# -*- coding: utf-8 -*- # Copyright 2014-2016 OpenMarket Ltd # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. from twisted.internet import defer from synapse import event_auth from synapse.util.logutils import log_function from synapse.util.caches.expiringcache import ExpiringCache from synapse.util.metrics import Measure from synapse.api.constants import EventTypes from synapse.api.errors import AuthError from synapse.events.snapshot import EventContext from synapse.util.async import Linearizer from synapse.util.caches import CACHE_SIZE_FACTOR from collections import namedtuple from frozendict import frozendict import logging import hashlib from six import iteritems, itervalues logger = logging.getLogger(__name__) KeyStateTuple = namedtuple("KeyStateTuple", ("context", "type", "state_key")) SIZE_OF_CACHE = int(100000 * CACHE_SIZE_FACTOR) EVICTION_TIMEOUT_SECONDS = 60 * 60 _NEXT_STATE_ID = 1 POWER_KEY = (EventTypes.PowerLevels, "") def _gen_state_id(): global _NEXT_STATE_ID s = "X%d" % (_NEXT_STATE_ID,) _NEXT_STATE_ID += 1 return s class _StateCacheEntry(object): __slots__ = ["state", "state_group", "state_id", "prev_group", "delta_ids"] def __init__(self, state, state_group, prev_group=None, delta_ids=None): # dict[(str, str), str] map from (type, state_key) to event_id self.state = frozendict(state) # the ID of a state group if one and only one is involved. # otherwise, None otherwise? self.state_group = state_group self.prev_group = prev_group self.delta_ids = frozendict(delta_ids) if delta_ids is not None else None # The `state_id` is a unique ID we generate that can be used as ID for # this collection of state. Usually this would be the same as the # state group, but on worker instances we can't generate a new state # group each time we resolve state, so we generate a separate one that # isn't persisted and is used solely for caches. # `state_id` is either a state_group (and so an int) or a string. This # ensures we don't accidentally persist a state_id as a stateg_group if state_group: self.state_id = state_group else: self.state_id = _gen_state_id() def __len__(self): return len(self.state) class StateHandler(object): """Fetches bits of state from the stores, and does state resolution where necessary """ def __init__(self, hs): self.clock = hs.get_clock() self.store = hs.get_datastore() self.hs = hs self._state_resolution_handler = hs.get_state_resolution_handler() def start_caching(self): # TODO: remove this shim self._state_resolution_handler.start_caching() @defer.inlineCallbacks def get_current_state(self, room_id, event_type=None, state_key="", latest_event_ids=None): """ Retrieves the current state for the room. 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`. Returns: map from (type, state_key) to event """ if not latest_event_ids: latest_event_ids = yield self.store.get_latest_event_ids_in_room(room_id) logger.debug("calling resolve_state_groups from get_current_state") ret = yield self.resolve_state_groups_for_events(room_id, latest_event_ids) state = ret.state if event_type: event_id = state.get((event_type, state_key)) event = None if event_id: event = yield self.store.get_event(event_id, allow_none=True) defer.returnValue(event) return state_map = yield self.store.get_events(list(state.values()), get_prev_content=False) state = { key: state_map[e_id] for key, e_id in iteritems(state) if e_id in state_map } defer.returnValue(state) @defer.inlineCallbacks def get_current_state_ids(self, room_id, latest_event_ids=None): """Get the current state, or the state at a set of events, for a room Args: room_id (str): latest_event_ids (iterable[str]|None): if given, the forward extremities to resolve. If None, we look them up from the database (via a cache) Returns: Deferred[dict[(str, str), str)]]: the state dict, mapping from (event_type, state_key) -> event_id """ if not latest_event_ids: latest_event_ids = yield self.store.get_latest_event_ids_in_room(room_id) logger.debug("calling resolve_state_groups from get_current_state_ids") ret = yield self.resolve_state_groups_for_events(room_id, latest_event_ids) state = ret.state defer.returnValue(state) @defer.inlineCallbacks def get_current_user_in_room(self, room_id, latest_event_ids=None): if not latest_event_ids: latest_event_ids = yield self.store.get_latest_event_ids_in_room(room_id) logger.debug("calling resolve_state_groups from get_current_user_in_room") entry = yield self.resolve_state_groups_for_events(room_id, latest_event_ids) joined_users = yield self.store.get_joined_users_from_state(room_id, entry) defer.returnValue(joined_users) @defer.inlineCallbacks def get_current_hosts_in_room(self, room_id, latest_event_ids=None): if not latest_event_ids: latest_event_ids = yield self.store.get_latest_event_ids_in_room(room_id) logger.debug("calling resolve_state_groups from get_current_hosts_in_room") entry = yield self.resolve_state_groups_for_events(room_id, latest_event_ids) joined_hosts = yield self.store.get_joined_hosts(room_id, entry) defer.returnValue(joined_hosts) @defer.inlineCallbacks def compute_event_context(self, event, old_state=None): """Build an EventContext structure for the event. This works out what the current state should be for the event, and generates a new state group if necessary. Args: event (synapse.events.EventBase): old_state (dict|None): The state at the event if it can't be calculated from existing events. This is normally only specified when receiving an event from federation where we don't have the prev events for, e.g. when backfilling. Returns: synapse.events.snapshot.EventContext: """ if event.internal_metadata.is_outlier(): # If this is an outlier, then we know it shouldn't have any current # state. Certainly store.get_current_state won't return any, and # persisting the event won't store the state group. context = EventContext() if old_state: context.prev_state_ids = { (s.type, s.state_key): s.event_id for s in old_state } if event.is_state(): context.current_state_ids = dict(context.prev_state_ids) key = (event.type, event.state_key) context.current_state_ids[key] = event.event_id else: context.current_state_ids = context.prev_state_ids else: context.current_state_ids = {} context.prev_state_ids = {} context.prev_state_events = [] # We don't store state for outliers, so we don't generate a state # froup for it. context.state_group = None defer.returnValue(context) if old_state: # We already have the state, so we don't need to calculate it. # Let's just correctly fill out the context and create a # new state group for it. context = EventContext() context.prev_state_ids = { (s.type, s.state_key): s.event_id for s in old_state } if event.is_state(): key = (event.type, event.state_key) if key in context.prev_state_ids: replaces = context.prev_state_ids[key] if replaces != event.event_id: # Paranoia check event.unsigned["replaces_state"] = replaces context.current_state_ids = dict(context.prev_state_ids) context.current_state_ids[key] = event.event_id else: context.current_state_ids = context.prev_state_ids context.state_group = yield self.store.store_state_group( event.event_id, event.room_id, prev_group=None, delta_ids=None, current_state_ids=context.current_state_ids, ) context.prev_state_events = [] defer.returnValue(context) logger.debug("calling resolve_state_groups from compute_event_context") entry = yield self.resolve_state_groups_for_events( event.room_id, [e for e, _ in event.prev_events], ) curr_state = entry.state context = EventContext() context.prev_state_ids = curr_state if event.is_state(): # If this is a state event then we need to create a new state # group for the state after this event. key = (event.type, event.state_key) if key in context.prev_state_ids: replaces = context.prev_state_ids[key] event.unsigned["replaces_state"] = replaces context.current_state_ids = dict(context.prev_state_ids) context.current_state_ids[key] = event.event_id if entry.state_group: # If the state at the event has a state group assigned then # we can use that as the prev group context.prev_group = entry.state_group context.delta_ids = { key: event.event_id } elif entry.prev_group: # If the state at the event only has a prev group, then we can # use that as a prev group too. context.prev_group = entry.prev_group context.delta_ids = dict(entry.delta_ids) context.delta_ids[key] = event.event_id context.state_group = yield self.store.store_state_group( event.event_id, event.room_id, prev_group=context.prev_group, delta_ids=context.delta_ids, current_state_ids=context.current_state_ids, ) else: context.current_state_ids = context.prev_state_ids context.prev_group = entry.prev_group context.delta_ids = entry.delta_ids if entry.state_group is None: entry.state_group = yield self.store.store_state_group( event.event_id, event.room_id, prev_group=entry.prev_group, delta_ids=entry.delta_ids, current_state_ids=context.current_state_ids, ) entry.state_id = entry.state_group context.state_group = entry.state_group context.prev_state_events = [] defer.returnValue(context) @defer.inlineCallbacks def resolve_state_groups_for_events(self, room_id, event_ids): """ Given a list of event_ids this method fetches the state at each event, resolves conflicts between them and returns them. Args: room_id (str): event_ids (list[str]): Returns: Deferred[_StateCacheEntry]: resolved state """ logger.debug("resolve_state_groups event_ids %s", event_ids) # map from state group id to the state in that state group (where # 'state' is a map from state key to event id) # dict[int, dict[(str, str), str]] state_groups_ids = yield self.store.get_state_groups_ids( room_id, event_ids ) if len(state_groups_ids) == 1: name, state_list = list(state_groups_ids.items()).pop() prev_group, delta_ids = yield self.store.get_state_group_delta(name) defer.returnValue(_StateCacheEntry( state=state_list, state_group=name, prev_group=prev_group, delta_ids=delta_ids, )) result = yield self._state_resolution_handler.resolve_state_groups( room_id, state_groups_ids, None, self._state_map_factory, ) defer.returnValue(result) def _state_map_factory(self, ev_ids): return self.store.get_events( ev_ids, get_prev_content=False, check_redacted=False, ) def resolve_events(self, state_sets, event): logger.info( "Resolving state for %s with %d groups", event.room_id, len(state_sets) ) state_set_ids = [{ (ev.type, ev.state_key): ev.event_id for ev in st } for st in state_sets] state_map = { ev.event_id: ev for st in state_sets for ev in st } with Measure(self.clock, "state._resolve_events"): new_state = resolve_events_with_state_map(state_set_ids, state_map) new_state = { key: state_map[ev_id] for key, ev_id in iteritems(new_state) } return new_state class StateResolutionHandler(object): """Responsible for doing state conflict resolution. Note that the storage layer depends on this handler, so all functions must be storage-independent. """ def __init__(self, hs): self.clock = hs.get_clock() # dict of set of event_ids -> _StateCacheEntry. self._state_cache = None self.resolve_linearizer = Linearizer(name="state_resolve_lock") def start_caching(self): logger.debug("start_caching") self._state_cache = ExpiringCache( cache_name="state_cache", clock=self.clock, max_len=SIZE_OF_CACHE, expiry_ms=EVICTION_TIMEOUT_SECONDS * 1000, iterable=True, reset_expiry_on_get=True, ) self._state_cache.start() @defer.inlineCallbacks @log_function def resolve_state_groups( self, room_id, state_groups_ids, event_map, state_map_factory, ): """Resolves conflicts between a set of state groups Always generates a new state group (unless we hit the cache), so should not be called for a single state group Args: room_id (str): room we are resolving for (used for logging) 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) 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. Returns: Deferred[_StateCacheEntry]: resolved state """ logger.debug( "resolve_state_groups state_groups %s", state_groups_ids.keys() ) group_names = frozenset(state_groups_ids.keys()) with (yield self.resolve_linearizer.queue(group_names)): if self._state_cache is not None: cache = self._state_cache.get(group_names, None) if cache: defer.returnValue(cache) logger.info( "Resolving state for %s with %d groups", room_id, len(state_groups_ids) ) # build a map from state key to the event_ids which set that state. # dict[(str, str), set[str]) state = {} for st in itervalues(state_groups_ids): for key, e_id in iteritems(st): state.setdefault(key, set()).add(e_id) # build a map from state key to the event_ids which set that state, # including only those where there are state keys in conflict. conflicted_state = { k: list(v) for k, v in iteritems(state) if len(v) > 1 } 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_factory( list(state_groups_ids.values()), event_map=event_map, state_map_factory=state_map_factory, ) else: new_state = { key: e_ids.pop() for key, e_ids in iteritems(state) } with Measure(self.clock, "state.create_group_ids"): # 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. state_group = None new_state_event_ids = frozenset(itervalues(new_state)) for sg, events in iteritems(state_groups_ids): if new_state_event_ids == frozenset(e_id for e_id in events): state_group = sg break # 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 prev_group = None delta_ids = None for old_group, old_ids in iteritems(state_groups_ids): if not set(new_state) - set(old_ids): n_delta_ids = { k: v for k, v in iteritems(new_state) if old_ids.get(k) != v } if not delta_ids or len(n_delta_ids) < len(delta_ids): prev_group = old_group delta_ids = n_delta_ids cache = _StateCacheEntry( state=new_state, state_group=state_group, prev_group=prev_group, delta_ids=delta_ids, ) if self._state_cache is not None: self._state_cache[group_names] = cache defer.returnValue(cache) def _ordered_events(events): def key_func(e): return -int(e.depth), hashlib.sha1(e.event_id.encode()).hexdigest() return sorted(events, key=key_func) def resolve_events_with_state_map(state_sets, state_map): """ Args: state_sets(list): List of dicts of (type, state_key) -> event_id, which are the different state groups to resolve. state_map(dict): a dict from event_id to event, for all events in state_sets. Returns dict[(str, str), str]: a map from (type, state_key) to event_id. """ if len(state_sets) == 1: return state_sets[0] unconflicted_state, conflicted_state = _seperate( state_sets, ) auth_events = _create_auth_events_from_maps( unconflicted_state, conflicted_state, state_map ) return _resolve_with_state( unconflicted_state, conflicted_state, auth_events, state_map ) def _seperate(state_sets): """Takes the state_sets and figures out which keys are conflicted and which aren't. i.e., which have multiple different event_ids associated with them in different state sets. Args: state_sets(list[dict[(str, str), str]]): List of dicts of (type, state_key) -> event_id, which are the different state groups to resolve. Returns: (dict[(str, str), str], dict[(str, str), set[str]]): A tuple of (unconflicted_state, conflicted_state), where: unconflicted_state is a dict mapping (type, state_key)->event_id for unconflicted state keys. conflicted_state is a dict mapping (type, state_key) to a set of event ids for conflicted state keys. """ unconflicted_state = dict(state_sets[0]) conflicted_state = {} for state_set in state_sets[1:]: for key, value in iteritems(state_set): # Check if there is an unconflicted entry for the state key. unconflicted_value = unconflicted_state.get(key) if unconflicted_value is None: # There isn't an unconflicted entry so check if there is a # conflicted entry. ls = conflicted_state.get(key) if ls is None: # There wasn't a conflicted entry so haven't seen this key before. # Therefore it isn't conflicted yet. unconflicted_state[key] = value else: # This key is already conflicted, add our value to the conflict set. ls.add(value) elif unconflicted_value != value: # If the unconflicted value is not the same as our value then we # have a new conflict. So move the key from the unconflicted_state # to the conflicted state. conflicted_state[key] = {value, unconflicted_value} unconflicted_state.pop(key, None) return unconflicted_state, conflicted_state @defer.inlineCallbacks def resolve_events_with_factory(state_sets, event_map, state_map_factory): """ Args: 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_map_factory(func): will be called with a list of event_ids that are needed, and should return with a Deferred of dict of event_id to event. Returns Deferred[dict[(str, str), str]]: a map from (type, state_key) to event_id. """ if len(state_sets) == 1: defer.returnValue(state_sets[0]) unconflicted_state, conflicted_state = _seperate( state_sets, ) needed_events = set( event_id for event_ids in itervalues(conflicted_state) for event_id in event_ids ) if event_map is not None: needed_events -= set(event_map.iterkeys()) logger.info("Asking for %d conflicted events", len(needed_events)) # dict[str, FrozenEvent]: a map from state event id to event. Only includes # the state events which are in conflict (and those in event_map) state_map = yield state_map_factory(needed_events) if event_map is not None: state_map.update(event_map) # get the ids of the auth events which allow us to authenticate the # conflicted state, picking only from the unconflicting state. # # dict[(str, str), str]: a map from state key to event id auth_events = _create_auth_events_from_maps( unconflicted_state, conflicted_state, state_map ) new_needed_events = set(itervalues(auth_events)) new_needed_events -= needed_events if event_map is not None: new_needed_events -= set(event_map.iterkeys()) logger.info("Asking for %d auth events", len(new_needed_events)) state_map_new = yield state_map_factory(new_needed_events) state_map.update(state_map_new) defer.returnValue(_resolve_with_state( unconflicted_state, conflicted_state, auth_events, state_map )) def _create_auth_events_from_maps(unconflicted_state, conflicted_state, state_map): auth_events = {} for event_ids in itervalues(conflicted_state): for event_id in event_ids: if event_id in state_map: keys = event_auth.auth_types_for_event(state_map[event_id]) for key in keys: if key not in auth_events: event_id = unconflicted_state.get(key, None) if event_id: auth_events[key] = event_id return auth_events def _resolve_with_state(unconflicted_state_ids, conflicted_state_ds, auth_event_ids, state_map): conflicted_state = {} for key, event_ids in iteritems(conflicted_state_ds): events = [state_map[ev_id] for ev_id in event_ids if ev_id in state_map] if len(events) > 1: conflicted_state[key] = events elif len(events) == 1: unconflicted_state_ids[key] = events[0].event_id auth_events = { key: state_map[ev_id] for key, ev_id in iteritems(auth_event_ids) if ev_id in state_map } try: resolved_state = _resolve_state_events( conflicted_state, auth_events ) except Exception: logger.exception("Failed to resolve state") raise new_state = unconflicted_state_ids for key, event in iteritems(resolved_state): new_state[key] = event.event_id return new_state def _resolve_state_events(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 = {} if POWER_KEY in conflicted_state: events = conflicted_state[POWER_KEY] logger.debug("Resolving conflicted power levels %r", events) resolved_state[POWER_KEY] = _resolve_auth_events( events, auth_events) auth_events.update(resolved_state) for key, events in iteritems(conflicted_state): if key[0] == EventTypes.JoinRules: logger.debug("Resolving conflicted join rules %r", events) resolved_state[key] = _resolve_auth_events( events, auth_events ) auth_events.update(resolved_state) for key, events in iteritems(conflicted_state): if key[0] == EventTypes.Member: logger.debug("Resolving conflicted member lists %r", events) resolved_state[key] = _resolve_auth_events( events, auth_events ) auth_events.update(resolved_state) for key, events in iteritems(conflicted_state): if key not in resolved_state: logger.debug("Resolving conflicted state %r:%r", key, events) resolved_state[key] = _resolve_normal_events( events, auth_events ) return resolved_state def _resolve_auth_events(events, auth_events): reverse = [i for i in reversed(_ordered_events(events))] auth_keys = set( key for event in events for key in event_auth.auth_types_for_event(event) ) new_auth_events = {} for key in auth_keys: auth_event = auth_events.get(key, None) if auth_event: new_auth_events[key] = auth_event auth_events = new_auth_events prev_event = reverse[0] for event in reverse[1:]: auth_events[(prev_event.type, prev_event.state_key)] = prev_event try: # The signatures have already been checked at this point event_auth.check(event, auth_events, do_sig_check=False, do_size_check=False) prev_event = event except AuthError: return prev_event return event def _resolve_normal_events(events, auth_events): for event in _ordered_events(events): try: # The signatures have already been checked at this point event_auth.check(event, auth_events, do_sig_check=False, do_size_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