641 lines
24 KiB
Python
641 lines
24 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 typing import Dict, Hashable, Iterable, List, Optional, Set, Tuple
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from prometheus_client import Counter
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from twisted.internet import defer
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import synapse
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import synapse.metrics
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from synapse.api.presence import UserPresenceState
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from synapse.events import EventBase
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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.types import ReadReceipt, RoomStreamToken
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from synapse.util.metrics import Measure, 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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# Time (in s) after Synapse's startup that we will begin to wake up destinations
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# that have catch-up outstanding.
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CATCH_UP_STARTUP_DELAY_SEC = 15
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# Time (in s) to wait in between waking up each destination, i.e. one destination
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# will be woken up every <x> seconds after Synapse's startup until we have woken
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# every destination has outstanding catch-up.
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CATCH_UP_STARTUP_INTERVAL_SEC = 5
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class FederationSender:
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def __init__(self, hs: "synapse.server.HomeServer"):
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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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self._instance_name = hs.get_instance_name()
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self._federation_shard_config = hs.config.worker.federation_shard_config
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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 = {} # type: Dict[str, UserPresenceState]
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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._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.config.federation_rr_transactions_per_room_per_second
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)
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# wake up destinations that have outstanding PDUs to be caught up
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self._catchup_after_startup_timer = self.clock.call_later(
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CATCH_UP_STARTUP_DELAY_SEC,
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run_as_background_process,
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"wake_destinations_needing_catchup",
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self._wake_destinations_needing_catchup,
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)
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self._external_cache = hs.get_external_cache()
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def _get_per_destination_queue(self, destination: str) -> PerDestinationQueue:
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"""Get or create a PerDestinationQueue for the given destination
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Args:
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destination: server_name of remote server
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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, max_token: RoomStreamToken) -> None:
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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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# We just use the minimum stream ordering and ignore the vector clock
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# component. This is safe to do as long as we *always* ignore the vector
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# clock components.
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current_id = max_token.stream
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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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async def _process_event_queue_loop(self) -> None:
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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 = await self.store.get_federation_out_pos("events")
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next_token, events = await 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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async def handle_event(event: EventBase) -> None:
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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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destinations = None # type: Optional[Set[str]]
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if not event.prev_event_ids():
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# If there are no prev event IDs then the state is empty
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# and so no remote servers in the room
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destinations = set()
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else:
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# We check the external cache for the destinations, which is
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# stored per state group.
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sg = await self._external_cache.get(
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"event_to_prev_state_group", event.event_id
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)
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if sg:
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destinations = await self._external_cache.get(
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"get_joined_hosts", str(sg)
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)
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if destinations is None:
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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 = await self.state.get_hosts_in_room_at_events(
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event.room_id, 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 = {
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d
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for d in destinations
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if self._federation_shard_config.should_handle(
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self._instance_name, d
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)
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}
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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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if destinations:
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await self._send_pdu(event, destinations)
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now = self.clock.time_msec()
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ts = await self.store.get_received_ts(event.event_id)
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synapse.metrics.event_processing_lag_by_event.labels(
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"federation_sender"
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).observe((now - ts) / 1000)
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async def handle_room_events(events: Iterable[EventBase]) -> None:
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with Measure(self.clock, "handle_room_events"):
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for event in events:
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await handle_event(event)
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events_by_room = {} # type: Dict[str, List[EventBase]]
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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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await 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 events_by_room.values()
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],
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consumeErrors=True,
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)
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)
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await 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 = await 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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async def _send_pdu(self, pdu: EventBase, destinations: Iterable[str]) -> None:
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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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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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assert pdu.internal_metadata.stream_ordering
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# track the fact that we have a PDU for these destinations,
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# to allow us to perform catch-up later on if the remote is unreachable
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# for a while.
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await self.store.store_destination_rooms_entries(
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destinations, pdu.room_id, pdu.internal_metadata.stream_ordering,
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)
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for destination in destinations:
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self._get_per_destination_queue(destination).send_pdu(pdu)
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async def send_read_receipt(self, receipt: ReadReceipt) -> None:
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"""Send a RR to any other servers in the room
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Args:
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receipt: 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_set = await self.state.get_current_hosts_in_room(room_id)
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domains = [
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d
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for d in domains_set
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if d != self.server_name
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and self._federation_shard_config.should_handle(self._instance_name, d)
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]
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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: str, n_domains: int) -> None:
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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: str) -> None:
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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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async def send_presence(self, states: List[UserPresenceState]):
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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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"""
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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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await 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(
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self, states: List[UserPresenceState], destinations: List[str]
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) -> None:
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"""Send the given presence states to the given destinations.
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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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if not self._federation_shard_config.should_handle(
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self._instance_name, destination
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):
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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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async def _process_presence_inner(self, states: List[UserPresenceState]):
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"""Given a list of states populate self.pending_presence_by_dest and
|
|
poke to send a new transaction to each destination
|
|
"""
|
|
hosts_and_states = await get_interested_remotes(self.store, states, self.state)
|
|
|
|
for destinations, states in hosts_and_states:
|
|
for destination in destinations:
|
|
if destination == self.server_name:
|
|
continue
|
|
|
|
if not self._federation_shard_config.should_handle(
|
|
self._instance_name, destination
|
|
):
|
|
continue
|
|
|
|
self._get_per_destination_queue(destination).send_presence(states)
|
|
|
|
def build_and_send_edu(
|
|
self,
|
|
destination: str,
|
|
edu_type: str,
|
|
content: dict,
|
|
key: Optional[Hashable] = None,
|
|
):
|
|
"""Construct an Edu object, and queue it for sending
|
|
|
|
Args:
|
|
destination: name of server to send to
|
|
edu_type: type of EDU to send
|
|
content: content of EDU
|
|
key: clobbering key for this edu
|
|
"""
|
|
if destination == self.server_name:
|
|
logger.info("Not sending EDU to ourselves")
|
|
return
|
|
|
|
if not self._federation_shard_config.should_handle(
|
|
self._instance_name, destination
|
|
):
|
|
return
|
|
|
|
edu = Edu(
|
|
origin=self.server_name,
|
|
destination=destination,
|
|
edu_type=edu_type,
|
|
content=content,
|
|
)
|
|
|
|
self.send_edu(edu, key)
|
|
|
|
def send_edu(self, edu: Edu, key: Optional[Hashable]):
|
|
"""Queue an EDU for sending
|
|
|
|
Args:
|
|
edu: edu to send
|
|
key: clobbering key for this edu
|
|
"""
|
|
if not self._federation_shard_config.should_handle(
|
|
self._instance_name, edu.destination
|
|
):
|
|
return
|
|
|
|
queue = self._get_per_destination_queue(edu.destination)
|
|
if key:
|
|
queue.send_keyed_edu(edu, key)
|
|
else:
|
|
queue.send_edu(edu)
|
|
|
|
def send_device_messages(self, destination: str):
|
|
if destination == self.server_name:
|
|
logger.warning("Not sending device update to ourselves")
|
|
return
|
|
|
|
if not self._federation_shard_config.should_handle(
|
|
self._instance_name, destination
|
|
):
|
|
return
|
|
|
|
self._get_per_destination_queue(destination).attempt_new_transaction()
|
|
|
|
def wake_destination(self, destination: str):
|
|
"""Called when we want to retry sending transactions to a remote.
|
|
|
|
This is mainly useful if the remote server has been down and we think it
|
|
might have come back.
|
|
"""
|
|
|
|
if destination == self.server_name:
|
|
logger.warning("Not waking up ourselves")
|
|
return
|
|
|
|
if not self._federation_shard_config.should_handle(
|
|
self._instance_name, destination
|
|
):
|
|
return
|
|
|
|
self._get_per_destination_queue(destination).attempt_new_transaction()
|
|
|
|
@staticmethod
|
|
def get_current_token() -> int:
|
|
# Dummy implementation for case where federation sender isn't offloaded
|
|
# to a worker.
|
|
return 0
|
|
|
|
@staticmethod
|
|
async def get_replication_rows(
|
|
instance_name: str, from_token: int, to_token: int, target_row_count: int
|
|
) -> Tuple[List[Tuple[int, Tuple]], int, bool]:
|
|
# Dummy implementation for case where federation sender isn't offloaded
|
|
# to a worker.
|
|
return [], 0, False
|
|
|
|
async def _wake_destinations_needing_catchup(self):
|
|
"""
|
|
Wakes up destinations that need catch-up and are not currently being
|
|
backed off from.
|
|
|
|
In order to reduce load spikes, adds a delay between each destination.
|
|
"""
|
|
|
|
last_processed = None # type: Optional[str]
|
|
|
|
while True:
|
|
destinations_to_wake = await self.store.get_catch_up_outstanding_destinations(
|
|
last_processed
|
|
)
|
|
|
|
if not destinations_to_wake:
|
|
# finished waking all destinations!
|
|
self._catchup_after_startup_timer = None
|
|
break
|
|
|
|
destinations_to_wake = [
|
|
d
|
|
for d in destinations_to_wake
|
|
if self._federation_shard_config.should_handle(self._instance_name, d)
|
|
]
|
|
|
|
for last_processed in destinations_to_wake:
|
|
logger.info(
|
|
"Destination %s has outstanding catch-up, waking up.",
|
|
last_processed,
|
|
)
|
|
self.wake_destination(last_processed)
|
|
await self.clock.sleep(CATCH_UP_STARTUP_INTERVAL_SEC)
|