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Rename database classes to make some sense (#8033)

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Erik Johnston 2020-08-05 21:38:57 +01:00 • committed by GitHub
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synapse/storage/databases/main/purge_events.py Normal file
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# -*- coding: utf-8 -*-
# Copyright 2020 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 typing import Any, Tuple
from synapse.api.errors import SynapseError
from synapse.storage._base import SQLBaseStore
from synapse.storage.databases.main.state import StateGroupWorkerStore
from synapse.types import RoomStreamToken
logger = logging.getLogger(__name__)
class PurgeEventsStore(StateGroupWorkerStore, SQLBaseStore):
def purge_history(self, room_id, token, delete_local_events):
"""Deletes room history before a certain point
Args:
room_id (str):
token (str): A topological token to delete events before
delete_local_events (bool):
if True, we will delete local events as well as remote ones
(instead of just marking them as outliers and deleting their
state groups).
Returns:
Deferred[set[int]]: The set of state groups that are referenced by
deleted events.
"""
return self.db_pool.runInteraction(
"purge_history",
self._purge_history_txn,
room_id,
token,
delete_local_events,
)
def _purge_history_txn(self, txn, room_id, token_str, delete_local_events):
token = RoomStreamToken.parse(token_str)
# Tables that should be pruned:
# event_auth
# event_backward_extremities
# event_edges
# event_forward_extremities
# event_json
# event_push_actions
# event_reference_hashes
# event_relations
# event_search
# event_to_state_groups
# events
# rejections
# room_depth
# state_groups
# state_groups_state
# we will build a temporary table listing the events so that we don't
# have to keep shovelling the list back and forth across the
# connection. Annoyingly the python sqlite driver commits the
# transaction on CREATE, so let's do this first.
#
# furthermore, we might already have the table from a previous (failed)
# purge attempt, so let's drop the table first.
txn.execute("DROP TABLE IF EXISTS events_to_purge")
txn.execute(
"CREATE TEMPORARY TABLE events_to_purge ("
" event_id TEXT NOT NULL,"
" should_delete BOOLEAN NOT NULL"
")"
)
# First ensure that we're not about to delete all the forward extremeties
txn.execute(
"SELECT e.event_id, e.depth FROM events as e "
"INNER JOIN event_forward_extremities as f "
"ON e.event_id = f.event_id "
"AND e.room_id = f.room_id "
"WHERE f.room_id = ?",
(room_id,),
)
rows = txn.fetchall()
max_depth = max(row[1] for row in rows)
if max_depth < token.topological:
# We need to ensure we don't delete all the events from the database
# otherwise we wouldn't be able to send any events (due to not
# having any backwards extremeties)
raise SynapseError(
400, "topological_ordering is greater than forward extremeties"
)
logger.info("[purge] looking for events to delete")
should_delete_expr = "state_key IS NULL"
should_delete_params = () # type: Tuple[Any, ...]
if not delete_local_events:
should_delete_expr += " AND event_id NOT LIKE ?"
# We include the parameter twice since we use the expression twice
should_delete_params += ("%:" + self.hs.hostname, "%:" + self.hs.hostname)
should_delete_params += (room_id, token.topological)
# Note that we insert events that are outliers and aren't going to be
# deleted, as nothing will happen to them.
txn.execute(
"INSERT INTO events_to_purge"
" SELECT event_id, %s"
" FROM events AS e LEFT JOIN state_events USING (event_id)"
" WHERE (NOT outlier OR (%s)) AND e.room_id = ? AND topological_ordering < ?"
% (should_delete_expr, should_delete_expr),
should_delete_params,
)
# We create the indices *after* insertion as that's a lot faster.
# create an index on should_delete because later we'll be looking for
# the should_delete / shouldn't_delete subsets
txn.execute(
"CREATE INDEX events_to_purge_should_delete"
" ON events_to_purge(should_delete)"
)
# We do joins against events_to_purge for e.g. calculating state
# groups to purge, etc., so lets make an index.
txn.execute("CREATE INDEX events_to_purge_id ON events_to_purge(event_id)")
txn.execute("SELECT event_id, should_delete FROM events_to_purge")
event_rows = txn.fetchall()
logger.info(
"[purge] found %i events before cutoff, of which %i can be deleted",
len(event_rows),
sum(1 for e in event_rows if e[1]),
)
logger.info("[purge] Finding new backward extremities")
# We calculate the new entries for the backward extremeties by finding
# events to be purged that are pointed to by events we're not going to
# purge.
txn.execute(
"SELECT DISTINCT e.event_id FROM events_to_purge AS e"
" INNER JOIN event_edges AS ed ON e.event_id = ed.prev_event_id"
" LEFT JOIN events_to_purge AS ep2 ON ed.event_id = ep2.event_id"
" WHERE ep2.event_id IS NULL"
)
new_backwards_extrems = txn.fetchall()
logger.info("[purge] replacing backward extremities: %r", new_backwards_extrems)
txn.execute(
"DELETE FROM event_backward_extremities WHERE room_id = ?", (room_id,)
)
# Update backward extremeties
txn.executemany(
"INSERT INTO event_backward_extremities (room_id, event_id)"
" VALUES (?, ?)",
[(room_id, event_id) for event_id, in new_backwards_extrems],
)
logger.info("[purge] finding state groups referenced by deleted events")
# Get all state groups that are referenced by events that are to be
# deleted.
txn.execute(
"""
SELECT DISTINCT state_group FROM events_to_purge
INNER JOIN event_to_state_groups USING (event_id)
"""
)
referenced_state_groups = {sg for sg, in txn}
logger.info(
"[purge] found %i referenced state groups", len(referenced_state_groups)
)
logger.info("[purge] removing events from event_to_state_groups")
txn.execute(
"DELETE FROM event_to_state_groups "
"WHERE event_id IN (SELECT event_id from events_to_purge)"
)
for event_id, _ in event_rows:
txn.call_after(self._get_state_group_for_event.invalidate, (event_id,))
# Delete all remote non-state events
for table in (
"events",
"event_json",
"event_auth",
"event_edges",
"event_forward_extremities",
"event_reference_hashes",
"event_relations",
"event_search",
"rejections",
):
logger.info("[purge] removing events from %s", table)
txn.execute(
"DELETE FROM %s WHERE event_id IN ("
" SELECT event_id FROM events_to_purge WHERE should_delete"
")" % (table,)
)
# event_push_actions lacks an index on event_id, and has one on
# (room_id, event_id) instead.
for table in ("event_push_actions",):
logger.info("[purge] removing events from %s", table)
txn.execute(
"DELETE FROM %s WHERE room_id = ? AND event_id IN ("
" SELECT event_id FROM events_to_purge WHERE should_delete"
")" % (table,),
(room_id,),
)
# Mark all state and own events as outliers
logger.info("[purge] marking remaining events as outliers")
txn.execute(
"UPDATE events SET outlier = ?"
" WHERE event_id IN ("
" SELECT event_id FROM events_to_purge "
" WHERE NOT should_delete"
")",
(True,),
)
# synapse tries to take out an exclusive lock on room_depth whenever it
# persists events (because upsert), and once we run this update, we
# will block that for the rest of our transaction.
#
# So, let's stick it at the end so that we don't block event
# persistence.
#
# We do this by calculating the minimum depth of the backwards
# extremities. However, the events in event_backward_extremities
# are ones we don't have yet so we need to look at the events that
# point to it via event_edges table.
txn.execute(
"""
SELECT COALESCE(MIN(depth), 0)
FROM event_backward_extremities AS eb
INNER JOIN event_edges AS eg ON eg.prev_event_id = eb.event_id
INNER JOIN events AS e ON e.event_id = eg.event_id
WHERE eb.room_id = ?
""",
(room_id,),
)
(min_depth,) = txn.fetchone()
logger.info("[purge] updating room_depth to %d", min_depth)
txn.execute(
"UPDATE room_depth SET min_depth = ? WHERE room_id = ?",
(min_depth, room_id),
)
# finally, drop the temp table. this will commit the txn in sqlite,
# so make sure to keep this actually last.
txn.execute("DROP TABLE events_to_purge")
logger.info("[purge] done")
return referenced_state_groups
def purge_room(self, room_id):
"""Deletes all record of a room
Args:
room_id (str)
Returns:
Deferred[List[int]]: The list of state groups to delete.
"""
return self.db_pool.runInteraction("purge_room", self._purge_room_txn, room_id)
def _purge_room_txn(self, txn, room_id):
# First we fetch all the state groups that should be deleted, before
# we delete that information.
txn.execute(
"""
SELECT DISTINCT state_group FROM events
INNER JOIN event_to_state_groups USING(event_id)
WHERE events.room_id = ?
""",
(room_id,),
)
state_groups = [row[0] for row in txn]
# Now we delete tables which lack an index on room_id but have one on event_id
for table in (
"event_auth",
"event_edges",
"event_push_actions_staging",
"event_reference_hashes",
"event_relations",
"event_to_state_groups",
"redactions",
"rejections",
"state_events",
):
logger.info("[purge] removing %s from %s", room_id, table)
txn.execute(
"""
DELETE FROM %s WHERE event_id IN (
SELECT event_id FROM events WHERE room_id=?
)
"""
% (table,),
(room_id,),
)
# and finally, the tables with an index on room_id (or no useful index)
for table in (
"current_state_events",
"event_backward_extremities",
"event_forward_extremities",
"event_json",
"event_push_actions",
"event_search",
"events",
"group_rooms",
"public_room_list_stream",
"receipts_graph",
"receipts_linearized",
"room_aliases",
"room_depth",
"room_memberships",
"room_stats_state",
"room_stats_current",
"room_stats_historical",
"room_stats_earliest_token",
"rooms",
"stream_ordering_to_exterm",
"users_in_public_rooms",
"users_who_share_private_rooms",
# no useful index, but let's clear them anyway
"appservice_room_list",
"e2e_room_keys",
"event_push_summary",
"pusher_throttle",
"group_summary_rooms",
"room_account_data",
"room_tags",
"local_current_membership",
):
logger.info("[purge] removing %s from %s", room_id, table)
txn.execute("DELETE FROM %s WHERE room_id=?" % (table,), (room_id,))
# Other tables we do NOT need to clear out:
#
# - blocked_rooms
# This is important, to make sure that we don't accidentally rejoin a blocked
# room after it was purged
#
# - user_directory
# This has a room_id column, but it is unused
#
# Other tables that we might want to consider clearing out include:
#
# - event_reports
# Given that these are intended for abuse management my initial
# inclination is to leave them in place.
#
# - current_state_delta_stream
# - ex_outlier_stream
# - room_tags_revisions
# The problem with these is that they are largeish and there is no room_id
# index on them. In any case we should be clearing out 'stream' tables
# periodically anyway (#5888)
# TODO: we could probably usefully do a bunch of cache invalidation here
logger.info("[purge] done")
return state_groups