forked-synapse/synapse/federation/sender/__init__.py
Erik Johnston 197fae1639 Use event streams to calculate presence
Primarily this fixes a bug in the handling of remote users joining a
room where the server sent out the presence for all local users in the
room to all servers in the room.

We also change to using the state delta stream, rather than the
distributor, as it will make it easier to split processing out of the
master process (as well as being more flexible).

Finally, when sending presence states to newly joined servers we filter
out old presence states to reduce the number sent. Initially we filter
out states that are offline and have a last active more than a week ago,
though this can be changed down the line.

Fixes #3962
2019-03-27 13:41:36 +00:00

483 lines
18 KiB
Python

# -*- coding: utf-8 -*-
# Copyright 2019 New Vector Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import logging
from six import itervalues
from prometheus_client import Counter
from twisted.internet import defer
import synapse.metrics
from synapse.federation.sender.per_destination_queue import PerDestinationQueue
from synapse.federation.sender.transaction_manager import TransactionManager
from synapse.federation.units import Edu
from synapse.handlers.presence import get_interested_remotes
from synapse.metrics import (
LaterGauge,
event_processing_loop_counter,
event_processing_loop_room_count,
events_processed_counter,
)
from synapse.metrics.background_process_metrics import run_as_background_process
from synapse.util import logcontext
from synapse.util.metrics import measure_func
logger = logging.getLogger(__name__)
sent_pdus_destination_dist_count = Counter(
"synapse_federation_client_sent_pdu_destinations:count",
"Number of PDUs queued for sending to one or more destinations",
)
sent_pdus_destination_dist_total = Counter(
"synapse_federation_client_sent_pdu_destinations:total", ""
"Total number of PDUs queued for sending across all destinations",
)
class FederationSender(object):
def __init__(self, hs):
self.hs = hs
self.server_name = hs.hostname
self.store = hs.get_datastore()
self.state = hs.get_state_handler()
self.clock = hs.get_clock()
self.is_mine_id = hs.is_mine_id
self._transaction_manager = TransactionManager(hs)
# map from destination to PerDestinationQueue
self._per_destination_queues = {} # type: dict[str, PerDestinationQueue]
LaterGauge(
"synapse_federation_transaction_queue_pending_destinations",
"",
[],
lambda: sum(
1 for d in self._per_destination_queues.values()
if d.transmission_loop_running
),
)
# Map of user_id -> UserPresenceState for all the pending presence
# to be sent out by user_id. Entries here get processed and put in
# pending_presence_by_dest
self.pending_presence = {}
LaterGauge(
"synapse_federation_transaction_queue_pending_pdus",
"",
[],
lambda: sum(
d.pending_pdu_count() for d in self._per_destination_queues.values()
),
)
LaterGauge(
"synapse_federation_transaction_queue_pending_edus",
"",
[],
lambda: sum(
d.pending_edu_count() for d in self._per_destination_queues.values()
),
)
self._order = 1
self._is_processing = False
self._last_poked_id = -1
self._processing_pending_presence = False
# map from room_id to a set of PerDestinationQueues which we believe are
# awaiting a call to flush_read_receipts_for_room. The presence of an entry
# here for a given room means that we are rate-limiting RR flushes to that room,
# and that there is a pending call to _flush_rrs_for_room in the system.
self._queues_awaiting_rr_flush_by_room = {
} # type: dict[str, set[PerDestinationQueue]]
self._rr_txn_interval_per_room_ms = (
1000.0 / hs.get_config().federation_rr_transactions_per_room_per_second
)
def _get_per_destination_queue(self, destination):
"""Get or create a PerDestinationQueue for the given destination
Args:
destination (str): server_name of remote server
Returns:
PerDestinationQueue
"""
queue = self._per_destination_queues.get(destination)
if not queue:
queue = PerDestinationQueue(self.hs, self._transaction_manager, destination)
self._per_destination_queues[destination] = queue
return queue
def notify_new_events(self, current_id):
"""This gets called when we have some new events we might want to
send out to other servers.
"""
self._last_poked_id = max(current_id, self._last_poked_id)
if self._is_processing:
return
# fire off a processing loop in the background
run_as_background_process(
"process_event_queue_for_federation",
self._process_event_queue_loop,
)
@defer.inlineCallbacks
def _process_event_queue_loop(self):
try:
self._is_processing = True
while True:
last_token = yield self.store.get_federation_out_pos("events")
next_token, events = yield self.store.get_all_new_events_stream(
last_token, self._last_poked_id, limit=100,
)
logger.debug("Handling %s -> %s", last_token, next_token)
if not events and next_token >= self._last_poked_id:
break
@defer.inlineCallbacks
def handle_event(event):
# Only send events for this server.
send_on_behalf_of = event.internal_metadata.get_send_on_behalf_of()
is_mine = self.is_mine_id(event.sender)
if not is_mine and send_on_behalf_of is None:
return
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 = yield self.state.get_current_hosts_in_room(
event.room_id, latest_event_ids=event.prev_event_ids(),
)
except Exception:
logger.exception(
"Failed to calculate hosts in room for event: %s",
event.event_id,
)
return
destinations = set(destinations)
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.
destinations.discard(send_on_behalf_of)
logger.debug("Sending %s to %r", event, destinations)
self._send_pdu(event, destinations)
@defer.inlineCallbacks
def handle_room_events(events):
for event in events:
yield handle_event(event)
events_by_room = {}
for event in events:
events_by_room.setdefault(event.room_id, []).append(event)
yield logcontext.make_deferred_yieldable(defer.gatherResults(
[
logcontext.run_in_background(handle_room_events, evs)
for evs in itervalues(events_by_room)
],
consumeErrors=True
))
yield self.store.update_federation_out_pos(
"events", next_token
)
if events:
now = self.clock.time_msec()
ts = yield self.store.get_received_ts(events[-1].event_id)
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(events))
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
def _send_pdu(self, pdu, destinations):
# 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.
order = self._order
self._order += 1
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()
for destination in destinations:
self._get_per_destination_queue(destination).send_pdu(pdu, order)
@defer.inlineCallbacks
def send_read_receipt(self, receipt):
"""Send a RR to any other servers in the room
Args:
receipt (synapse.types.ReadReceipt): 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 = yield self.state.get_current_hosts_in_room(room_id)
domains = [d for d in domains if d != self.server_name]
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, n_domains):
# 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):
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)
@logcontext.preserve_fn # the caller should not yield on this
@defer.inlineCallbacks
def send_presence(self, states):
"""Send the new presence states to the appropriate destinations.
This actually queues up the presence states ready for sending and
triggers a background task to process them and send out the transactions.
Args:
states (list(UserPresenceState))
"""
if not self.hs.config.use_presence:
# No-op if presence is disabled.
return
# First we queue up the new presence by user ID, so multiple presence
# updates in quick succession are correctly handled.
# We only want to send presence for our own users, so lets always just
# filter here just in case.
self.pending_presence.update({
state.user_id: state for state in states
if self.is_mine_id(state.user_id)
})
# We then handle the new pending presence in batches, first figuring
# out the destinations we need to send each state to and then poking it
# to attempt a new transaction. We linearize this so that we don't
# accidentally mess up the ordering and send multiple presence updates
# in the wrong order
if self._processing_pending_presence:
return
self._processing_pending_presence = True
try:
while True:
states_map = self.pending_presence
self.pending_presence = {}
if not states_map:
break
yield self._process_presence_inner(list(states_map.values()))
except Exception:
logger.exception("Error sending presence states to servers")
finally:
self._processing_pending_presence = False
def send_presence_to_destinations(self, states, destinations):
"""Send the given presence states to the given destinations.
Args:
states (list[UserPresenceState])
destinations (list[str])
"""
if not states or not self.hs.config.use_presence:
# No-op if presence is disabled.
return
for destination in destinations:
if destination == self.server_name:
continue
self._get_per_destination_queue(destination).send_presence(states)
@measure_func("txnqueue._process_presence")
@defer.inlineCallbacks
def _process_presence_inner(self, states):
"""Given a list of states populate self.pending_presence_by_dest and
poke to send a new transaction to each destination
Args:
states (list(UserPresenceState))
"""
hosts_and_states = yield 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
self._get_per_destination_queue(destination).send_presence(states)
def build_and_send_edu(self, destination, edu_type, content, key=None):
"""Construct an Edu object, and queue it for sending
Args:
destination (str): name of server to send to
edu_type (str): type of EDU to send
content (dict): content of EDU
key (Any|None): clobbering key for this edu
"""
if destination == self.server_name:
logger.info("Not sending EDU to ourselves")
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, key):
"""Queue an EDU for sending
Args:
edu (Edu): edu to send
key (Any|None): clobbering key for this edu
"""
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):
if destination == self.server_name:
logger.info("Not sending device update to ourselves")
return
self._get_per_destination_queue(destination).attempt_new_transaction()
def get_current_token(self):
return 0