118 lines
		
	
	
		
			3.9 KiB
		
	
	
	
		
			Python
		
	
	
			
		
		
	
	
			118 lines
		
	
	
		
			3.9 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 twisted.internet import defer
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logger = logging.getLogger(__name__)
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class PurgeEventsStorage(object):
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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, stores):
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        self.stores = stores
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    @defer.inlineCallbacks
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    def purge_room(self, room_id: str):
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        """Deletes all record of a room
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        """
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        state_groups_to_delete = yield self.stores.main.purge_room(room_id)
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        yield self.stores.state.purge_room_state(room_id, state_groups_to_delete)
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    @defer.inlineCallbacks
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    def purge_history(self, room_id, token, delete_local_events):
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        """Deletes room history before a certain point
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        Args:
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            room_id (str):
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            token (str): A topological token to delete events before
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            delete_local_events (bool):
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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 = yield 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 = yield self._find_unreferenced_groups(state_groups)
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        yield self.stores.state.purge_unreferenced_state_groups(room_id, sg_to_delete)
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    @defer.inlineCallbacks
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    def _find_unreferenced_groups(self, state_groups):
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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[int]): 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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            Deferred[set[int]] 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 = yield 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 = yield 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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