121 lines
4.0 KiB
Python
121 lines
4.0 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2019 The Matrix.org Foundation C.I.C.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import itertools
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import logging
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from typing import TYPE_CHECKING, Set
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from synapse.storage.databases import Databases
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if TYPE_CHECKING:
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from synapse.app.homeserver import HomeServer
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logger = logging.getLogger(__name__)
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class PurgeEventsStorage:
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"""High level interface for purging rooms and event history.
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"""
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def __init__(self, hs: "HomeServer", stores: Databases):
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self.stores = stores
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async def purge_room(self, room_id: str) -> None:
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"""Deletes all record of a room
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"""
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state_groups_to_delete = await self.stores.main.purge_room(room_id)
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await self.stores.state.purge_room_state(room_id, state_groups_to_delete)
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async def purge_history(
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self, room_id: str, token: str, delete_local_events: bool
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) -> None:
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"""Deletes room history before a certain point
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Args:
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room_id: The room ID
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token: A topological token to delete events before
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delete_local_events:
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if True, we will delete local events as well as remote ones
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(instead of just marking them as outliers and deleting their
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state groups).
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"""
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state_groups = await self.stores.main.purge_history(
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room_id, token, delete_local_events
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)
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logger.info("[purge] finding state groups that can be deleted")
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sg_to_delete = await self._find_unreferenced_groups(state_groups)
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await self.stores.state.purge_unreferenced_state_groups(room_id, sg_to_delete)
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async def _find_unreferenced_groups(self, state_groups: Set[int]) -> Set[int]:
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"""Used when purging history to figure out which state groups can be
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deleted.
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Args:
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state_groups: Set of state groups referenced by events
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that are going to be deleted.
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Returns:
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The set of state groups that can be deleted.
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"""
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# Graph of state group -> previous group
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graph = {}
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# Set of events that we have found to be referenced by events
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referenced_groups = set()
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# Set of state groups we've already seen
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state_groups_seen = set(state_groups)
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# Set of state groups to handle next.
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next_to_search = set(state_groups)
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while next_to_search:
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# We bound size of groups we're looking up at once, to stop the
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# SQL query getting too big
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if len(next_to_search) < 100:
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current_search = next_to_search
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next_to_search = set()
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else:
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current_search = set(itertools.islice(next_to_search, 100))
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next_to_search -= current_search
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referenced = await self.stores.main.get_referenced_state_groups(
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current_search
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)
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referenced_groups |= referenced
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# We don't continue iterating up the state group graphs for state
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# groups that are referenced.
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current_search -= referenced
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edges = await self.stores.state.get_previous_state_groups(current_search)
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prevs = set(edges.values())
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# We don't bother re-handling groups we've already seen
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prevs -= state_groups_seen
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next_to_search |= prevs
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state_groups_seen |= prevs
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graph.update(edges)
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to_delete = state_groups_seen - referenced_groups
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return to_delete
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