237 lines
		
	
	
		
			9.3 KiB
		
	
	
	
		
			Python
		
	
	
			
		
		
	
	
			237 lines
		
	
	
		
			9.3 KiB
		
	
	
	
		
			Python
		
	
	
# -*- coding: utf-8 -*-
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# Copyright 2017 Vector Creations 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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"""A replication client for use by synapse workers.
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"""
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import logging
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from typing import TYPE_CHECKING, Dict, List, Tuple
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from twisted.internet.defer import Deferred
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from twisted.internet.protocol import ReconnectingClientFactory
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from synapse.api.constants import EventTypes
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from synapse.logging.context import PreserveLoggingContext, make_deferred_yieldable
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from synapse.replication.tcp.protocol import ClientReplicationStreamProtocol
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from synapse.replication.tcp.streams import TypingStream
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from synapse.replication.tcp.streams.events import (
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    EventsStream,
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    EventsStreamEventRow,
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    EventsStreamRow,
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)
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from synapse.types import PersistedEventPosition, UserID
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from synapse.util.async_helpers import timeout_deferred
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from synapse.util.metrics import Measure
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if TYPE_CHECKING:
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    from synapse.replication.tcp.handler import ReplicationCommandHandler
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    from synapse.server import HomeServer
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logger = logging.getLogger(__name__)
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# How long we allow callers to wait for replication updates before timing out.
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_WAIT_FOR_REPLICATION_TIMEOUT_SECONDS = 30
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class DirectTcpReplicationClientFactory(ReconnectingClientFactory):
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    """Factory for building connections to the master. Will reconnect if the
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    connection is lost.
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    Accepts a handler that is passed to `ClientReplicationStreamProtocol`.
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    """
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    initialDelay = 0.1
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    maxDelay = 1  # Try at least once every N seconds
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    def __init__(
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        self,
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        hs: "HomeServer",
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        client_name: str,
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        command_handler: "ReplicationCommandHandler",
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    ):
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        self.client_name = client_name
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        self.command_handler = command_handler
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        self.server_name = hs.config.server_name
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        self.hs = hs
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        self._clock = hs.get_clock()  # As self.clock is defined in super class
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        hs.get_reactor().addSystemEventTrigger("before", "shutdown", self.stopTrying)
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    def startedConnecting(self, connector):
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        logger.info("Connecting to replication: %r", connector.getDestination())
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    def buildProtocol(self, addr):
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        logger.info("Connected to replication: %r", addr)
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        return ClientReplicationStreamProtocol(
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            self.hs,
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            self.client_name,
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            self.server_name,
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            self._clock,
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            self.command_handler,
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        )
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    def clientConnectionLost(self, connector, reason):
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        logger.error("Lost replication conn: %r", reason)
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        ReconnectingClientFactory.clientConnectionLost(self, connector, reason)
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    def clientConnectionFailed(self, connector, reason):
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        logger.error("Failed to connect to replication: %r", reason)
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        ReconnectingClientFactory.clientConnectionFailed(self, connector, reason)
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class ReplicationDataHandler:
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    """Handles incoming stream updates from replication.
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    This instance notifies the slave data store about updates. Can be subclassed
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    to handle updates in additional ways.
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    """
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    def __init__(self, hs: "HomeServer"):
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        self.store = hs.get_datastore()
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        self.notifier = hs.get_notifier()
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        self._reactor = hs.get_reactor()
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        self._clock = hs.get_clock()
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        self._streams = hs.get_replication_streams()
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        self._instance_name = hs.get_instance_name()
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        self._typing_handler = hs.get_typing_handler()
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        # Map from stream to list of deferreds waiting for the stream to
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        # arrive at a particular position. The lists are sorted by stream position.
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        self._streams_to_waiters = (
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            {}
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        )  # type: Dict[str, List[Tuple[int, Deferred[None]]]]
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    async def on_rdata(
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        self, stream_name: str, instance_name: str, token: int, rows: list
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    ):
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        """Called to handle a batch of replication data with a given stream token.
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        By default this just pokes the slave store. Can be overridden in subclasses to
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        handle more.
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        Args:
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            stream_name: name of the replication stream for this batch of rows
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            instance_name: the instance that wrote the rows.
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            token: stream token for this batch of rows
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            rows: a list of Stream.ROW_TYPE objects as returned by Stream.parse_row.
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        """
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        self.store.process_replication_rows(stream_name, instance_name, token, rows)
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        if stream_name == TypingStream.NAME:
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            self._typing_handler.process_replication_rows(token, rows)
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            self.notifier.on_new_event(
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                "typing_key", token, rooms=[row.room_id for row in rows]
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            )
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        if stream_name == EventsStream.NAME:
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            # We shouldn't get multiple rows per token for events stream, so
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            # we don't need to optimise this for multiple rows.
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            for row in rows:
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                if row.type != EventsStreamEventRow.TypeId:
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                    continue
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                assert isinstance(row, EventsStreamRow)
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                event = await self.store.get_event(
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                    row.data.event_id, allow_rejected=True
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                )
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                if event.rejected_reason:
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                    continue
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                extra_users = ()  # type: Tuple[UserID, ...]
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                if event.type == EventTypes.Member:
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                    extra_users = (UserID.from_string(event.state_key),)
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                max_token = self.store.get_room_max_token()
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                event_pos = PersistedEventPosition(instance_name, token)
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                self.notifier.on_new_room_event(
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                    event, event_pos, max_token, extra_users
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                )
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        # Notify any waiting deferreds. The list is ordered by position so we
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        # just iterate through the list until we reach a position that is
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        # greater than the received row position.
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        waiting_list = self._streams_to_waiters.get(stream_name, [])
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        # Index of first item with a position after the current token, i.e we
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        # have called all deferreds before this index. If not overwritten by
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        # loop below means either a) no items in list so no-op or b) all items
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        # in list were called and so the list should be cleared. Setting it to
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        # `len(list)` works for both cases.
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        index_of_first_deferred_not_called = len(waiting_list)
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        for idx, (position, deferred) in enumerate(waiting_list):
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            if position <= token:
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                try:
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                    with PreserveLoggingContext():
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                        deferred.callback(None)
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                except Exception:
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                    # The deferred has been cancelled or timed out.
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                    pass
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            else:
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                # The list is sorted by position so we don't need to continue
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                # checking any further entries in the list.
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                index_of_first_deferred_not_called = idx
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                break
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        # Drop all entries in the waiting list that were called in the above
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        # loop. (This maintains the order so no need to resort)
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        waiting_list[:] = waiting_list[index_of_first_deferred_not_called:]
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    async def on_position(self, stream_name: str, instance_name: str, token: int):
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        self.store.process_replication_rows(stream_name, instance_name, token, [])
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        # We poke the generic "replication" notifier to wake anything up that
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        # may be streaming.
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        self.notifier.notify_replication()
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    def on_remote_server_up(self, server: str):
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        """Called when get a new REMOTE_SERVER_UP command."""
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    async def wait_for_stream_position(
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        self, instance_name: str, stream_name: str, position: int
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    ):
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        """Wait until this instance has received updates up to and including
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        the given stream position.
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        """
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        if instance_name == self._instance_name:
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            # We don't get told about updates written by this process, and
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            # anyway in that case we don't need to wait.
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            return
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        current_position = self._streams[stream_name].current_token(self._instance_name)
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        if position <= current_position:
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            # We're already past the position
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            return
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        # Create a new deferred that times out after N seconds, as we don't want
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        # to wedge here forever.
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        deferred = Deferred()
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        deferred = timeout_deferred(
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            deferred, _WAIT_FOR_REPLICATION_TIMEOUT_SECONDS, self._reactor
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        )
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        waiting_list = self._streams_to_waiters.setdefault(stream_name, [])
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        waiting_list.append((position, deferred))
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        waiting_list.sort(key=lambda t: t[0])
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        # We measure here to get in flight counts and average waiting time.
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        with Measure(self._clock, "repl.wait_for_stream_position"):
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            logger.info("Waiting for repl stream %r to reach %s", stream_name, position)
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            await make_deferred_yieldable(deferred)
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            logger.info(
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                "Finished waiting for repl stream %r to reach %s", stream_name, position
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            )
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