MatrixSynapse/synapse/state.py

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# -*- coding: utf-8 -*-
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# Copyright 2014-2016 OpenMarket Ltd
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#
# 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.
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from twisted.internet import defer
from synapse.util.logutils import log_function
from synapse.util.caches.expiringcache import ExpiringCache
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from synapse.util.metrics import Measure
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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
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from collections import namedtuple
import logging
import hashlib
import os
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logger = logging.getLogger(__name__)
KeyStateTuple = namedtuple("KeyStateTuple", ("context", "type", "state_key"))
CACHE_SIZE_FACTOR = float(os.environ.get("SYNAPSE_CACHE_FACTOR", 0.1))
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SIZE_OF_CACHE = int(1000 * CACHE_SIZE_FACTOR)
EVICTION_TIMEOUT_SECONDS = 60 * 60
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_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 = state
self.state_group = state_group
self.prev_group = prev_group
self.delta_ids = delta_ids
# 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()
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class StateHandler(object):
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""" Responsible for doing state conflict resolution.
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"""
def __init__(self, hs):
self.clock = hs.get_clock()
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self.store = hs.get_datastore()
self.hs = hs
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# dict of set of event_ids -> _StateCacheEntry.
self._state_cache = None
self.resolve_linearizer = Linearizer()
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def start_caching(self):
logger.debug("start_caching")
self._state_cache = ExpiringCache(
cache_name="state_cache",
clock=self.clock,
max_len=SIZE_OF_CACHE,
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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
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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
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"""
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
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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():
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# 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.
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if old_state:
context.prev_state_ids = {
(s.type, s.state_key): s.event_id for s in old_state
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}
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
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else:
context.current_state_ids = {}
context.prev_state_ids = {}
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context.prev_state_events = []
context.state_group = self.store.get_next_state_group()
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defer.returnValue(context)
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if old_state:
context.prev_state_ids = {
(s.type, s.state_key): s.event_id for s in old_state
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}
context.state_group = self.store.get_next_state_group()
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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
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context.prev_state_events = []
defer.returnValue(context)
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if event.is_state():
entry = yield self.resolve_state_groups(
event.room_id, [e for e, _ in event.prev_events],
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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()
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
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if event.is_state():
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[key] = event.event_id
else:
context.current_state_ids = context.prev_state_ids
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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=""):
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""" 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.
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"""
logger.debug("resolve_state_groups event_ids %s", event_ids)
state_groups_ids = yield self.store.get_state_groups_ids(
room_id, event_ids
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)
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()
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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.
"""
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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
}
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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 = []
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auth_events = {
k: e for k, e in unconflicted_state.items()
if k[0] in AuthEventTypes
}
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try:
resolved_state = self._resolve_state_events(
conflicted_state, auth_events
)
except:
logger.exception("Failed to resolve state")
raise
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new_state = unconflicted_state
new_state.update(resolved_state)
return new_state, prev_states
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@log_function
def _resolve_state_events(self, conflicted_state, auth_events):
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""" 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.
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"""
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
)
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auth_events.update(resolved_state)
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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
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def _resolve_auth_events(self, events, auth_events):
reverse = [i for i in reversed(self._ordered_events(events))]
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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.
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# The signatures have already been checked at this point
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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.
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# The signatures have already been checked at this point
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self.hs.get_auth().check(event, auth_events, do_sig_check=False)
return event
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except AuthError:
pass
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# 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()
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return sorted(events, key=key_func)