Move client command handling out of TCP protocol (#7185)

The aim here is to move the command handling out of the TCP protocol classes and to also merge the client and server command handling (so that we can reuse them for redis protocol). This PR simply moves the client paths to the new `ReplicationCommandHandler`, a future PR will move the server paths too.

changelog.d/7185.misc

@@ -0,0 +1 @@
+Move client command handling out of TCP protocol.

synapse/app/admin_cmd.py

@@ -43,7 +43,6 @@
 from synapse.replication.slave.storage.receipts import SlavedReceiptsStore
 from synapse.replication.slave.storage.registration import SlavedRegistrationStore
 from synapse.replication.slave.storage.room import RoomStore
-from synapse.replication.tcp.client import ReplicationClientHandler
 from synapse.server import HomeServer
 from synapse.util.logcontext import LoggingContext
 from synapse.util.versionstring import get_version_string
@@ -79,17 +78,6 @@ def _listen_http(self, listener_config):
     def start_listening(self, listeners):
         pass
 
-    def build_tcp_replication(self):
-        return AdminCmdReplicationHandler(self)
-
-
-class AdminCmdReplicationHandler(ReplicationClientHandler):
-    async def on_rdata(self, stream_name, token, rows):
-        pass
-
-    def get_streams_to_replicate(self):
-        return {}
-
 
 @defer.inlineCallbacks
 def export_data_command(hs, args):

synapse/app/generic_worker.py

@@ -64,7 +64,7 @@
 from synapse.replication.slave.storage.registration import SlavedRegistrationStore
 from synapse.replication.slave.storage.room import RoomStore
 from synapse.replication.slave.storage.transactions import SlavedTransactionStore
-from synapse.replication.tcp.client import ReplicationClientHandler
+from synapse.replication.tcp.client import ReplicationDataHandler
 from synapse.replication.tcp.commands import ClearUserSyncsCommand
 from synapse.replication.tcp.streams import (
     AccountDataStream,
@@ -603,7 +603,7 @@ def start_listening(self, listeners):
     def remove_pusher(self, app_id, push_key, user_id):
         self.get_tcp_replication().send_remove_pusher(app_id, push_key, user_id)
 
-    def build_tcp_replication(self):
+    def build_replication_data_handler(self):
         return GenericWorkerReplicationHandler(self)
 
     def build_presence_handler(self):
@@ -613,7 +613,7 @@ def build_typing_handler(self):
         return GenericWorkerTyping(self)
 
 
-class GenericWorkerReplicationHandler(ReplicationClientHandler):
+class GenericWorkerReplicationHandler(ReplicationDataHandler):
     def __init__(self, hs):
         super(GenericWorkerReplicationHandler, self).__init__(hs.get_datastore())
 
@@ -644,9 +644,6 @@ def get_streams_to_replicate(self):
             args.update(self.send_handler.stream_positions())
         return args
 
-    def get_currently_syncing_users(self):
-        return self.presence_handler.get_currently_syncing_users()
-
     async def process_and_notify(self, stream_name, token, rows):
         try:
             if self.send_handler:

synapse/replication/tcp/__init__.py

@@ -20,11 +20,31 @@
 
 
 Structure of the module:
- * client.py   - the client classes used for workers to connect to master
+ * handler.py  - the classes used to handle sending/receiving commands to
+                 replication
  * command.py  - the definitions of all the valid commands
- * protocol.py - contains bot the client and server protocol implementations,
-                 these should not be used directly
- * resource.py - the server classes that accepts and handle client connections
- * streams.py  - the definitons of all the valid streams
+ * protocol.py - the TCP protocol classes
+ * resource.py - handles streaming stream updates to replications
+ * streams/    - the definitons of all the valid streams
 
+
+The general interaction of the classes are:
+
+        +---------------------+
+        | ReplicationStreamer |
+        +---------------------+
+                    |
+                    v
+        +---------------------------+     +----------------------+
+        | ReplicationCommandHandler |---->|ReplicationDataHandler|
+        +---------------------------+     +----------------------+
+                    | ^
+                    v |
+            +-------------+
+            | Protocols   |
+            | (TCP/redis) |
+            +-------------+
+
+Where the ReplicationDataHandler (or subclasses) handles incoming stream
+updates.
 """

synapse/replication/tcp/client.py

@@ -16,26 +16,16 @@
 """
 
 import logging
-from typing import Dict, List, Optional
+from typing import TYPE_CHECKING, Dict
 
-from twisted.internet import defer
 from twisted.internet.protocol import ReconnectingClientFactory
 
 from synapse.replication.slave.storage._base import BaseSlavedStore
-from synapse.replication.tcp.protocol import (
-    AbstractReplicationClientHandler,
-    ClientReplicationStreamProtocol,
-)
-
-from .commands import (
-    Command,
-    FederationAckCommand,
-    InvalidateCacheCommand,
-    RemoteServerUpCommand,
-    RemovePusherCommand,
-    UserIpCommand,
-    UserSyncCommand,
-)
+from synapse.replication.tcp.protocol import ClientReplicationStreamProtocol
+
+if TYPE_CHECKING:
+    from synapse.server import HomeServer
+    from synapse.replication.tcp.handler import ReplicationCommandHandler
 
 logger = logging.getLogger(__name__)
 
@@ -44,16 +34,20 @@ class ReplicationClientFactory(ReconnectingClientFactory):
     """Factory for building connections to the master. Will reconnect if the
     connection is lost.
 
-    Accepts a handler that will be called when new data is available or data
-    is required.
+    Accepts a handler that is passed to `ClientReplicationStreamProtocol`.
     """
 
     initialDelay = 0.1
     maxDelay = 1  # Try at least once every N seconds
 
-    def __init__(self, hs, client_name, handler: AbstractReplicationClientHandler):
+    def __init__(
+        self,
+        hs: "HomeServer",
+        client_name: str,
+        command_handler: "ReplicationCommandHandler",
+    ):
         self.client_name = client_name
-        self.handler = handler
+        self.command_handler = command_handler
         self.server_name = hs.config.server_name
         self.hs = hs
         self._clock = hs.get_clock()  # As self.clock is defined in super class
@@ -66,7 +60,11 @@ def startedConnecting(self, connector):
     def buildProtocol(self, addr):
         logger.info("Connected to replication: %r", addr)
         return ClientReplicationStreamProtocol(
-            self.hs, self.client_name, self.server_name, self._clock, self.handler,
+            self.hs,
+            self.client_name,
+            self.server_name,
+            self._clock,
+            self.command_handler,
         )
 
     def clientConnectionLost(self, connector, reason):
@@ -78,41 +76,17 @@ def clientConnectionFailed(self, connector, reason):
         ReconnectingClientFactory.clientConnectionFailed(self, connector, reason)
 
 
-class ReplicationClientHandler(AbstractReplicationClientHandler):
-    """A base handler that can be passed to the ReplicationClientFactory.
+class ReplicationDataHandler:
+    """Handles incoming stream updates from replication.
 
-    By default proxies incoming replication data to the SlaveStore.
+    This instance notifies the slave data store about updates. Can be subclassed
+    to handle updates in additional ways.
     """
 
     def __init__(self, store: BaseSlavedStore):
         self.store = store
 
-        # The current connection. None if we are currently (re)connecting
-        self.connection = None
-
-        # Any pending commands to be sent once a new connection has been
-        # established
-        self.pending_commands = []  # type: List[Command]
-
-        # Map from string -> deferred, to wake up when receiveing a SYNC with
-        # the given string.
-        # Used for tests.
-        self.awaiting_syncs = {}  # type: Dict[str, defer.Deferred]
-
-        # The factory used to create connections.
-        self.factory = None  # type: Optional[ReplicationClientFactory]
-
-    def start_replication(self, hs):
-        """Helper method to start a replication connection to the remote server
-        using TCP.
-        """
-        client_name = hs.config.worker_name
-        self.factory = ReplicationClientFactory(hs, client_name, self)
-        host = hs.config.worker_replication_host
-        port = hs.config.worker_replication_port
-        hs.get_reactor().connectTCP(host, port, self.factory)
-
-    async def on_rdata(self, stream_name, token, rows):
+    async def on_rdata(self, stream_name: str, token: int, rows: list):
         """Called to handle a batch of replication data with a given stream token.
 
         By default this just pokes the slave store. Can be overridden in subclasses to
@@ -124,30 +98,8 @@ async def on_rdata(self, stream_name, token, rows):
             rows (list): a list of Stream.ROW_TYPE objects as returned by
                 Stream.parse_row.
         """
-        logger.debug("Received rdata %s -> %s", stream_name, token)
         self.store.process_replication_rows(stream_name, token, rows)
 
-    async def on_position(self, stream_name, token):
-        """Called when we get new position data. By default this just pokes
-        the slave store.
-
-        Can be overriden in subclasses to handle more.
-        """
-        self.store.process_replication_rows(stream_name, token, [])
-
-    def on_sync(self, data):
-        """When we received a SYNC we wake up any deferreds that were waiting
-        for the sync with the given data.
-
-        Used by tests.
-        """
-        d = self.awaiting_syncs.pop(data, None)
-        if d:
-            d.callback(data)
-
-    def on_remote_server_up(self, server: str):
-        """Called when get a new REMOTE_SERVER_UP command."""
-
     def get_streams_to_replicate(self) -> Dict[str, int]:
         """Called when a new connection has been established and we need to
         subscribe to streams.
@@ -163,85 +115,10 @@ def get_streams_to_replicate(self) -> Dict[str, int]:
             args["account_data"] = user_account_data
         elif room_account_data:
             args["account_data"] = room_account_data
-
         return args
 
-    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
-        currently syncing users. (Overriden by the synchrotron's only)
-        """
-        return []
-
-    def send_command(self, cmd):
-        """Send a command to master (when we get establish a connection if we
-        don't have one already.)
-        """
-        if self.connection:
-            self.connection.send_command(cmd)
-        else:
-            logger.warning("Queuing command as not connected: %r", cmd.NAME)
-            self.pending_commands.append(cmd)
-
-    def send_federation_ack(self, token):
-        """Ack data for the federation stream. This allows the master to drop
-        data stored purely in memory.
-        """
-        self.send_command(FederationAckCommand(token))
-
-    def send_user_sync(self, instance_id, user_id, is_syncing, last_sync_ms):
-        """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_remove_pusher(self, app_id, push_key, user_id):
-        """Poke the master to remove a pusher for a user
-        """
-        cmd = RemovePusherCommand(app_id, push_key, user_id)
-        self.send_command(cmd)
-
-    def send_invalidate_cache(self, cache_func, keys):
-        """Poke the master to invalidate a cache.
-        """
-        cmd = InvalidateCacheCommand(cache_func.__name__, keys)
-        self.send_command(cmd)
-
-    def send_user_ip(self, user_id, access_token, ip, user_agent, device_id, last_seen):
-        """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):
-        self.send_command(RemoteServerUpCommand(server))
-
-    def await_sync(self, data):
-        """Returns a deferred that is resolved when we receive a SYNC command
-        with given data.
-
-        [Not currently] used by tests.
-        """
-        return self.awaiting_syncs.setdefault(data, defer.Deferred())
-
-    def update_connection(self, connection):
-        """Called when a connection has been established (or lost with None).
-        """
-        self.connection = connection
-        if connection:
-            for cmd in self.pending_commands:
-                connection.send_command(cmd)
-            self.pending_commands = []
-
-    def finished_connecting(self):
-        """Called when we have successfully subscribed and caught up to all
-        streams we're interested in.
-        """
-        logger.info("Finished connecting to server")
+    async def on_position(self, stream_name: str, token: int):
+        self.store.process_replication_rows(stream_name, token, [])
 
-        # 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 on_remote_server_up(self, server: str):
+        """Called when get a new REMOTE_SERVER_UP command."""