555 lines
19 KiB
Python
555 lines
19 KiB
Python
# Copyright 2017 Vector Creations 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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"""This module contains the implementation of both the client and server
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protocols.
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An explanation of this protocol is available in docs/tcp_replication.md
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"""
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import fcntl
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import logging
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import struct
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from inspect import isawaitable
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from typing import TYPE_CHECKING, Any, Collection, List, Optional
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from prometheus_client import Counter
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from zope.interface import Interface, implementer
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from twisted.internet import task
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from twisted.internet.tcp import Connection
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from twisted.protocols.basic import LineOnlyReceiver
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from twisted.python.failure import Failure
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from synapse.logging.context import PreserveLoggingContext
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from synapse.metrics import LaterGauge
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from synapse.metrics.background_process_metrics import (
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BackgroundProcessLoggingContext,
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run_as_background_process,
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)
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from synapse.replication.tcp.commands import (
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VALID_CLIENT_COMMANDS,
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VALID_SERVER_COMMANDS,
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Command,
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ErrorCommand,
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NameCommand,
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PingCommand,
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ReplicateCommand,
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ServerCommand,
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parse_command_from_line,
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)
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from synapse.util import Clock
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from synapse.util.stringutils import random_string
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if TYPE_CHECKING:
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from synapse.replication.tcp.handler import ReplicationCommandHandler
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from synapse.server import HomeServer
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connection_close_counter = Counter(
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"synapse_replication_tcp_protocol_close_reason", "", ["reason_type"]
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)
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tcp_inbound_commands_counter = Counter(
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"synapse_replication_tcp_protocol_inbound_commands",
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"Number of commands received from replication, by command and name of process connected to",
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["command", "name"],
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)
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tcp_outbound_commands_counter = Counter(
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"synapse_replication_tcp_protocol_outbound_commands",
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"Number of commands sent to replication, by command and name of process connected to",
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["command", "name"],
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)
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# A list of all connected protocols. This allows us to send metrics about the
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# connections.
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connected_connections: "List[BaseReplicationStreamProtocol]" = []
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logger = logging.getLogger(__name__)
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PING_TIME = 5000
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PING_TIMEOUT_MULTIPLIER = 5
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PING_TIMEOUT_MS = PING_TIME * PING_TIMEOUT_MULTIPLIER
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class ConnectionStates:
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CONNECTING = "connecting"
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ESTABLISHED = "established"
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PAUSED = "paused"
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CLOSED = "closed"
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class IReplicationConnection(Interface):
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"""An interface for replication connections."""
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def send_command(cmd: Command) -> None:
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"""Send the command down the connection"""
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@implementer(IReplicationConnection)
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class BaseReplicationStreamProtocol(LineOnlyReceiver):
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"""Base replication protocol shared between client and server.
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Reads lines (ignoring blank ones) and parses them into command classes,
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asserting that they are valid for the given direction, i.e. server commands
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are only sent by the server.
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On receiving a new command it calls `on_<COMMAND_NAME>` with the parsed
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command before delegating to `ReplicationCommandHandler.on_<COMMAND_NAME>`.
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`ReplicationCommandHandler.on_<COMMAND_NAME>` can optionally return a coroutine;
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if so, that will get run as a background process.
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It also sends `PING` periodically, and correctly times out remote connections
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(if they send a `PING` command)
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"""
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# The transport is going to be an ITCPTransport, but that doesn't have the
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# (un)registerProducer methods, those are only on the implementation.
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transport: Connection
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delimiter = b"\n"
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# Valid commands we expect to receive
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VALID_INBOUND_COMMANDS: Collection[str] = []
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# Valid commands we can send
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VALID_OUTBOUND_COMMANDS: Collection[str] = []
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max_line_buffer = 10000
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def __init__(self, clock: Clock, handler: "ReplicationCommandHandler"):
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self.clock = clock
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self.command_handler = handler
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self.last_received_command = self.clock.time_msec()
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self.last_sent_command = 0
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# When we requested the connection be closed
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self.time_we_closed: Optional[int] = None
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self.received_ping = False # Have we received a ping from the other side
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self.state = ConnectionStates.CONNECTING
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self.name = "anon" # The name sent by a client.
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self.conn_id = random_string(5) # To dedupe in case of name clashes.
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# List of pending commands to send once we've established the connection
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self.pending_commands: List[Command] = []
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# The LoopingCall for sending pings.
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self._send_ping_loop: Optional[task.LoopingCall] = None
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# a logcontext which we use for processing incoming commands. We declare it as a
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# background process so that the CPU stats get reported to prometheus.
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with PreserveLoggingContext():
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# thanks to `PreserveLoggingContext()`, the new logcontext is guaranteed to
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# capture the sentinel context as its containing context and won't prevent
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# GC of / unintentionally reactivate what would be the current context.
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self._logging_context = BackgroundProcessLoggingContext(
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"replication-conn", self.conn_id
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)
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def connectionMade(self) -> None:
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logger.info("[%s] Connection established", self.id())
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self.state = ConnectionStates.ESTABLISHED
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connected_connections.append(self) # Register connection for metrics
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assert self.transport is not None
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self.transport.registerProducer(self, True) # For the *Producing callbacks
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self._send_pending_commands()
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# Starts sending pings
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self._send_ping_loop = self.clock.looping_call(self.send_ping, 5000)
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# Always send the initial PING so that the other side knows that they
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# can time us out.
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self.send_command(PingCommand(str(self.clock.time_msec())))
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self.command_handler.new_connection(self)
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def send_ping(self) -> None:
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"""Periodically sends a ping and checks if we should close the connection
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due to the other side timing out.
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"""
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now = self.clock.time_msec()
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if self.time_we_closed:
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if now - self.time_we_closed > PING_TIMEOUT_MS:
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logger.info(
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"[%s] Failed to close connection gracefully, aborting", self.id()
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)
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assert self.transport is not None
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self.transport.abortConnection()
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else:
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if now - self.last_sent_command >= PING_TIME:
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self.send_command(PingCommand(str(now)))
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if (
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self.received_ping
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and now - self.last_received_command > PING_TIMEOUT_MS
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):
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logger.info(
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"[%s] Connection hasn't received command in %r ms. Closing.",
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self.id(),
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now - self.last_received_command,
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)
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self.send_error("ping timeout")
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def lineReceived(self, line: bytes) -> None:
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"""Called when we've received a line"""
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with PreserveLoggingContext(self._logging_context):
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self._parse_and_dispatch_line(line)
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def _parse_and_dispatch_line(self, line: bytes) -> None:
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if line.strip() == b"":
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# Ignore blank lines
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return
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linestr = line.decode("utf-8")
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try:
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cmd = parse_command_from_line(linestr)
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except Exception as e:
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logger.exception("[%s] failed to parse line: %r", self.id(), linestr)
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self.send_error("failed to parse line: %r (%r):" % (e, linestr))
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return
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if cmd.NAME not in self.VALID_INBOUND_COMMANDS:
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logger.error("[%s] invalid command %s", self.id(), cmd.NAME)
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self.send_error("invalid command: %s", cmd.NAME)
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return
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self.last_received_command = self.clock.time_msec()
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tcp_inbound_commands_counter.labels(cmd.NAME, self.name).inc()
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self.handle_command(cmd)
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def handle_command(self, cmd: Command) -> None:
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"""Handle a command we have received over the replication stream.
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First calls `self.on_<COMMAND>` if it exists, then calls
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`self.command_handler.on_<COMMAND>` if it exists (which can optionally
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return an Awaitable).
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This allows for protocol level handling of commands (e.g. PINGs), before
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delegating to the handler.
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Args:
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cmd: received command
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"""
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handled = False
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# First call any command handlers on this instance. These are for TCP
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# specific handling.
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cmd_func = getattr(self, "on_%s" % (cmd.NAME,), None)
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if cmd_func:
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cmd_func(cmd)
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handled = True
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# Then call out to the handler.
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cmd_func = getattr(self.command_handler, "on_%s" % (cmd.NAME,), None)
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if cmd_func:
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res = cmd_func(self, cmd)
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# the handler might be a coroutine: fire it off as a background process
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# if so.
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if isawaitable(res):
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run_as_background_process(
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"replication-" + cmd.get_logcontext_id(), lambda: res
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)
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handled = True
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if not handled:
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logger.warning("Unhandled command: %r", cmd)
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def close(self) -> None:
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logger.warning("[%s] Closing connection", self.id())
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self.time_we_closed = self.clock.time_msec()
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assert self.transport is not None
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self.transport.loseConnection()
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self.on_connection_closed()
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def send_error(self, error_string: str, *args: Any) -> None:
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"""Send an error to remote and close the connection."""
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self.send_command(ErrorCommand(error_string % args))
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self.close()
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def send_command(self, cmd: Command, do_buffer: bool = True) -> None:
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"""Send a command if connection has been established.
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Args:
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cmd
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do_buffer: Whether to buffer the message or always attempt
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to send the command. This is mostly used to send an error
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message if we're about to close the connection due our buffers
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becoming full.
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"""
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if self.state == ConnectionStates.CLOSED:
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logger.debug("[%s] Not sending, connection closed", self.id())
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return
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if do_buffer and self.state != ConnectionStates.ESTABLISHED:
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self._queue_command(cmd)
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return
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tcp_outbound_commands_counter.labels(cmd.NAME, self.name).inc()
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string = "%s %s" % (cmd.NAME, cmd.to_line())
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if "\n" in string:
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raise Exception("Unexpected newline in command: %r", string)
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encoded_string = string.encode("utf-8")
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if len(encoded_string) > self.MAX_LENGTH:
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raise Exception(
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"Failed to send command %s as too long (%d > %d)"
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% (cmd.NAME, len(encoded_string), self.MAX_LENGTH)
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)
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self.sendLine(encoded_string)
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self.last_sent_command = self.clock.time_msec()
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def _queue_command(self, cmd: Command) -> None:
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"""Queue the command until the connection is ready to write to again."""
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logger.debug("[%s] Queueing as conn %r, cmd: %r", self.id(), self.state, cmd)
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self.pending_commands.append(cmd)
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if len(self.pending_commands) > self.max_line_buffer:
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# The other side is failing to keep up and out buffers are becoming
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# full, so lets close the connection.
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# XXX: should we squawk more loudly?
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logger.error("[%s] Remote failed to keep up", self.id())
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self.send_command(ErrorCommand("Failed to keep up"), do_buffer=False)
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self.close()
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def _send_pending_commands(self) -> None:
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"""Send any queued commandes"""
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pending = self.pending_commands
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self.pending_commands = []
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for cmd in pending:
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self.send_command(cmd)
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def on_PING(self, cmd: PingCommand) -> None:
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self.received_ping = True
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def on_ERROR(self, cmd: ErrorCommand) -> None:
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logger.error("[%s] Remote reported error: %r", self.id(), cmd.data)
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def pauseProducing(self) -> None:
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"""This is called when both the kernel send buffer and the twisted
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tcp connection send buffers have become full.
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We don't actually have any control over those sizes, so we buffer some
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commands ourselves before knifing the connection due to the remote
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failing to keep up.
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"""
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logger.info("[%s] Pause producing", self.id())
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self.state = ConnectionStates.PAUSED
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def resumeProducing(self) -> None:
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"""The remote has caught up after we started buffering!"""
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logger.info("[%s] Resume producing", self.id())
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self.state = ConnectionStates.ESTABLISHED
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self._send_pending_commands()
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def stopProducing(self) -> None:
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"""We're never going to send any more data (normally because either
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we or the remote has closed the connection)
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"""
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logger.info("[%s] Stop producing", self.id())
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self.on_connection_closed()
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def connectionLost(self, reason: Failure) -> None: # type: ignore[override]
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logger.info("[%s] Replication connection closed: %r", self.id(), reason)
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if isinstance(reason, Failure):
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assert reason.type is not None
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connection_close_counter.labels(reason.type.__name__).inc()
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else:
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connection_close_counter.labels(reason.__class__.__name__).inc() # type: ignore[unreachable]
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try:
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# Remove us from list of connections to be monitored
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connected_connections.remove(self)
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except ValueError:
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pass
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# Stop the looping call sending pings.
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if self._send_ping_loop and self._send_ping_loop.running:
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self._send_ping_loop.stop()
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self.on_connection_closed()
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def on_connection_closed(self) -> None:
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logger.info("[%s] Connection was closed", self.id())
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self.state = ConnectionStates.CLOSED
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self.pending_commands = []
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self.command_handler.lost_connection(self)
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if self.transport:
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self.transport.unregisterProducer()
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# mark the logging context as finished by triggering `__exit__()`
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with PreserveLoggingContext():
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with self._logging_context:
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pass
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# the sentinel context is now active, which may not be correct.
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# PreserveLoggingContext() will restore the correct logging context.
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def __str__(self) -> str:
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addr = None
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if self.transport:
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addr = str(self.transport.getPeer())
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return "ReplicationConnection<name=%s,conn_id=%s,addr=%s>" % (
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self.name,
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self.conn_id,
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addr,
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)
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def id(self) -> str:
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return "%s-%s" % (self.name, self.conn_id)
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def lineLengthExceeded(self, line: str) -> None:
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"""Called when we receive a line that is above the maximum line length"""
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self.send_error("Line length exceeded")
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class ServerReplicationStreamProtocol(BaseReplicationStreamProtocol):
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VALID_INBOUND_COMMANDS = VALID_CLIENT_COMMANDS
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VALID_OUTBOUND_COMMANDS = VALID_SERVER_COMMANDS
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def __init__(
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self, server_name: str, clock: Clock, handler: "ReplicationCommandHandler"
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):
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super().__init__(clock, handler)
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self.server_name = server_name
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def connectionMade(self) -> None:
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self.send_command(ServerCommand(self.server_name))
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super().connectionMade()
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def on_NAME(self, cmd: NameCommand) -> None:
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logger.info("[%s] Renamed to %r", self.id(), cmd.data)
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self.name = cmd.data
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class ClientReplicationStreamProtocol(BaseReplicationStreamProtocol):
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VALID_INBOUND_COMMANDS = VALID_SERVER_COMMANDS
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VALID_OUTBOUND_COMMANDS = VALID_CLIENT_COMMANDS
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def __init__(
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self,
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hs: "HomeServer",
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client_name: str,
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server_name: str,
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clock: Clock,
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command_handler: "ReplicationCommandHandler",
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):
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super().__init__(clock, command_handler)
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self.client_name = client_name
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self.server_name = server_name
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def connectionMade(self) -> None:
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self.send_command(NameCommand(self.client_name))
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super().connectionMade()
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# Once we've connected subscribe to the necessary streams
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self.replicate()
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def on_SERVER(self, cmd: ServerCommand) -> None:
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if cmd.data != self.server_name:
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logger.error("[%s] Connected to wrong remote: %r", self.id(), cmd.data)
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self.send_error("Wrong remote")
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def replicate(self) -> None:
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"""Send the subscription request to the server"""
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logger.info("[%s] Subscribing to replication streams", self.id())
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self.send_command(ReplicateCommand())
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# The following simply registers metrics for the replication connections
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pending_commands = LaterGauge(
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"synapse_replication_tcp_protocol_pending_commands",
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"",
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["name"],
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lambda: {(p.name,): len(p.pending_commands) for p in connected_connections},
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)
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def transport_buffer_size(protocol: BaseReplicationStreamProtocol) -> int:
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if protocol.transport:
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size = len(protocol.transport.dataBuffer) + protocol.transport._tempDataLen
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return size
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return 0
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transport_send_buffer = LaterGauge(
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"synapse_replication_tcp_protocol_transport_send_buffer",
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"",
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["name"],
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lambda: {(p.name,): transport_buffer_size(p) for p in connected_connections},
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)
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def transport_kernel_read_buffer_size(
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protocol: BaseReplicationStreamProtocol, read: bool = True
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) -> int:
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SIOCINQ = 0x541B
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SIOCOUTQ = 0x5411
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if protocol.transport:
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fileno = protocol.transport.getHandle().fileno()
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if read:
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op = SIOCINQ
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else:
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op = SIOCOUTQ
|
|
size = struct.unpack("I", fcntl.ioctl(fileno, op, b"\0\0\0\0"))[0]
|
|
return size
|
|
return 0
|
|
|
|
|
|
tcp_transport_kernel_send_buffer = LaterGauge(
|
|
"synapse_replication_tcp_protocol_transport_kernel_send_buffer",
|
|
"",
|
|
["name"],
|
|
lambda: {
|
|
(p.name,): transport_kernel_read_buffer_size(p, False)
|
|
for p in connected_connections
|
|
},
|
|
)
|
|
|
|
|
|
tcp_transport_kernel_read_buffer = LaterGauge(
|
|
"synapse_replication_tcp_protocol_transport_kernel_read_buffer",
|
|
"",
|
|
["name"],
|
|
lambda: {
|
|
(p.name,): transport_kernel_read_buffer_size(p, True)
|
|
for p in connected_connections
|
|
},
|
|
)
|