806 lines
30 KiB
Python
806 lines
30 KiB
Python
# Copyright 2017 Vector Creations Ltd
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# Copyright 2020, 2022 The Matrix.org Foundation C.I.C.
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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 (
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TYPE_CHECKING,
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Any,
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Awaitable,
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Dict,
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Iterable,
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Iterator,
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List,
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Optional,
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Set,
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Tuple,
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TypeVar,
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Union,
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)
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from prometheus_client import Counter
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from typing_extensions import Deque
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from twisted.internet.protocol import ReconnectingClientFactory
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from synapse.metrics import LaterGauge
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from synapse.metrics.background_process_metrics import run_as_background_process
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from synapse.replication.tcp.commands import (
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ClearUserSyncsCommand,
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Command,
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FederationAckCommand,
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PositionCommand,
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RdataCommand,
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RemoteServerUpCommand,
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ReplicateCommand,
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UserIpCommand,
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UserSyncCommand,
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)
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from synapse.replication.tcp.protocol import IReplicationConnection
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from synapse.replication.tcp.streams import (
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STREAMS_MAP,
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AccountDataStream,
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BackfillStream,
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CachesStream,
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EventsStream,
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FederationStream,
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PresenceFederationStream,
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PresenceStream,
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ReceiptsStream,
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Stream,
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ToDeviceStream,
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TypingStream,
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)
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if TYPE_CHECKING:
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from synapse.server import HomeServer
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logger = logging.getLogger(__name__)
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# number of updates received for each RDATA stream
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inbound_rdata_count = Counter(
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"synapse_replication_tcp_protocol_inbound_rdata_count", "", ["stream_name"]
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)
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user_sync_counter = Counter("synapse_replication_tcp_resource_user_sync", "")
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federation_ack_counter = Counter("synapse_replication_tcp_resource_federation_ack", "")
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remove_pusher_counter = Counter("synapse_replication_tcp_resource_remove_pusher", "")
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user_ip_cache_counter = Counter("synapse_replication_tcp_resource_user_ip_cache", "")
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# the type of the entries in _command_queues_by_stream
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_StreamCommandQueue = Deque[
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Tuple[Union[RdataCommand, PositionCommand], IReplicationConnection]
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]
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class ReplicationCommandHandler:
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"""Handles incoming commands from replication as well as sending commands
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back out to connections.
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"""
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def __init__(self, hs: "HomeServer"):
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self._replication_data_handler = hs.get_replication_data_handler()
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self._presence_handler = hs.get_presence_handler()
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self._store = hs.get_datastores().main
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self._notifier = hs.get_notifier()
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self._clock = hs.get_clock()
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self._instance_id = hs.get_instance_id()
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self._instance_name = hs.get_instance_name()
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# Additional Redis channel suffixes to subscribe to.
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self._channels_to_subscribe_to: List[str] = []
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self._is_presence_writer = (
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hs.get_instance_name() in hs.config.worker.writers.presence
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)
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self._streams: Dict[str, Stream] = {
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stream.NAME: stream(hs) for stream in STREAMS_MAP.values()
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}
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# List of streams that this instance is the source of
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self._streams_to_replicate: List[Stream] = []
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for stream in self._streams.values():
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if hs.config.redis.redis_enabled and stream.NAME == CachesStream.NAME:
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# All workers can write to the cache invalidation stream when
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# using redis.
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self._streams_to_replicate.append(stream)
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continue
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if isinstance(stream, (EventsStream, BackfillStream)):
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# Only add EventStream and BackfillStream as a source on the
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# instance in charge of event persistence.
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if hs.get_instance_name() in hs.config.worker.writers.events:
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self._streams_to_replicate.append(stream)
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continue
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if isinstance(stream, ToDeviceStream):
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# Only add ToDeviceStream as a source on instances in charge of
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# sending to device messages.
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if hs.get_instance_name() in hs.config.worker.writers.to_device:
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self._streams_to_replicate.append(stream)
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continue
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if isinstance(stream, TypingStream):
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# Only add TypingStream as a source on the instance in charge of
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# typing.
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if hs.get_instance_name() in hs.config.worker.writers.typing:
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self._streams_to_replicate.append(stream)
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continue
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if isinstance(stream, AccountDataStream):
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# Only add AccountDataStream and TagAccountDataStream as a source on the
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# instance in charge of account_data persistence.
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if hs.get_instance_name() in hs.config.worker.writers.account_data:
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self._streams_to_replicate.append(stream)
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continue
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if isinstance(stream, ReceiptsStream):
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# Only add ReceiptsStream as a source on the instance in charge of
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# receipts.
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if hs.get_instance_name() in hs.config.worker.writers.receipts:
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self._streams_to_replicate.append(stream)
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continue
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if isinstance(stream, (PresenceStream, PresenceFederationStream)):
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# Only add PresenceStream as a source on the instance in charge
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# of presence.
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if self._is_presence_writer:
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self._streams_to_replicate.append(stream)
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continue
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# Only add any other streams if we're on master.
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if hs.config.worker.worker_app is not None:
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continue
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if (
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stream.NAME == FederationStream.NAME
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and hs.config.worker.send_federation
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):
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# We only support federation stream if federation sending
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# has been disabled on the master.
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continue
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self._streams_to_replicate.append(stream)
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# Map of stream name to batched updates. See RdataCommand for info on
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# how batching works.
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self._pending_batches: Dict[str, List[Any]] = {}
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# The factory used to create connections.
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self._factory: Optional[ReconnectingClientFactory] = None
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# The currently connected connections. (The list of places we need to send
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# outgoing replication commands to.)
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self._connections: List[IReplicationConnection] = []
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LaterGauge(
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"synapse_replication_tcp_resource_total_connections",
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"",
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[],
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lambda: len(self._connections),
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)
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# When POSITION or RDATA commands arrive, we stick them in a queue and process
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# them in order in a separate background process.
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# the streams which are currently being processed by _unsafe_process_queue
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self._processing_streams: Set[str] = set()
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# for each stream, a queue of commands that are awaiting processing, and the
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# connection that they arrived on.
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self._command_queues_by_stream = {
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stream_name: _StreamCommandQueue() for stream_name in self._streams
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}
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# For each connection, the incoming stream names that have received a POSITION
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# from that connection.
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self._streams_by_connection: Dict[IReplicationConnection, Set[str]] = {}
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LaterGauge(
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"synapse_replication_tcp_command_queue",
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"Number of inbound RDATA/POSITION commands queued for processing",
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["stream_name"],
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lambda: {
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(stream_name,): len(queue)
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for stream_name, queue in self._command_queues_by_stream.items()
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},
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)
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self._is_master = hs.config.worker.worker_app is None
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self._federation_sender = None
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if self._is_master and not hs.config.worker.send_federation:
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self._federation_sender = hs.get_federation_sender()
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self._server_notices_sender = None
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if self._is_master:
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self._server_notices_sender = hs.get_server_notices_sender()
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if hs.config.redis.redis_enabled:
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# If we're using Redis, it's the background worker that should
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# receive USER_IP commands and store the relevant client IPs.
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self._should_insert_client_ips = hs.config.worker.run_background_tasks
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else:
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# If we're NOT using Redis, this must be handled by the master
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self._should_insert_client_ips = hs.get_instance_name() == "master"
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if self._is_master or self._should_insert_client_ips:
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self.subscribe_to_channel("USER_IP")
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def subscribe_to_channel(self, channel_name: str) -> None:
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"""
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Indicates that we wish to subscribe to a Redis channel by name.
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(The name will later be prefixed with the server name; i.e. subscribing
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to the 'ABC' channel actually subscribes to 'example.com/ABC' Redis-side.)
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Raises:
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- If replication has already started, then it's too late to subscribe
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to new channels.
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"""
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if self._factory is not None:
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# We don't allow subscribing after the fact to avoid the chance
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# of missing an important message because we didn't subscribe in time.
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raise RuntimeError(
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"Cannot subscribe to more channels after replication started."
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)
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if channel_name not in self._channels_to_subscribe_to:
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self._channels_to_subscribe_to.append(channel_name)
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def _add_command_to_stream_queue(
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self, conn: IReplicationConnection, cmd: Union[RdataCommand, PositionCommand]
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) -> None:
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"""Queue the given received command for processing
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Adds the given command to the per-stream queue, and processes the queue if
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necessary
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"""
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stream_name = cmd.stream_name
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queue = self._command_queues_by_stream.get(stream_name)
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if queue is None:
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logger.error("Got %s for unknown stream: %s", cmd.NAME, stream_name)
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return
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queue.append((cmd, conn))
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# if we're already processing this stream, there's nothing more to do:
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# the new entry on the queue will get picked up in due course
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if stream_name in self._processing_streams:
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return
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# fire off a background process to start processing the queue.
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run_as_background_process(
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"process-replication-data", self._unsafe_process_queue, stream_name
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)
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async def _unsafe_process_queue(self, stream_name: str) -> None:
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"""Processes the command queue for the given stream, until it is empty
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Does not check if there is already a thread processing the queue, hence "unsafe"
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"""
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assert stream_name not in self._processing_streams
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self._processing_streams.add(stream_name)
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try:
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queue = self._command_queues_by_stream.get(stream_name)
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while queue:
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cmd, conn = queue.popleft()
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try:
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await self._process_command(cmd, conn, stream_name)
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except Exception:
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logger.exception("Failed to handle command %s", cmd)
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finally:
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self._processing_streams.discard(stream_name)
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async def _process_command(
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self,
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cmd: Union[PositionCommand, RdataCommand],
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conn: IReplicationConnection,
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stream_name: str,
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) -> None:
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if isinstance(cmd, PositionCommand):
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await self._process_position(stream_name, conn, cmd)
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elif isinstance(cmd, RdataCommand):
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await self._process_rdata(stream_name, conn, cmd)
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else:
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# This shouldn't be possible
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raise Exception("Unrecognised command %s in stream queue", cmd.NAME)
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def start_replication(self, hs: "HomeServer") -> None:
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"""Helper method to start replication."""
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from synapse.replication.tcp.redis import RedisDirectTcpReplicationClientFactory
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# First let's ensure that we have a ReplicationStreamer started.
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hs.get_replication_streamer()
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# We need two connections to redis, one for the subscription stream and
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# one to send commands to (as you can't send further redis commands to a
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# connection after SUBSCRIBE is called).
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# First create the connection for sending commands.
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outbound_redis_connection = hs.get_outbound_redis_connection()
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# Now create the factory/connection for the subscription stream.
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self._factory = RedisDirectTcpReplicationClientFactory(
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hs,
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outbound_redis_connection,
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channel_names=self._channels_to_subscribe_to,
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)
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hs.get_reactor().connectTCP(
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hs.config.redis.redis_host,
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hs.config.redis.redis_port,
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self._factory,
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timeout=30,
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bindAddress=None,
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)
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def get_streams(self) -> Dict[str, Stream]:
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"""Get a map from stream name to all streams."""
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return self._streams
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def get_streams_to_replicate(self) -> List[Stream]:
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"""Get a list of streams that this instances replicates."""
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return self._streams_to_replicate
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def on_REPLICATE(self, conn: IReplicationConnection, cmd: ReplicateCommand) -> None:
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self.send_positions_to_connection(conn)
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def send_positions_to_connection(self, conn: IReplicationConnection) -> None:
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"""Send current position of all streams this process is source of to
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the connection.
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"""
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# We respond with current position of all streams this instance
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# replicates.
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for stream in self.get_streams_to_replicate():
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# Note that we use the current token as the prev token here (rather
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# than stream.last_token), as we can't be sure that there have been
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# no rows written between last token and the current token (since we
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# might be racing with the replication sending bg process).
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current_token = stream.current_token(self._instance_name)
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self.send_command(
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PositionCommand(
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stream.NAME,
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self._instance_name,
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current_token,
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current_token,
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)
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)
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def on_USER_SYNC(
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self, conn: IReplicationConnection, cmd: UserSyncCommand
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) -> Optional[Awaitable[None]]:
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user_sync_counter.inc()
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if self._is_presence_writer:
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return self._presence_handler.update_external_syncs_row(
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cmd.instance_id, cmd.user_id, cmd.is_syncing, cmd.last_sync_ms
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)
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else:
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return None
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def on_CLEAR_USER_SYNC(
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self, conn: IReplicationConnection, cmd: ClearUserSyncsCommand
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) -> Optional[Awaitable[None]]:
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if self._is_presence_writer:
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return self._presence_handler.update_external_syncs_clear(cmd.instance_id)
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else:
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return None
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def on_FEDERATION_ACK(
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self, conn: IReplicationConnection, cmd: FederationAckCommand
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) -> None:
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federation_ack_counter.inc()
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if self._federation_sender:
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self._federation_sender.federation_ack(cmd.instance_name, cmd.token)
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def on_USER_IP(
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self, conn: IReplicationConnection, cmd: UserIpCommand
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) -> Optional[Awaitable[None]]:
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user_ip_cache_counter.inc()
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if self._is_master or self._should_insert_client_ips:
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# We make a point of only returning an awaitable if there's actually
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# something to do; on_USER_IP is not an async function, but
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# _handle_user_ip is.
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# If on_USER_IP returns an awaitable, it gets scheduled as a
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# background process (see `BaseReplicationStreamProtocol.handle_command`).
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return self._handle_user_ip(cmd)
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else:
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# Returning None when this process definitely has nothing to do
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# reduces the overhead of handling the USER_IP command, which is
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# currently broadcast to all workers regardless of utility.
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return None
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async def _handle_user_ip(self, cmd: UserIpCommand) -> None:
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"""
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Handles a User IP, branching depending on whether we are the main process
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and/or the background worker.
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"""
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if self._is_master:
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assert self._server_notices_sender is not None
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await self._server_notices_sender.on_user_ip(cmd.user_id)
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if self._should_insert_client_ips:
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await self._store.insert_client_ip(
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cmd.user_id,
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cmd.access_token,
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cmd.ip,
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cmd.user_agent,
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cmd.device_id,
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cmd.last_seen,
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)
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def on_RDATA(self, conn: IReplicationConnection, cmd: RdataCommand) -> None:
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if cmd.instance_name == self._instance_name:
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# Ignore RDATA that are just our own echoes
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return
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stream_name = cmd.stream_name
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inbound_rdata_count.labels(stream_name).inc()
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# We put the received command into a queue here for two reasons:
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# 1. so we don't try and concurrently handle multiple rows for the
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# same stream, and
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# 2. so we don't race with getting a POSITION command and fetching
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# missing RDATA.
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self._add_command_to_stream_queue(conn, cmd)
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async def _process_rdata(
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self, stream_name: str, conn: IReplicationConnection, cmd: RdataCommand
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) -> None:
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"""Process an RDATA command
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Called after the command has been popped off the queue of inbound commands
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"""
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try:
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row = STREAMS_MAP[stream_name].parse_row(cmd.row)
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except Exception as e:
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raise Exception(
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"Failed to parse RDATA: %r %r" % (stream_name, cmd.row)
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) from e
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# make sure that we've processed a POSITION for this stream *on this
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# connection*. (A POSITION on another connection is no good, as there
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# is no guarantee that we have seen all the intermediate updates.)
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sbc = self._streams_by_connection.get(conn)
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if not sbc or stream_name not in sbc:
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# Let's drop the row for now, on the assumption we'll receive a
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# `POSITION` soon and we'll catch up correctly then.
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logger.debug(
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"Discarding RDATA for unconnected stream %s -> %s",
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stream_name,
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cmd.token,
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)
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return
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if cmd.token is None:
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# I.e. this is part of a batch of updates for this stream (in
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# which case batch until we get an update for the stream with a non
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# None token).
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self._pending_batches.setdefault(stream_name, []).append(row)
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return
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# Check if this is the last of a batch of updates
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rows = self._pending_batches.pop(stream_name, [])
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rows.append(row)
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stream = self._streams[stream_name]
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# Find where we previously streamed up to.
|
|
current_token = stream.current_token(cmd.instance_name)
|
|
|
|
# Discard this data if this token is earlier than the current
|
|
# position. Note that streams can be reset (in which case you
|
|
# expect an earlier token), but that must be preceded by a
|
|
# POSITION command.
|
|
if cmd.token <= current_token:
|
|
logger.debug(
|
|
"Discarding RDATA from stream %s at position %s before previous position %s",
|
|
stream_name,
|
|
cmd.token,
|
|
current_token,
|
|
)
|
|
else:
|
|
await self.on_rdata(stream_name, cmd.instance_name, cmd.token, rows)
|
|
|
|
async def on_rdata(
|
|
self, stream_name: str, instance_name: str, token: int, rows: list
|
|
) -> None:
|
|
"""Called to handle a batch of replication data with a given stream token.
|
|
|
|
Args:
|
|
stream_name: name of the replication stream for this batch of rows
|
|
instance_name: the instance that wrote the rows.
|
|
token: stream token for this batch of rows
|
|
rows: a list of Stream.ROW_TYPE objects as returned by
|
|
Stream.parse_row.
|
|
"""
|
|
logger.debug("Received rdata %s (%s) -> %s", stream_name, instance_name, token)
|
|
await self._replication_data_handler.on_rdata(
|
|
stream_name, instance_name, token, rows
|
|
)
|
|
|
|
def on_POSITION(self, conn: IReplicationConnection, cmd: PositionCommand) -> None:
|
|
if cmd.instance_name == self._instance_name:
|
|
# Ignore POSITION that are just our own echoes
|
|
return
|
|
|
|
logger.debug("Handling '%s %s'", cmd.NAME, cmd.to_line())
|
|
|
|
self._add_command_to_stream_queue(conn, cmd)
|
|
|
|
async def _process_position(
|
|
self, stream_name: str, conn: IReplicationConnection, cmd: PositionCommand
|
|
) -> None:
|
|
"""Process a POSITION command
|
|
|
|
Called after the command has been popped off the queue of inbound commands
|
|
"""
|
|
stream = self._streams[stream_name]
|
|
|
|
# We're about to go and catch up with the stream, so remove from set
|
|
# of connected streams.
|
|
for streams in self._streams_by_connection.values():
|
|
streams.discard(stream_name)
|
|
|
|
# We clear the pending batches for the stream as the fetching of the
|
|
# missing updates below will fetch all rows in the batch.
|
|
self._pending_batches.pop(stream_name, [])
|
|
|
|
# Find where we previously streamed up to.
|
|
current_token = stream.current_token(cmd.instance_name)
|
|
|
|
# If the position token matches our current token then we're up to
|
|
# date and there's nothing to do. Otherwise, fetch all updates
|
|
# between then and now.
|
|
missing_updates = cmd.prev_token != current_token
|
|
while missing_updates:
|
|
# Note: There may very well not be any new updates, but we check to
|
|
# make sure. This can particularly happen for the event stream where
|
|
# event persisters continuously send `POSITION`. See `resource.py`
|
|
# for why this can happen.
|
|
|
|
logger.info(
|
|
"Fetching replication rows for '%s' between %i and %i",
|
|
stream_name,
|
|
current_token,
|
|
cmd.new_token,
|
|
)
|
|
(updates, current_token, missing_updates) = await stream.get_updates_since(
|
|
cmd.instance_name, current_token, cmd.new_token
|
|
)
|
|
|
|
# TODO: add some tests for this
|
|
|
|
# Some streams return multiple rows with the same stream IDs,
|
|
# which need to be processed in batches.
|
|
|
|
for token, rows in _batch_updates(updates):
|
|
await self.on_rdata(
|
|
stream_name,
|
|
cmd.instance_name,
|
|
token,
|
|
[stream.parse_row(row) for row in rows],
|
|
)
|
|
|
|
logger.info("Caught up with stream '%s' to %i", stream_name, cmd.new_token)
|
|
|
|
# We've now caught up to position sent to us, notify handler.
|
|
await self._replication_data_handler.on_position(
|
|
cmd.stream_name, cmd.instance_name, cmd.new_token
|
|
)
|
|
|
|
self._streams_by_connection.setdefault(conn, set()).add(stream_name)
|
|
|
|
def on_REMOTE_SERVER_UP(
|
|
self, conn: IReplicationConnection, cmd: RemoteServerUpCommand
|
|
) -> None:
|
|
"""Called when get a new REMOTE_SERVER_UP command."""
|
|
self._replication_data_handler.on_remote_server_up(cmd.data)
|
|
|
|
self._notifier.notify_remote_server_up(cmd.data)
|
|
|
|
# We relay to all other connections to ensure every instance gets the
|
|
# notification.
|
|
#
|
|
# When configured to use redis we'll always only have one connection and
|
|
# so this is a no-op (all instances will have already received the same
|
|
# REMOTE_SERVER_UP command).
|
|
#
|
|
# For direct TCP connections this will relay to all other connections
|
|
# connected to us. When on master this will correctly fan out to all
|
|
# other direct TCP clients and on workers there'll only be the one
|
|
# connection to master.
|
|
#
|
|
# (The logic here should also be sound if we have a mix of Redis and
|
|
# direct TCP connections so long as there is only one traffic route
|
|
# between two instances, but that is not currently supported).
|
|
self.send_command(cmd, ignore_conn=conn)
|
|
|
|
def new_connection(self, connection: IReplicationConnection) -> None:
|
|
"""Called when we have a new connection."""
|
|
self._connections.append(connection)
|
|
|
|
# If we are connected to replication as a client (rather than a server)
|
|
# we need to reset the reconnection delay on the client factory (which
|
|
# is used to do exponential back off when the connection drops).
|
|
#
|
|
# Ideally we would reset the delay when we've "fully established" the
|
|
# connection (for some definition thereof) to stop us from tightlooping
|
|
# on reconnection if something fails after this point and we drop the
|
|
# connection. Unfortunately, we don't really have a better definition of
|
|
# "fully established" than the connection being established.
|
|
if self._factory:
|
|
self._factory.resetDelay()
|
|
|
|
# Tell the other end if we have any users currently syncing.
|
|
currently_syncing = (
|
|
self._presence_handler.get_currently_syncing_users_for_replication()
|
|
)
|
|
|
|
now = self._clock.time_msec()
|
|
for user_id in currently_syncing:
|
|
connection.send_command(
|
|
UserSyncCommand(self._instance_id, user_id, True, now)
|
|
)
|
|
|
|
def lost_connection(self, connection: IReplicationConnection) -> None:
|
|
"""Called when a connection is closed/lost."""
|
|
# we no longer need _streams_by_connection for this connection.
|
|
streams = self._streams_by_connection.pop(connection, None)
|
|
if streams:
|
|
logger.info(
|
|
"Lost replication connection; streams now disconnected: %s", streams
|
|
)
|
|
try:
|
|
self._connections.remove(connection)
|
|
except ValueError:
|
|
pass
|
|
|
|
def connected(self) -> bool:
|
|
"""Do we have any replication connections open?
|
|
|
|
Is used by e.g. `ReplicationStreamer` to no-op if nothing is connected.
|
|
"""
|
|
return bool(self._connections)
|
|
|
|
def send_command(
|
|
self, cmd: Command, ignore_conn: Optional[IReplicationConnection] = None
|
|
) -> None:
|
|
"""Send a command to all connected connections.
|
|
|
|
Args:
|
|
cmd
|
|
ignore_conn: If set don't send command to the given connection.
|
|
Used when relaying commands from one connection to all others.
|
|
"""
|
|
if self._connections:
|
|
for connection in self._connections:
|
|
if connection == ignore_conn:
|
|
continue
|
|
|
|
try:
|
|
connection.send_command(cmd)
|
|
except Exception:
|
|
# We probably want to catch some types of exceptions here
|
|
# and log them as warnings (e.g. connection gone), but I
|
|
# can't find what those exception types they would be.
|
|
logger.exception(
|
|
"Failed to write command %s to connection %s",
|
|
cmd.NAME,
|
|
connection,
|
|
)
|
|
else:
|
|
logger.warning("Dropping command as not connected: %r", cmd.NAME)
|
|
|
|
def send_federation_ack(self, token: int) -> None:
|
|
"""Ack data for the federation stream. This allows the master to drop
|
|
data stored purely in memory.
|
|
"""
|
|
self.send_command(FederationAckCommand(self._instance_name, token))
|
|
|
|
def send_user_sync(
|
|
self, instance_id: str, user_id: str, is_syncing: bool, last_sync_ms: int
|
|
) -> None:
|
|
"""Poke the master that a user has started/stopped syncing."""
|
|
self.send_command(
|
|
UserSyncCommand(instance_id, user_id, is_syncing, last_sync_ms)
|
|
)
|
|
|
|
def send_user_ip(
|
|
self,
|
|
user_id: str,
|
|
access_token: str,
|
|
ip: str,
|
|
user_agent: str,
|
|
device_id: Optional[str],
|
|
last_seen: int,
|
|
) -> None:
|
|
"""Tell the master that the user made a request."""
|
|
cmd = UserIpCommand(user_id, access_token, ip, user_agent, device_id, last_seen)
|
|
self.send_command(cmd)
|
|
|
|
def send_remote_server_up(self, server: str) -> None:
|
|
self.send_command(RemoteServerUpCommand(server))
|
|
|
|
def stream_update(self, stream_name: str, token: Optional[int], data: Any) -> None:
|
|
"""Called when a new update is available to stream to Redis subscribers.
|
|
|
|
We need to check if the client is interested in the stream or not
|
|
"""
|
|
self.send_command(RdataCommand(stream_name, self._instance_name, token, data))
|
|
|
|
|
|
UpdateToken = TypeVar("UpdateToken")
|
|
UpdateRow = TypeVar("UpdateRow")
|
|
|
|
|
|
def _batch_updates(
|
|
updates: Iterable[Tuple[UpdateToken, UpdateRow]]
|
|
) -> Iterator[Tuple[UpdateToken, List[UpdateRow]]]:
|
|
"""Collect stream updates with the same token together
|
|
|
|
Given a series of updates returned by Stream.get_updates_since(), collects
|
|
the updates which share the same stream_id together.
|
|
|
|
For example:
|
|
|
|
[(1, a), (1, b), (2, c), (3, d), (3, e)]
|
|
|
|
becomes:
|
|
|
|
[
|
|
(1, [a, b]),
|
|
(2, [c]),
|
|
(3, [d, e]),
|
|
]
|
|
"""
|
|
|
|
update_iter = iter(updates)
|
|
|
|
first_update = next(update_iter, None)
|
|
if first_update is None:
|
|
# empty input
|
|
return
|
|
|
|
current_batch_token = first_update[0]
|
|
current_batch = [first_update[1]]
|
|
|
|
for token, row in update_iter:
|
|
if token != current_batch_token:
|
|
# different token to the previous row: flush the previous
|
|
# batch and start anew
|
|
yield current_batch_token, current_batch
|
|
current_batch_token = token
|
|
current_batch = []
|
|
|
|
current_batch.append(row)
|
|
|
|
# flush the final batch
|
|
yield current_batch_token, current_batch
|