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- # -*- 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.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.api.auth import AuthEventTypes
- from synapse.events.snapshot import EventContext
- from synapse.util.async import Linearizer
- from collections import namedtuple
- from frozendict import frozendict
- import logging
- import hashlib
- import os
- logger = logging.getLogger(__name__)
- KeyStateTuple = namedtuple("KeyStateTuple", ("context", "type", "state_key"))
- CACHE_SIZE_FACTOR = float(os.environ.get("SYNAPSE_CACHE_FACTOR", 0.1))
- SIZE_OF_CACHE = int(1000 * CACHE_SIZE_FACTOR)
- EVICTION_TIMEOUT_SECONDS = 60 * 60
- _NEXT_STATE_ID = 1
- 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):
- self.state = frozendict(state)
- 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()
- class StateHandler(object):
- """ Responsible for doing state conflict resolution.
- """
- def __init__(self, hs):
- self.clock = hs.get_clock()
- self.store = hs.get_datastore()
- self.hs = hs
- # dict of set of event_ids -> _StateCacheEntry.
- self._state_cache = None
- self.resolve_linearizer = Linearizer()
- 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,
- reset_expiry_on_get=True,
- )
- self._state_cache.start()
- @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)
- ret = yield self.resolve_state_groups(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(state.values(), get_prev_content=False)
- state = {
- key: state_map[e_id] for key, e_id in state.items() if e_id in state_map
- }
- defer.returnValue(state)
- @defer.inlineCallbacks
- def get_current_state_ids(self, room_id, event_type=None, state_key="",
- latest_event_ids=None):
- if not latest_event_ids:
- latest_event_ids = yield self.store.get_latest_event_ids_in_room(room_id)
- ret = yield self.resolve_state_groups(room_id, latest_event_ids)
- state = ret.state
- if event_type:
- defer.returnValue(state.get((event_type, state_key)))
- return
- 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)
- entry = yield self.resolve_state_groups(room_id, latest_event_ids)
- joined_users = yield self.store.get_joined_users_from_state(
- room_id, entry.state_id, entry.state
- )
- defer.returnValue(joined_users)
- @defer.inlineCallbacks
- def compute_event_context(self, event, old_state=None):
- """ Fills out the context with the `current state` of the graph. The
- `current state` here is defined to be the state of the event graph
- just before the event - i.e. it never includes `event`
- If `event` has `auth_events` then this will also fill out the
- `auth_events` field on `context` from the `current_state`.
- Args:
- event (EventBase)
- Returns:
- an EventContext
- """
- context = 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:
- context.prev_state_ids = {
- (s.type, s.state_key): s.event_id for s in old_state
- }
- if event.is_state():
- context.current_state_events = dict(context.prev_state_ids)
- key = (event.type, event.state_key)
- context.current_state_events[key] = event.event_id
- else:
- context.current_state_events = context.prev_state_ids
- else:
- context.current_state_ids = {}
- context.prev_state_ids = {}
- context.prev_state_events = []
- context.state_group = self.store.get_next_state_group()
- defer.returnValue(context)
- if old_state:
- context.prev_state_ids = {
- (s.type, s.state_key): s.event_id for s in old_state
- }
- context.state_group = self.store.get_next_state_group()
- 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.prev_state_events = []
- defer.returnValue(context)
- if event.is_state():
- entry = yield self.resolve_state_groups(
- event.room_id, [e for e, _ in event.prev_events],
- event_type=event.type,
- state_key=event.state_key,
- )
- else:
- entry = yield self.resolve_state_groups(
- event.room_id, [e for e, _ in event.prev_events],
- )
- curr_state = entry.state
- context.prev_state_ids = curr_state
- if event.is_state():
- context.state_group = self.store.get_next_state_group()
- 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
- context.prev_group = entry.prev_group
- context.delta_ids = entry.delta_ids
- if context.delta_ids is not None:
- context.delta_ids = dict(context.delta_ids)
- context.delta_ids[key] = event.event_id
- else:
- if entry.state_group is None:
- entry.state_group = self.store.get_next_state_group()
- entry.state_id = entry.state_group
- context.state_group = entry.state_group
- context.current_state_ids = context.prev_state_ids
- context.prev_group = entry.prev_group
- context.delta_ids = entry.delta_ids
- context.prev_state_events = []
- defer.returnValue(context)
- @defer.inlineCallbacks
- @log_function
- def resolve_state_groups(self, room_id, 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.
- Returns:
- a Deferred tuple of (`state_group`, `state`, `prev_state`).
- `state_group` is the name of a state group if one and only one is
- involved. `state` is a map from (type, state_key) to event, and
- `prev_state` is a list of event ids.
- """
- logger.debug("resolve_state_groups event_ids %s", event_ids)
- state_groups_ids = yield self.store.get_state_groups_ids(
- room_id, event_ids
- )
- logger.debug(
- "resolve_state_groups state_groups %s",
- state_groups_ids.keys()
- )
- group_names = frozenset(state_groups_ids.keys())
- if len(group_names) == 1:
- name, state_list = state_groups_ids.items().pop()
- defer.returnValue(_StateCacheEntry(
- state=state_list,
- state_group=name,
- prev_group=name,
- delta_ids={},
- ))
- 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)
- )
- state = {}
- for st in state_groups_ids.values():
- for key, e_id in st.items():
- state.setdefault(key, set()).add(e_id)
- conflicted_state = {
- k: list(v)
- for k, v in state.items()
- if len(v) > 1
- }
- if conflicted_state:
- logger.info("Resolving conflicted state for %r", room_id)
- state_map = yield self.store.get_events(
- [e_id for st in state_groups_ids.values() for e_id in st.values()],
- get_prev_content=False
- )
- state_sets = [
- [state_map[e_id] for key, e_id in st.items() if e_id in state_map]
- for st in state_groups_ids.values()
- ]
- new_state, _ = self._resolve_events(
- state_sets, event_type, state_key
- )
- new_state = {
- key: e.event_id for key, e in new_state.items()
- }
- else:
- new_state = {
- key: e_ids.pop() for key, e_ids in state.items()
- }
- state_group = None
- new_state_event_ids = frozenset(new_state.values())
- for sg, events in state_groups_ids.items():
- if new_state_event_ids == frozenset(e_id for e_id in events):
- state_group = sg
- break
- if state_group is None:
- # Worker instances don't have access to this method, but we want
- # to set the state_group on the main instance to increase cache
- # hits.
- if hasattr(self.store, "get_next_state_group"):
- state_group = self.store.get_next_state_group()
- prev_group = None
- delta_ids = None
- for old_group, old_ids in state_groups_ids.items():
- if not set(new_state.iterkeys()) - set(old_ids.iterkeys()):
- n_delta_ids = {
- k: v
- for k, v in new_state.items()
- 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 resolve_events(self, state_sets, event):
- logger.info(
- "Resolving state for %s with %d groups", event.room_id, len(state_sets)
- )
- if event.is_state():
- return self._resolve_events(
- state_sets, event.type, event.state_key
- )
- else:
- return self._resolve_events(state_sets)
- def _resolve_events(self, state_sets, event_type=None, state_key=""):
- """
- Returns
- (dict[(str, str), synapse.events.FrozenEvent], list[str]): a tuple
- (new_state, prev_states). new_state is a map from (type, state_key)
- to event. prev_states is a list of event_ids.
- """
- with Measure(self.clock, "state._resolve_events"):
- state = {}
- for st in state_sets:
- for e in st:
- state.setdefault(
- (e.type, e.state_key),
- {}
- )[e.event_id] = e
- 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_events = conflicted_state.get(
- (event_type, state_key), []
- )
- prev_states = [s.event_id for s in prev_states_events]
- else:
- prev_states = []
- auth_events = {
- k: e for k, e in unconflicted_state.items()
- if k[0] in AuthEventTypes
- }
- try:
- resolved_state = self._resolve_state_events(
- conflicted_state, auth_events
- )
- except:
- logger.exception("Failed to resolve state")
- raise
- new_state = unconflicted_state
- new_state.update(resolved_state)
- return new_state, prev_states
- @log_function
- def _resolve_state_events(self, conflicted_state, auth_events):
- """ This is where we actually decide which of the conflicted state to
- use.
- We resolve conflicts in the following order:
- 1. power levels
- 2. join rules
- 3. memberships
- 4. other events.
- """
- resolved_state = {}
- power_key = (EventTypes.PowerLevels, "")
- if power_key in conflicted_state:
- events = conflicted_state[power_key]
- logger.debug("Resolving conflicted power levels %r", events)
- resolved_state[power_key] = self._resolve_auth_events(
- events, auth_events)
- auth_events.update(resolved_state)
- for key, events in conflicted_state.items():
- if key[0] == EventTypes.JoinRules:
- logger.debug("Resolving conflicted join rules %r", events)
- resolved_state[key] = self._resolve_auth_events(
- events,
- auth_events
- )
- auth_events.update(resolved_state)
- for key, events in conflicted_state.items():
- if key[0] == EventTypes.Member:
- logger.debug("Resolving conflicted member lists %r", events)
- resolved_state[key] = self._resolve_auth_events(
- events,
- auth_events
- )
- auth_events.update(resolved_state)
- for key, events in conflicted_state.items():
- if key not in resolved_state:
- logger.debug("Resolving conflicted state %r:%r", key, events)
- resolved_state[key] = self._resolve_normal_events(
- events, auth_events
- )
- return resolved_state
- def _resolve_auth_events(self, events, auth_events):
- reverse = [i for i in reversed(self._ordered_events(events))]
- auth_events = dict(auth_events)
- prev_event = reverse[0]
- for event in reverse[1:]:
- auth_events[(prev_event.type, prev_event.state_key)] = prev_event
- try:
- # FIXME: hs.get_auth() is bad style, but we need to do it to
- # get around circular deps.
- # The signatures have already been checked at this point
- self.hs.get_auth().check(event, auth_events, do_sig_check=False)
- prev_event = event
- except AuthError:
- return prev_event
- return event
- def _resolve_normal_events(self, events, auth_events):
- for event in self._ordered_events(events):
- try:
- # FIXME: hs.get_auth() is bad style, but we need to do it to
- # get around circular deps.
- # The signatures have already been checked at this point
- self.hs.get_auth().check(event, auth_events, do_sig_check=False)
- return event
- except AuthError:
- pass
- # Use the last event (the one with the least depth) if they all fail
- # the auth check.
- return event
- def _ordered_events(self, events):
- def key_func(e):
- return -int(e.depth), hashlib.sha1(e.event_id).hexdigest()
- return sorted(events, key=key_func)
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