491 lines
18 KiB
Python
491 lines
18 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2019 New Vector Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import logging
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from six import itervalues
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from prometheus_client import Counter
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from twisted.internet import defer
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import synapse.metrics
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from synapse.federation.sender.per_destination_queue import PerDestinationQueue
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from synapse.federation.sender.transaction_manager import TransactionManager
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from synapse.federation.units import Edu
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from synapse.handlers.presence import get_interested_remotes
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from synapse.logging.context import (
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make_deferred_yieldable,
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preserve_fn,
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run_in_background,
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)
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from synapse.metrics import (
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LaterGauge,
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event_processing_loop_counter,
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event_processing_loop_room_count,
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events_processed_counter,
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)
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from synapse.metrics.background_process_metrics import run_as_background_process
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from synapse.util.metrics import measure_func
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logger = logging.getLogger(__name__)
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sent_pdus_destination_dist_count = Counter(
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"synapse_federation_client_sent_pdu_destinations:count",
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"Number of PDUs queued for sending to one or more destinations",
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)
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sent_pdus_destination_dist_total = Counter(
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"synapse_federation_client_sent_pdu_destinations:total",
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"" "Total number of PDUs queued for sending across all destinations",
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)
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class FederationSender(object):
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def __init__(self, hs):
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self.hs = hs
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self.server_name = hs.hostname
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self.store = hs.get_datastore()
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self.state = hs.get_state_handler()
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self.clock = hs.get_clock()
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self.is_mine_id = hs.is_mine_id
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self._transaction_manager = TransactionManager(hs)
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# map from destination to PerDestinationQueue
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self._per_destination_queues = {} # type: dict[str, PerDestinationQueue]
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LaterGauge(
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"synapse_federation_transaction_queue_pending_destinations",
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"",
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[],
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lambda: sum(
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1
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for d in self._per_destination_queues.values()
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if d.transmission_loop_running
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),
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)
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# Map of user_id -> UserPresenceState for all the pending presence
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# to be sent out by user_id. Entries here get processed and put in
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# pending_presence_by_dest
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self.pending_presence = {}
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LaterGauge(
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"synapse_federation_transaction_queue_pending_pdus",
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"",
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[],
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lambda: sum(
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d.pending_pdu_count() for d in self._per_destination_queues.values()
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),
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)
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LaterGauge(
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"synapse_federation_transaction_queue_pending_edus",
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"",
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[],
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lambda: sum(
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d.pending_edu_count() for d in self._per_destination_queues.values()
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),
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)
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self._order = 1
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self._is_processing = False
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self._last_poked_id = -1
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self._processing_pending_presence = False
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# map from room_id to a set of PerDestinationQueues which we believe are
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# awaiting a call to flush_read_receipts_for_room. The presence of an entry
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# here for a given room means that we are rate-limiting RR flushes to that room,
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# and that there is a pending call to _flush_rrs_for_room in the system.
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self._queues_awaiting_rr_flush_by_room = (
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{}
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) # type: dict[str, set[PerDestinationQueue]]
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self._rr_txn_interval_per_room_ms = (
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1000.0 / hs.get_config().federation_rr_transactions_per_room_per_second
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)
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def _get_per_destination_queue(self, destination):
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"""Get or create a PerDestinationQueue for the given destination
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Args:
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destination (str): server_name of remote server
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Returns:
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PerDestinationQueue
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"""
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queue = self._per_destination_queues.get(destination)
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if not queue:
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queue = PerDestinationQueue(self.hs, self._transaction_manager, destination)
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self._per_destination_queues[destination] = queue
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return queue
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def notify_new_events(self, current_id):
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"""This gets called when we have some new events we might want to
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send out to other servers.
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"""
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self._last_poked_id = max(current_id, self._last_poked_id)
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if self._is_processing:
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return
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# fire off a processing loop in the background
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run_as_background_process(
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"process_event_queue_for_federation", self._process_event_queue_loop
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)
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@defer.inlineCallbacks
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def _process_event_queue_loop(self):
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try:
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self._is_processing = True
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while True:
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last_token = yield self.store.get_federation_out_pos("events")
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next_token, events = yield self.store.get_all_new_events_stream(
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last_token, self._last_poked_id, limit=100
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)
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logger.debug("Handling %s -> %s", last_token, next_token)
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if not events and next_token >= self._last_poked_id:
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break
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@defer.inlineCallbacks
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def handle_event(event):
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# Only send events for this server.
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send_on_behalf_of = event.internal_metadata.get_send_on_behalf_of()
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is_mine = self.is_mine_id(event.sender)
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if not is_mine and send_on_behalf_of is None:
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return
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if not event.internal_metadata.should_proactively_send():
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return
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try:
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# Get the state from before the event.
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# We need to make sure that this is the state from before
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# the event and not from after it.
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# Otherwise if the last member on a server in a room is
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# banned then it won't receive the event because it won't
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# be in the room after the ban.
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destinations = yield self.state.get_current_hosts_in_room(
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event.room_id, latest_event_ids=event.prev_event_ids()
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)
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except Exception:
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logger.exception(
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"Failed to calculate hosts in room for event: %s",
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event.event_id,
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)
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return
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destinations = set(destinations)
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if send_on_behalf_of is not None:
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# If we are sending the event on behalf of another server
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# then it already has the event and there is no reason to
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# send the event to it.
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destinations.discard(send_on_behalf_of)
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logger.debug("Sending %s to %r", event, destinations)
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self._send_pdu(event, destinations)
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@defer.inlineCallbacks
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def handle_room_events(events):
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for event in events:
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yield handle_event(event)
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events_by_room = {}
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for event in events:
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events_by_room.setdefault(event.room_id, []).append(event)
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yield make_deferred_yieldable(
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defer.gatherResults(
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[
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run_in_background(handle_room_events, evs)
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for evs in itervalues(events_by_room)
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],
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consumeErrors=True,
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)
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)
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yield self.store.update_federation_out_pos("events", next_token)
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if events:
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now = self.clock.time_msec()
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ts = yield self.store.get_received_ts(events[-1].event_id)
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synapse.metrics.event_processing_lag.labels(
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"federation_sender"
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).set(now - ts)
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synapse.metrics.event_processing_last_ts.labels(
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"federation_sender"
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).set(ts)
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events_processed_counter.inc(len(events))
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event_processing_loop_room_count.labels("federation_sender").inc(
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len(events_by_room)
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)
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event_processing_loop_counter.labels("federation_sender").inc()
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synapse.metrics.event_processing_positions.labels(
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"federation_sender"
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).set(next_token)
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finally:
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self._is_processing = False
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def _send_pdu(self, pdu, destinations):
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# We loop through all destinations to see whether we already have
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# a transaction in progress. If we do, stick it in the pending_pdus
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# table and we'll get back to it later.
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order = self._order
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self._order += 1
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destinations = set(destinations)
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destinations.discard(self.server_name)
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logger.debug("Sending to: %s", str(destinations))
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if not destinations:
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return
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sent_pdus_destination_dist_total.inc(len(destinations))
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sent_pdus_destination_dist_count.inc()
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for destination in destinations:
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self._get_per_destination_queue(destination).send_pdu(pdu, order)
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@defer.inlineCallbacks
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def send_read_receipt(self, receipt):
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"""Send a RR to any other servers in the room
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Args:
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receipt (synapse.types.ReadReceipt): receipt to be sent
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"""
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# Some background on the rate-limiting going on here.
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#
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# It turns out that if we attempt to send out RRs as soon as we get them from
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# a client, then we end up trying to do several hundred Hz of federation
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# transactions. (The number of transactions scales as O(N^2) on the size of a
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# room, since in a large room we have both more RRs coming in, and more servers
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# to send them to.)
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#
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# This leads to a lot of CPU load, and we end up getting behind. The solution
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# currently adopted is as follows:
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#
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# The first receipt in a given room is sent out immediately, at time T0. Any
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# further receipts are, in theory, batched up for N seconds, where N is calculated
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# based on the number of servers in the room to achieve a transaction frequency
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# of around 50Hz. So, for example, if there were 100 servers in the room, then
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# N would be 100 / 50Hz = 2 seconds.
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#
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# Then, after T+N, we flush out any receipts that have accumulated, and restart
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# the timer to flush out more receipts at T+2N, etc. If no receipts accumulate,
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# we stop the cycle and go back to the start.
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#
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# However, in practice, it is often possible to flush out receipts earlier: in
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# particular, if we are sending a transaction to a given server anyway (for
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# example, because we have a PDU or a RR in another room to send), then we may
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# as well send out all of the pending RRs for that server. So it may be that
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# by the time we get to T+N, we don't actually have any RRs left to send out.
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# Nevertheless we continue to buffer up RRs for the room in question until we
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# reach the point that no RRs arrive between timer ticks.
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#
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# For even more background, see https://github.com/matrix-org/synapse/issues/4730.
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room_id = receipt.room_id
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# Work out which remote servers should be poked and poke them.
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domains = yield self.state.get_current_hosts_in_room(room_id)
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domains = [d for d in domains if d != self.server_name]
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if not domains:
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return
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queues_pending_flush = self._queues_awaiting_rr_flush_by_room.get(room_id)
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# if there is no flush yet scheduled, we will send out these receipts with
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# immediate flushes, and schedule the next flush for this room.
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if queues_pending_flush is not None:
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logger.debug("Queuing receipt for: %r", domains)
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else:
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logger.debug("Sending receipt to: %r", domains)
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self._schedule_rr_flush_for_room(room_id, len(domains))
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for domain in domains:
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queue = self._get_per_destination_queue(domain)
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queue.queue_read_receipt(receipt)
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# if there is already a RR flush pending for this room, then make sure this
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# destination is registered for the flush
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if queues_pending_flush is not None:
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queues_pending_flush.add(queue)
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else:
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queue.flush_read_receipts_for_room(room_id)
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def _schedule_rr_flush_for_room(self, room_id, n_domains):
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# that is going to cause approximately len(domains) transactions, so now back
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# off for that multiplied by RR_TXN_INTERVAL_PER_ROOM
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backoff_ms = self._rr_txn_interval_per_room_ms * n_domains
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logger.debug("Scheduling RR flush in %s in %d ms", room_id, backoff_ms)
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self.clock.call_later(backoff_ms, self._flush_rrs_for_room, room_id)
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self._queues_awaiting_rr_flush_by_room[room_id] = set()
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def _flush_rrs_for_room(self, room_id):
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queues = self._queues_awaiting_rr_flush_by_room.pop(room_id)
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logger.debug("Flushing RRs in %s to %s", room_id, queues)
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if not queues:
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# no more RRs arrived for this room; we are done.
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return
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# schedule the next flush
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self._schedule_rr_flush_for_room(room_id, len(queues))
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for queue in queues:
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queue.flush_read_receipts_for_room(room_id)
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@preserve_fn # the caller should not yield on this
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@defer.inlineCallbacks
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def send_presence(self, states):
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"""Send the new presence states to the appropriate destinations.
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This actually queues up the presence states ready for sending and
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triggers a background task to process them and send out the transactions.
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Args:
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states (list(UserPresenceState))
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"""
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if not self.hs.config.use_presence:
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# No-op if presence is disabled.
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return
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# First we queue up the new presence by user ID, so multiple presence
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# updates in quick succession are correctly handled.
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# We only want to send presence for our own users, so lets always just
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# filter here just in case.
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self.pending_presence.update(
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{state.user_id: state for state in states if self.is_mine_id(state.user_id)}
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)
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# We then handle the new pending presence in batches, first figuring
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# out the destinations we need to send each state to and then poking it
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# to attempt a new transaction. We linearize this so that we don't
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# accidentally mess up the ordering and send multiple presence updates
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# in the wrong order
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if self._processing_pending_presence:
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return
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self._processing_pending_presence = True
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try:
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while True:
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states_map = self.pending_presence
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self.pending_presence = {}
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if not states_map:
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break
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yield self._process_presence_inner(list(states_map.values()))
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except Exception:
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logger.exception("Error sending presence states to servers")
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finally:
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self._processing_pending_presence = False
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def send_presence_to_destinations(self, states, destinations):
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"""Send the given presence states to the given destinations.
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Args:
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states (list[UserPresenceState])
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destinations (list[str])
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"""
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if not states or not self.hs.config.use_presence:
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# No-op if presence is disabled.
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return
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for destination in destinations:
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if destination == self.server_name:
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continue
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self._get_per_destination_queue(destination).send_presence(states)
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@measure_func("txnqueue._process_presence")
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@defer.inlineCallbacks
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def _process_presence_inner(self, states):
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"""Given a list of states populate self.pending_presence_by_dest and
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poke to send a new transaction to each destination
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Args:
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states (list(UserPresenceState))
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"""
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hosts_and_states = yield get_interested_remotes(self.store, states, self.state)
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for destinations, states in hosts_and_states:
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for destination in destinations:
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if destination == self.server_name:
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continue
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self._get_per_destination_queue(destination).send_presence(states)
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def build_and_send_edu(self, destination, edu_type, content, key=None):
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"""Construct an Edu object, and queue it for sending
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Args:
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destination (str): name of server to send to
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edu_type (str): type of EDU to send
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content (dict): content of EDU
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key (Any|None): clobbering key for this edu
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"""
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if destination == self.server_name:
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logger.info("Not sending EDU to ourselves")
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return
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edu = Edu(
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origin=self.server_name,
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destination=destination,
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edu_type=edu_type,
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content=content,
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)
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self.send_edu(edu, key)
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def send_edu(self, edu, key):
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"""Queue an EDU for sending
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Args:
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edu (Edu): edu to send
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key (Any|None): clobbering key for this edu
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"""
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queue = self._get_per_destination_queue(edu.destination)
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if key:
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queue.send_keyed_edu(edu, key)
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else:
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queue.send_edu(edu)
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def send_device_messages(self, destination):
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if destination == self.server_name:
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logger.info("Not sending device update to ourselves")
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return
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self._get_per_destination_queue(destination).attempt_new_transaction()
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def get_current_token(self):
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return 0
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