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Diffstat (limited to 'synapse/state/__init__.py')
| -rw-r--r-- | synapse/state/__init__.py | 574 |
1 files changed, 574 insertions, 0 deletions
diff --git a/synapse/state/__init__.py b/synapse/state/__init__.py new file mode 100644 index 0000000000..8c091d07c9 --- /dev/null +++ b/synapse/state/__init__.py @@ -0,0 +1,574 @@ +# -*- coding: utf-8 -*- +# Copyright 2014-2016 OpenMarket Ltd +# Copyright 2018 New Vector 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. + +import logging +from collections import namedtuple + +from six import iteritems, itervalues + +from frozendict import frozendict + +from twisted.internet import defer + +from synapse.api.constants import EventTypes +from synapse.events.snapshot import EventContext +from synapse.util.async import Linearizer +from synapse.util.caches import CACHE_SIZE_FACTOR +from synapse.util.caches.expiringcache import ExpiringCache +from synapse.util.logutils import log_function +from synapse.util.metrics import Measure + +from .v1 import resolve_events_with_factory, resolve_events_with_state_map + +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. + if old_state: + prev_state_ids = { + (s.type, s.state_key): s.event_id for s in old_state + } + if event.is_state(): + current_state_ids = dict(prev_state_ids) + key = (event.type, event.state_key) + current_state_ids[key] = event.event_id + else: + current_state_ids = prev_state_ids + else: + current_state_ids = {} + prev_state_ids = {} + + # We don't store state for outliers, so we don't generate a state + # group for it. + context = EventContext.with_state( + state_group=None, + current_state_ids=current_state_ids, + prev_state_ids=prev_state_ids, + ) + + 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. + + 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 prev_state_ids: + replaces = prev_state_ids[key] + if replaces != event.event_id: # Paranoia check + event.unsigned["replaces_state"] = replaces + current_state_ids = dict(prev_state_ids) + current_state_ids[key] = event.event_id + else: + current_state_ids = prev_state_ids + + state_group = yield self.store.store_state_group( + event.event_id, + event.room_id, + prev_group=None, + delta_ids=None, + current_state_ids=current_state_ids, + ) + + context = EventContext.with_state( + state_group=state_group, + current_state_ids=current_state_ids, + prev_state_ids=prev_state_ids, + ) + + 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], + ) + + prev_state_ids = entry.state + prev_group = None + delta_ids = None + + 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 prev_state_ids: + replaces = prev_state_ids[key] + event.unsigned["replaces_state"] = replaces + + current_state_ids = dict(prev_state_ids) + 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 + prev_group = entry.state_group + 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. + prev_group = entry.prev_group + delta_ids = dict(entry.delta_ids) + delta_ids[key] = event.event_id + + state_group = yield self.store.store_state_group( + event.event_id, + event.room_id, + prev_group=prev_group, + delta_ids=delta_ids, + current_state_ids=current_state_ids, + ) + else: + current_state_ids = prev_state_ids + prev_group = entry.prev_group + 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=current_state_ids, + ) + entry.state_id = entry.state_group + + state_group = entry.state_group + + context = EventContext.with_state( + state_group=state_group, + current_state_ids=current_state_ids, + prev_state_ids=prev_state_ids, + prev_group=prev_group, + delta_ids=delta_ids, + ) + + 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) + ) + + # start by assuming we won't have any conflicted state, and build up the new + # state map by iterating through the state groups. If we discover a conflict, + # we give up and instead use `resolve_events_with_factory`. + # + # XXX: is this actually worthwhile, or should we just let + # resolve_events_with_factory do it? + new_state = {} + conflicted_state = False + for st in itervalues(state_groups_ids): + for key, e_id in iteritems(st): + if key in new_state: + conflicted_state = True + 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_factory( + list(itervalues(state_groups_ids)), + event_map=event_map, + state_map_factory=state_map_factory, + ) + + # 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 + + defer.returnValue(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, + ) |