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- # -*- coding: utf-8 -*-
- # Copyright 2014, 2015 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.util.caches.expiringcache import ExpiringCache
- 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 collections import namedtuple
- 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"))
- SIZE_OF_CACHE = 1000
- EVICTION_TIMEOUT_SECONDS = 20
- class _StateCacheEntry(object):
- def __init__(self, state, state_group, ts):
- self.state = state
- self.state_group = state_group
- 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
- 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=""):
- """ 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`.
- """
- event_ids = yield self.store.get_latest_event_ids_in_room(room_id)
- cache = None
- if self._state_cache is not None:
- cache = self._state_cache.get(frozenset(event_ids), None)
- if cache:
- cache.ts = self.clock.time_msec()
- state = cache.state
- else:
- res = yield self.resolve_state_groups(room_id, event_ids)
- state = res[1]
- if event_type:
- defer.returnValue(state.get((event_type, state_key)))
- return
- defer.returnValue(state)
- @defer.inlineCallbacks
- def compute_event_context(self, event, old_state=None, outlier=False):
- """ 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
- """
- yield run_on_reactor()
- context = EventContext()
- if 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.current_state = {
- (s.type, s.state_key): s for s in old_state
- }
- else:
- context.current_state = {}
- context.prev_state_events = []
- context.state_group = None
- defer.returnValue(context)
- if old_state:
- context.current_state = {
- (s.type, s.state_key): s for s in old_state
- }
- context.state_group = None
- if event.is_state():
- key = (event.type, event.state_key)
- if key in context.current_state:
- replaces = context.current_state[key]
- if replaces.event_id != event.event_id: # Paranoia check
- event.unsigned["replaces_state"] = replaces.event_id
- context.prev_state_events = []
- defer.returnValue(context)
- if event.is_state():
- ret = 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:
- ret = yield self.resolve_state_groups(
- event.room_id, [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
- 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
- context.prev_state_events = prev_state
- 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.
- 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`.
- """
- logger.debug("resolve_state_groups event_ids %s", event_ids)
- if self._state_cache is not None:
- cache = self._state_cache.get(frozenset(event_ids), None)
- if cache and cache.state_group:
- cache.ts = self.clock.time_msec()
- prev_state = cache.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(
- (cache.state_group, cache.state, prev_states)
- )
- state_groups = yield self.store.get_state_groups(
- room_id, event_ids
- )
- logger.debug(
- "resolve_state_groups state_groups %s",
- state_groups.keys()
- )
- 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 = []
- if self._state_cache is not None:
- cache = _StateCacheEntry(
- state=state,
- state_group=name,
- ts=self.clock.time_msec()
- )
- self._state_cache[frozenset(event_ids)] = cache
- defer.returnValue((name, state, prev_states))
- new_state, prev_states = self._resolve_events(
- state_groups.values(), event_type, state_key
- )
- if self._state_cache is not None:
- cache = _StateCacheEntry(
- state=new_state,
- state_group=None,
- ts=self.clock.time_msec()
- )
- self._state_cache[frozenset(event_ids)] = cache
- defer.returnValue((None, new_state, prev_states))
- def resolve_events(self, state_sets, event):
- 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=""):
- 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. memberships
- 3. other events.
- """
- resolved_state = {}
- power_key = (EventTypes.PowerLevels, "")
- if power_key in conflicted_state.items():
- power_levels = conflicted_state[power_key]
- resolved_state[power_key] = self._resolve_auth_events(power_levels)
- auth_events.update(resolved_state)
- for key, events in conflicted_state.items():
- if key[0] == EventTypes.JoinRules:
- 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:
- 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:
- 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.
- self.hs.get_auth().check(event, auth_events)
- 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.
- self.hs.get_auth().check(event, auth_events)
- 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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