305 lines
		
	
	
		
			9.1 KiB
		
	
	
	
		
			Python
		
	
	
			
		
		
	
	
			305 lines
		
	
	
		
			9.1 KiB
		
	
	
	
		
			Python
		
	
	
# -*- coding: utf-8 -*-
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# Copyright 2014 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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""" This module is responsible for getting events from the DB for pagination
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and event streaming.
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The order it returns events in depend on whether we are streaming forwards or
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are paginating backwards. We do this because we want to handle out of order
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messages nicely, while still returning them in the correct order when we
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paginate bacwards.
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This is implemented by keeping two ordering columns: stream_ordering and
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topological_ordering. Stream ordering is basically insertion/received order
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(except for events from backfill requests). The topolgical_ordering is a
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weak ordering of events based on the pdu graph.
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This means that we have to have two different types of tokens, depending on
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what sort order was used:
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    - stream tokens are of the form: "s%d", which maps directly to the column
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    - topological tokems: "t%d-%d", where the integers map to the topological
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      and stream ordering columns respectively.
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"""
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from twisted.internet import defer
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from ._base import SQLBaseStore
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from synapse.api.errors import SynapseError
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from synapse.util.logutils import log_function
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import logging
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logger = logging.getLogger(__name__)
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MAX_STREAM_SIZE = 1000
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_STREAM_TOKEN = "stream"
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_TOPOLOGICAL_TOKEN = "topological"
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def _parse_stream_token(string):
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    try:
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        if string[0] != 's':
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            raise
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        return int(string[1:])
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    except:
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        raise SynapseError(400, "Invalid token")
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def _parse_topological_token(string):
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    try:
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        if string[0] != 't':
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            raise
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        parts = string[1:].split('-', 1)
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        return (int(parts[0]), int(parts[1]))
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    except:
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        raise SynapseError(400, "Invalid token")
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def is_stream_token(string):
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    try:
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        _parse_stream_token(string)
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        return True
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    except:
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        return False
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def is_topological_token(string):
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    try:
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        _parse_topological_token(string)
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        return True
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    except:
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        return False
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def _get_token_bound(token, comparison):
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    try:
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        s = _parse_stream_token(token)
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        return "%s %s %d" % ("stream_ordering", comparison, s)
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    except:
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        pass
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    try:
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        top, stream = _parse_topological_token(token)
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        return "%s %s %d AND %s %s %d" % (
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            "topological_ordering", comparison, top,
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            "stream_ordering", comparison, stream,
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        )
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    except:
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        pass
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    raise SynapseError(400, "Invalid token")
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class StreamStore(SQLBaseStore):
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    @log_function
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    def get_room_events(self, user_id, from_key, to_key, room_id, limit=0,
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                        direction='f', with_feedback=False):
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        # We deal with events request in two different ways depending on if
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        # this looks like an /events request or a pagination request.
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        is_events = (
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            direction == 'f'
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            and user_id
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            and is_stream_token(from_key)
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            and to_key and is_stream_token(to_key)
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        )
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        if is_events:
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            return self.get_room_events_stream(
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                user_id=user_id,
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                from_key=from_key,
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                to_key=to_key,
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                room_id=room_id,
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                limit=limit,
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                with_feedback=with_feedback,
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            )
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        else:
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            return self.paginate_room_events(
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                from_key=from_key,
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                to_key=to_key,
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                room_id=room_id,
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                limit=limit,
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                with_feedback=with_feedback,
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            )
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    @defer.inlineCallbacks
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    @log_function
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    def get_room_events_stream(self, user_id, from_key, to_key, room_id,
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                               limit=0, with_feedback=False):
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        # TODO (erikj): Handle compressed feedback
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        current_room_membership_sql = (
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            "SELECT m.room_id FROM room_memberships as m "
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            "INNER JOIN current_state_events as c ON m.event_id = c.event_id "
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            "WHERE m.user_id = ? AND m.membership = 'join'"
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        )
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        # We also want to get any membership events about that user, e.g.
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        # invites or leave notifications.
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        membership_sql = (
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            "SELECT m.event_id FROM room_memberships as m "
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            "INNER JOIN current_state_events as c ON m.event_id = c.event_id "
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            "WHERE m.user_id = ? "
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        )
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        if limit:
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            limit = max(limit, MAX_STREAM_SIZE)
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        else:
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            limit = MAX_STREAM_SIZE
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        # From and to keys should be integers from ordering.
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        from_id = _parse_stream_token(from_key)
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        to_id = _parse_stream_token(to_key)
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        if from_key == to_key:
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            defer.returnValue(([], to_key))
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            return
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        sql = (
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            "SELECT * FROM events as e WHERE "
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            "((room_id IN (%(current)s)) OR "
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            "(event_id IN (%(invites)s))) "
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            "AND e.stream_ordering > ? AND e.stream_ordering <= ? "
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            "AND e.outlier = 0 "
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            "ORDER BY stream_ordering ASC LIMIT %(limit)d "
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        ) % {
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            "current": current_room_membership_sql,
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            "invites": membership_sql,
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            "limit": limit
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        }
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        rows = yield self._execute_and_decode(
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            sql,
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            user_id, user_id, from_id, to_id
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        )
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        ret = yield self._parse_events(rows)
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        if rows:
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            key = "s%d" % max([r["stream_ordering"] for r in rows])
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        else:
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            # Assume we didn't get anything because there was nothing to get.
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            key = to_key
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        defer.returnValue((ret, key))
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    @defer.inlineCallbacks
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    @log_function
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    def paginate_room_events(self, room_id, from_key, to_key=None,
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                             direction='b', limit=-1,
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                             with_feedback=False):
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        # TODO (erikj): Handle compressed feedback
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        # Tokens really represent positions between elements, but we use
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        # the convention of pointing to the event before the gap. Hence
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        # we have a bit of asymmetry when it comes to equalities.
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        from_comp = '<=' if direction =='b' else '>'
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        to_comp = '>' if direction =='b' else '<='
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        order = "DESC" if direction == 'b' else "ASC"
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        args = [room_id]
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        bounds = _get_token_bound(from_key, from_comp)
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        if to_key:
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            bounds = "%s AND %s" % (bounds, _get_token_bound(to_key, to_comp))
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        if int(limit) > 0:
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            args.append(int(limit))
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            limit_str = " LIMIT ?"
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        else:
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            limit_str = ""
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        sql = (
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            "SELECT * FROM events "
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            "WHERE outlier = 0 AND room_id = ? AND %(bounds)s "
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            "ORDER BY topological_ordering %(order)s, stream_ordering %(order)s %(limit)s "
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        ) % {"bounds": bounds, "order": order, "limit": limit_str}
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        rows = yield self._execute_and_decode(
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            sql,
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            *args
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        )
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        if rows:
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            topo = rows[-1]["topological_ordering"]
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            toke = rows[-1]["stream_ordering"]
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            next_token = "t%s-%s" % (topo, toke)
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        else:
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            # TODO (erikj): We should work out what to do here instead.
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            next_token = to_key if to_key else from_key
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        events = yield self._parse_events(rows)
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        defer.returnValue(
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            (
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                events,
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                next_token
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            )
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        )
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    @defer.inlineCallbacks
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    def get_recent_events_for_room(self, room_id, limit, end_token,
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                                   with_feedback=False):
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        # TODO (erikj): Handle compressed feedback
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        sql = (
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            "SELECT * FROM events "
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            "WHERE room_id = ? AND stream_ordering <= ? "
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            "ORDER BY topological_ordering DESC, stream_ordering DESC LIMIT ? "
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        )
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        rows = yield self._execute_and_decode(
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            sql,
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            room_id, end_token, limit
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        )
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        rows.reverse()  # As we selected with reverse ordering
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        if rows:
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            topo = rows[0]["topological_ordering"]
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            toke = rows[0]["stream_ordering"]
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            start_token = "t%s-%s" % (topo, toke)
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            token = (start_token, end_token)
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        else:
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            token = (end_token, end_token)
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        events = yield self._parse_events(rows)
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        ret = (events, token)
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        defer.returnValue(ret)
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    def get_room_events_max_id(self):
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        return self.runInteraction(self._get_room_events_max_id_txn)
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    def _get_room_events_max_id_txn(self, txn):
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        txn.execute(
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            "SELECT MAX(stream_ordering) as m FROM events"
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        )
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        res = self.cursor_to_dict(txn)
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        logger.debug("get_room_events_max_id: %s", res)
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        if not res or not res[0] or not res[0]["m"]:
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            return "s0"
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        key = res[0]["m"]
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        return "s%d" % (key,)
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