1021 lines
40 KiB
Python
1021 lines
40 KiB
Python
# 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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"""
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The Federation Sender is responsible for sending Persistent Data Units (PDUs)
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and Ephemeral Data Units (EDUs) to other homeservers using
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the `/send` Federation API.
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## How do PDUs get sent?
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The Federation Sender is made aware of new PDUs due to `FederationSender.notify_new_events`.
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When the sender is notified about a newly-persisted PDU that originates from this homeserver
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and is not an out-of-band event, we pass the PDU to the `_PerDestinationQueue` for each
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remote homeserver that is in the room at that point in the DAG.
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### Per-Destination Queues
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There is one `PerDestinationQueue` per 'destination' homeserver.
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The `PerDestinationQueue` maintains the following information about the destination:
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- whether the destination is currently in [catch-up mode (see below)](#catch-up-mode);
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- a queue of PDUs to be sent to the destination; and
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- a queue of EDUs to be sent to the destination (not considered in this section).
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Upon a new PDU being enqueued, `attempt_new_transaction` is called to start a new
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transaction if there is not already one in progress.
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### Transactions and the Transaction Transmission Loop
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Each federation HTTP request to the `/send` endpoint is referred to as a 'transaction'.
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The body of the HTTP request contains a list of PDUs and EDUs to send to the destination.
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The *Transaction Transmission Loop* (`_transaction_transmission_loop`) is responsible
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for emptying the queued PDUs (and EDUs) from a `PerDestinationQueue` by sending
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them to the destination.
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There can only be one transaction in flight for a given destination at any time.
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(Other than preventing us from overloading the destination, this also makes it easier to
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reason about because we process events sequentially for each destination.
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This is useful for *Catch-Up Mode*, described later.)
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The loop continues so long as there is anything to send. At each iteration of the loop, we:
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- dequeue up to 50 PDUs (and up to 100 EDUs).
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- make the `/send` request to the destination homeserver with the dequeued PDUs and EDUs.
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- if successful, make note of the fact that we succeeded in transmitting PDUs up to
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the given `stream_ordering` of the latest PDU by
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- if unsuccessful, back off from the remote homeserver for some time.
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If we have been unsuccessful for too long (when the backoff interval grows to exceed 1 hour),
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the in-memory queues are emptied and we enter [*Catch-Up Mode*, described below](#catch-up-mode).
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### Catch-Up Mode
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When the `PerDestinationQueue` has the catch-up flag set, the *Catch-Up Transmission Loop*
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(`_catch_up_transmission_loop`) is used in lieu of the regular `_transaction_transmission_loop`.
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(Only once the catch-up mode has been exited can the regular transaction transmission behaviour
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be resumed.)
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*Catch-Up Mode*, entered upon Synapse startup or once a homeserver has fallen behind due to
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connection problems, is responsible for sending PDUs that have been missed by the destination
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homeserver. (PDUs can be missed because the `PerDestinationQueue` is volatile — i.e. resets
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on startup — and it does not hold PDUs forever if `/send` requests to the destination fail.)
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The catch-up mechanism makes use of the `last_successful_stream_ordering` column in the
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`destinations` table (which gives the `stream_ordering` of the most recent successfully
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sent PDU) and the `stream_ordering` column in the `destination_rooms` table (which gives,
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for each room, the `stream_ordering` of the most recent PDU that needs to be sent to this
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destination).
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Each iteration of the loop pulls out 50 `destination_rooms` entries with the oldest
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`stream_ordering`s that are greater than the `last_successful_stream_ordering`.
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In other words, from the set of latest PDUs in each room to be sent to the destination,
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the 50 oldest such PDUs are pulled out.
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These PDUs could, in principle, now be directly sent to the destination. However, as an
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optimisation intended to prevent overloading destination homeservers, we instead attempt
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to send the latest forward extremities so long as the destination homeserver is still
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eligible to receive those.
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This reduces load on the destination **in aggregate** because all Synapse homeservers
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will behave according to this principle and therefore avoid sending lots of different PDUs
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at different points in the DAG to a recovering homeserver.
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*This optimisation is not currently valid in rooms which are partial-state on this homeserver,
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since we are unable to determine whether the destination homeserver is eligible to receive
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the latest forward extremities unless this homeserver sent those PDUs — in this case, we
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just send the latest PDUs originating from this server and skip this optimisation.*
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Whilst PDUs are sent through this mechanism, the position of `last_successful_stream_ordering`
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is advanced as normal.
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Once there are no longer any rooms containing outstanding PDUs to be sent to the destination
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*that are not already in the `PerDestinationQueue` because they arrived since Catch-Up Mode
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was enabled*, Catch-Up Mode is exited and we return to `_transaction_transmission_loop`.
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#### A note on failures and back-offs
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If a remote server is unreachable over federation, we back off from that server,
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with an exponentially-increasing retry interval.
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We automatically retry after the retry interval expires (roughly, the logic to do so
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being triggered every minute).
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If the backoff grows too large (> 1 hour), the in-memory queue is emptied (to prevent
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unbounded growth) and Catch-Up Mode is entered.
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It is worth noting that the back-off for a remote server is cleared once an inbound
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request from that remote server is received (see `notify_remote_server_up`).
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At this point, the transaction transmission loop is also started up, to proactively
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send missed PDUs and EDUs to the destination (i.e. you don't need to wait for a new PDU
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or EDU, destined for that destination, to be created in order to send out missed PDUs and
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EDUs).
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"""
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import abc
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import logging
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from collections import OrderedDict
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from typing import (
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TYPE_CHECKING,
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Collection,
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Dict,
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Hashable,
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Iterable,
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List,
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Optional,
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Set,
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Tuple,
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)
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import attr
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from prometheus_client import Counter
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from typing_extensions import Literal
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from twisted.internet import defer
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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 (
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CATCHUP_RETRY_INTERVAL,
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PerDestinationQueue,
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)
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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.logging.context import make_deferred_yieldable, run_in_background
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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 (
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run_as_background_process,
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wrap_as_background_process,
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)
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from synapse.types import JsonDict, ReadReceipt, RoomStreamToken, StrCollection
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from synapse.util import Clock
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from synapse.util.metrics import Measure
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from synapse.util.retryutils import filter_destinations_by_retry_limiter
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if TYPE_CHECKING:
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from synapse.events.presence_router import PresenceRouter
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from synapse.server import HomeServer
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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",
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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) to wait before trying to wake up destinations that have
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# catch-up outstanding. This will also be the delay applied at startup
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# before trying the same.
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# Please note that rate limiting still applies, so while the loop is
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# executed every X seconds the destinations may not be wake up because
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# they are being rate limited following previous attempt failures.
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WAKEUP_RETRY_PERIOD_SEC = 60
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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 until we have woken every destination
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# has outstanding catch-up.
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WAKEUP_INTERVAL_BETWEEN_DESTINATIONS_SEC = 5
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class AbstractFederationSender(metaclass=abc.ABCMeta):
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@abc.abstractmethod
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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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raise NotImplementedError()
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@abc.abstractmethod
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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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raise NotImplementedError()
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@abc.abstractmethod
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async def send_presence_to_destinations(
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self, states: Iterable[UserPresenceState], destinations: Iterable[str]
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) -> None:
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"""Send the given presence states to the given destinations.
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Args:
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destinations:
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"""
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raise NotImplementedError()
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@abc.abstractmethod
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def build_and_send_edu(
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self,
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destination: str,
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edu_type: str,
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content: JsonDict,
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key: Optional[Hashable] = None,
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) -> None:
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"""Construct an Edu object, and queue it for sending
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Args:
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destination: name of server to send to
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edu_type: type of EDU to send
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content: content of EDU
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key: clobbering key for this edu
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"""
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raise NotImplementedError()
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@abc.abstractmethod
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async def send_device_messages(
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self, destinations: StrCollection, immediate: bool = True
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) -> None:
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"""Tells the sender that a new device message is ready to be sent to the
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destinations. The `immediate` flag specifies whether the messages should
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be tried to be sent immediately, or whether it can be delayed for a
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short while (to aid performance).
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"""
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raise NotImplementedError()
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@abc.abstractmethod
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def wake_destination(self, destination: str) -> None:
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"""Called when we want to retry sending transactions to a remote.
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This is mainly useful if the remote server has been down and we think it
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might have come back.
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"""
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raise NotImplementedError()
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@abc.abstractmethod
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def get_current_token(self) -> int:
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raise NotImplementedError()
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@abc.abstractmethod
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def federation_ack(self, instance_name: str, token: int) -> None:
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raise NotImplementedError()
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@abc.abstractmethod
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async def get_replication_rows(
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self, instance_name: str, from_token: int, to_token: int, target_row_count: int
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) -> Tuple[List[Tuple[int, Tuple]], int, bool]:
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raise NotImplementedError()
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@attr.s
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class _DestinationWakeupQueue:
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"""A queue of destinations that need to be woken up due to new updates.
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Staggers waking up of per destination queues to ensure that we don't attempt
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to start TLS connections with many hosts all at once, leading to pinned CPU.
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"""
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# The maximum duration in seconds between queuing up a destination and it
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# being woken up.
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_MAX_TIME_IN_QUEUE = 30.0
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# The maximum duration in seconds between waking up consecutive destination
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# queues.
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_MAX_DELAY = 0.1
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sender: "FederationSender" = attr.ib()
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clock: Clock = attr.ib()
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queue: "OrderedDict[str, Literal[None]]" = attr.ib(factory=OrderedDict)
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processing: bool = attr.ib(default=False)
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def add_to_queue(self, destination: str) -> None:
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"""Add a destination to the queue to be woken up."""
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self.queue[destination] = None
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if not self.processing:
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self._handle()
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@wrap_as_background_process("_DestinationWakeupQueue.handle")
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async def _handle(self) -> None:
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"""Background process to drain the queue."""
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if not self.queue:
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return
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assert not self.processing
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self.processing = True
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try:
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# We start with a delay that should drain the queue quickly enough that
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# we process all destinations in the queue in _MAX_TIME_IN_QUEUE
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# seconds.
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#
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# We also add an upper bound to the delay, to gracefully handle the
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# case where the queue only has a few entries in it.
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current_sleep_seconds = min(
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self._MAX_DELAY, self._MAX_TIME_IN_QUEUE / len(self.queue)
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)
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while self.queue:
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destination, _ = self.queue.popitem(last=False)
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queue = self.sender._get_per_destination_queue(destination)
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if not queue._new_data_to_send:
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# The per destination queue has already been woken up.
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continue
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queue.attempt_new_transaction()
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await self.clock.sleep(current_sleep_seconds)
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if not self.queue:
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break
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# More destinations may have been added to the queue, so we may
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# need to reduce the delay to ensure everything gets processed
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# within _MAX_TIME_IN_QUEUE seconds.
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current_sleep_seconds = min(
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current_sleep_seconds, self._MAX_TIME_IN_QUEUE / len(self.queue)
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)
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finally:
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self.processing = False
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class FederationSender(AbstractFederationSender):
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def __init__(self, hs: "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_datastores().main
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self.state = hs.get_state_handler()
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self._storage_controllers = hs.get_storage_controllers()
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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.is_mine_server_name = hs.is_mine_server_name
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self._presence_router: Optional["PresenceRouter"] = None
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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: 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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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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# 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: Dict[str, Set[PerDestinationQueue]] = {}
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self._rr_txn_interval_per_room_ms = (
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1000.0
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/ hs.config.ratelimiting.federation_rr_transactions_per_room_per_second
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)
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# Regularly wake up destinations that have outstanding PDUs to be caught up
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self.clock.looping_call(
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run_as_background_process,
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WAKEUP_RETRY_PERIOD_SEC * 1000.0,
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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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self._destination_wakeup_queue = _DestinationWakeupQueue(self, self.clock)
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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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(
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next_token,
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event_to_received_ts,
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) = await self.store.get_all_new_event_ids_stream(
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last_token, self._last_poked_id, limit=100
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)
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event_ids = event_to_received_ts.keys()
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event_entries = await self.store.get_unredacted_events_from_cache_or_db(
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event_ids
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)
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logger.debug(
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"Handling %i -> %i: %i events to send (current id %i)",
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last_token,
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next_token,
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len(event_entries),
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self._last_poked_id,
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)
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if not event_entries and next_token >= self._last_poked_id:
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logger.debug("All events processed")
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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)
|
|
if not is_mine and send_on_behalf_of is None:
|
|
logger.debug("Not sending remote-origin event %s", event)
|
|
return
|
|
|
|
# We also want to not send out-of-band membership events.
|
|
#
|
|
# OOB memberships are used in three (and a half) situations:
|
|
#
|
|
# (1) invite events which we have received over federation. Those
|
|
# will have a `sender` on a different server, so will be
|
|
# skipped by the "is_mine" test above anyway.
|
|
#
|
|
# (2) rejections of invites to federated rooms - either remotely
|
|
# or locally generated. (Such rejections are normally
|
|
# created via federation, in which case the remote server is
|
|
# responsible for sending out the rejection. If that fails,
|
|
# we'll create a leave event locally, but that's only really
|
|
# for the benefit of the invited user - we don't have enough
|
|
# information to send it out over federation).
|
|
#
|
|
# (2a) rescinded knocks. These are identical to rejected invites.
|
|
#
|
|
# (3) knock events which we have sent over federation. As with
|
|
# invite rejections, the remote server should send them out to
|
|
# the federation.
|
|
#
|
|
# So, in all the above cases, we want to ignore such events.
|
|
#
|
|
# OOB memberships are always(?) outliers anyway, so if we *don't*
|
|
# ignore them, we'll get an exception further down when we try to
|
|
# fetch the membership list for the room.
|
|
#
|
|
# Arguably, we could equivalently ignore all outliers here, since
|
|
# in theory the only way for an outlier with a local `sender` to
|
|
# exist is by being an OOB membership (via one of (2), (2a) or (3)
|
|
# above).
|
|
#
|
|
if event.internal_metadata.is_out_of_band_membership():
|
|
logger.debug("Not sending OOB membership event %s", event)
|
|
return
|
|
|
|
# Finally, there are some other events that we should not send out
|
|
# until someone asks for them. They are explicitly flagged as such
|
|
# with `proactively_send: False`.
|
|
if not event.internal_metadata.should_proactively_send():
|
|
logger.debug(
|
|
"Not sending event with proactively_send=false: %s", event
|
|
)
|
|
return
|
|
|
|
destinations: Optional[Collection[str]] = None
|
|
if not event.prev_event_ids():
|
|
# If there are no prev event IDs then the state is empty
|
|
# and so no remote servers in the room
|
|
destinations = set()
|
|
|
|
if destinations is None:
|
|
# During partial join we use the set of servers that we got
|
|
# when beginning the join. It's still possible that we send
|
|
# events to servers that left the room in the meantime, but
|
|
# we consider that an acceptable risk since it is only our own
|
|
# events that we leak and not other server's ones.
|
|
partial_state_destinations = (
|
|
await self.store.get_partial_state_servers_at_join(
|
|
event.room_id
|
|
)
|
|
)
|
|
|
|
if partial_state_destinations is not None:
|
|
destinations = partial_state_destinations
|
|
|
|
if destinations is None:
|
|
# We check the external cache for the destinations, which is
|
|
# stored per state group.
|
|
|
|
sg = await self._external_cache.get(
|
|
"event_to_prev_state_group", event.event_id
|
|
)
|
|
if sg:
|
|
destinations = await self._external_cache.get(
|
|
"get_joined_hosts", str(sg)
|
|
)
|
|
if destinations is None:
|
|
# Add logging to help track down #13444
|
|
logger.info(
|
|
"Unexpectedly did not have cached destinations for %s / %s",
|
|
sg,
|
|
event.event_id,
|
|
)
|
|
else:
|
|
# Add logging to help track down #13444
|
|
logger.info(
|
|
"Unexpectedly did not have cached prev group for %s",
|
|
event.event_id,
|
|
)
|
|
|
|
if destinations is None:
|
|
try:
|
|
# Get the state from before the event.
|
|
# We need to make sure that this is the state from before
|
|
# the event and not from after it.
|
|
# Otherwise if the last member on a server in a room is
|
|
# banned then it won't receive the event because it won't
|
|
# be in the room after the ban.
|
|
destinations = await self.state.get_hosts_in_room_at_events(
|
|
event.room_id, event_ids=event.prev_event_ids()
|
|
)
|
|
except Exception:
|
|
logger.exception(
|
|
"Failed to calculate hosts in room for event: %s",
|
|
event.event_id,
|
|
)
|
|
return
|
|
|
|
sharded_destinations = {
|
|
d
|
|
for d in destinations
|
|
if self._federation_shard_config.should_handle(
|
|
self._instance_name, d
|
|
)
|
|
}
|
|
|
|
if send_on_behalf_of is not None:
|
|
# If we are sending the event on behalf of another server
|
|
# then it already has the event and there is no reason to
|
|
# send the event to it.
|
|
sharded_destinations.discard(send_on_behalf_of)
|
|
|
|
logger.debug("Sending %s to %r", event, sharded_destinations)
|
|
|
|
if sharded_destinations:
|
|
await self._send_pdu(event, sharded_destinations)
|
|
|
|
now = self.clock.time_msec()
|
|
ts = event_to_received_ts[event.event_id]
|
|
assert ts is not None
|
|
synapse.metrics.event_processing_lag_by_event.labels(
|
|
"federation_sender"
|
|
).observe((now - ts) / 1000)
|
|
|
|
async def handle_room_events(events: List[EventBase]) -> None:
|
|
logger.debug(
|
|
"Handling %i events in room %s", len(events), events[0].room_id
|
|
)
|
|
with Measure(self.clock, "handle_room_events"):
|
|
for event in events:
|
|
await handle_event(event)
|
|
|
|
events_by_room: Dict[str, List[EventBase]] = {}
|
|
|
|
for event_id in event_ids:
|
|
# `event_entries` is unsorted, so we have to iterate over `event_ids`
|
|
# to ensure the events are in the right order
|
|
event_cache = event_entries.get(event_id)
|
|
if event_cache:
|
|
event = event_cache.event
|
|
events_by_room.setdefault(event.room_id, []).append(event)
|
|
|
|
await make_deferred_yieldable(
|
|
defer.gatherResults(
|
|
[
|
|
run_in_background(handle_room_events, evs)
|
|
for evs in events_by_room.values()
|
|
],
|
|
consumeErrors=True,
|
|
)
|
|
)
|
|
|
|
logger.debug("Successfully handled up to %i", next_token)
|
|
await self.store.update_federation_out_pos("events", next_token)
|
|
|
|
if event_entries:
|
|
now = self.clock.time_msec()
|
|
ts = max(t for t in event_to_received_ts.values() if t)
|
|
assert ts is not None
|
|
|
|
synapse.metrics.event_processing_lag.labels(
|
|
"federation_sender"
|
|
).set(now - ts)
|
|
synapse.metrics.event_processing_last_ts.labels(
|
|
"federation_sender"
|
|
).set(ts)
|
|
|
|
events_processed_counter.inc(len(event_entries))
|
|
|
|
event_processing_loop_room_count.labels("federation_sender").inc(
|
|
len(events_by_room)
|
|
)
|
|
|
|
event_processing_loop_counter.labels("federation_sender").inc()
|
|
|
|
synapse.metrics.event_processing_positions.labels(
|
|
"federation_sender"
|
|
).set(next_token)
|
|
|
|
finally:
|
|
self._is_processing = False
|
|
|
|
async def _send_pdu(self, pdu: EventBase, destinations: Iterable[str]) -> None:
|
|
# We loop through all destinations to see whether we already have
|
|
# a transaction in progress. If we do, stick it in the pending_pdus
|
|
# table and we'll get back to it later.
|
|
|
|
destinations = set(destinations)
|
|
destinations.discard(self.server_name)
|
|
logger.debug("Sending to: %s", str(destinations))
|
|
|
|
if not destinations:
|
|
return
|
|
|
|
sent_pdus_destination_dist_total.inc(len(destinations))
|
|
sent_pdus_destination_dist_count.inc()
|
|
|
|
assert pdu.internal_metadata.stream_ordering
|
|
|
|
# track the fact that we have a PDU for these destinations,
|
|
# to allow us to perform catch-up later on if the remote is unreachable
|
|
# for a while.
|
|
await self.store.store_destination_rooms_entries(
|
|
destinations,
|
|
pdu.room_id,
|
|
pdu.internal_metadata.stream_ordering,
|
|
)
|
|
|
|
destinations = await filter_destinations_by_retry_limiter(
|
|
destinations,
|
|
clock=self.clock,
|
|
store=self.store,
|
|
retry_due_within_ms=CATCHUP_RETRY_INTERVAL,
|
|
)
|
|
|
|
for destination in destinations:
|
|
self._get_per_destination_queue(destination).send_pdu(pdu)
|
|
|
|
async def send_read_receipt(self, receipt: ReadReceipt) -> None:
|
|
"""Send a RR to any other servers in the room
|
|
|
|
Args:
|
|
receipt: receipt to be sent
|
|
"""
|
|
|
|
# Some background on the rate-limiting going on here.
|
|
#
|
|
# It turns out that if we attempt to send out RRs as soon as we get them from
|
|
# a client, then we end up trying to do several hundred Hz of federation
|
|
# transactions. (The number of transactions scales as O(N^2) on the size of a
|
|
# room, since in a large room we have both more RRs coming in, and more servers
|
|
# to send them to.)
|
|
#
|
|
# This leads to a lot of CPU load, and we end up getting behind. The solution
|
|
# currently adopted is as follows:
|
|
#
|
|
# The first receipt in a given room is sent out immediately, at time T0. Any
|
|
# further receipts are, in theory, batched up for N seconds, where N is calculated
|
|
# based on the number of servers in the room to achieve a transaction frequency
|
|
# of around 50Hz. So, for example, if there were 100 servers in the room, then
|
|
# N would be 100 / 50Hz = 2 seconds.
|
|
#
|
|
# Then, after T+N, we flush out any receipts that have accumulated, and restart
|
|
# the timer to flush out more receipts at T+2N, etc. If no receipts accumulate,
|
|
# we stop the cycle and go back to the start.
|
|
#
|
|
# However, in practice, it is often possible to flush out receipts earlier: in
|
|
# particular, if we are sending a transaction to a given server anyway (for
|
|
# example, because we have a PDU or a RR in another room to send), then we may
|
|
# as well send out all of the pending RRs for that server. So it may be that
|
|
# by the time we get to T+N, we don't actually have any RRs left to send out.
|
|
# Nevertheless we continue to buffer up RRs for the room in question until we
|
|
# reach the point that no RRs arrive between timer ticks.
|
|
#
|
|
# For even more background, see https://github.com/matrix-org/synapse/issues/4730.
|
|
|
|
room_id = receipt.room_id
|
|
|
|
# Work out which remote servers should be poked and poke them.
|
|
domains_set = await self._storage_controllers.state.get_current_hosts_in_room_or_partial_state_approximation(
|
|
room_id
|
|
)
|
|
domains: StrCollection = [
|
|
d
|
|
for d in domains_set
|
|
if not self.is_mine_server_name(d)
|
|
and self._federation_shard_config.should_handle(self._instance_name, d)
|
|
]
|
|
|
|
domains = await filter_destinations_by_retry_limiter(
|
|
domains,
|
|
clock=self.clock,
|
|
store=self.store,
|
|
retry_due_within_ms=CATCHUP_RETRY_INTERVAL,
|
|
)
|
|
|
|
if not domains:
|
|
return
|
|
|
|
queues_pending_flush = self._queues_awaiting_rr_flush_by_room.get(room_id)
|
|
|
|
# if there is no flush yet scheduled, we will send out these receipts with
|
|
# immediate flushes, and schedule the next flush for this room.
|
|
if queues_pending_flush is not None:
|
|
logger.debug("Queuing receipt for: %r", domains)
|
|
else:
|
|
logger.debug("Sending receipt to: %r", domains)
|
|
self._schedule_rr_flush_for_room(room_id, len(domains))
|
|
|
|
for domain in domains:
|
|
queue = self._get_per_destination_queue(domain)
|
|
queue.queue_read_receipt(receipt)
|
|
|
|
# if there is already a RR flush pending for this room, then make sure this
|
|
# destination is registered for the flush
|
|
if queues_pending_flush is not None:
|
|
queues_pending_flush.add(queue)
|
|
else:
|
|
queue.flush_read_receipts_for_room(room_id)
|
|
|
|
def _schedule_rr_flush_for_room(self, room_id: str, n_domains: int) -> None:
|
|
# that is going to cause approximately len(domains) transactions, so now back
|
|
# off for that multiplied by RR_TXN_INTERVAL_PER_ROOM
|
|
backoff_ms = self._rr_txn_interval_per_room_ms * n_domains
|
|
|
|
logger.debug("Scheduling RR flush in %s in %d ms", room_id, backoff_ms)
|
|
self.clock.call_later(backoff_ms, self._flush_rrs_for_room, room_id)
|
|
self._queues_awaiting_rr_flush_by_room[room_id] = set()
|
|
|
|
def _flush_rrs_for_room(self, room_id: str) -> None:
|
|
queues = self._queues_awaiting_rr_flush_by_room.pop(room_id)
|
|
logger.debug("Flushing RRs in %s to %s", room_id, queues)
|
|
|
|
if not queues:
|
|
# no more RRs arrived for this room; we are done.
|
|
return
|
|
|
|
# schedule the next flush
|
|
self._schedule_rr_flush_for_room(room_id, len(queues))
|
|
|
|
for queue in queues:
|
|
queue.flush_read_receipts_for_room(room_id)
|
|
|
|
async def send_presence_to_destinations(
|
|
self, states: Iterable[UserPresenceState], destinations: Iterable[str]
|
|
) -> None:
|
|
"""Send the given presence states to the given destinations.
|
|
destinations (list[str])
|
|
"""
|
|
|
|
if not states or not self.hs.config.server.track_presence:
|
|
# No-op if presence is disabled.
|
|
return
|
|
|
|
# Ensure we only send out presence states for local users.
|
|
for state in states:
|
|
assert self.is_mine_id(state.user_id)
|
|
|
|
destinations = await filter_destinations_by_retry_limiter(
|
|
[
|
|
d
|
|
for d in destinations
|
|
if self._federation_shard_config.should_handle(self._instance_name, d)
|
|
],
|
|
clock=self.clock,
|
|
store=self.store,
|
|
retry_due_within_ms=CATCHUP_RETRY_INTERVAL,
|
|
)
|
|
|
|
for destination in destinations:
|
|
if self.is_mine_server_name(destination):
|
|
continue
|
|
|
|
self._get_per_destination_queue(destination).send_presence(
|
|
states, start_loop=False
|
|
)
|
|
|
|
self._destination_wakeup_queue.add_to_queue(destination)
|
|
|
|
def build_and_send_edu(
|
|
self,
|
|
destination: str,
|
|
edu_type: str,
|
|
content: JsonDict,
|
|
key: Optional[Hashable] = None,
|
|
) -> 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 self.is_mine_server_name(destination):
|
|
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]) -> None:
|
|
"""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)
|
|
|
|
async def send_device_messages(
|
|
self, destinations: StrCollection, immediate: bool = True
|
|
) -> None:
|
|
destinations = await filter_destinations_by_retry_limiter(
|
|
[
|
|
destination
|
|
for destination in destinations
|
|
if self._federation_shard_config.should_handle(
|
|
self._instance_name, destination
|
|
)
|
|
and not self.is_mine_server_name(destination)
|
|
],
|
|
clock=self.clock,
|
|
store=self.store,
|
|
retry_due_within_ms=CATCHUP_RETRY_INTERVAL,
|
|
)
|
|
|
|
for destination in destinations:
|
|
if immediate:
|
|
self._get_per_destination_queue(destination).attempt_new_transaction()
|
|
else:
|
|
self._get_per_destination_queue(destination).mark_new_data()
|
|
self._destination_wakeup_queue.add_to_queue(destination)
|
|
|
|
def wake_destination(self, destination: str) -> None:
|
|
"""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 self.is_mine_server_name(destination):
|
|
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
|
|
|
|
def federation_ack(self, instance_name: str, token: int) -> None:
|
|
# It is not expected that this gets called on FederationSender.
|
|
raise NotImplementedError()
|
|
|
|
@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) -> None:
|
|
"""
|
|
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: Optional[str] = None
|
|
|
|
while True:
|
|
destinations_to_wake = (
|
|
await self.store.get_catch_up_outstanding_destinations(last_processed)
|
|
)
|
|
|
|
if not destinations_to_wake:
|
|
# finished waking all destinations!
|
|
break
|
|
|
|
last_processed = destinations_to_wake[-1]
|
|
|
|
destinations_to_wake = [
|
|
d
|
|
for d in destinations_to_wake
|
|
if self._federation_shard_config.should_handle(self._instance_name, d)
|
|
]
|
|
|
|
for destination in destinations_to_wake:
|
|
logger.info(
|
|
"Destination %s has outstanding catch-up, waking up.",
|
|
last_processed,
|
|
)
|
|
self.wake_destination(destination)
|
|
await self.clock.sleep(WAKEUP_INTERVAL_BETWEEN_DESTINATIONS_SEC)
|