Await un-partial-stating after a partial-state join (#12399)

When we join a room via the faster-joins mechanism, we end up with "partial
state" at some points on the event DAG. Many parts of the codebase need to
wait for the full state to load. So, we implement a mechanism to keep track of
which events have partial state, and wait for them to be fully-populated.
This commit is contained in:
Richard van der Hoff 2022-04-21 07:42:03 +01:00 committed by GitHub
parent 09b4f6e46d
commit f5668f0b4a
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10 changed files with 291 additions and 6 deletions

1
changelog.d/12399.misc Normal file
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@ -0,0 +1 @@
Preparation for faster-room-join work: Implement a tracking mechanism to allow functions to wait for full room state to arrive.

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@ -103,8 +103,10 @@ experimental_features:
spaces_enabled: true
# Enable history backfilling support
msc2716_enabled: true
# server-side support for partial state in /send_join
# server-side support for partial state in /send_join responses
msc3706_enabled: true
# client-side support for partial state in /send_join responses
faster_joins: true
# Enable jump to date endpoint
msc3030_enabled: true

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@ -64,4 +64,4 @@ docker build -t $COMPLEMENT_BASE_IMAGE -f "docker/complement/$COMPLEMENT_DOCKERF
# Run the tests!
echo "Images built; running complement"
cd "$COMPLEMENT_DIR"
go test -v -tags synapse_blacklist,msc2716,msc3030 -count=1 "$@" ./tests/...
go test -v -tags synapse_blacklist,msc2716,msc3030,faster_joins -count=1 "$@" ./tests/...

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@ -515,6 +515,7 @@ class FederationEventHandler:
)
return
await self._store.update_state_for_partial_state_event(event, context)
self._state_store.notify_event_un_partial_stated(event.event_id)
async def backfill(
self, dest: str, room_id: str, limit: int, extremities: Collection[str]

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@ -1974,7 +1974,15 @@ class EventsWorkerStore(SQLBaseStore):
async def get_partial_state_events(
self, event_ids: Collection[str]
) -> Dict[str, bool]:
"""Checks which of the given events have partial state"""
"""Checks which of the given events have partial state
Args:
event_ids: the events we want to check for partial state.
Returns:
a dict mapping from event id to partial-stateness. We return True for
any of the events which are unknown (or are outliers).
"""
result = await self.db_pool.simple_select_many_batch(
table="partial_state_events",
column="event_id",

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@ -396,6 +396,7 @@ class StateGroupWorkerStore(EventsWorkerStore, SQLBaseStore):
)
# TODO(faster_joins): need to do something about workers here
txn.call_after(self.is_partial_state_event.invalidate, (event.event_id,))
txn.call_after(
self._get_state_group_for_event.prefill,
(event.event_id,),

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@ -31,6 +31,7 @@ from frozendict import frozendict
from synapse.api.constants import EventTypes
from synapse.events import EventBase
from synapse.storage.util.partial_state_events_tracker import PartialStateEventsTracker
from synapse.types import MutableStateMap, StateKey, StateMap
if TYPE_CHECKING:
@ -542,6 +543,10 @@ class StateGroupStorage:
def __init__(self, hs: "HomeServer", stores: "Databases"):
self.stores = stores
self._partial_state_events_tracker = PartialStateEventsTracker(stores.main)
def notify_event_un_partial_stated(self, event_id: str) -> None:
self._partial_state_events_tracker.notify_un_partial_stated(event_id)
async def get_state_group_delta(
self, state_group: int
@ -579,7 +584,7 @@ class StateGroupStorage:
if not event_ids:
return {}
event_to_groups = await self.stores.main._get_state_group_for_events(event_ids)
event_to_groups = await self._get_state_group_for_events(event_ids)
groups = set(event_to_groups.values())
group_to_state = await self.stores.state._get_state_for_groups(groups)
@ -668,7 +673,7 @@ class StateGroupStorage:
RuntimeError if we don't have a state group for one or more of the events
(ie they are outliers or unknown)
"""
event_to_groups = await self.stores.main._get_state_group_for_events(event_ids)
event_to_groups = await self._get_state_group_for_events(event_ids)
groups = set(event_to_groups.values())
group_to_state = await self.stores.state._get_state_for_groups(
@ -709,7 +714,7 @@ class StateGroupStorage:
RuntimeError if we don't have a state group for one or more of the events
(ie they are outliers or unknown)
"""
event_to_groups = await self.stores.main._get_state_group_for_events(event_ids)
event_to_groups = await self._get_state_group_for_events(event_ids)
groups = set(event_to_groups.values())
group_to_state = await self.stores.state._get_state_for_groups(
@ -785,6 +790,23 @@ class StateGroupStorage:
groups, state_filter or StateFilter.all()
)
async def _get_state_group_for_events(
self,
event_ids: Collection[str],
await_full_state: bool = True,
) -> Mapping[str, int]:
"""Returns mapping event_id -> state_group
Args:
event_ids: events to get state groups for
await_full_state: if true, will block if we do not yet have complete
state at this event.
"""
if await_full_state:
await self._partial_state_events_tracker.await_full_state(event_ids)
return await self.stores.main._get_state_group_for_events(event_ids)
async def store_state_group(
self,
event_id: str,

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@ -0,0 +1,120 @@
# Copyright 2022 The Matrix.org Foundation C.I.C.
#
# 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 logging
from collections import defaultdict
from typing import Collection, Dict, Set
from twisted.internet import defer
from twisted.internet.defer import Deferred
from synapse.logging.context import PreserveLoggingContext, make_deferred_yieldable
from synapse.storage.databases.main.events_worker import EventsWorkerStore
from synapse.util import unwrapFirstError
logger = logging.getLogger(__name__)
class PartialStateEventsTracker:
"""Keeps track of which events have partial state, after a partial-state join"""
def __init__(self, store: EventsWorkerStore):
self._store = store
# a map from event id to a set of Deferreds which are waiting for that event to be
# un-partial-stated.
self._observers: Dict[str, Set[Deferred[None]]] = defaultdict(set)
def notify_un_partial_stated(self, event_id: str) -> None:
"""Notify that we now have full state for a given event
Called by the state-resynchronization loop whenever we resynchronize the state
for a particular event. Unblocks any callers to await_full_state() for that
event.
Args:
event_id: the event that now has full state.
"""
observers = self._observers.pop(event_id, None)
if not observers:
return
logger.info(
"Notifying %i things waiting for un-partial-stating of event %s",
len(observers),
event_id,
)
with PreserveLoggingContext():
for o in observers:
o.callback(None)
async def await_full_state(self, event_ids: Collection[str]) -> None:
"""Wait for all the given events to have full state.
Args:
event_ids: the list of event ids that we want full state for
"""
# first try the happy path: if there are no partial-state events, we can return
# quickly
partial_state_event_ids = [
ev
for ev, p in (await self._store.get_partial_state_events(event_ids)).items()
if p
]
if not partial_state_event_ids:
return
logger.info(
"Awaiting un-partial-stating of events %s",
partial_state_event_ids,
stack_info=True,
)
# create an observer for each lazy-joined event
observers: Dict[str, Deferred[None]] = {
event_id: Deferred() for event_id in partial_state_event_ids
}
for event_id, observer in observers.items():
self._observers[event_id].add(observer)
try:
# some of them may have been un-lazy-joined between us checking the db and
# registering the observer, in which case we'd wait forever for the
# notification. Call back the observers now.
for event_id, partial in (
await self._store.get_partial_state_events(observers.keys())
).items():
# there may have been a call to notify_un_partial_stated during the
# db query, so the observers may already have been called.
if not partial and not observers[event_id].called:
observers[event_id].callback(None)
await make_deferred_yieldable(
defer.gatherResults(
observers.values(),
consumeErrors=True,
)
).addErrback(unwrapFirstError)
logger.info("Events %s all un-partial-stated", observers.keys())
finally:
# remove any observers we created. This should happen when the notification
# is received, but that might not happen for two reasons:
# (a) we're bailing out early on an exception (including us being
# cancelled during the await)
# (b) the event got de-lazy-joined before we set up the observer.
for event_id, observer in observers.items():
observer_set = self._observers.get(event_id)
if observer_set:
observer_set.discard(observer)
if not observer_set:
del self._observers[event_id]

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@ -0,0 +1,13 @@
# Copyright 2022 The Matrix.org Foundation C.I.C.
#
# 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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@ -0,0 +1,117 @@
# Copyright 2022 The Matrix.org Foundation C.I.C.
#
# 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 typing import Dict
from unittest import mock
from twisted.internet.defer import CancelledError, ensureDeferred
from synapse.storage.util.partial_state_events_tracker import PartialStateEventsTracker
from tests.unittest import TestCase
class PartialStateEventsTrackerTestCase(TestCase):
def setUp(self) -> None:
# the results to be returned by the mocked get_partial_state_events
self._events_dict: Dict[str, bool] = {}
async def get_partial_state_events(events):
return {e: self._events_dict[e] for e in events}
self.mock_store = mock.Mock(spec_set=["get_partial_state_events"])
self.mock_store.get_partial_state_events.side_effect = get_partial_state_events
self.tracker = PartialStateEventsTracker(self.mock_store)
def test_does_not_block_for_full_state_events(self):
self._events_dict = {"event1": False, "event2": False}
self.successResultOf(
ensureDeferred(self.tracker.await_full_state(["event1", "event2"]))
)
self.mock_store.get_partial_state_events.assert_called_once_with(
["event1", "event2"]
)
def test_blocks_for_partial_state_events(self):
self._events_dict = {"event1": True, "event2": False}
d = ensureDeferred(self.tracker.await_full_state(["event1", "event2"]))
# there should be no result yet
self.assertNoResult(d)
# notifying that the event has been de-partial-stated should unblock
self.tracker.notify_un_partial_stated("event1")
self.successResultOf(d)
def test_un_partial_state_race(self):
# if the event is un-partial-stated between the initial check and the
# registration of the listener, it should not block.
self._events_dict = {"event1": True, "event2": False}
async def get_partial_state_events(events):
res = {e: self._events_dict[e] for e in events}
# change the result for next time
self._events_dict = {"event1": False, "event2": False}
return res
self.mock_store.get_partial_state_events.side_effect = get_partial_state_events
self.successResultOf(
ensureDeferred(self.tracker.await_full_state(["event1", "event2"]))
)
def test_un_partial_state_during_get_partial_state_events(self):
# we should correctly handle a call to notify_un_partial_stated during the
# second call to get_partial_state_events.
self._events_dict = {"event1": True, "event2": False}
async def get_partial_state_events1(events):
self.mock_store.get_partial_state_events.side_effect = (
get_partial_state_events2
)
return {e: self._events_dict[e] for e in events}
async def get_partial_state_events2(events):
self.tracker.notify_un_partial_stated("event1")
self._events_dict["event1"] = False
return {e: self._events_dict[e] for e in events}
self.mock_store.get_partial_state_events.side_effect = get_partial_state_events1
self.successResultOf(
ensureDeferred(self.tracker.await_full_state(["event1", "event2"]))
)
def test_cancellation(self):
self._events_dict = {"event1": True, "event2": False}
d1 = ensureDeferred(self.tracker.await_full_state(["event1", "event2"]))
self.assertNoResult(d1)
d2 = ensureDeferred(self.tracker.await_full_state(["event1"]))
self.assertNoResult(d2)
d1.cancel()
self.assertFailure(d1, CancelledError)
# d2 should still be waiting!
self.assertNoResult(d2)
self.tracker.notify_un_partial_stated("event1")
self.successResultOf(d2)