Move server command handling out of TCP protocol (#7187)

This completes the merging of server and client command processing.

3 files changed, 236 insertions, 269 deletions

diff --git a/synapse/replication/tcp/handler.py b/synapse/replication/tcp/handler.py
index 12a1cfd6d1..8ec0119697 100644
--- a/synapse/replication/tcp/handler.py
+++ b/synapse/replication/tcp/handler.py
@@ -19,8 +19,10 @@ from typing import Any, Callable, Dict, List, Optional, Set
 
 from prometheus_client import Counter
 
+from synapse.metrics import LaterGauge
 from synapse.replication.tcp.client import ReplicationClientFactory
 from synapse.replication.tcp.commands import (
+    ClearUserSyncsCommand,
     Command,
     FederationAckCommand,
     InvalidateCacheCommand,
@@ -28,10 +30,12 @@ from synapse.replication.tcp.commands import (
     RdataCommand,
     RemoteServerUpCommand,
     RemovePusherCommand,
+    ReplicateCommand,
     SyncCommand,
     UserIpCommand,
     UserSyncCommand,
 )
+from synapse.replication.tcp.protocol import AbstractConnection
 from synapse.replication.tcp.streams import STREAMS_MAP, Stream
 from synapse.util.async_helpers import Linearizer
 
@@ -42,6 +46,13 @@ logger = logging.getLogger(__name__)
 inbound_rdata_count = Counter(
     "synapse_replication_tcp_protocol_inbound_rdata_count", "", ["stream_name"]
 )
+user_sync_counter = Counter("synapse_replication_tcp_resource_user_sync", "")
+federation_ack_counter = Counter("synapse_replication_tcp_resource_federation_ack", "")
+remove_pusher_counter = Counter("synapse_replication_tcp_resource_remove_pusher", "")
+invalidate_cache_counter = Counter(
+    "synapse_replication_tcp_resource_invalidate_cache", ""
+)
+user_ip_cache_counter = Counter("synapse_replication_tcp_resource_user_ip_cache", "")
 
 
 class ReplicationCommandHandler:
@@ -52,6 +63,10 @@ class ReplicationCommandHandler:
     def __init__(self, hs):
         self._replication_data_handler = hs.get_replication_data_handler()
         self._presence_handler = hs.get_presence_handler()
+        self._store = hs.get_datastore()
+        self._notifier = hs.get_notifier()
+        self._clock = hs.get_clock()
+        self._instance_id = hs.get_instance_id()
 
         # Set of streams that we've caught up with.
         self._streams_connected = set()  # type: Set[str]
@@ -69,8 +84,26 @@ class ReplicationCommandHandler:
         # The factory used to create connections.
         self._factory = None  # type: Optional[ReplicationClientFactory]
 
-        # The current connection. None if we are currently (re)connecting
-        self._connection = None
+        # The currently connected connections.
+        self._connections = []  # type: List[AbstractConnection]
+
+        LaterGauge(
+            "synapse_replication_tcp_resource_total_connections",
+            "",
+            [],
+            lambda: len(self._connections),
+        )
+
+        self._is_master = hs.config.worker_app is None
+
+        self._federation_sender = None
+        if self._is_master and not hs.config.send_federation:
+            self._federation_sender = hs.get_federation_sender()
+
+        self._server_notices_sender = None
+        if self._is_master:
+            self._server_notices_sender = hs.get_server_notices_sender()
+            self._notifier.add_remote_server_up_callback(self.send_remote_server_up)
 
     def start_replication(self, hs):
         """Helper method to start a replication connection to the remote server
@@ -82,6 +115,70 @@ class ReplicationCommandHandler:
         port = hs.config.worker_replication_port
         hs.get_reactor().connectTCP(host, port, self._factory)
 
+    async def on_REPLICATE(self, cmd: ReplicateCommand):
+        # We only want to announce positions by the writer of the streams.
+        # Currently this is just the master process.
+        if not self._is_master:
+            return
+
+        for stream_name, stream in self._streams.items():
+            current_token = stream.current_token()
+            self.send_command(PositionCommand(stream_name, current_token))
+
+    async def on_USER_SYNC(self, cmd: UserSyncCommand):
+        user_sync_counter.inc()
+
+        if self._is_master:
+            await self._presence_handler.update_external_syncs_row(
+                cmd.instance_id, cmd.user_id, cmd.is_syncing, cmd.last_sync_ms
+            )
+
+    async def on_CLEAR_USER_SYNC(self, cmd: ClearUserSyncsCommand):
+        if self._is_master:
+            await self._presence_handler.update_external_syncs_clear(cmd.instance_id)
+
+    async def on_FEDERATION_ACK(self, cmd: FederationAckCommand):
+        federation_ack_counter.inc()
+
+        if self._federation_sender:
+            self._federation_sender.federation_ack(cmd.token)
+
+    async def on_REMOVE_PUSHER(self, cmd: RemovePusherCommand):
+        remove_pusher_counter.inc()
+
+        if self._is_master:
+            await self._store.delete_pusher_by_app_id_pushkey_user_id(
+                app_id=cmd.app_id, pushkey=cmd.push_key, user_id=cmd.user_id
+            )
+
+            self._notifier.on_new_replication_data()
+
+    async def on_INVALIDATE_CACHE(self, cmd: InvalidateCacheCommand):
+        invalidate_cache_counter.inc()
+
+        if self._is_master:
+            # We invalidate the cache locally, but then also stream that to other
+            # workers.
+            await self._store.invalidate_cache_and_stream(
+                cmd.cache_func, tuple(cmd.keys)
+            )
+
+    async def on_USER_IP(self, cmd: UserIpCommand):
+        user_ip_cache_counter.inc()
+
+        if self._is_master:
+            await self._store.insert_client_ip(
+                cmd.user_id,
+                cmd.access_token,
+                cmd.ip,
+                cmd.user_agent,
+                cmd.device_id,
+                cmd.last_seen,
+            )
+
+        if self._server_notices_sender:
+            await self._server_notices_sender.on_user_ip(cmd.user_id)
+
     async def on_RDATA(self, cmd: RdataCommand):
         stream_name = cmd.stream_name
         inbound_rdata_count.labels(stream_name).inc()
@@ -174,6 +271,9 @@ class ReplicationCommandHandler:
         """"Called when get a new REMOTE_SERVER_UP command."""
         self._replication_data_handler.on_remote_server_up(cmd.data)
 
+        if self._is_master:
+            self._notifier.notify_remote_server_up(cmd.data)
+
     def get_currently_syncing_users(self):
         """Get the list of currently syncing users (if any). This is called
         when a connection has been established and we need to send the
@@ -181,29 +281,63 @@ class ReplicationCommandHandler:
         """
         return self._presence_handler.get_currently_syncing_users()
 
-    def update_connection(self, connection):
-        """Called when a connection has been established (or lost with None).
+    def new_connection(self, connection: AbstractConnection):
+        """Called when we have a new connection.
         """
-        self._connection = 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 server if we have any users currently syncing (should only
+        # happen on synchrotrons)
+        currently_syncing = self.get_currently_syncing_users()
+        now = self._clock.time_msec()
+        for user_id in currently_syncing:
+            connection.send_command(
+                UserSyncCommand(self._instance_id, user_id, True, now)
+            )
 
-    def finished_connecting(self):
-        """Called when we have successfully subscribed and caught up to all
-        streams we're interested in.
+    def lost_connection(self, connection: AbstractConnection):
+        """Called when a connection is closed/lost.
         """
-        logger.info("Finished connecting to server")
+        try:
+            self._connections.remove(connection)
+        except ValueError:
+            pass
 
-        # We don't reset the delay any earlier as otherwise if there is a
-        # problem during start up we'll end up tight looping connecting to the
-        # server.
-        if self._factory:
-            self._factory.resetDelay()
+    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):
-        """Send a command to master (when we get establish a connection if we
-        don't have one already.)
+        """Send a command to all connected connections.
         """
-        if self._connection:
-            self._connection.send_command(cmd)
+        if self._connections:
+            for connection in self._connections:
+                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)
 
@@ -250,3 +384,10 @@ class ReplicationCommandHandler:
 
     def send_remote_server_up(self, server: str):
         self.send_command(RemoteServerUpCommand(server))
+
+    def stream_update(self, stream_name: str, token: str, data: Any):
+        """Called when a new update is available to stream to clients.
+
+        We need to check if the client is interested in the stream or not
+        """
+        self.send_command(RdataCommand(stream_name, token, data))
diff --git a/synapse/replication/tcp/protocol.py b/synapse/replication/tcp/protocol.py
index f2a37f568e..9aabb9c586 100644
--- a/synapse/replication/tcp/protocol.py
+++ b/synapse/replication/tcp/protocol.py
@@ -46,6 +46,7 @@ indicate which side is sending, these are *not* included on the wire::
     > ERROR server stopping
     * connection closed by server *
 """
+import abc
 import fcntl
 import logging
 import struct
@@ -69,13 +70,8 @@ from synapse.replication.tcp.commands import (
     ErrorCommand,
     NameCommand,
     PingCommand,
-    PositionCommand,
-    RdataCommand,
-    RemoteServerUpCommand,
     ReplicateCommand,
     ServerCommand,
-    SyncCommand,
-    UserSyncCommand,
 )
 from synapse.types import Collection
 from synapse.util import Clock
@@ -118,7 +114,7 @@ class BaseReplicationStreamProtocol(LineOnlyReceiver):
     are only sent by the server.
 
     On receiving a new command it calls `on_<COMMAND_NAME>` with the parsed
-    command.
+    command before delegating to `ReplicationCommandHandler.on_<COMMAND_NAME>`.
 
     It also sends `PING` periodically, and correctly times out remote connections
     (if they send a `PING` command)
@@ -134,8 +130,9 @@ class BaseReplicationStreamProtocol(LineOnlyReceiver):
 
     max_line_buffer = 10000
 
-    def __init__(self, clock):
+    def __init__(self, clock: Clock, handler: "ReplicationCommandHandler"):
         self.clock = clock
+        self.command_handler = handler
 
         self.last_received_command = self.clock.time_msec()
         self.last_sent_command = 0
@@ -175,6 +172,8 @@ class BaseReplicationStreamProtocol(LineOnlyReceiver):
         # can time us out.
         self.send_command(PingCommand(self.clock.time_msec()))
 
+        self.command_handler.new_connection(self)
+
     def send_ping(self):
         """Periodically sends a ping and checks if we should close the connection
         due to the other side timing out.
@@ -243,13 +242,31 @@ class BaseReplicationStreamProtocol(LineOnlyReceiver):
     async def handle_command(self, cmd: Command):
         """Handle a command we have received over the replication stream.
 
-        By default delegates to on_<COMMAND>, which should return an awaitable.
+        First calls `self.on_<COMMAND>` if it exists, then calls
+        `self.command_handler.on_<COMMAND>` if it exists. This allows for
+        protocol level handling of commands (e.g. PINGs), before delegating to
+        the handler.
 
         Args:
             cmd: received command
         """
-        handler = getattr(self, "on_%s" % (cmd.NAME,))
-        await handler(cmd)
+        handled = False
+
+        # First call any command handlers on this instance. These are for TCP
+        # specific handling.
+        cmd_func = getattr(self, "on_%s" % (cmd.NAME,), None)
+        if cmd_func:
+            await cmd_func(cmd)
+            handled = True
+
+        # Then call out to the handler.
+        cmd_func = getattr(self.command_handler, "on_%s" % (cmd.NAME,), None)
+        if cmd_func:
+            await cmd_func(cmd)
+            handled = True
+
+        if not handled:
+            logger.warning("Unhandled command: %r", cmd)
 
     def close(self):
         logger.warning("[%s] Closing connection", self.id())
@@ -378,6 +395,8 @@ class BaseReplicationStreamProtocol(LineOnlyReceiver):
         self.state = ConnectionStates.CLOSED
         self.pending_commands = []
 
+        self.command_handler.lost_connection(self)
+
         if self.transport:
             self.transport.unregisterProducer()
 
@@ -404,74 +423,21 @@ class ServerReplicationStreamProtocol(BaseReplicationStreamProtocol):
     VALID_INBOUND_COMMANDS = VALID_CLIENT_COMMANDS
     VALID_OUTBOUND_COMMANDS = VALID_SERVER_COMMANDS
 
-    def __init__(self, server_name, clock, streamer):
-        BaseReplicationStreamProtocol.__init__(self, clock)  # Old style class
+    def __init__(
+        self, server_name: str, clock: Clock, handler: "ReplicationCommandHandler"
+    ):
+        super().__init__(clock, handler)
 
         self.server_name = server_name
-        self.streamer = streamer
 
     def connectionMade(self):
         self.send_command(ServerCommand(self.server_name))
-        BaseReplicationStreamProtocol.connectionMade(self)
-        self.streamer.new_connection(self)
+        super().connectionMade()
 
     async def on_NAME(self, cmd):
         logger.info("[%s] Renamed to %r", self.id(), cmd.data)
         self.name = cmd.data
 
-    async def on_USER_SYNC(self, cmd):
-        await self.streamer.on_user_sync(
-            cmd.instance_id, cmd.user_id, cmd.is_syncing, cmd.last_sync_ms
-        )
-
-    async def on_CLEAR_USER_SYNC(self, cmd):
-        await self.streamer.on_clear_user_syncs(cmd.instance_id)
-
-    async def on_REPLICATE(self, cmd):
-        # Subscribe to all streams we're publishing to.
-        for stream_name in self.streamer.streams_by_name:
-            current_token = self.streamer.get_stream_token(stream_name)
-            self.send_command(PositionCommand(stream_name, current_token))
-
-    async def on_FEDERATION_ACK(self, cmd):
-        self.streamer.federation_ack(cmd.token)
-
-    async def on_REMOVE_PUSHER(self, cmd):
-        await self.streamer.on_remove_pusher(cmd.app_id, cmd.push_key, cmd.user_id)
-
-    async def on_INVALIDATE_CACHE(self, cmd):
-        await self.streamer.on_invalidate_cache(cmd.cache_func, cmd.keys)
-
-    async def on_REMOTE_SERVER_UP(self, cmd: RemoteServerUpCommand):
-        self.streamer.on_remote_server_up(cmd.data)
-
-    async def on_USER_IP(self, cmd):
-        self.streamer.on_user_ip(
-            cmd.user_id,
-            cmd.access_token,
-            cmd.ip,
-            cmd.user_agent,
-            cmd.device_id,
-            cmd.last_seen,
-        )
-
-    def stream_update(self, stream_name, token, data):
-        """Called when a new update is available to stream to clients.
-
-        We need to check if the client is interested in the stream or not
-        """
-        self.send_command(RdataCommand(stream_name, token, data))
-
-    def send_sync(self, data):
-        self.send_command(SyncCommand(data))
-
-    def send_remote_server_up(self, server: str):
-        self.send_command(RemoteServerUpCommand(server))
-
-    def on_connection_closed(self):
-        BaseReplicationStreamProtocol.on_connection_closed(self)
-        self.streamer.lost_connection(self)
-
 
 class ClientReplicationStreamProtocol(BaseReplicationStreamProtocol):
     VALID_INBOUND_COMMANDS = VALID_SERVER_COMMANDS
@@ -485,59 +451,18 @@ class ClientReplicationStreamProtocol(BaseReplicationStreamProtocol):
         clock: Clock,
         command_handler: "ReplicationCommandHandler",
     ):
-        BaseReplicationStreamProtocol.__init__(self, clock)
-
-        self.instance_id = hs.get_instance_id()
+        super().__init__(clock, command_handler)
 
         self.client_name = client_name
         self.server_name = server_name
-        self.handler = command_handler
 
     def connectionMade(self):
         self.send_command(NameCommand(self.client_name))
-        BaseReplicationStreamProtocol.connectionMade(self)
+        super().connectionMade()
 
         # Once we've connected subscribe to the necessary streams
         self.replicate()
 
-        # Tell the server if we have any users currently syncing (should only
-        # happen on synchrotrons)
-        currently_syncing = self.handler.get_currently_syncing_users()
-        now = self.clock.time_msec()
-        for user_id in currently_syncing:
-            self.send_command(UserSyncCommand(self.instance_id, user_id, True, now))
-
-        # We've now finished connecting to so inform the client handler
-        self.handler.update_connection(self)
-        self.handler.finished_connecting()
-
-    async def handle_command(self, cmd: Command):
-        """Handle a command we have received over the replication stream.
-
-        Delegates to `command_handler.on_<COMMAND>`, which must return an
-        awaitable.
-
-        Args:
-            cmd: received command
-        """
-        handled = False
-
-        # First call any command handlers on this instance. These are for TCP
-        # specific handling.
-        cmd_func = getattr(self, "on_%s" % (cmd.NAME,), None)
-        if cmd_func:
-            await cmd_func(cmd)
-            handled = True
-
-        # Then call out to the handler.
-        cmd_func = getattr(self.handler, "on_%s" % (cmd.NAME,), None)
-        if cmd_func:
-            await cmd_func(cmd)
-            handled = True
-
-        if not handled:
-            logger.warning("Unhandled command: %r", cmd)
-
     async def on_SERVER(self, cmd):
         if cmd.data != self.server_name:
             logger.error("[%s] Connected to wrong remote: %r", self.id(), cmd.data)
@@ -550,9 +475,21 @@ class ClientReplicationStreamProtocol(BaseReplicationStreamProtocol):
 
         self.send_command(ReplicateCommand())
 
-    def on_connection_closed(self):
-        BaseReplicationStreamProtocol.on_connection_closed(self)
-        self.handler.update_connection(None)
+
+class AbstractConnection(abc.ABC):
+    """An interface for replication connections.
+    """
+
+    @abc.abstractmethod
+    def send_command(self, cmd: Command):
+        """Send the command down the connection
+        """
+        pass
+
+
+# This tells python that `BaseReplicationStreamProtocol` implements the
+# interface.
+AbstractConnection.register(BaseReplicationStreamProtocol)
 
 
 # The following simply registers metrics for the replication connections
diff --git a/synapse/replication/tcp/resource.py b/synapse/replication/tcp/resource.py
index 30021ee309..b2d6baa2a2 100644
--- a/synapse/replication/tcp/resource.py
+++ b/synapse/replication/tcp/resource.py
@@ -17,7 +17,7 @@
 
 import logging
 import random
-from typing import Any, Dict, List
+from typing import Dict
 
 from six import itervalues
 
@@ -25,24 +25,14 @@ from prometheus_client import Counter
 
 from twisted.internet.protocol import Factory
 
-from synapse.metrics import LaterGauge
 from synapse.metrics.background_process_metrics import run_as_background_process
-from synapse.util.metrics import Measure, measure_func
-
-from .protocol import ServerReplicationStreamProtocol
-from .streams import STREAMS_MAP, Stream
-from .streams.federation import FederationStream
+from synapse.replication.tcp.protocol import ServerReplicationStreamProtocol
+from synapse.replication.tcp.streams import STREAMS_MAP, FederationStream, Stream
+from synapse.util.metrics import Measure
 
 stream_updates_counter = Counter(
     "synapse_replication_tcp_resource_stream_updates", "", ["stream_name"]
 )
-user_sync_counter = Counter("synapse_replication_tcp_resource_user_sync", "")
-federation_ack_counter = Counter("synapse_replication_tcp_resource_federation_ack", "")
-remove_pusher_counter = Counter("synapse_replication_tcp_resource_remove_pusher", "")
-invalidate_cache_counter = Counter(
-    "synapse_replication_tcp_resource_invalidate_cache", ""
-)
-user_ip_cache_counter = Counter("synapse_replication_tcp_resource_user_ip_cache", "")
 
 logger = logging.getLogger(__name__)
 
@@ -52,13 +42,23 @@ class ReplicationStreamProtocolFactory(Factory):
     """
 
     def __init__(self, hs):
-        self.streamer = hs.get_replication_streamer()
+        self.command_handler = hs.get_tcp_replication()
         self.clock = hs.get_clock()
         self.server_name = hs.config.server_name
 
+        # If we've created a `ReplicationStreamProtocolFactory` then we're
+        # almost certainly registering a replication listener, so let's ensure
+        # that we've started a `ReplicationStreamer` instance to actually push
+        # data.
+        #
+        # (This is a bit of a weird place to do this, but the alternatives such
+        # as putting this in `HomeServer.setup()`, requires either passing the
+        # listener config again or always starting a `ReplicationStreamer`.)
+        hs.get_replication_streamer()
+
     def buildProtocol(self, addr):
         return ServerReplicationStreamProtocol(
-            self.server_name, self.clock, self.streamer
+            self.server_name, self.clock, self.command_handler
         )
 
 
@@ -78,16 +78,6 @@ class ReplicationStreamer(object):
 
         self._replication_torture_level = hs.config.replication_torture_level
 
-        # Current connections.
-        self.connections = []  # type: List[ServerReplicationStreamProtocol]
-
-        LaterGauge(
-            "synapse_replication_tcp_resource_total_connections",
-            "",
-            [],
-            lambda: len(self.connections),
-        )
-
         # List of streams that clients can subscribe to.
         # We only support federation stream if federation sending hase been
         # disabled on the master.
@@ -104,18 +94,12 @@ class ReplicationStreamer(object):
             self.federation_sender = hs.get_federation_sender()
 
         self.notifier.add_replication_callback(self.on_notifier_poke)
-        self.notifier.add_remote_server_up_callback(self.send_remote_server_up)
 
         # Keeps track of whether we are currently checking for updates
         self.is_looping = False
         self.pending_updates = False
 
-        hs.get_reactor().addSystemEventTrigger("before", "shutdown", self.on_shutdown)
-
-    def on_shutdown(self):
-        # close all connections on shutdown
-        for conn in self.connections:
-            conn.send_error("server shutting down")
+        self.command_handler = hs.get_tcp_replication()
 
     def get_streams(self) -> Dict[str, Stream]:
         """Get a mapp from stream name to stream instance.
@@ -129,7 +113,7 @@ class ReplicationStreamer(object):
         This should get called each time new data is available, even if it
         is currently being executed, so that nothing gets missed
         """
-        if not self.connections:
+        if not self.command_handler.connected():
             # Don't bother if nothing is listening. We still need to advance
             # the stream tokens otherwise they'll fall beihind forever
             for stream in self.streams:
@@ -186,9 +170,7 @@ class ReplicationStreamer(object):
                             raise
 
                         logger.debug(
-                            "Sending %d updates to %d connections",
-                            len(updates),
-                            len(self.connections),
+                            "Sending %d updates", len(updates),
                         )
 
                         if updates:
@@ -204,112 +186,19 @@ class ReplicationStreamer(object):
                         # token. See RdataCommand for more details.
                         batched_updates = _batch_updates(updates)
 
-                        for conn in self.connections:
-                            for token, row in batched_updates:
-                                try:
-                                    conn.stream_update(stream.NAME, token, row)
-                                except Exception:
-                                    logger.exception("Failed to replicate")
+                        for token, row in batched_updates:
+                            try:
+                                self.command_handler.stream_update(
+                                    stream.NAME, token, row
+                                )
+                            except Exception:
+                                logger.exception("Failed to replicate")
 
             logger.debug("No more pending updates, breaking poke loop")
         finally:
             self.pending_updates = False
             self.is_looping = False
 
-    def get_stream_token(self, stream_name):
-        """For a given stream get all updates since token. This is called when
-        a client first subscribes to a stream.
-        """
-        stream = self.streams_by_name.get(stream_name, None)
-        if not stream:
-            raise Exception("unknown stream %s", stream_name)
-
-        return stream.current_token()
-
-    @measure_func("repl.federation_ack")
-    def federation_ack(self, token):
-        """We've received an ack for federation stream from a client.
-        """
-        federation_ack_counter.inc()
-        if self.federation_sender:
-            self.federation_sender.federation_ack(token)
-
-    @measure_func("repl.on_user_sync")
-    async def on_user_sync(self, instance_id, user_id, is_syncing, last_sync_ms):
-        """A client has started/stopped syncing on a worker.
-        """
-        user_sync_counter.inc()
-        await self.presence_handler.update_external_syncs_row(
-            instance_id, user_id, is_syncing, last_sync_ms
-        )
-
-    async def on_clear_user_syncs(self, instance_id):
-        """A replication client wants us to drop all their UserSync data.
-        """
-        await self.presence_handler.update_external_syncs_clear(instance_id)
-
-    @measure_func("repl.on_remove_pusher")
-    async def on_remove_pusher(self, app_id, push_key, user_id):
-        """A client has asked us to remove a pusher
-        """
-        remove_pusher_counter.inc()
-        await self.store.delete_pusher_by_app_id_pushkey_user_id(
-            app_id=app_id, pushkey=push_key, user_id=user_id
-        )
-
-        self.notifier.on_new_replication_data()
-
-    @measure_func("repl.on_invalidate_cache")
-    async def on_invalidate_cache(self, cache_func: str, keys: List[Any]):
-        """The client has asked us to invalidate a cache
-        """
-        invalidate_cache_counter.inc()
-
-        # We invalidate the cache locally, but then also stream that to other
-        # workers.
-        await self.store.invalidate_cache_and_stream(cache_func, tuple(keys))
-
-    @measure_func("repl.on_user_ip")
-    async def on_user_ip(
-        self, user_id, access_token, ip, user_agent, device_id, last_seen
-    ):
-        """The client saw a user request
-        """
-        user_ip_cache_counter.inc()
-        await self.store.insert_client_ip(
-            user_id, access_token, ip, user_agent, device_id, last_seen
-        )
-        await self._server_notices_sender.on_user_ip(user_id)
-
-    @measure_func("repl.on_remote_server_up")
-    def on_remote_server_up(self, server: str):
-        self.notifier.notify_remote_server_up(server)
-
-    def send_remote_server_up(self, server: str):
-        for conn in self.connections:
-            conn.send_remote_server_up(server)
-
-    def send_sync_to_all_connections(self, data):
-        """Sends a SYNC command to all clients.
-
-        Used in tests.
-        """
-        for conn in self.connections:
-            conn.send_sync(data)
-
-    def new_connection(self, connection):
-        """A new client connection has been established
-        """
-        self.connections.append(connection)
-
-    def lost_connection(self, connection):
-        """A client connection has been lost
-        """
-        try:
-            self.connections.remove(connection)
-        except ValueError:
-            pass
-
 
 def _batch_updates(updates):
     """Takes a list of updates of form [(token, row)] and sets the token to