# -*- coding: utf-8 -*- # Copyright 2014 OpenMarket Ltd # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. from twisted.internet import defer from synapse.util.logutils import log_function from synapse.util.async import run_on_reactor from synapse.api.events.room import RoomPowerLevelsEvent from collections import namedtuple import copy import logging import hashlib logger = logging.getLogger(__name__) def _get_state_key_from_event(event): return event.state_key KeyStateTuple = namedtuple("KeyStateTuple", ("context", "type", "state_key")) class StateHandler(object): """ Responsible for doing state conflict resolution. """ def __init__(self, hs): self.store = hs.get_datastore() @defer.inlineCallbacks @log_function def annotate_event_with_state(self, event, old_state=None): """ Annotates the event with the current state events as of that event. This method adds three new attributes to the event: * `state_events`: The state up to and including the event. Encoded as a dict mapping tuple (type, state_key) -> event. * `old_state_events`: The state up to, but excluding, the event. Encoded similarly as `state_events`. * `state_group`: If there is an existing state group that can be used, then return that. Otherwise return `None`. See state storage for more information. If the argument `old_state` is given (in the form of a list of events), then they are used as a the values for `old_state_events` and the value for `state_events` is generated from it. `state_group` is set to None. This needs to be called before persisting the event. """ yield run_on_reactor() if old_state: event.state_group = None event.old_state_events = { (s.type, s.state_key): s for s in old_state } event.state_events = event.old_state_events if hasattr(event, "state_key"): event.state_events[(event.type, event.state_key)] = event defer.returnValue(False) return if hasattr(event, "outlier") and event.outlier: event.state_group = None event.old_state_events = None event.state_events = None defer.returnValue(False) return ids = [e for e, _ in event.prev_events] ret = yield self.resolve_state_groups(ids) state_group, new_state, _ = ret event.old_state_events = copy.deepcopy(new_state) if hasattr(event, "state_key"): key = (event.type, event.state_key) if key in new_state: event.replaces_state = new_state[key].event_id new_state[key] = event elif state_group: event.state_group = state_group event.state_events = new_state defer.returnValue(False) event.state_group = None event.state_events = new_state defer.returnValue(hasattr(event, "state_key")) @defer.inlineCallbacks def get_current_state(self, room_id, event_type=None, state_key=""): """ Returns the current state for the room as a list. This is done by calling `get_latest_events_in_room` to get the leading edges of the event graph and then resolving any of the state conflicts. This is equivalent to getting the state of an event that were to send next before receiving any new events. If `event_type` is specified, then the method returns only the one event (or None) with that `event_type` and `state_key`. """ events = yield self.store.get_latest_events_in_room(room_id) event_ids = [ e_id for e_id, _, _ in events ] res = yield self.resolve_state_groups(event_ids) if event_type: defer.returnValue(res[1].get((event_type, state_key))) return defer.returnValue(res[1].values()) @defer.inlineCallbacks def annotate_context_with_state(self, event, context, old_state=None): yield run_on_reactor() if old_state: context.current_state = { (s.type, s.state_key): s for s in old_state } context.state_group = None if hasattr(event, "auth_events") and event.auth_events: auth_ids = zip(*event.auth_events)[0] context.auth_events = { k: v for k, v in context.current_state.items() if v.event_id in auth_ids } else: context.auth_events = {} if event.is_state(): key = (event.type, event.state_key) if key in context.current_state: replaces = context.current_state[key] event.unsigned["replaces_state"] = replaces.event_id defer.returnValue([]) if event.is_state(): ret = yield self.resolve_state_groups( [e for e, _ in event.prev_events], event_type=event.type, state_key=event.state_key, ) else: ret = yield self.resolve_state_groups( [e for e, _ in event.prev_events], ) group, curr_state, prev_state = ret context.current_state = curr_state context.state_group = group if not event.is_state() else None prev_state = yield self.store.add_event_hashes( prev_state ) if event.is_state(): key = (event.type, event.state_key) if key in context.current_state: replaces = context.current_state[key] event.unsigned["replaces_state"] = replaces.event_id if hasattr(event, "auth_events") and event.auth_events: auth_ids = zip(*event.auth_events)[0] context.auth_events = { k: v for k, v in context.current_state.items() if v.event_id in auth_ids } else: context.auth_events = {} defer.returnValue(prev_state) @defer.inlineCallbacks @log_function def resolve_state_groups(self, event_ids, event_type=None, state_key=""): """ Given a list of event_ids this method fetches the state at each event, resolves conflicts between them and returns them. Return format is a tuple: (`state_group`, `state_events`), where the first is the name of a state group if one and only one is involved, otherwise `None`. """ state_groups = yield self.store.get_state_groups( event_ids ) group_names = set(state_groups.keys()) if len(group_names) == 1: name, state_list = state_groups.items().pop() state = { (e.type, e.state_key): e for e in state_list } prev_state = state.get((event_type, state_key), None) if prev_state: prev_state = prev_state.event_id prev_states = [prev_state] else: prev_states = [] defer.returnValue((name, state, prev_states)) state = {} for group, g_state in state_groups.items(): for s in g_state: state.setdefault( (s.type, s.state_key), {} )[s.event_id] = s unconflicted_state = { k: v.values()[0] for k, v in state.items() if len(v.values()) == 1 } conflicted_state = { k: v.values() for k, v in state.items() if len(v.values()) > 1 } if event_type: prev_states = conflicted_state.get( (event_type, state_key), {} ).keys() else: prev_states = [] try: new_state = {} new_state.update(unconflicted_state) for key, events in conflicted_state.items(): new_state[key] = self._resolve_state_events(events) except: logger.exception("Failed to resolve state") raise defer.returnValue((None, new_state, prev_states)) def _get_power_level_from_event_state(self, event, user_id): if hasattr(event, "old_state_events") and event.old_state_events: key = (RoomPowerLevelsEvent.TYPE, "", ) power_level_event = event.old_state_events.get(key) level = None if power_level_event: level = power_level_event.content.get("users", {}).get( user_id ) if not level: level = power_level_event.content.get("users_default", 0) return level else: return 0 @log_function def _resolve_state_events(self, events): curr_events = events new_powers = [ self._get_power_level_from_event_state(e, e.user_id) for e in curr_events ] new_powers = [ int(p) if p else 0 for p in new_powers ] max_power = max(new_powers) curr_events = [ z[0] for z in zip(curr_events, new_powers) if z[1] == max_power ] if not curr_events: raise RuntimeError("Max didn't get a max?") elif len(curr_events) == 1: return curr_events[0] # TODO: For now, just choose the one with the largest event_id. return ( sorted( curr_events, key=lambda e: hashlib.sha1( e.event_id + e.user_id + e.room_id + e.type ).hexdigest() )[0] )