From 639480e14a06723adf6817ddd2b2ff9e4f4cdf2a Mon Sep 17 00:00:00 2001 From: Richard van der Hoff Date: Mon, 16 Apr 2018 18:41:37 +0100 Subject: [PATCH] Avoid creating events with huge numbers of prev_events In most cases, we limit the number of prev_events for a given event to 10 events. This fixes a particular code path which created events with huge numbers of prev_events. --- synapse/handlers/message.py | 78 +++++++++++++++----------- synapse/handlers/room_member.py | 13 +++-- synapse/storage/event_federation.py | 57 +++++++++++++------ tests/storage/test_event_federation.py | 68 ++++++++++++++++++++++ 4 files changed, 162 insertions(+), 54 deletions(-) create mode 100644 tests/storage/test_event_federation.py diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py index 54cd691f91..21628a8540 100644 --- a/synapse/handlers/message.py +++ b/synapse/handlers/message.py @@ -37,7 +37,6 @@ from ._base import BaseHandler from canonicaljson import encode_canonical_json import logging -import random import simplejson logger = logging.getLogger(__name__) @@ -433,7 +432,7 @@ class EventCreationHandler(object): @defer.inlineCallbacks def create_event(self, requester, event_dict, token_id=None, txn_id=None, - prev_event_ids=None): + prev_events_and_hashes=None): """ Given a dict from a client, create a new event. @@ -447,7 +446,13 @@ class EventCreationHandler(object): event_dict (dict): An entire event token_id (str) txn_id (str) - prev_event_ids (list): The prev event ids to use when creating the event + + prev_events_and_hashes (list[(str, dict[str, str], int)]|None): + the forward extremities to use as the prev_events for the + new event. For each event, a tuple of (event_id, hashes, depth) + where *hashes* is a map from algorithm to hash. + + If None, they will be requested from the database. Returns: Tuple of created event (FrozenEvent), Context @@ -485,7 +490,7 @@ class EventCreationHandler(object): event, context = yield self.create_new_client_event( builder=builder, requester=requester, - prev_event_ids=prev_event_ids, + prev_events_and_hashes=prev_events_and_hashes, ) defer.returnValue((event, context)) @@ -588,39 +593,44 @@ class EventCreationHandler(object): @measure_func("create_new_client_event") @defer.inlineCallbacks - def create_new_client_event(self, builder, requester=None, prev_event_ids=None): - if prev_event_ids: - prev_events = yield self.store.add_event_hashes(prev_event_ids) - prev_max_depth = yield self.store.get_max_depth_of_events(prev_event_ids) - depth = prev_max_depth + 1 - else: - latest_ret = yield self.store.get_latest_event_ids_and_hashes_in_room( - builder.room_id, + def create_new_client_event(self, builder, requester=None, + prev_events_and_hashes=None): + """Create a new event for a local client + + Args: + builder (EventBuilder): + + requester (synapse.types.Requester|None): + + prev_events_and_hashes (list[(str, dict[str, str], int)]|None): + the forward extremities to use as the prev_events for the + new event. For each event, a tuple of (event_id, hashes, depth) + where *hashes* is a map from algorithm to hash. + + If None, they will be requested from the database. + + Returns: + Deferred[(synapse.events.EventBase, synapse.events.snapshot.EventContext)] + """ + + if prev_events_and_hashes is not None: + assert len(prev_events_and_hashes) <= 10, \ + "Attempting to create an event with %i prev_events" % ( + len(prev_events_and_hashes), ) + else: + prev_events_and_hashes = \ + yield self.store.get_prev_events_for_room(builder.room_id) - # We want to limit the max number of prev events we point to in our - # new event - if len(latest_ret) > 10: - # Sort by reverse depth, so we point to the most recent. - latest_ret.sort(key=lambda a: -a[2]) - new_latest_ret = latest_ret[:5] + if prev_events_and_hashes: + depth = max([d for _, _, d in prev_events_and_hashes]) + 1 + else: + depth = 1 - # We also randomly point to some of the older events, to make - # sure that we don't completely ignore the older events. - if latest_ret[5:]: - sample_size = min(5, len(latest_ret[5:])) - new_latest_ret.extend(random.sample(latest_ret[5:], sample_size)) - latest_ret = new_latest_ret - - if latest_ret: - depth = max([d for _, _, d in latest_ret]) + 1 - else: - depth = 1 - - prev_events = [ - (event_id, prev_hashes) - for event_id, prev_hashes, _ in latest_ret - ] + prev_events = [ + (event_id, prev_hashes) + for event_id, prev_hashes, _ in prev_events_and_hashes + ] builder.prev_events = prev_events builder.depth = depth diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py index c45142d38d..714583f1d5 100644 --- a/synapse/handlers/room_member.py +++ b/synapse/handlers/room_member.py @@ -149,7 +149,7 @@ class RoomMemberHandler(object): @defer.inlineCallbacks def _local_membership_update( self, requester, target, room_id, membership, - prev_event_ids, + prev_events_and_hashes, txn_id=None, ratelimit=True, content=None, @@ -175,7 +175,7 @@ class RoomMemberHandler(object): }, token_id=requester.access_token_id, txn_id=txn_id, - prev_event_ids=prev_event_ids, + prev_events_and_hashes=prev_events_and_hashes, ) # Check if this event matches the previous membership event for the user. @@ -314,7 +314,12 @@ class RoomMemberHandler(object): 403, "Invites have been disabled on this server", ) - latest_event_ids = yield self.store.get_latest_event_ids_in_room(room_id) + prev_events_and_hashes = yield self.store.get_prev_events_for_room( + room_id, + ) + latest_event_ids = ( + event_id for (event_id, _, _) in prev_events_and_hashes + ) current_state_ids = yield self.state_handler.get_current_state_ids( room_id, latest_event_ids=latest_event_ids, ) @@ -403,7 +408,7 @@ class RoomMemberHandler(object): membership=effective_membership_state, txn_id=txn_id, ratelimit=ratelimit, - prev_event_ids=latest_event_ids, + prev_events_and_hashes=prev_events_and_hashes, content=content, ) defer.returnValue(res) diff --git a/synapse/storage/event_federation.py b/synapse/storage/event_federation.py index 00ee82d300..a183fc6b50 100644 --- a/synapse/storage/event_federation.py +++ b/synapse/storage/event_federation.py @@ -12,6 +12,7 @@ # 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 random from twisted.internet import defer @@ -133,7 +134,47 @@ class EventFederationWorkerStore(EventsWorkerStore, SignatureWorkerStore, retcol="event_id", ) + @defer.inlineCallbacks + def get_prev_events_for_room(self, room_id): + """ + Gets a subset of the current forward extremities in the given room. + + Limits the result to 10 extremities, so that we can avoid creating + events which refer to hundreds of prev_events. + + Args: + room_id (str): room_id + + Returns: + Deferred[list[(str, dict[str, str], int)]] + for each event, a tuple of (event_id, hashes, depth) + where *hashes* is a map from algorithm to hash. + """ + res = yield self.get_latest_event_ids_and_hashes_in_room(room_id) + if len(res) > 10: + # Sort by reverse depth, so we point to the most recent. + res.sort(key=lambda a: -a[2]) + + # we use half of the limit for the actual most recent events, and + # the other half to randomly point to some of the older events, to + # make sure that we don't completely ignore the older events. + res = res[0:5] + random.sample(res[5:], 5) + + defer.returnValue(res) + def get_latest_event_ids_and_hashes_in_room(self, room_id): + """ + Gets the current forward extremities in the given room + + Args: + room_id (str): room_id + + Returns: + Deferred[list[(str, dict[str, str], int)]] + for each event, a tuple of (event_id, hashes, depth) + where *hashes* is a map from algorithm to hash. + """ + return self.runInteraction( "get_latest_event_ids_and_hashes_in_room", self._get_latest_event_ids_and_hashes_in_room, @@ -182,22 +223,6 @@ class EventFederationWorkerStore(EventsWorkerStore, SignatureWorkerStore, room_id, ) - @defer.inlineCallbacks - def get_max_depth_of_events(self, event_ids): - sql = ( - "SELECT MAX(depth) FROM events WHERE event_id IN (%s)" - ) % (",".join(["?"] * len(event_ids)),) - - rows = yield self._execute( - "get_max_depth_of_events", None, - sql, *event_ids - ) - - if rows: - defer.returnValue(rows[0][0]) - else: - defer.returnValue(1) - def _get_min_depth_interaction(self, txn, room_id): min_depth = self._simple_select_one_onecol_txn( txn, diff --git a/tests/storage/test_event_federation.py b/tests/storage/test_event_federation.py new file mode 100644 index 0000000000..30683e7888 --- /dev/null +++ b/tests/storage/test_event_federation.py @@ -0,0 +1,68 @@ +# -*- 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. + +from twisted.internet import defer + +import tests.unittest +import tests.utils + + +class EventFederationWorkerStoreTestCase(tests.unittest.TestCase): + @defer.inlineCallbacks + def setUp(self): + hs = yield tests.utils.setup_test_homeserver() + self.store = hs.get_datastore() + + @defer.inlineCallbacks + def test_get_prev_events_for_room(self): + room_id = '@ROOM:local' + + # add a bunch of events and hashes to act as forward extremities + def insert_event(txn, i): + event_id = '$event_%i:local' % i + + txn.execute(( + "INSERT INTO events (" + " room_id, event_id, type, depth, topological_ordering," + " content, processed, outlier) " + "VALUES (?, ?, 'm.test', ?, ?, 'test', ?, ?)" + ), (room_id, event_id, i, i, True, False)) + + txn.execute(( + 'INSERT INTO event_forward_extremities (room_id, event_id) ' + 'VALUES (?, ?)' + ), (room_id, event_id)) + + txn.execute(( + 'INSERT INTO event_reference_hashes ' + '(event_id, algorithm, hash) ' + "VALUES (?, 'sha256', ?)" + ), (event_id, 'ffff')) + + for i in range(0, 11): + yield self.store.runInteraction("insert", insert_event, i) + + # this should get the last five and five others + r = yield self.store.get_prev_events_for_room(room_id) + self.assertEqual(10, len(r)) + for i in range(0, 5): + el = r[i] + depth = el[2] + self.assertEqual(10 - i, depth) + + for i in range(5, 5): + el = r[i] + depth = el[2] + self.assertLessEqual(5, depth)