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- # -*- coding: utf-8 -*-
- # Copyright 2014-2016 OpenMarket Ltd
- # Copyright 2017 Vector Creations Ltd
- # Copyright 2018-2019 New Vector Ltd
- # 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.
- """ This module is responsible for getting events from the DB for pagination
- and event streaming.
- The order it returns events in depend on whether we are streaming forwards or
- are paginating backwards. We do this because we want to handle out of order
- messages nicely, while still returning them in the correct order when we
- paginate bacwards.
- This is implemented by keeping two ordering columns: stream_ordering and
- topological_ordering. Stream ordering is basically insertion/received order
- (except for events from backfill requests). The topological_ordering is a
- weak ordering of events based on the pdu graph.
- This means that we have to have two different types of tokens, depending on
- what sort order was used:
- - stream tokens are of the form: "s%d", which maps directly to the column
- - topological tokems: "t%d-%d", where the integers map to the topological
- and stream ordering columns respectively.
- """
- import abc
- import logging
- from collections import namedtuple
- from twisted.internet import defer
- from synapse.logging.context import make_deferred_yieldable, run_in_background
- from synapse.storage._base import SQLBaseStore
- from synapse.storage.data_stores.main.events_worker import EventsWorkerStore
- from synapse.storage.database import Database
- from synapse.storage.engines import PostgresEngine
- from synapse.types import RoomStreamToken
- from synapse.util.caches.stream_change_cache import StreamChangeCache
- logger = logging.getLogger(__name__)
- MAX_STREAM_SIZE = 1000
- _STREAM_TOKEN = "stream"
- _TOPOLOGICAL_TOKEN = "topological"
- # Used as return values for pagination APIs
- _EventDictReturn = namedtuple(
- "_EventDictReturn", ("event_id", "topological_ordering", "stream_ordering")
- )
- def generate_pagination_where_clause(
- direction, column_names, from_token, to_token, engine
- ):
- """Creates an SQL expression to bound the columns by the pagination
- tokens.
- For example creates an SQL expression like:
- (6, 7) >= (topological_ordering, stream_ordering)
- AND (5, 3) < (topological_ordering, stream_ordering)
- would be generated for dir=b, from_token=(6, 7) and to_token=(5, 3).
- Note that tokens are considered to be after the row they are in, e.g. if
- a row A has a token T, then we consider A to be before T. This convention
- is important when figuring out inequalities for the generated SQL, and
- produces the following result:
- - If paginating forwards then we exclude any rows matching the from
- token, but include those that match the to token.
- - If paginating backwards then we include any rows matching the from
- token, but include those that match the to token.
- Args:
- direction (str): Whether we're paginating backwards("b") or
- forwards ("f").
- column_names (tuple[str, str]): The column names to bound. Must *not*
- be user defined as these get inserted directly into the SQL
- statement without escapes.
- from_token (tuple[int, int]|None): The start point for the pagination.
- This is an exclusive minimum bound if direction is "f", and an
- inclusive maximum bound if direction is "b".
- to_token (tuple[int, int]|None): The endpoint point for the pagination.
- This is an inclusive maximum bound if direction is "f", and an
- exclusive minimum bound if direction is "b".
- engine: The database engine to generate the clauses for
- Returns:
- str: The sql expression
- """
- assert direction in ("b", "f")
- where_clause = []
- if from_token:
- where_clause.append(
- _make_generic_sql_bound(
- bound=">=" if direction == "b" else "<",
- column_names=column_names,
- values=from_token,
- engine=engine,
- )
- )
- if to_token:
- where_clause.append(
- _make_generic_sql_bound(
- bound="<" if direction == "b" else ">=",
- column_names=column_names,
- values=to_token,
- engine=engine,
- )
- )
- return " AND ".join(where_clause)
- def _make_generic_sql_bound(bound, column_names, values, engine):
- """Create an SQL expression that bounds the given column names by the
- values, e.g. create the equivalent of `(1, 2) < (col1, col2)`.
- Only works with two columns.
- Older versions of SQLite don't support that syntax so we have to expand it
- out manually.
- Args:
- bound (str): The comparison operator to use. One of ">", "<", ">=",
- "<=", where the values are on the left and columns on the right.
- names (tuple[str, str]): The column names. Must *not* be user defined
- as these get inserted directly into the SQL statement without
- escapes.
- values (tuple[int|None, int]): The values to bound the columns by. If
- the first value is None then only creates a bound on the second
- column.
- engine: The database engine to generate the SQL for
- Returns:
- str
- """
- assert bound in (">", "<", ">=", "<=")
- name1, name2 = column_names
- val1, val2 = values
- if val1 is None:
- val2 = int(val2)
- return "(%d %s %s)" % (val2, bound, name2)
- val1 = int(val1)
- val2 = int(val2)
- if isinstance(engine, PostgresEngine):
- # Postgres doesn't optimise ``(x < a) OR (x=a AND y<b)`` as well
- # as it optimises ``(x,y) < (a,b)`` on multicolumn indexes. So we
- # use the later form when running against postgres.
- return "((%d,%d) %s (%s,%s))" % (val1, val2, bound, name1, name2)
- # We want to generate queries of e.g. the form:
- #
- # (val1 < name1 OR (val1 = name1 AND val2 <= name2))
- #
- # which is equivalent to (val1, val2) < (name1, name2)
- return """(
- {val1:d} {strict_bound} {name1}
- OR ({val1:d} = {name1} AND {val2:d} {bound} {name2})
- )""".format(
- name1=name1,
- val1=val1,
- name2=name2,
- val2=val2,
- strict_bound=bound[0], # The first bound must always be strict equality here
- bound=bound,
- )
- def filter_to_clause(event_filter):
- # NB: This may create SQL clauses that don't optimise well (and we don't
- # have indices on all possible clauses). E.g. it may create
- # "room_id == X AND room_id != X", which postgres doesn't optimise.
- if not event_filter:
- return "", []
- clauses = []
- args = []
- if event_filter.types:
- clauses.append("(%s)" % " OR ".join("type = ?" for _ in event_filter.types))
- args.extend(event_filter.types)
- for typ in event_filter.not_types:
- clauses.append("type != ?")
- args.append(typ)
- if event_filter.senders:
- clauses.append("(%s)" % " OR ".join("sender = ?" for _ in event_filter.senders))
- args.extend(event_filter.senders)
- for sender in event_filter.not_senders:
- clauses.append("sender != ?")
- args.append(sender)
- if event_filter.rooms:
- clauses.append("(%s)" % " OR ".join("room_id = ?" for _ in event_filter.rooms))
- args.extend(event_filter.rooms)
- for room_id in event_filter.not_rooms:
- clauses.append("room_id != ?")
- args.append(room_id)
- if event_filter.contains_url:
- clauses.append("contains_url = ?")
- args.append(event_filter.contains_url)
- # We're only applying the "labels" filter on the database query, because applying the
- # "not_labels" filter via a SQL query is non-trivial. Instead, we let
- # event_filter.check_fields apply it, which is not as efficient but makes the
- # implementation simpler.
- if event_filter.labels:
- clauses.append("(%s)" % " OR ".join("label = ?" for _ in event_filter.labels))
- args.extend(event_filter.labels)
- return " AND ".join(clauses), args
- class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
- """This is an abstract base class where subclasses must implement
- `get_room_max_stream_ordering` and `get_room_min_stream_ordering`
- which can be called in the initializer.
- """
- __metaclass__ = abc.ABCMeta
- def __init__(self, database: Database, db_conn, hs):
- super(StreamWorkerStore, self).__init__(database, db_conn, hs)
- events_max = self.get_room_max_stream_ordering()
- event_cache_prefill, min_event_val = self.db.get_cache_dict(
- db_conn,
- "events",
- entity_column="room_id",
- stream_column="stream_ordering",
- max_value=events_max,
- )
- self._events_stream_cache = StreamChangeCache(
- "EventsRoomStreamChangeCache",
- min_event_val,
- prefilled_cache=event_cache_prefill,
- )
- self._membership_stream_cache = StreamChangeCache(
- "MembershipStreamChangeCache", events_max
- )
- self._stream_order_on_start = self.get_room_max_stream_ordering()
- @abc.abstractmethod
- def get_room_max_stream_ordering(self):
- raise NotImplementedError()
- @abc.abstractmethod
- def get_room_min_stream_ordering(self):
- raise NotImplementedError()
- @defer.inlineCallbacks
- def get_room_events_stream_for_rooms(
- self, room_ids, from_key, to_key, limit=0, order="DESC"
- ):
- """Get new room events in stream ordering since `from_key`.
- Args:
- room_id (str)
- from_key (str): Token from which no events are returned before
- to_key (str): Token from which no events are returned after. (This
- is typically the current stream token)
- limit (int): Maximum number of events to return
- order (str): Either "DESC" or "ASC". Determines which events are
- returned when the result is limited. If "DESC" then the most
- recent `limit` events are returned, otherwise returns the
- oldest `limit` events.
- Returns:
- Deferred[dict[str,tuple[list[FrozenEvent], str]]]
- A map from room id to a tuple containing:
- - list of recent events in the room
- - stream ordering key for the start of the chunk of events returned.
- """
- from_id = RoomStreamToken.parse_stream_token(from_key).stream
- room_ids = yield self._events_stream_cache.get_entities_changed(
- room_ids, from_id
- )
- if not room_ids:
- return {}
- results = {}
- room_ids = list(room_ids)
- for rm_ids in (room_ids[i : i + 20] for i in range(0, len(room_ids), 20)):
- res = yield make_deferred_yieldable(
- defer.gatherResults(
- [
- run_in_background(
- self.get_room_events_stream_for_room,
- room_id,
- from_key,
- to_key,
- limit,
- order=order,
- )
- for room_id in rm_ids
- ],
- consumeErrors=True,
- )
- )
- results.update(dict(zip(rm_ids, res)))
- return results
- def get_rooms_that_changed(self, room_ids, from_key):
- """Given a list of rooms and a token, return rooms where there may have
- been changes.
- Args:
- room_ids (list)
- from_key (str): The room_key portion of a StreamToken
- """
- from_key = RoomStreamToken.parse_stream_token(from_key).stream
- return {
- room_id
- for room_id in room_ids
- if self._events_stream_cache.has_entity_changed(room_id, from_key)
- }
- @defer.inlineCallbacks
- def get_room_events_stream_for_room(
- self, room_id, from_key, to_key, limit=0, order="DESC"
- ):
- """Get new room events in stream ordering since `from_key`.
- Args:
- room_id (str)
- from_key (str): Token from which no events are returned before
- to_key (str): Token from which no events are returned after. (This
- is typically the current stream token)
- limit (int): Maximum number of events to return
- order (str): Either "DESC" or "ASC". Determines which events are
- returned when the result is limited. If "DESC" then the most
- recent `limit` events are returned, otherwise returns the
- oldest `limit` events.
- Returns:
- Deferred[tuple[list[FrozenEvent], str]]: Returns the list of
- events (in ascending order) and the token from the start of
- the chunk of events returned.
- """
- if from_key == to_key:
- return [], from_key
- from_id = RoomStreamToken.parse_stream_token(from_key).stream
- to_id = RoomStreamToken.parse_stream_token(to_key).stream
- has_changed = yield self._events_stream_cache.has_entity_changed(
- room_id, from_id
- )
- if not has_changed:
- return [], from_key
- def f(txn):
- sql = (
- "SELECT event_id, stream_ordering FROM events WHERE"
- " room_id = ?"
- " AND not outlier"
- " AND stream_ordering > ? AND stream_ordering <= ?"
- " ORDER BY stream_ordering %s LIMIT ?"
- ) % (order,)
- txn.execute(sql, (room_id, from_id, to_id, limit))
- rows = [_EventDictReturn(row[0], None, row[1]) for row in txn]
- return rows
- rows = yield self.db.runInteraction("get_room_events_stream_for_room", f)
- ret = yield self.get_events_as_list(
- [r.event_id for r in rows], get_prev_content=True
- )
- self._set_before_and_after(ret, rows, topo_order=from_id is None)
- if order.lower() == "desc":
- ret.reverse()
- if rows:
- key = "s%d" % min(r.stream_ordering for r in rows)
- else:
- # Assume we didn't get anything because there was nothing to
- # get.
- key = from_key
- return ret, key
- @defer.inlineCallbacks
- def get_membership_changes_for_user(self, user_id, from_key, to_key):
- from_id = RoomStreamToken.parse_stream_token(from_key).stream
- to_id = RoomStreamToken.parse_stream_token(to_key).stream
- if from_key == to_key:
- return []
- if from_id:
- has_changed = self._membership_stream_cache.has_entity_changed(
- user_id, int(from_id)
- )
- if not has_changed:
- return []
- def f(txn):
- sql = (
- "SELECT m.event_id, stream_ordering FROM events AS e,"
- " room_memberships AS m"
- " WHERE e.event_id = m.event_id"
- " AND m.user_id = ?"
- " AND e.stream_ordering > ? AND e.stream_ordering <= ?"
- " ORDER BY e.stream_ordering ASC"
- )
- txn.execute(sql, (user_id, from_id, to_id))
- rows = [_EventDictReturn(row[0], None, row[1]) for row in txn]
- return rows
- rows = yield self.db.runInteraction("get_membership_changes_for_user", f)
- ret = yield self.get_events_as_list(
- [r.event_id for r in rows], get_prev_content=True
- )
- self._set_before_and_after(ret, rows, topo_order=False)
- return ret
- @defer.inlineCallbacks
- def get_recent_events_for_room(self, room_id, limit, end_token):
- """Get the most recent events in the room in topological ordering.
- Args:
- room_id (str)
- limit (int)
- end_token (str): The stream token representing now.
- Returns:
- Deferred[tuple[list[FrozenEvent], str]]: Returns a list of
- events and a token pointing to the start of the returned
- events.
- The events returned are in ascending order.
- """
- rows, token = yield self.get_recent_event_ids_for_room(
- room_id, limit, end_token
- )
- events = yield self.get_events_as_list(
- [r.event_id for r in rows], get_prev_content=True
- )
- self._set_before_and_after(events, rows)
- return (events, token)
- @defer.inlineCallbacks
- def get_recent_event_ids_for_room(self, room_id, limit, end_token):
- """Get the most recent events in the room in topological ordering.
- Args:
- room_id (str)
- limit (int)
- end_token (str): The stream token representing now.
- Returns:
- Deferred[tuple[list[_EventDictReturn], str]]: Returns a list of
- _EventDictReturn and a token pointing to the start of the returned
- events.
- The events returned are in ascending order.
- """
- # Allow a zero limit here, and no-op.
- if limit == 0:
- return [], end_token
- end_token = RoomStreamToken.parse(end_token)
- rows, token = yield self.db.runInteraction(
- "get_recent_event_ids_for_room",
- self._paginate_room_events_txn,
- room_id,
- from_token=end_token,
- limit=limit,
- )
- # We want to return the results in ascending order.
- rows.reverse()
- return rows, token
- def get_room_event_before_stream_ordering(self, room_id, stream_ordering):
- """Gets details of the first event in a room at or before a stream ordering
- Args:
- room_id (str):
- stream_ordering (int):
- Returns:
- Deferred[(int, int, str)]:
- (stream ordering, topological ordering, event_id)
- """
- def _f(txn):
- sql = (
- "SELECT stream_ordering, topological_ordering, event_id"
- " FROM events"
- " WHERE room_id = ? AND stream_ordering <= ?"
- " AND NOT outlier"
- " ORDER BY stream_ordering DESC"
- " LIMIT 1"
- )
- txn.execute(sql, (room_id, stream_ordering))
- return txn.fetchone()
- return self.db.runInteraction("get_room_event_before_stream_ordering", _f)
- @defer.inlineCallbacks
- def get_room_events_max_id(self, room_id=None):
- """Returns the current token for rooms stream.
- By default, it returns the current global stream token. Specifying a
- `room_id` causes it to return the current room specific topological
- token.
- """
- token = yield self.get_room_max_stream_ordering()
- if room_id is None:
- return "s%d" % (token,)
- else:
- topo = yield self.db.runInteraction(
- "_get_max_topological_txn", self._get_max_topological_txn, room_id
- )
- return "t%d-%d" % (topo, token)
- def get_stream_token_for_event(self, event_id):
- """The stream token for an event
- Args:
- event_id(str): The id of the event to look up a stream token for.
- Raises:
- StoreError if the event wasn't in the database.
- Returns:
- A deferred "s%d" stream token.
- """
- return self.db.simple_select_one_onecol(
- table="events", keyvalues={"event_id": event_id}, retcol="stream_ordering"
- ).addCallback(lambda row: "s%d" % (row,))
- def get_topological_token_for_event(self, event_id):
- """The stream token for an event
- Args:
- event_id(str): The id of the event to look up a stream token for.
- Raises:
- StoreError if the event wasn't in the database.
- Returns:
- A deferred "t%d-%d" topological token.
- """
- return self.db.simple_select_one(
- table="events",
- keyvalues={"event_id": event_id},
- retcols=("stream_ordering", "topological_ordering"),
- desc="get_topological_token_for_event",
- ).addCallback(
- lambda row: "t%d-%d" % (row["topological_ordering"], row["stream_ordering"])
- )
- def get_max_topological_token(self, room_id, stream_key):
- """Get the max topological token in a room before the given stream
- ordering.
- Args:
- room_id (str)
- stream_key (int)
- Returns:
- Deferred[int]
- """
- sql = (
- "SELECT coalesce(max(topological_ordering), 0) FROM events"
- " WHERE room_id = ? AND stream_ordering < ?"
- )
- return self.db.execute(
- "get_max_topological_token", None, sql, room_id, stream_key
- ).addCallback(lambda r: r[0][0] if r else 0)
- def _get_max_topological_txn(self, txn, room_id):
- txn.execute(
- "SELECT MAX(topological_ordering) FROM events WHERE room_id = ?",
- (room_id,),
- )
- rows = txn.fetchall()
- return rows[0][0] if rows else 0
- @staticmethod
- def _set_before_and_after(events, rows, topo_order=True):
- """Inserts ordering information to events' internal metadata from
- the DB rows.
- Args:
- events (list[FrozenEvent])
- rows (list[_EventDictReturn])
- topo_order (bool): Whether the events were ordered topologically
- or by stream ordering. If true then all rows should have a non
- null topological_ordering.
- """
- for event, row in zip(events, rows):
- stream = row.stream_ordering
- if topo_order and row.topological_ordering:
- topo = row.topological_ordering
- else:
- topo = None
- internal = event.internal_metadata
- internal.before = str(RoomStreamToken(topo, stream - 1))
- internal.after = str(RoomStreamToken(topo, stream))
- internal.order = (int(topo) if topo else 0, int(stream))
- @defer.inlineCallbacks
- def get_events_around(
- self, room_id, event_id, before_limit, after_limit, event_filter=None
- ):
- """Retrieve events and pagination tokens around a given event in a
- room.
- Args:
- room_id (str)
- event_id (str)
- before_limit (int)
- after_limit (int)
- event_filter (Filter|None)
- Returns:
- dict
- """
- results = yield self.db.runInteraction(
- "get_events_around",
- self._get_events_around_txn,
- room_id,
- event_id,
- before_limit,
- after_limit,
- event_filter,
- )
- events_before = yield self.get_events_as_list(
- list(results["before"]["event_ids"]), get_prev_content=True
- )
- events_after = yield self.get_events_as_list(
- list(results["after"]["event_ids"]), get_prev_content=True
- )
- return {
- "events_before": events_before,
- "events_after": events_after,
- "start": results["before"]["token"],
- "end": results["after"]["token"],
- }
- def _get_events_around_txn(
- self, txn, room_id, event_id, before_limit, after_limit, event_filter
- ):
- """Retrieves event_ids and pagination tokens around a given event in a
- room.
- Args:
- room_id (str)
- event_id (str)
- before_limit (int)
- after_limit (int)
- event_filter (Filter|None)
- Returns:
- dict
- """
- results = self.db.simple_select_one_txn(
- txn,
- "events",
- keyvalues={"event_id": event_id, "room_id": room_id},
- retcols=["stream_ordering", "topological_ordering"],
- )
- # Paginating backwards includes the event at the token, but paginating
- # forward doesn't.
- before_token = RoomStreamToken(
- results["topological_ordering"] - 1, results["stream_ordering"]
- )
- after_token = RoomStreamToken(
- results["topological_ordering"], results["stream_ordering"]
- )
- rows, start_token = self._paginate_room_events_txn(
- txn,
- room_id,
- before_token,
- direction="b",
- limit=before_limit,
- event_filter=event_filter,
- )
- events_before = [r.event_id for r in rows]
- rows, end_token = self._paginate_room_events_txn(
- txn,
- room_id,
- after_token,
- direction="f",
- limit=after_limit,
- event_filter=event_filter,
- )
- events_after = [r.event_id for r in rows]
- return {
- "before": {"event_ids": events_before, "token": start_token},
- "after": {"event_ids": events_after, "token": end_token},
- }
- @defer.inlineCallbacks
- def get_all_new_events_stream(self, from_id, current_id, limit):
- """Get all new events
- Returns all events with from_id < stream_ordering <= current_id.
- Args:
- from_id (int): the stream_ordering of the last event we processed
- current_id (int): the stream_ordering of the most recently processed event
- limit (int): the maximum number of events to return
- Returns:
- Deferred[Tuple[int, list[FrozenEvent]]]: A tuple of (next_id, events), where
- `next_id` is the next value to pass as `from_id` (it will either be the
- stream_ordering of the last returned event, or, if fewer than `limit` events
- were found, `current_id`.
- """
- def get_all_new_events_stream_txn(txn):
- sql = (
- "SELECT e.stream_ordering, e.event_id"
- " FROM events AS e"
- " WHERE"
- " ? < e.stream_ordering AND e.stream_ordering <= ?"
- " ORDER BY e.stream_ordering ASC"
- " LIMIT ?"
- )
- txn.execute(sql, (from_id, current_id, limit))
- rows = txn.fetchall()
- upper_bound = current_id
- if len(rows) == limit:
- upper_bound = rows[-1][0]
- return upper_bound, [row[1] for row in rows]
- upper_bound, event_ids = yield self.db.runInteraction(
- "get_all_new_events_stream", get_all_new_events_stream_txn
- )
- events = yield self.get_events_as_list(event_ids)
- return upper_bound, events
- def get_federation_out_pos(self, typ):
- return self.db.simple_select_one_onecol(
- table="federation_stream_position",
- retcol="stream_id",
- keyvalues={"type": typ},
- desc="get_federation_out_pos",
- )
- def update_federation_out_pos(self, typ, stream_id):
- return self.db.simple_update_one(
- table="federation_stream_position",
- keyvalues={"type": typ},
- updatevalues={"stream_id": stream_id},
- desc="update_federation_out_pos",
- )
- def has_room_changed_since(self, room_id, stream_id):
- return self._events_stream_cache.has_entity_changed(room_id, stream_id)
- def _paginate_room_events_txn(
- self,
- txn,
- room_id,
- from_token,
- to_token=None,
- direction="b",
- limit=-1,
- event_filter=None,
- ):
- """Returns list of events before or after a given token.
- Args:
- txn
- room_id (str)
- from_token (RoomStreamToken): The token used to stream from
- to_token (RoomStreamToken|None): A token which if given limits the
- results to only those before
- direction(char): Either 'b' or 'f' to indicate whether we are
- paginating forwards or backwards from `from_key`.
- limit (int): The maximum number of events to return.
- event_filter (Filter|None): If provided filters the events to
- those that match the filter.
- Returns:
- Deferred[tuple[list[_EventDictReturn], str]]: Returns the results
- as a list of _EventDictReturn and a token that points to the end
- of the result set. If no events are returned then the end of the
- stream has been reached (i.e. there are no events between
- `from_token` and `to_token`), or `limit` is zero.
- """
- assert int(limit) >= 0
- # Tokens really represent positions between elements, but we use
- # the convention of pointing to the event before the gap. Hence
- # we have a bit of asymmetry when it comes to equalities.
- args = [False, room_id]
- if direction == "b":
- order = "DESC"
- else:
- order = "ASC"
- bounds = generate_pagination_where_clause(
- direction=direction,
- column_names=("topological_ordering", "stream_ordering"),
- from_token=from_token,
- to_token=to_token,
- engine=self.database_engine,
- )
- filter_clause, filter_args = filter_to_clause(event_filter)
- if filter_clause:
- bounds += " AND " + filter_clause
- args.extend(filter_args)
- args.append(int(limit))
- select_keywords = "SELECT"
- join_clause = ""
- if event_filter and event_filter.labels:
- # If we're not filtering on a label, then joining on event_labels will
- # return as many row for a single event as the number of labels it has. To
- # avoid this, only join if we're filtering on at least one label.
- join_clause = """
- LEFT JOIN event_labels
- USING (event_id, room_id, topological_ordering)
- """
- if len(event_filter.labels) > 1:
- # Using DISTINCT in this SELECT query is quite expensive, because it
- # requires the engine to sort on the entire (not limited) result set,
- # i.e. the entire events table. We only need to use it when we're
- # filtering on more than two labels, because that's the only scenario
- # in which we can possibly to get multiple times the same event ID in
- # the results.
- select_keywords += "DISTINCT"
- sql = """
- %(select_keywords)s event_id, topological_ordering, stream_ordering
- FROM events
- %(join_clause)s
- WHERE outlier = ? AND room_id = ? AND %(bounds)s
- ORDER BY topological_ordering %(order)s,
- stream_ordering %(order)s LIMIT ?
- """ % {
- "select_keywords": select_keywords,
- "join_clause": join_clause,
- "bounds": bounds,
- "order": order,
- }
- txn.execute(sql, args)
- rows = [_EventDictReturn(row[0], row[1], row[2]) for row in txn]
- if rows:
- topo = rows[-1].topological_ordering
- toke = rows[-1].stream_ordering
- if direction == "b":
- # Tokens are positions between events.
- # This token points *after* the last event in the chunk.
- # We need it to point to the event before it in the chunk
- # when we are going backwards so we subtract one from the
- # stream part.
- toke -= 1
- next_token = RoomStreamToken(topo, toke)
- else:
- # TODO (erikj): We should work out what to do here instead.
- next_token = to_token if to_token else from_token
- return rows, str(next_token)
- @defer.inlineCallbacks
- def paginate_room_events(
- self, room_id, from_key, to_key=None, direction="b", limit=-1, event_filter=None
- ):
- """Returns list of events before or after a given token.
- Args:
- room_id (str)
- from_key (str): The token used to stream from
- to_key (str|None): A token which if given limits the results to
- only those before
- direction(char): Either 'b' or 'f' to indicate whether we are
- paginating forwards or backwards from `from_key`.
- limit (int): The maximum number of events to return.
- event_filter (Filter|None): If provided filters the events to
- those that match the filter.
- Returns:
- tuple[list[FrozenEvent], str]: Returns the results as a list of
- events and a token that points to the end of the result set. If no
- events are returned then the end of the stream has been reached
- (i.e. there are no events between `from_key` and `to_key`).
- """
- from_key = RoomStreamToken.parse(from_key)
- if to_key:
- to_key = RoomStreamToken.parse(to_key)
- rows, token = yield self.db.runInteraction(
- "paginate_room_events",
- self._paginate_room_events_txn,
- room_id,
- from_key,
- to_key,
- direction,
- limit,
- event_filter,
- )
- events = yield self.get_events_as_list(
- [r.event_id for r in rows], get_prev_content=True
- )
- self._set_before_and_after(events, rows)
- return (events, token)
- class StreamStore(StreamWorkerStore):
- def get_room_max_stream_ordering(self):
- return self._stream_id_gen.get_current_token()
- def get_room_min_stream_ordering(self):
- return self._backfill_id_gen.get_current_token()
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