442 lines
		
	
	
		
			16 KiB
		
	
	
	
		
			Python
		
	
	
			
		
		
	
	
			442 lines
		
	
	
		
			16 KiB
		
	
	
	
		
			Python
		
	
	
# -*- coding: utf-8 -*-
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# Copyright 2014, 2015 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.constants import EventTypes
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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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from collections import namedtuple
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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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class _StreamToken(namedtuple("_StreamToken", "topological stream")):
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    """Tokens are positions between events. The token "s1" comes after event 1.
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            s0    s1
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            |     |
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        [0] V [1] V [2]
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    Tokens can either be a point in the live event stream or a cursor going
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    through historic events.
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    When traversing the live event stream events are ordered by when they
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    arrived at the homeserver.
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    When traversing historic events the events are ordered by their depth in
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    the event graph "topological_ordering" and then by when they arrived at the
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    homeserver "stream_ordering".
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    Live tokens start with an "s" followed by the "stream_ordering" id of the
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    event it comes after. Historic tokens start with a "t" followed by the
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    "topological_ordering" id of the event it comes after, follewed by "-",
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    followed by the "stream_ordering" id of the event it comes after.
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    """
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    __slots__ = []
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    @classmethod
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    def parse(cls, string):
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        try:
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            if string[0] == 's':
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                return cls(topological=None, stream=int(string[1:]))
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            if string[0] == 't':
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                parts = string[1:].split('-', 1)
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                return cls(topological=int(parts[0]), stream=int(parts[1]))
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        except:
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            pass
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        raise SynapseError(400, "Invalid token %r" % (string,))
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    @classmethod
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    def parse_stream_token(cls, string):
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        try:
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            if string[0] == 's':
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                return cls(topological=None, stream=int(string[1:]))
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        except:
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            pass
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        raise SynapseError(400, "Invalid token %r" % (string,))
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    def __str__(self):
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        if self.topological is not None:
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            return "t%d-%d" % (self.topological, self.stream)
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        else:
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            return "s%d" % (self.stream,)
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    def lower_bound(self):
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        if self.topological is None:
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            return "(%d < %s)" % (self.stream, "stream_ordering")
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        else:
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            return "(%d < %s OR (%d = %s AND %d < %s))" % (
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                self.topological, "topological_ordering",
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                self.topological, "topological_ordering",
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                self.stream, "stream_ordering",
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            )
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    def upper_bound(self):
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        if self.topological is None:
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            return "(%d >= %s)" % (self.stream, "stream_ordering")
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        else:
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            return "(%d > %s OR (%d = %s AND %d >= %s))" % (
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                self.topological, "topological_ordering",
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                self.topological, "topological_ordering",
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                self.stream, "stream_ordering",
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            )
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class StreamStore(SQLBaseStore):
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    @defer.inlineCallbacks
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    def get_appservice_room_stream(self, service, from_key, to_key, limit=0):
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        # NB this lives here instead of appservice.py so we can reuse the
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        # 'private' StreamToken class in this file.
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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 = _StreamToken.parse_stream_token(from_key)
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        to_id = _StreamToken.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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        # select all the events between from/to with a sensible limit
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        sql = (
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            "SELECT e.event_id, e.room_id, e.type, s.state_key, "
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            "e.stream_ordering FROM events AS e LEFT JOIN state_events as s ON "
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            "e.event_id = s.event_id "
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            "WHERE e.stream_ordering > ? AND e.stream_ordering <= ? "
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            "ORDER BY stream_ordering ASC LIMIT %(limit)d "
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        ) % {
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            "limit": limit
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        }
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        def f(txn):
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            # pull out all the events between the tokens
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            txn.execute(sql, (from_id.stream, to_id.stream,))
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            rows = self.cursor_to_dict(txn)
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            # Logic:
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            #  - We want ALL events which match the AS room_id regex
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            #  - We want ALL events which match the rooms represented by the AS
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            #    room_alias regex
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            #  - We want ALL events for rooms that AS users have joined.
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            # This is currently supported via get_app_service_rooms (which is
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            # used for the Notifier listener rooms). We can't reasonably make a
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            # SQL query for these room IDs, so we'll pull all the events between
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            # from/to and filter in python.
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            rooms_for_as = self._get_app_service_rooms_txn(txn, service)
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            room_ids_for_as = [r.room_id for r in rooms_for_as]
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            def app_service_interested(row):
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                if row["room_id"] in room_ids_for_as:
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                    return True
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                if row["type"] == EventTypes.Member:
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                    if service.is_interested_in_user(row.get("state_key")):
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                        return True
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                return False
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            ret = self._get_events_txn(
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                txn,
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                # apply the filter on the room id list
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                [
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                    r["event_id"] for r in rows
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                    if app_service_interested(r)
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                ],
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                get_prev_content=True
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            )
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            self._set_before_and_after(ret, 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
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                # get.
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                key = to_key
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            return ret, key
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        results = yield self.runInteraction("get_appservice_room_stream", f)
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        defer.returnValue(results)
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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 = _StreamToken.parse_stream_token(from_key)
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        to_id = _StreamToken.parse_stream_token(to_key)
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        if from_key == to_key:
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            return defer.succeed(([], to_key))
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        sql = (
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            "SELECT e.event_id, e.stream_ordering FROM events AS e WHERE "
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            "(e.outlier = 0 AND (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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            "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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        def f(txn):
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            txn.execute(sql, (user_id, user_id, from_id.stream, to_id.stream,))
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            rows = self.cursor_to_dict(txn)
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            ret = self._get_events_txn(
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                txn,
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                [r["event_id"] for r in rows],
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                get_prev_content=True
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            )
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            self._set_before_and_after(ret, 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
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                # get.
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                key = to_key
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            return ret, key
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        return self.runInteraction("get_room_events_stream", f)
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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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        args = [room_id]
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        if direction == 'b':
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            order = "DESC"
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            bounds = _StreamToken.parse(from_key).upper_bound()
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            if to_key:
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                bounds = "%s AND %s" % (
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                    bounds, _StreamToken.parse(to_key).lower_bound()
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                )
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        else:
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            order = "ASC"
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            bounds = _StreamToken.parse(from_key).lower_bound()
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            if to_key:
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                bounds = "%s AND %s" % (
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                    bounds, _StreamToken.parse(to_key).upper_bound()
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                )
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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,"
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            " stream_ordering %(order)s %(limit)s"
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        ) % {
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            "bounds": bounds,
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            "order": order,
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            "limit": limit_str
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        }
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        def f(txn):
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            txn.execute(sql, args)
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            rows = self.cursor_to_dict(txn)
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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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                if direction == 'b':
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                    # Tokens are positions between events.
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                    # This token points *after* the last event in the chunk.
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                    # We need it to point to the event before it in the chunk
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                    # when we are going backwards so we subtract one from the
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                    # stream part.
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                    toke -= 1
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                next_token = str(_StreamToken(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 = self._get_events_txn(
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                txn,
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                [r["event_id"] for r in rows],
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                get_prev_content=True
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            )
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            self._set_before_and_after(events, rows)
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            return events, next_token,
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        return self.runInteraction("paginate_room_events", f)
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    def get_recent_events_for_room(self, room_id, limit, end_token,
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                                   with_feedback=False, from_token=None):
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        # TODO (erikj): Handle compressed feedback
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        end_token = _StreamToken.parse_stream_token(end_token)
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        if from_token is None:
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            sql = (
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                "SELECT stream_ordering, topological_ordering, event_id"
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                " FROM events"
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                " WHERE room_id = ? AND stream_ordering <= ? AND outlier = 0"
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                " ORDER BY topological_ordering DESC, stream_ordering DESC"
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                " LIMIT ?"
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            )
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        else:
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            from_token = _StreamToken.parse_stream_token(from_token)
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            sql = (
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                "SELECT stream_ordering, topological_ordering, event_id"
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                " FROM events"
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                " WHERE room_id = ? AND stream_ordering > ?"
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                " AND stream_ordering <= ? AND outlier = 0"
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                " ORDER BY topological_ordering DESC, stream_ordering DESC"
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                " LIMIT ?"
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            )
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        def get_recent_events_for_room_txn(txn):
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            if from_token is None:
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                txn.execute(sql, (room_id, end_token.stream, limit,))
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            else:
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                txn.execute(sql, (
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                    room_id, from_token.stream, end_token.stream, limit
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                ))
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            rows = self.cursor_to_dict(txn)
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            rows.reverse()  # As we selected with reverse ordering
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            if rows:
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                # Tokens are positions between events.
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                # This token points *after* the last event in the chunk.
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                # We need it to point to the event before it in the chunk
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                # since we are going backwards so we subtract one from the
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                # stream part.
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                topo = rows[0]["topological_ordering"]
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                toke = rows[0]["stream_ordering"] - 1
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                start_token = str(_StreamToken(topo, toke))
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                token = (start_token, str(end_token))
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            else:
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                token = (str(end_token), str(end_token))
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            events = self._get_events_txn(
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                txn,
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                [r["event_id"] for r in rows],
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                get_prev_content=True
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            )
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            self._set_before_and_after(events, rows)
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            return events, token
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        return self.runInteraction(
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            "get_recent_events_for_room", get_recent_events_for_room_txn
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        )
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    @defer.inlineCallbacks
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    def get_room_events_max_id(self):
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        token = yield self._stream_id_gen.get_max_token(self)
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        defer.returnValue("s%d" % (token,))
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    @defer.inlineCallbacks
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    def _get_min_token(self):
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        row = yield self._execute(
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            "_get_min_token", None, "SELECT MIN(stream_ordering) FROM events"
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        )
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        self.min_token = row[0][0] if row and row[0] and row[0][0] else -1
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        self.min_token = min(self.min_token, -1)
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        logger.debug("min_token is: %s", self.min_token)
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        defer.returnValue(self.min_token)
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    @staticmethod
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    def _set_before_and_after(events, rows):
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        for event, row in zip(events, rows):
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            stream = row["stream_ordering"]
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            topo = event.depth
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            internal = event.internal_metadata
 | 
						|
            internal.before = str(_StreamToken(topo, stream - 1))
 | 
						|
            internal.after = str(_StreamToken(topo, stream))
 |