diff --git a/synapse/storage/purge_events.py b/synapse/storage/purge_events.py
new file mode 100644
index 0000000000..a368182034
--- /dev/null
+++ b/synapse/storage/purge_events.py
@@ -0,0 +1,117 @@
+# -*- coding: utf-8 -*-
+# 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.
+
+import itertools
+import logging
+
+from twisted.internet import defer
+
+logger = logging.getLogger(__name__)
+
+
+class PurgeEventsStorage(object):
+ """High level interface for purging rooms and event history.
+ """
+
+ def __init__(self, hs, stores):
+ self.stores = stores
+
+ @defer.inlineCallbacks
+ def purge_room(self, room_id: str):
+ """Deletes all record of a room
+ """
+
+ state_groups_to_delete = yield self.stores.main.purge_room(room_id)
+ yield self.stores.main.purge_room_state(room_id, state_groups_to_delete)
+
+ @defer.inlineCallbacks
+ 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).
+ """
+ state_groups = yield self.stores.main.purge_history(
+ room_id, token, delete_local_events
+ )
+
+ logger.info("[purge] finding state groups that can be deleted")
+
+ sg_to_delete = yield self._find_unreferenced_groups(state_groups)
+
+ yield self.stores.main.purge_unreferenced_state_groups(room_id, sg_to_delete)
+
+ @defer.inlineCallbacks
+ def _find_unreferenced_groups(self, state_groups):
+ """Used when purging history to figure out which state groups can be
+ deleted.
+
+ Args:
+ state_groups (set[int]): Set of state groups referenced by events
+ that are going to be deleted.
+
+ Returns:
+ Deferred[set[int]] The set of state groups that can be deleted.
+ """
+ # Graph of state group -> previous group
+ graph = {}
+
+ # Set of events that we have found to be referenced by events
+ referenced_groups = set()
+
+ # Set of state groups we've already seen
+ state_groups_seen = set(state_groups)
+
+ # Set of state groups to handle next.
+ next_to_search = set(state_groups)
+ while next_to_search:
+ # We bound size of groups we're looking up at once, to stop the
+ # SQL query getting too big
+ if len(next_to_search) < 100:
+ current_search = next_to_search
+ next_to_search = set()
+ else:
+ current_search = set(itertools.islice(next_to_search, 100))
+ next_to_search -= current_search
+
+ referenced = yield self.stores.main.get_referenced_state_groups(
+ current_search
+ )
+ referenced_groups |= referenced
+
+ # We don't continue iterating up the state group graphs for state
+ # groups that are referenced.
+ current_search -= referenced
+
+ edges = yield self.stores.main.get_previous_state_groups(current_search)
+
+ prevs = set(edges.values())
+ # We don't bother re-handling groups we've already seen
+ prevs -= state_groups_seen
+ next_to_search |= prevs
+ state_groups_seen |= prevs
+
+ graph.update(edges)
+
+ to_delete = state_groups_seen - referenced_groups
+
+ return to_delete
|
