386 lines
11 KiB
Python
386 lines
11 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2014 OpenMarket Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from twisted.internet import defer
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from synapse.federation.pdu_codec import encode_event_id, decode_event_id
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from synapse.util.logutils import log_function
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from collections import namedtuple
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import copy
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import logging
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import hashlib
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logger = logging.getLogger(__name__)
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def _get_state_key_from_event(event):
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return event.state_key
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KeyStateTuple = namedtuple("KeyStateTuple", ("context", "type", "state_key"))
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class StateHandler(object):
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""" Responsible for doing state conflict resolution.
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"""
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def __init__(self, hs):
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self.store = hs.get_datastore()
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self._replication = hs.get_replication_layer()
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self.server_name = hs.hostname
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@defer.inlineCallbacks
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@log_function
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def handle_new_event(self, event, snapshot):
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""" Given an event this works out if a) we have sufficient power level
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to update the state and b) works out what the prev_state should be.
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Returns:
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Deferred: Resolved with a boolean indicating if we successfully
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updated the state.
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Raised:
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AuthError
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"""
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# This needs to be done in a transaction.
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if not hasattr(event, "state_key"):
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return
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key = KeyStateTuple(
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event.room_id,
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event.type,
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_get_state_key_from_event(event)
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)
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# Now I need to fill out the prev state and work out if it has auth
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# (w.r.t. to power levels)
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snapshot.fill_out_prev_events(event)
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yield self.annotate_state_groups(event)
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current_state = snapshot.prev_state_pdu
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if current_state:
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event.prev_state = encode_event_id(
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current_state.pdu_id, current_state.origin
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)
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# TODO check current_state to see if the min power level is less
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# than the power level of the user
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# power_level = self._get_power_level_for_event(event)
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pdu_id, origin = decode_event_id(event.event_id, self.server_name)
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yield self.store.update_current_state(
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pdu_id=pdu_id,
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origin=origin,
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context=key.context,
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pdu_type=key.type,
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state_key=key.state_key
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)
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defer.returnValue(True)
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@defer.inlineCallbacks
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@log_function
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def handle_new_state(self, new_pdu):
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""" Apply conflict resolution to `new_pdu`.
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This should be called on every new state pdu, regardless of whether or
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not there is a conflict.
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This function is safe against the race of it getting called with two
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`PDU`s trying to update the same state.
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"""
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# This needs to be done in a transaction.
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is_new = yield self._handle_new_state(new_pdu)
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logger.debug("is_new: %s %s %s", is_new, new_pdu.pdu_id, new_pdu.origin)
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if is_new:
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yield self.store.update_current_state(
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pdu_id=new_pdu.pdu_id,
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origin=new_pdu.origin,
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context=new_pdu.context,
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pdu_type=new_pdu.pdu_type,
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state_key=new_pdu.state_key
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)
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defer.returnValue(is_new)
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@defer.inlineCallbacks
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@log_function
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def annotate_state_groups(self, event, state=None):
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if state:
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event.state_group = None
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event.old_state_events = None
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event.state_events = {(s.type, s.state_key): s for s in state}
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defer.returnValue(False)
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return
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if hasattr(event, "outlier") and event.outlier:
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event.state_group = None
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event.old_state_events = None
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event.state_events = {}
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defer.returnValue(False)
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return
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new_state = yield self.resolve_state_groups(
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[e for e, _ in event.prev_events]
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)
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event.old_state_events = copy.deepcopy(new_state)
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if hasattr(event, "state_key"):
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new_state[(event.type, event.state_key)] = event
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event.state_group = None
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event.state_events = new_state
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defer.returnValue(hasattr(event, "state_key"))
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@defer.inlineCallbacks
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def get_current_state(self, room_id, event_type=None, state_key=""):
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events = yield self.store.get_latest_events_in_room(room_id)
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event_ids = [
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e_id
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for e_id, _ in events
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]
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res = yield self.resolve_state_groups(event_ids)
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if event_type:
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defer.returnValue(res.get((event_type, state_key)))
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return
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defer.returnValue(res.values())
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@defer.inlineCallbacks
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@log_function
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def resolve_state_groups(self, event_ids):
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state_groups = yield self.store.get_state_groups(
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event_ids
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)
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state = {}
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for group in state_groups:
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for s in group.state:
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state.setdefault(
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(s.type, s.state_key),
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{}
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)[s.event_id] = s
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unconflicted_state = {
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k: v.values()[0] for k, v in state.items()
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if len(v.values()) == 1
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}
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conflicted_state = {
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k: v.values()
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for k, v in state.items()
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if len(v.values()) > 1
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}
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try:
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new_state = {}
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new_state.update(unconflicted_state)
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for key, events in conflicted_state.items():
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new_state[key] = yield self._resolve_state_events(events)
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except:
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logger.exception("Failed to resolve state")
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raise
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defer.returnValue(new_state)
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@defer.inlineCallbacks
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@log_function
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def _resolve_state_events(self, events):
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curr_events = events
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new_powers_deferreds = []
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for e in curr_events:
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new_powers_deferreds.append(
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self.store.get_power_level(e.room_id, e.user_id)
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)
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new_powers = yield defer.gatherResults(
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new_powers_deferreds,
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consumeErrors=True
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)
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max_power = max([int(p) for p in new_powers])
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curr_events = [
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z[0] for z in zip(curr_events, new_powers)
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if int(z[1]) == max_power
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]
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if not curr_events:
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raise RuntimeError("Max didn't get a max?")
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elif len(curr_events) == 1:
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defer.returnValue(curr_events[0])
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# TODO: For now, just choose the one with the largest event_id.
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defer.returnValue(
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sorted(
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curr_events,
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key=lambda e: hashlib.sha1(
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e.event_id + e.user_id + e.room_id + e.type
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).hexdigest()
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)[0]
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)
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def _get_power_level_for_event(self, event):
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# return self._persistence.get_power_level_for_user(event.room_id,
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# event.sender)
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return event.power_level
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@defer.inlineCallbacks
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@log_function
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def _handle_new_state(self, new_pdu):
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tree, missing_branch = yield self.store.get_unresolved_state_tree(
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new_pdu
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)
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new_branch, current_branch = tree
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logger.debug(
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"_handle_new_state new=%s, current=%s",
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new_branch, current_branch
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)
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if missing_branch is not None:
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# We're missing some PDUs. Fetch them.
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# TODO (erikj): Limit this.
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missing_prev = tree[missing_branch][-1]
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pdu_id = missing_prev.prev_state_id
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origin = missing_prev.prev_state_origin
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is_missing = yield self.store.get_pdu(pdu_id, origin) is None
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if not is_missing:
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raise Exception("Conflict resolution failed")
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yield self._replication.get_pdu(
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destination=missing_prev.origin,
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pdu_origin=origin,
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pdu_id=pdu_id,
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outlier=True
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)
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updated_current = yield self._handle_new_state(new_pdu)
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defer.returnValue(updated_current)
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if not current_branch:
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# There is no current state
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defer.returnValue(True)
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return
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n = new_branch[-1]
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c = current_branch[-1]
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common_ancestor = n.pdu_id == c.pdu_id and n.origin == c.origin
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if common_ancestor:
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# We found a common ancestor!
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if len(current_branch) == 1:
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# This is a direct clobber so we can just...
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defer.returnValue(True)
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else:
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# We didn't find a common ancestor. This is probably fine.
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pass
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result = yield self._do_conflict_res(
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new_branch, current_branch, common_ancestor
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)
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defer.returnValue(result)
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@defer.inlineCallbacks
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def _do_conflict_res(self, new_branch, current_branch, common_ancestor):
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conflict_res = [
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self._do_power_level_conflict_res,
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self._do_chain_length_conflict_res,
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self._do_hash_conflict_res,
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]
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for algo in conflict_res:
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new_res, curr_res = yield defer.maybeDeferred(
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algo,
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new_branch, current_branch, common_ancestor
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)
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if new_res < curr_res:
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defer.returnValue(False)
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elif new_res > curr_res:
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defer.returnValue(True)
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raise Exception("Conflict resolution failed.")
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@defer.inlineCallbacks
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def _do_power_level_conflict_res(self, new_branch, current_branch,
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common_ancestor):
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new_powers_deferreds = []
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for e in new_branch[:-1] if common_ancestor else new_branch:
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if hasattr(e, "user_id"):
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new_powers_deferreds.append(
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self.store.get_power_level(e.context, e.user_id)
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)
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current_powers_deferreds = []
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for e in current_branch[:-1] if common_ancestor else current_branch:
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if hasattr(e, "user_id"):
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current_powers_deferreds.append(
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self.store.get_power_level(e.context, e.user_id)
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)
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new_powers = yield defer.gatherResults(
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new_powers_deferreds,
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consumeErrors=True
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)
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current_powers = yield defer.gatherResults(
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current_powers_deferreds,
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consumeErrors=True
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)
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max_power_new = max(new_powers)
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max_power_current = max(current_powers)
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defer.returnValue(
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(max_power_new, max_power_current)
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)
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def _do_chain_length_conflict_res(self, new_branch, current_branch,
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common_ancestor):
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return (len(new_branch), len(current_branch))
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def _do_hash_conflict_res(self, new_branch, current_branch,
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common_ancestor):
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new_str = "".join([p.pdu_id + p.origin for p in new_branch])
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c_str = "".join([p.pdu_id + p.origin for p in current_branch])
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return (
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hashlib.sha1(new_str).hexdigest(),
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hashlib.sha1(c_str).hexdigest()
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)
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