375 lines
		
	
	
		
			14 KiB
		
	
	
	
		
			Python
		
	
	
			
		
		
	
	
			375 lines
		
	
	
		
			14 KiB
		
	
	
	
		
			Python
		
	
	
# -*- coding: utf-8 -*-
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# Copyright 2014-2016 OpenMarket Ltd
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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 logging
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from twisted.internet import defer
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from synapse.storage._base import SQLBaseStore
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from synapse.storage.database import DatabasePool
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from synapse.storage.engines import PostgresEngine
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from synapse.storage.state import StateFilter
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logger = logging.getLogger(__name__)
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MAX_STATE_DELTA_HOPS = 100
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class StateGroupBackgroundUpdateStore(SQLBaseStore):
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    """Defines functions related to state groups needed to run the state backgroud
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    updates.
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    """
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    def _count_state_group_hops_txn(self, txn, state_group):
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        """Given a state group, count how many hops there are in the tree.
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        This is used to ensure the delta chains don't get too long.
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        """
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        if isinstance(self.database_engine, PostgresEngine):
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            sql = """
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                WITH RECURSIVE state(state_group) AS (
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                    VALUES(?::bigint)
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                    UNION ALL
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                    SELECT prev_state_group FROM state_group_edges e, state s
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                    WHERE s.state_group = e.state_group
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                )
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                SELECT count(*) FROM state;
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            """
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            txn.execute(sql, (state_group,))
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            row = txn.fetchone()
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            if row and row[0]:
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                return row[0]
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            else:
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                return 0
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        else:
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            # We don't use WITH RECURSIVE on sqlite3 as there are distributions
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            # that ship with an sqlite3 version that doesn't support it (e.g. wheezy)
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            next_group = state_group
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            count = 0
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            while next_group:
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                next_group = self.db_pool.simple_select_one_onecol_txn(
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                    txn,
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                    table="state_group_edges",
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                    keyvalues={"state_group": next_group},
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                    retcol="prev_state_group",
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                    allow_none=True,
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                )
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                if next_group:
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                    count += 1
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            return count
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    def _get_state_groups_from_groups_txn(
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        self, txn, groups, state_filter=StateFilter.all()
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    ):
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        results = {group: {} for group in groups}
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        where_clause, where_args = state_filter.make_sql_filter_clause()
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        # Unless the filter clause is empty, we're going to append it after an
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        # existing where clause
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        if where_clause:
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            where_clause = " AND (%s)" % (where_clause,)
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        if isinstance(self.database_engine, PostgresEngine):
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            # Temporarily disable sequential scans in this transaction. This is
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            # a temporary hack until we can add the right indices in
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            txn.execute("SET LOCAL enable_seqscan=off")
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            # The below query walks the state_group tree so that the "state"
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            # table includes all state_groups in the tree. It then joins
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            # against `state_groups_state` to fetch the latest state.
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            # It assumes that previous state groups are always numerically
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            # lesser.
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            # The PARTITION is used to get the event_id in the greatest state
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            # group for the given type, state_key.
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            # This may return multiple rows per (type, state_key), but last_value
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            # should be the same.
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            sql = """
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                WITH RECURSIVE state(state_group) AS (
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                    VALUES(?::bigint)
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                    UNION ALL
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                    SELECT prev_state_group FROM state_group_edges e, state s
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                    WHERE s.state_group = e.state_group
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                )
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                SELECT DISTINCT ON (type, state_key)
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                    type, state_key, event_id
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                FROM state_groups_state
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                WHERE state_group IN (
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                    SELECT state_group FROM state
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                ) %s
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                ORDER BY type, state_key, state_group DESC
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            """
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            for group in groups:
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                args = [group]
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                args.extend(where_args)
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                txn.execute(sql % (where_clause,), args)
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                for row in txn:
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                    typ, state_key, event_id = row
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                    key = (typ, state_key)
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                    results[group][key] = event_id
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        else:
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            max_entries_returned = state_filter.max_entries_returned()
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            # We don't use WITH RECURSIVE on sqlite3 as there are distributions
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            # that ship with an sqlite3 version that doesn't support it (e.g. wheezy)
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            for group in groups:
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                next_group = group
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                while next_group:
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                    # We did this before by getting the list of group ids, and
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                    # then passing that list to sqlite to get latest event for
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                    # each (type, state_key). However, that was terribly slow
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                    # without the right indices (which we can't add until
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                    # after we finish deduping state, which requires this func)
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                    args = [next_group]
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                    args.extend(where_args)
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                    txn.execute(
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                        "SELECT type, state_key, event_id FROM state_groups_state"
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                        " WHERE state_group = ? " + where_clause,
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                        args,
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                    )
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                    results[group].update(
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                        ((typ, state_key), event_id)
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                        for typ, state_key, event_id in txn
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                        if (typ, state_key) not in results[group]
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                    )
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                    # If the number of entries in the (type,state_key)->event_id dict
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                    # matches the number of (type,state_keys) types we were searching
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                    # for, then we must have found them all, so no need to go walk
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                    # further down the tree... UNLESS our types filter contained
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                    # wildcards (i.e. Nones) in which case we have to do an exhaustive
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                    # search
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                    if (
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                        max_entries_returned is not None
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                        and len(results[group]) == max_entries_returned
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                    ):
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                        break
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                    next_group = self.db_pool.simple_select_one_onecol_txn(
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                        txn,
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                        table="state_group_edges",
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                        keyvalues={"state_group": next_group},
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                        retcol="prev_state_group",
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                        allow_none=True,
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                    )
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        return results
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class StateBackgroundUpdateStore(StateGroupBackgroundUpdateStore):
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    STATE_GROUP_DEDUPLICATION_UPDATE_NAME = "state_group_state_deduplication"
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    STATE_GROUP_INDEX_UPDATE_NAME = "state_group_state_type_index"
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    STATE_GROUPS_ROOM_INDEX_UPDATE_NAME = "state_groups_room_id_idx"
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    def __init__(self, database: DatabasePool, db_conn, hs):
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        super(StateBackgroundUpdateStore, self).__init__(database, db_conn, hs)
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        self.db_pool.updates.register_background_update_handler(
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            self.STATE_GROUP_DEDUPLICATION_UPDATE_NAME,
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            self._background_deduplicate_state,
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        )
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        self.db_pool.updates.register_background_update_handler(
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            self.STATE_GROUP_INDEX_UPDATE_NAME, self._background_index_state
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        )
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        self.db_pool.updates.register_background_index_update(
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            self.STATE_GROUPS_ROOM_INDEX_UPDATE_NAME,
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            index_name="state_groups_room_id_idx",
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            table="state_groups",
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            columns=["room_id"],
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        )
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    @defer.inlineCallbacks
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    def _background_deduplicate_state(self, progress, batch_size):
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        """This background update will slowly deduplicate state by reencoding
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        them as deltas.
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        """
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        last_state_group = progress.get("last_state_group", 0)
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        rows_inserted = progress.get("rows_inserted", 0)
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        max_group = progress.get("max_group", None)
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        BATCH_SIZE_SCALE_FACTOR = 100
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        batch_size = max(1, int(batch_size / BATCH_SIZE_SCALE_FACTOR))
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        if max_group is None:
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            rows = yield self.db_pool.execute(
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                "_background_deduplicate_state",
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                None,
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                "SELECT coalesce(max(id), 0) FROM state_groups",
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            )
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            max_group = rows[0][0]
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        def reindex_txn(txn):
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            new_last_state_group = last_state_group
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            for count in range(batch_size):
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                txn.execute(
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                    "SELECT id, room_id FROM state_groups"
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                    " WHERE ? < id AND id <= ?"
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                    " ORDER BY id ASC"
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                    " LIMIT 1",
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                    (new_last_state_group, max_group),
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                )
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                row = txn.fetchone()
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                if row:
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                    state_group, room_id = row
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                if not row or not state_group:
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                    return True, count
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                txn.execute(
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                    "SELECT state_group FROM state_group_edges"
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                    " WHERE state_group = ?",
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                    (state_group,),
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                )
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                # If we reach a point where we've already started inserting
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                # edges we should stop.
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                if txn.fetchall():
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                    return True, count
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                txn.execute(
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                    "SELECT coalesce(max(id), 0) FROM state_groups"
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                    " WHERE id < ? AND room_id = ?",
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                    (state_group, room_id),
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                )
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                (prev_group,) = txn.fetchone()
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                new_last_state_group = state_group
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                if prev_group:
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                    potential_hops = self._count_state_group_hops_txn(txn, prev_group)
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                    if potential_hops >= MAX_STATE_DELTA_HOPS:
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                        # We want to ensure chains are at most this long,#
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                        # otherwise read performance degrades.
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                        continue
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                    prev_state = self._get_state_groups_from_groups_txn(
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                        txn, [prev_group]
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                    )
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                    prev_state = prev_state[prev_group]
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                    curr_state = self._get_state_groups_from_groups_txn(
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                        txn, [state_group]
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                    )
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                    curr_state = curr_state[state_group]
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                    if not set(prev_state.keys()) - set(curr_state.keys()):
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                        # We can only do a delta if the current has a strict super set
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                        # of keys
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                        delta_state = {
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                            key: value
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                            for key, value in curr_state.items()
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                            if prev_state.get(key, None) != value
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                        }
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                        self.db_pool.simple_delete_txn(
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                            txn,
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                            table="state_group_edges",
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                            keyvalues={"state_group": state_group},
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                        )
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                        self.db_pool.simple_insert_txn(
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                            txn,
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                            table="state_group_edges",
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                            values={
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                                "state_group": state_group,
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                                "prev_state_group": prev_group,
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                            },
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                        )
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                        self.db_pool.simple_delete_txn(
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                            txn,
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                            table="state_groups_state",
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                            keyvalues={"state_group": state_group},
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                        )
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                        self.db_pool.simple_insert_many_txn(
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                            txn,
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                            table="state_groups_state",
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                            values=[
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                                {
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                                    "state_group": state_group,
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                                    "room_id": room_id,
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                                    "type": key[0],
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                                    "state_key": key[1],
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                                    "event_id": state_id,
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                                }
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                                for key, state_id in delta_state.items()
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                            ],
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                        )
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            progress = {
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                "last_state_group": state_group,
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                "rows_inserted": rows_inserted + batch_size,
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                "max_group": max_group,
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            }
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            self.db_pool.updates._background_update_progress_txn(
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                txn, self.STATE_GROUP_DEDUPLICATION_UPDATE_NAME, progress
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            )
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            return False, batch_size
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        finished, result = yield self.db_pool.runInteraction(
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            self.STATE_GROUP_DEDUPLICATION_UPDATE_NAME, reindex_txn
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        )
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        if finished:
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            yield self.db_pool.updates._end_background_update(
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                self.STATE_GROUP_DEDUPLICATION_UPDATE_NAME
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            )
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        return result * BATCH_SIZE_SCALE_FACTOR
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    @defer.inlineCallbacks
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    def _background_index_state(self, progress, batch_size):
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        def reindex_txn(conn):
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            conn.rollback()
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            if isinstance(self.database_engine, PostgresEngine):
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                # postgres insists on autocommit for the index
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                conn.set_session(autocommit=True)
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                try:
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                    txn = conn.cursor()
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                    txn.execute(
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                        "CREATE INDEX CONCURRENTLY state_groups_state_type_idx"
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                        " ON state_groups_state(state_group, type, state_key)"
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                    )
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                    txn.execute("DROP INDEX IF EXISTS state_groups_state_id")
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                finally:
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                    conn.set_session(autocommit=False)
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            else:
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                txn = conn.cursor()
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                txn.execute(
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                    "CREATE INDEX state_groups_state_type_idx"
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                    " ON state_groups_state(state_group, type, state_key)"
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                )
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                txn.execute("DROP INDEX IF EXISTS state_groups_state_id")
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        yield self.db_pool.runWithConnection(reindex_txn)
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        yield self.db_pool.updates._end_background_update(
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            self.STATE_GROUP_INDEX_UPDATE_NAME
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        )
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        return 1
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