# -*- coding: utf-8 -*-
# Copyright 2014 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.api.events.room import RoomPowerLevelsEvent
from collections import namedtuple
import copy
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"))
class StateHandler(object):
""" Responsible for doing state conflict resolution.
"""
def __init__(self, hs):
self.store = hs.get_datastore()
@defer.inlineCallbacks
@log_function
def annotate_event_with_state(self, event, old_state=None):
""" Annotates the event with the current state events as of that event.
This method adds three new attributes to the event:
* `state_events`: The state up to and including the event. Encoded
as a dict mapping tuple (type, state_key) -> event.
* `old_state_events`: The state up to, but excluding, the event.
Encoded similarly as `state_events`.
* `state_group`: If there is an existing state group that can be
used, then return that. Otherwise return `None`. See state
storage for more information.
If the argument `old_state` is given (in the form of a list of
events), then they are used as a the values for `old_state_events` and
the value for `state_events` is generated from it. `state_group` is
set to None.
This needs to be called before persisting the event.
"""
yield run_on_reactor()
if old_state:
event.state_group = None
event.old_state_events = {
(s.type, s.state_key): s for s in old_state
}
event.state_events = event.old_state_events
if hasattr(event, "state_key"):
event.state_events[(event.type, event.state_key)] = event
defer.returnValue(False)
return
if hasattr(event, "outlier") and event.outlier:
event.state_group = None
event.old_state_events = None
event.state_events = None
defer.returnValue(False)
return
ids = [e for e, _ in event.prev_events]
ret = yield self.resolve_state_groups(ids)
state_group, new_state = ret
event.old_state_events = copy.deepcopy(new_state)
if hasattr(event, "state_key"):
key = (event.type, event.state_key)
if key in new_state:
event.replaces_state = new_state[key].event_id
new_state[key] = event
elif state_group:
event.state_group = state_group
event.state_events = new_state
defer.returnValue(False)
event.state_group = None
event.state_events = new_state
defer.returnValue(hasattr(event, "state_key"))
@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`.
"""
events = yield self.store.get_latest_events_in_room(room_id)
event_ids = [
e_id
for e_id, _, _ in events
]
res = yield self.resolve_state_groups(event_ids)
if event_type:
defer.returnValue(res[1].get((event_type, state_key)))
return
defer.returnValue(res[1].values())
@defer.inlineCallbacks
@log_function
def resolve_state_groups(self, event_ids):
""" 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`.
"""
state_groups = yield self.store.get_state_groups(
event_ids
)
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
}
defer.returnValue((name, state))
state = {}
for group, g_state in state_groups.items():
for s in g_state:
state.setdefault(
(s.type, s.state_key),
{}
)[s.event_id] = s
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
}
try:
new_state = {}
new_state.update(unconflicted_state)
for key, events in conflicted_state.items():
new_state[key] = self._resolve_state_events(events)
except:
logger.exception("Failed to resolve state")
raise
defer.returnValue((None, new_state))
def _get_power_level_from_event_state(self, event, user_id):
if hasattr(event, "old_state_events") and event.old_state_events:
key = (RoomPowerLevelsEvent.TYPE, "", )
power_level_event = event.old_state_events.get(key)
level = None
if power_level_event:
level = power_level_event.content.get("users", {}).get(
user_id
)
if not level:
level = power_level_event.content.get("users_default", 0)
return level
else:
return 0
@log_function
def _resolve_state_events(self, events):
curr_events = events
new_powers = [
self._get_power_level_from_event_state(e, e.user_id)
for e in curr_events
]
new_powers = [
int(p) if p else 0 for p in new_powers
]
max_power = max(new_powers)
curr_events = [
z[0] for z in zip(curr_events, new_powers)
if z[1] == max_power
]
if not curr_events:
raise RuntimeError("Max didn't get a max?")
elif len(curr_events) == 1:
return curr_events[0]
# TODO: For now, just choose the one with the largest event_id.
return (
sorted(
curr_events,
key=lambda e: hashlib.sha1(
e.event_id + e.user_id + e.room_id + e.type
).hexdigest()
)[0]
)