anonymousland-synapse/synapse/state/v1.py
Erik Johnston 119451dcd1 Refactor state module
We split out the actual state resolution algorithm to prepare for having
multiple versions.
2018-08-09 14:55:47 +01:00

322 lines
11 KiB
Python

# -*- coding: utf-8 -*-
# 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 hashlib
import logging
from six import iteritems, iterkeys, itervalues
from twisted.internet import defer
from synapse import event_auth
from synapse.api.constants import EventTypes
from synapse.api.errors import AuthError
logger = logging.getLogger(__name__)
POWER_KEY = (EventTypes.PowerLevels, "")
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
)
@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(iterkeys(event_map))
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(iterkeys(event_map))
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 _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(iterable[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.
"""
state_set_iterator = iter(state_sets)
unconflicted_state = dict(next(state_set_iterator))
conflicted_state = {}
for state_set in state_set_iterator:
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
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_ids, auth_event_ids,
state_map):
conflicted_state = {}
for key, event_ids in iteritems(conflicted_state_ids):
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
def _ordered_events(events):
def key_func(e):
return -int(e.depth), hashlib.sha1(e.event_id.encode('ascii')).hexdigest()
return sorted(events, key=key_func)