] for key, e_id in iteritems(state) if e_id in state_map
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|         }
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| 
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|         return state
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| 
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|     @defer.inlineCallbacks
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|     def get_current_state_ids(self, room_id, latest_event_ids=None):
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|         """Get the current state, or the state at a set of events, for a room
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| 
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|         Args:
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|             room_id (str):
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| 
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|             latest_event_ids (iterable[str]|None): if given, the forward
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|                 extremities to resolve. If None, we look them up from the
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|                 database (via a cache)
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| 
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|         Returns:
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|             Deferred[dict[(str, str), str)]]: the state dict, mapping from
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|                 (event_type, state_key) -> event_id
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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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| 
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|         logger.debug("calling resolve_state_groups from get_current_state_ids")
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|         ret = yield self.resolve_state_groups_for_events(room_id, latest_event_ids)
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|         state = ret.state
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| 
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|         return state
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| 
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|     @defer.inlineCallbacks
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|     def get_current_users_in_room(self, room_id, latest_event_ids=None):
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|         """
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|         Get the users who are currently in a room.
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| 
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|         Args:
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|             room_id (str): The ID of the room.
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|             latest_event_ids (List[str]|None): Precomputed list of latest
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|                 event IDs. Will be computed if None.
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|         Returns:
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|             Deferred[Dict[str,ProfileInfo]]: Dictionary of user IDs to their
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|                 profileinfo.
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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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|         logger.debug("calling resolve_state_groups from get_current_users_in_room")
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|         entry = yield self.resolve_state_groups_for_events(room_id, latest_event_ids)
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|         joined_users = yield self.store.get_joined_users_from_state(room_id, entry)
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|         return joined_users
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| 
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|     @defer.inlineCallbacks
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|     def get_current_hosts_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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|         logger.debug("calling resolve_state_groups from get_current_hosts_in_room")
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|         entry = yield self.resolve_state_groups_for_events(room_id, latest_event_ids)
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|         joined_hosts = yield self.store.get_joined_hosts(room_id, entry)
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|         return joined_hosts
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| 
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|     @defer.inlineCallbacks
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|     def compute_event_context(self, event, old_state=None):
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|         """Build an EventContext structure for the event.
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| 
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|         This works out what the current state should be for the event, and
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|         generates a new state group if necessary.
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| 
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|         Args:
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|             event (synapse.events.EventBase):
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|             old_state (dict|None): The state at the event if it can't be
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|                 calculated from existing events. This is normally only specified
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|                 when receiving an event from federation where we don't have the
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|                 prev events for, e.g. when backfilling.
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|         Returns:
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|             synapse.events.snapshot.EventContext:
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|         """
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| 
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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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|                 prev_state_ids = {(s.type, s.state_key): s.event_id for s in old_state}
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|                 if event.is_state():
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|                     current_state_ids = dict(prev_state_ids)
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|                     key = (event.type, event.state_key)
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|                     current_state_ids[key] = event.event_id
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|                 else:
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|                     current_state_ids = prev_state_ids
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|             else:
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|                 current_state_ids = {}
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|                 prev_state_ids = {}
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| 
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|             # We don't store state for outliers, so we don't generate a state
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|             # group for it.
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|             context = EventContext.with_state(
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|                 state_group=None,
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|                 current_state_ids=current_state_ids,
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|                 prev_state_ids=prev_state_ids,
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|             )
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| 
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|             return context
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| 
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|         if old_state:
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|             # We already have the state, so we don't need to calculate it.
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|             # Let's just correctly fill out the context and create a
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|             # new state group for it.
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| 
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|             prev_state_ids = {(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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|                 key = (event.type, event.state_key)
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|                 if key in prev_state_ids:
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|                     replaces = 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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|                 current_state_ids = dict(prev_state_ids)
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|                 current_state_ids[key] = event.event_id
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|             else:
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|                 current_state_ids = prev_state_ids
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| 
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|             state_group = yield self.store.store_state_group(
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|                 event.event_id,
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|                 event.room_id,
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|                 prev_group=None,
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|                 delta_ids=None,
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|                 current_state_ids=current_state_ids,
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|             )
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| 
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|             context = EventContext.with_state(
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|                 state_group=state_group,
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|                 current_state_ids=current_state_ids,
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|                 prev_state_ids=prev_state_ids,
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|             )
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| 
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|             return context
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| 
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|         logger.debug("calling resolve_state_groups from compute_event_context")
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| 
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|         entry = yield self.resolve_state_groups_for_events(
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|             event.room_id, event.prev_event_ids()
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|         )
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| 
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|         prev_state_ids = entry.state
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|         prev_group = None
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|         delta_ids = None
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| 
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|         if event.is_state():
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|             # If this is a state event then we need to create a new state
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|             # group for the state after this event.
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| 
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|             key = (event.type, event.state_key)
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|             if key in prev_state_ids:
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|                 replaces = prev_state_ids[key]
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|                 event.unsigned["replaces_state"] = replaces
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| 
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|             current_state_ids = dict(prev_state_ids)
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|             current_state_ids[key] = event.event_id
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| 
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|             if entry.state_group:
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|                 # If the state at the event has a state group assigned then
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|                 # we can use that as the prev group
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|                 prev_group = entry.state_group
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|                 delta_ids = {key: event.event_id}
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|             elif entry.prev_group:
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|                 # If the state at the event only has a prev group, then we can
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|                 # use that as a prev group too.
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|                 prev_group = entry.prev_group
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|                 delta_ids = dict(entry.delta_ids)
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|                 delta_ids[key] = event.event_id
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| 
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|             state_group = yield self.store.store_state_group(
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|                 event.event_id,
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|                 event.room_id,
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|                 prev_group=prev_group,
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|                 delta_ids=delta_ids,
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|                 current_state_ids=current_state_ids,
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|             )
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|         else:
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|             current_state_ids = prev_state_ids
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|             prev_group = entry.prev_group
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|             delta_ids = entry.delta_ids
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| 
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|             if entry.state_group is None:
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|                 entry.state_group = yield self.store.store_state_group(
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|                     event.event_id,
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|                     event.room_id,
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|                     prev_group=entry.prev_group,
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|                     delta_ids=entry.delta_ids,
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|                     current_state_ids=current_state_ids,
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|                 )
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|                 entry.state_id = entry.state_group
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| 
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|             state_group = entry.state_group
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| 
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|         context = EventContext.with_state(
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|             state_group=state_group,
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|             current_state_ids=current_state_ids,
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|             prev_state_ids=prev_state_ids,
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|             prev_group=prev_group,
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|             delta_ids=delta_ids,
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|         )
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| 
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|         return context
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| 
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|     @defer.inlineCallbacks
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|     def resolve_state_groups_for_events(self, room_id, event_ids):
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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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| 
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|         Args:
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|             room_id (str)
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|             event_ids (list[str])
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|             explicit_room_version (str|None): If set uses the the given room
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|                 version to choose the resolution algorithm. If None, then
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|                 checks the database for room version.
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| 
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|         Returns:
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|             Deferred[_StateCacheEntry]: resolved state
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|         """
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|         logger.debug("resolve_state_groups event_ids %s", event_ids)
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| 
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|         # map from state group id to the state in that state group (where
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|         # 'state' is a map from state key to event id)
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|         # dict[int, dict[(str, str), str]]
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|         state_groups_ids = yield self.store.get_state_groups_ids(room_id, event_ids)
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| 
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|         if len(state_groups_ids) == 0:
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|             return _StateCacheEntry(state={}, state_group=None)
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|         elif len(state_groups_ids) == 1:
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|             name, state_list = list(state_groups_ids.items()).pop()
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| 
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|             prev_group, delta_ids = yield self.store.get_state_group_delta(name)
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| 
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|             return _StateCacheEntry(
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|                 state=state_list,
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|                 state_group=name,
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|                 prev_group=prev_group,
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|                 delta_ids=delta_ids,
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|             )
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| 
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|         room_version = yield self.store.get_room_version(room_id)
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| 
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|         result = yield self._state_resolution_handler.resolve_state_groups(
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|             room_id,
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|             room_version,
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|             state_groups_ids,
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|             None,
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|             state_res_store=StateResolutionStore(self.store),
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|         )
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|         return result
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| 
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|     @defer.inlineCallbacks
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|     def resolve_events(self, room_version, 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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|         state_set_ids = [
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|             {(ev.type, ev.state_key): ev.event_id for ev in st} for st in state_sets
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|         ]
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| 
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|         state_map = {ev.event_id: ev for st in state_sets for ev in st}
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| 
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|         with Measure(self.clock, "state._resolve_events"):
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|             new_state = yield resolve_events_with_store(
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|                 room_version,
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|                 state_set_ids,
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|                 event_map=state_map,
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|                 state_res_store=StateResolutionStore(self.store),
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|             )
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| 
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|         new_state = {key: state_map[ev_id] for key, ev_id in iteritems(new_state)}
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| 
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|         return new_state
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| 
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| 
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| class StateResolutionHandler(object):
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|     """Responsible for doing state conflict resolution.
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| 
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|     Note that the storage layer depends on this handler, so all functions must
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|     be storage-independent.
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|     """
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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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| 
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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(name="state_resolve_lock")
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| 
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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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|             iterable=True,
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|             reset_expiry_on_get=True,
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|         )
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| 
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|     @defer.inlineCallbacks
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|     @log_function
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|     def resolve_state_groups(
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|         self, room_id, room_version, state_groups_ids, event_map, state_res_store
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|     ):
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|         """Resolves conflicts between a set of state groups
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| 
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|         Always generates a new state group (unless we hit the cache), so should
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|         not be called for a single state group
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| 
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|         Args:
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|             room_id (str): room we are resolving for (used for logging)
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|             room_version (str): version of the room
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|             state_groups_ids (dict[int, dict[(str, str), str]]):
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|                  map from state group id to the state in that state group
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|                 (where 'state' is a map from state key to event id)
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| 
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|             event_map(dict[str,FrozenEvent]|None):
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|                 a dict from event_id to event, for any events that we happen to
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|                 have in flight (eg, those currently being persisted). This will be
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|                 used as a starting point fof finding the state we need; any missing
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|                 events will be requested via state_res_store.
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| 
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|                 If None, all events will be fetched via state_res_store.
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| 
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|             state_res_store (StateResolutionStore)
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| 
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|         Returns:
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|             Deferred[_StateCacheEntry]: resolved state
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|         """
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|         logger.debug("resolve_state_groups state_groups %s", state_groups_ids.keys())
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| 
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|         group_names = frozenset(state_groups_ids.keys())
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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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|                     return 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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| 
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|             state_groups_histogram.observe(len(state_groups_ids))
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| 
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|             # start by assuming we won't have any conflicted state, and build up the new
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|             # state map by iterating through the state groups. If we discover a conflict,
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|             # we give up and instead use `resolve_events_with_store`.
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|             #
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|             # XXX: is this actually worthwhile, or should we just let
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|             # resolve_events_with_store do it?
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|             new_state = {}
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|             conflicted_state = False
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|             for st in itervalues(state_groups_ids):
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|                 for key, e_id in iteritems(st):
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|                     if key in new_state:
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|                         conflicted_state = True
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|                         break
 | |
|                     new_state[key] = e_id
 | |
|                 if conflicted_state:
 | |
|                     break
 | |
| 
 | |
|             if conflicted_state:
 | |
|                 logger.info("Resolving conflicted state for %r", room_id)
 | |
|                 with Measure(self.clock, "state._resolve_events"):
 | |
|                     new_state = yield resolve_events_with_store(
 | |
|                         room_version,
 | |
|                         list(itervalues(state_groups_ids)),
 | |
|                         event_map=event_map,
 | |
|                         state_res_store=state_res_store,
 | |
|                     )
 | |
| 
 | |
|             # if the new state matches any of the input state groups, we can
 | |
|             # use that state group again. Otherwise we will generate a state_id
 | |
|             # which will be used as a cache key for future resolutions, but
 | |
|             # not get persisted.
 | |
| 
 | |
|             with Measure(self.clock, "state.create_group_ids"):
 | |
|                 cache = _make_state_cache_entry(new_state, state_groups_ids)
 | |
| 
 | |
|             if self._state_cache is not None:
 | |
|                 self._state_cache[group_names] = cache
 | |
| 
 | |
|             return cache
 | |
| 
 | |
| 
 | |
| def _make_state_cache_entry(new_state, state_groups_ids):
 | |
|     """Given a resolved state, and a set of input state groups, pick one to base
 | |
|     a new state group on (if any), and return an appropriately-constructed
 | |
|     _StateCacheEntry.
 | |
| 
 | |
|     Args:
 | |
|         new_state (dict[(str, str), str]): resolved state map (mapping from
 | |
|            (type, state_key) to event_id)
 | |
| 
 | |
|         state_groups_ids (dict[int, dict[(str, str), str]]):
 | |
|                  map from state group id to the state in that state group
 | |
|                 (where 'state' is a map from state key to event id)
 | |
| 
 | |
|     Returns:
 | |
|         _StateCacheEntry
 | |
|     """
 | |
|     # if the new state matches any of the input state groups, we can
 | |
|     # use that state group again. Otherwise we will generate a state_id
 | |
|     # which will be used as a cache key for future resolutions, but
 | |
|     # not get persisted.
 | |
| 
 | |
|     # first look for exact matches
 | |
|     new_state_event_ids = set(itervalues(new_state))
 | |
|     for sg, state in iteritems(state_groups_ids):
 | |
|         if len(new_state_event_ids) != len(state):
 | |
|             continue
 | |
| 
 | |
|         old_state_event_ids = set(itervalues(state))
 | |
|         if new_state_event_ids == old_state_event_ids:
 | |
|             # got an exact match.
 | |
|             return _StateCacheEntry(state=new_state, state_group=sg)
 | |
| 
 | |
|     # TODO: We want to create a state group for this set of events, to
 | |
|     # increase cache hits, but we need to make sure that it doesn't
 | |
|     # end up as a prev_group without being added to the database
 | |
| 
 | |
|     # failing that, look for the closest match.
 | |
|     prev_group = None
 | |
|     delta_ids = None
 | |
| 
 | |
|     for old_group, old_state in iteritems(state_groups_ids):
 | |
|         n_delta_ids = {k: v for k, v in iteritems(new_state) if old_state.get(k) != v}
 | |
|         if not delta_ids or len(n_delta_ids) < len(delta_ids):
 | |
|             prev_group = old_group
 | |
|             delta_ids = n_delta_ids
 | |
| 
 | |
|     return _StateCacheEntry(
 | |
|         state=new_state, state_group=None, prev_group=prev_group, delta_ids=delta_ids
 | |
|     )
 | |
| 
 | |
| 
 | |
| def resolve_events_with_store(room_version, state_sets, event_map, state_res_store):
 | |
|     """
 | |
|     Args:
 | |
|         room_version(str): Version of the room
 | |
| 
 | |
|         state_sets(list): List of dicts of (type, state_key) -> event_id,
 | |
|             which are the different state groups to resolve.
 | |
| 
 | |
|         event_map(dict[str,FrozenEvent]|None):
 | |
|             a dict from event_id to event, for any events that we happen to
 | |
|             have in flight (eg, those currently being persisted). This will be
 | |
|             used as a starting point fof finding the state we need; any missing
 | |
|             events will be requested via state_map_factory.
 | |
| 
 | |
|             If None, all events will be fetched via state_map_factory.
 | |
| 
 | |
|         state_res_store (StateResolutionStore)
 | |
| 
 | |
|     Returns
 | |
|         Deferred[dict[(str, str), str]]:
 | |
|             a map from (type, state_key) to event_id.
 | |
|     """
 | |
|     v = KNOWN_ROOM_VERSIONS[room_version]
 | |
|     if v.state_res == StateResolutionVersions.V1:
 | |
|         return v1.resolve_events_with_store(
 | |
|             state_sets, event_map, state_res_store.get_events
 | |
|         )
 | |
|     else:
 | |
|         return v2.resolve_events_with_store(
 | |
|             room_version, state_sets, event_map, state_res_store
 | |
|         )
 | |
| 
 | |
| 
 | |
| @attr.s
 | |
| class StateResolutionStore(object):
 | |
|     """Interface that allows state resolution algorithms to access the database
 | |
|     in well defined way.
 | |
| 
 | |
|     Args:
 | |
|         store (DataStore)
 | |
|     """
 | |
| 
 | |
|     store = attr.ib()
 | |
| 
 | |
|     def get_events(self, event_ids, allow_rejected=False):
 | |
|         """Get events from the database
 | |
| 
 | |
|         Args:
 | |
|             event_ids (list): The event_ids of the events to fetch
 | |
|             allow_rejected (bool): If True return rejected events.
 | |
| 
 | |
|         Returns:
 | |
|             Deferred[dict[str, FrozenEvent]]: Dict from event_id to event.
 | |
|         """
 | |
| 
 | |
|         return self.store.get_events(
 | |
|             event_ids,
 | |
|             check_redacted=False,
 | |
|             get_prev_content=False,
 | |
|             allow_rejected=allow_rejected,
 | |
|         )
 | |
| 
 | |
|     def get_auth_chain(self, event_ids):
 | |
|         """Gets the full auth chain for a set of events (including rejected
 | |
|         events).
 | |
| 
 | |
|         Includes the given event IDs in the result.
 | |
| 
 | |
|         Note that:
 | |
|             1. All events must be state events.
 | |
|             2. For v1 rooms this may not have the full auth chain in the
 | |
|                presence of rejected events
 | |
| 
 | |
|         Args:
 | |
|             event_ids (list): The event IDs of the events to fetch the auth
 | |
|                 chain for. Must be state events.
 | |
| 
 | |
|         Returns:
 | |
|             Deferred[list[str]]: List of event IDs of the auth chain.
 | |
|         """
 | |
| 
 | |
|         return self.store.get_auth_chain_ids(event_ids, include_given=True)
 |