Add DB bg update to cleanup extremities.

Due to #5269 we may have extremities in our DB that we shouldn't have,
so lets add a cleanup task such to remove those.
pull/5278/head
Erik Johnston 2019-05-28 18:52:41 +01:00
parent 58c8ed5b0d
commit d79c9994f4
2 changed files with 205 additions and 0 deletions

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@ -221,6 +221,7 @@ class EventsStore(
):
EVENT_ORIGIN_SERVER_TS_NAME = "event_origin_server_ts"
EVENT_FIELDS_SENDER_URL_UPDATE_NAME = "event_fields_sender_url"
EVENT_DELETE_SOFT_FAILED_EXTREMITIES = "delete_soft_failed_extremities"
def __init__(self, db_conn, hs):
super(EventsStore, self).__init__(db_conn, hs)
@ -252,6 +253,11 @@ class EventsStore(
psql_only=True,
)
self.register_background_update_handler(
self.EVENT_DELETE_SOFT_FAILED_EXTREMITIES,
self._cleanup_extremities_bg_update,
)
self._event_persist_queue = _EventPeristenceQueue()
self._state_resolution_handler = hs.get_state_resolution_handler()
@ -2341,6 +2347,186 @@ class EventsStore(
get_all_updated_current_state_deltas_txn,
)
@defer.inlineCallbacks
def _cleanup_extremities_bg_update(self, progress, batch_size):
"""Background update to clean out extremities that should have been
deleted previously.
Mainly used to deal with the aftermath of #5269.
"""
# This works by first copying all existing forward extremities into the
# `_extremities_to_check` table at start up, and then checking each
# event in that table whether we have any descendants that are not
# soft-failed/rejected. If that is the case then we delete that event
# from the forward extremities table.
#
# For efficiency, we do this in batches by recursively pulling out all
# descendants of a batch until we find the non soft-failed/rejected
# events, i.e. the set of descendants whose chain of prev events back
# to the batch of extremities are all soft-failed or rejected.
# Typically, we won't find any such events as extremities will rarely
# have any descendants, but if they do then we should delete those
# extremities.
def _cleanup_extremities_bg_update_txn(txn):
# The set of extremity event IDs that we're checking this round
original_set = set()
# A dict[str, set[str]] of event ID to their prev events.
graph = {}
# The set of descendants of the original set that are not rejected
# nor soft-failed. Ancestors of these events should be removed
# from the forward extremities table.
non_rejected_leaves = set()
# Set of event IDs that have been soft failed, and for which we
# should check if they have descendants which haven't been soft
# failed.
soft_failed_events_to_lookup = set()
# First, we get `batch_size` events from the table, pulling out
# their prev events, if any, and their prev events rejection status.
txn.execute(
"""SELECT prev_event_id, event_id, internal_metadata,
rejections.event_id IS NOT NULL, events.outlier
FROM (
SELECT event_id AS prev_event_id
FROM _extremities_to_check
LIMIT ?
) AS f
LEFT JOIN event_edges USING (prev_event_id)
LEFT JOIN events USING (event_id)
LEFT JOIN event_json USING (event_id)
LEFT JOIN rejections USING (event_id)
""", (batch_size,)
)
for prev_event_id, event_id, metadata, rejected, outlier in txn:
original_set.add(prev_event_id)
if not event_id or outlier:
# Common case where the forward extremity doesn't have any
# descendants.
continue
graph.setdefault(event_id, set()).add(prev_event_id)
soft_failed = False
if metadata:
soft_failed = json.loads(metadata).get("soft_failed")
if soft_failed or rejected:
soft_failed_events_to_lookup.add(event_id)
else:
non_rejected_leaves.add(event_id)
# Now we recursively check all the soft-failed descendants we
# found above in the same way, until we have nothing left to
# check.
while soft_failed_events_to_lookup:
# We only want to do 100 at a time, so we split given list
# into two.
batch = list(soft_failed_events_to_lookup)
to_check, to_defer = batch[:100], batch[100:]
soft_failed_events_to_lookup = set(to_defer)
sql = """SELECT prev_event_id, event_id, internal_metadata,
rejections.event_id IS NOT NULL
FROM event_edges
INNER JOIN events USING (event_id)
INNER JOIN event_json USING (event_id)
LEFT JOIN rejections USING (event_id)
WHERE
prev_event_id IN (%s)
AND NOT events.outlier
""" % (
",".join("?" for _ in to_check),
)
txn.execute(sql, to_check)
for prev_event_id, event_id, metadata, rejected in txn:
if event_id in graph:
# Already handled this event previously, but we still
# want to record the edge.
graph.setdefault(event_id, set()).add(prev_event_id)
logger.info("Already handled")
continue
graph.setdefault(event_id, set()).add(prev_event_id)
soft_failed = json.loads(metadata).get("soft_failed")
if soft_failed or rejected:
soft_failed_events_to_lookup.add(event_id)
else:
non_rejected_leaves.add(event_id)
# We have a set of non-soft-failed descendants, so we recurse up
# the graph to find all ancestors and add them to the set of event
# IDs that we can delete from forward extremities table.
to_delete = set()
while non_rejected_leaves:
event_id = non_rejected_leaves.pop()
prev_event_ids = graph.get(event_id, set())
non_rejected_leaves.update(prev_event_ids)
to_delete.update(prev_event_ids)
to_delete.intersection_update(original_set)
logger.info("Deleting up to %d forward extremities", len(to_delete))
self._simple_delete_many_txn(
txn=txn,
table="event_forward_extremities",
column="event_id",
iterable=to_delete,
keyvalues={},
)
if to_delete:
# We now need to invalidate the caches of these rooms
rows = self._simple_select_many_txn(
txn,
table="events",
column="event_id",
iterable=to_delete,
keyvalues={},
retcols=("room_id",)
)
for row in rows:
txn.call_after(
self.get_latest_event_ids_in_room.invalidate,
(row["room_id"],)
)
self._simple_delete_many_txn(
txn=txn,
table="_extremities_to_check",
column="event_id",
iterable=original_set,
keyvalues={},
)
return len(original_set)
num_handled = yield self.runInteraction(
"_cleanup_extremities_bg_update", _cleanup_extremities_bg_update_txn,
)
if not num_handled:
yield self._end_background_update(self.EVENT_DELETE_SOFT_FAILED_EXTREMITIES)
def _drop_table_txn(txn):
txn.execute("DROP TABLE _extremities_to_check")
yield self.runInteraction(
"_cleanup_extremities_bg_update_drop_table",
_drop_table_txn,
)
defer.returnValue(num_handled)
AllNewEventsResult = namedtuple(
"AllNewEventsResult",

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@ -0,0 +1,19 @@
/* Copyright 2019 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.
*/
INSERT INTO background_updates (update_name, progress_json) VALUES
('delete_soft_failed_extremities', '{}');
CREATE TABLE _extremities_to_check AS SELECT event_id FROM event_forward_extremities;