Split `FederationHandler` in half (#10692)

The idea here is to take anything to do with incoming events and move it out to a separate handler, as a way of making FederationHandler smaller.

changelog.d/10692.misc

@@ -0,0 +1 @@
+Split the event-processing methods in `FederationHandler` into a separate `FederationEventHandler`.

synapse/federation/federation_server.py

@@ -110,6 +110,7 @@ class FederationServer(FederationBase):
         super().__init__(hs)
 
         self.handler = hs.get_federation_handler()
+        self._federation_event_handler = hs.get_federation_event_handler()
         self.state = hs.get_state_handler()
         self._event_auth_handler = hs.get_event_auth_handler()
 
@@ -787,7 +788,9 @@ class FederationServer(FederationBase):
 
         event = await self._check_sigs_and_hash(room_version, event)
 
-        return await self.handler.on_send_membership_event(origin, event)
+        return await self._federation_event_handler.on_send_membership_event(
+            origin, event
+        )
 
     async def on_event_auth(
         self, origin: str, room_id: str, event_id: str
@@ -1005,7 +1008,7 @@ class FederationServer(FederationBase):
             async with lock:
                 logger.info("handling received PDU: %s", event)
                 try:
-                    await self.handler.on_receive_pdu(origin, event)
+                    await self._federation_event_handler.on_receive_pdu(origin, event)
                 except FederationError as e:
                     # XXX: Ideally we'd inform the remote we failed to process
                     # the event, but we can't return an error in the transaction

synapse/replication/http/federation.py

@@ -62,7 +62,7 @@ class ReplicationFederationSendEventsRestServlet(ReplicationEndpoint):
         self.store = hs.get_datastore()
         self.storage = hs.get_storage()
         self.clock = hs.get_clock()
-        self.federation_handler = hs.get_federation_handler()
+        self.federation_event_handler = hs.get_federation_event_handler()
 
     @staticmethod
     async def _serialize_payload(store, room_id, event_and_contexts, backfilled):
@@ -127,7 +127,7 @@ class ReplicationFederationSendEventsRestServlet(ReplicationEndpoint):
 
         logger.info("Got %d events from federation", len(event_and_contexts))
 
-        max_stream_id = await self.federation_handler.persist_events_and_notify(
+        max_stream_id = await self.federation_event_handler.persist_events_and_notify(
             room_id, event_and_contexts, backfilled
         )
 

synapse/server.py

@@ -76,6 +76,7 @@ from synapse.handlers.e2e_room_keys import E2eRoomKeysHandler
 from synapse.handlers.event_auth import EventAuthHandler
 from synapse.handlers.events import EventHandler, EventStreamHandler
 from synapse.handlers.federation import FederationHandler
+from synapse.handlers.federation_event import FederationEventHandler
 from synapse.handlers.groups_local import GroupsLocalHandler, GroupsLocalWorkerHandler
 from synapse.handlers.identity import IdentityHandler
 from synapse.handlers.initial_sync import InitialSyncHandler
@@ -546,6 +547,10 @@ class HomeServer(metaclass=abc.ABCMeta):
     def get_federation_handler(self) -> FederationHandler:
         return FederationHandler(self)
 
+    @cache_in_self
+    def get_federation_event_handler(self) -> FederationEventHandler:
+        return FederationEventHandler(self)
+
     @cache_in_self
     def get_identity_handler(self) -> IdentityHandler:
         return IdentityHandler(self)

tests/federation/transport/test_knocking.py

@@ -208,7 +208,7 @@ class FederationKnockingTestCase(
         async def _check_event_auth(origin, event, context, *args, **kwargs):
             return context
 
-        homeserver.get_federation_handler()._check_event_auth = _check_event_auth
+        homeserver.get_federation_event_handler()._check_event_auth = _check_event_auth
 
         return super().prepare(reactor, clock, homeserver)
 

tests/handlers/test_federation.py

@@ -130,7 +130,9 @@ class FederationTestCase(unittest.HomeserverTestCase):
         )
 
         with LoggingContext("send_rejected"):
-            d = run_in_background(self.handler.on_receive_pdu, OTHER_SERVER, ev)
+            d = run_in_background(
+                self.hs.get_federation_event_handler().on_receive_pdu, OTHER_SERVER, ev
+            )
         self.get_success(d)
 
         # that should have been rejected
@@ -182,7 +184,9 @@ class FederationTestCase(unittest.HomeserverTestCase):
         )
 
         with LoggingContext("send_rejected"):
-            d = run_in_background(self.handler.on_receive_pdu, OTHER_SERVER, ev)
+            d = run_in_background(
+                self.hs.get_federation_event_handler().on_receive_pdu, OTHER_SERVER, ev
+            )
         self.get_success(d)
 
         # that should have been rejected
@@ -311,7 +315,9 @@ class FederationTestCase(unittest.HomeserverTestCase):
         with LoggingContext("receive_pdu"):
             # Fake the OTHER_SERVER federating the message event over to our local homeserver
             d = run_in_background(
-                self.handler.on_receive_pdu, OTHER_SERVER, message_event
+                self.hs.get_federation_event_handler().on_receive_pdu,
+                OTHER_SERVER,
+                message_event,
             )
         self.get_success(d)
 
@@ -382,7 +388,9 @@ class FederationTestCase(unittest.HomeserverTestCase):
         join_event.signatures[other_server] = {"x": "y"}
         with LoggingContext("send_join"):
             d = run_in_background(
-                self.handler.on_send_membership_event, other_server, join_event
+                self.hs.get_federation_event_handler().on_send_membership_event,
+                other_server,
+                join_event,
             )
         self.get_success(d)
 

tests/handlers/test_presence.py

@@ -885,7 +885,7 @@ class PresenceJoinTestCase(unittest.HomeserverTestCase):
     def prepare(self, reactor, clock, hs):
         self.federation_sender = hs.get_federation_sender()
         self.event_builder_factory = hs.get_event_builder_factory()
-        self.federation_handler = hs.get_federation_handler()
+        self.federation_event_handler = hs.get_federation_event_handler()
         self.presence_handler = hs.get_presence_handler()
 
         # self.event_builder_for_2 = EventBuilderFactory(hs)
@@ -1026,7 +1026,7 @@ class PresenceJoinTestCase(unittest.HomeserverTestCase):
             builder.build(prev_event_ids=prev_event_ids, auth_event_ids=None)
         )
 
-        self.get_success(self.federation_handler.on_receive_pdu(hostname, event))
+        self.get_success(self.federation_event_handler.on_receive_pdu(hostname, event))
 
         # Check that it was successfully persisted.
         self.get_success(self.store.get_event(event.event_id))

tests/replication/test_federation_sender_shard.py

@@ -205,7 +205,7 @@ class FederationSenderTestCase(BaseMultiWorkerStreamTestCase):
     def create_room_with_remote_server(self, user, token, remote_server="other_server"):
         room = self.helper.create_room_as(user, tok=token)
         store = self.hs.get_datastore()
-        federation = self.hs.get_federation_handler()
+        federation = self.hs.get_federation_event_handler()
 
         prev_event_ids = self.get_success(store.get_latest_event_ids_in_room(room))
         room_version = self.get_success(store.get_room_version(room))

tests/test_federation.py

@@ -75,7 +75,8 @@ class MessageAcceptTests(unittest.HomeserverTestCase):
         )
 
         self.handler = self.homeserver.get_federation_handler()
-        self.handler._check_event_auth = lambda origin, event, context, state, claimed_auth_event_map, backfilled: succeed(
+        federation_event_handler = self.homeserver.get_federation_event_handler()
+        federation_event_handler._check_event_auth = lambda origin, event, context, state, claimed_auth_event_map, backfilled: succeed(
             context
         )
         self.client = self.homeserver.get_federation_client()
@@ -85,7 +86,9 @@ class MessageAcceptTests(unittest.HomeserverTestCase):
 
         # Send the join, it should return None (which is not an error)
         self.assertEqual(
-            self.get_success(self.handler.on_receive_pdu("test.serv", join_event)),
+            self.get_success(
+                federation_event_handler.on_receive_pdu("test.serv", join_event)
+            ),
             None,
         )
 
@@ -129,9 +132,10 @@ class MessageAcceptTests(unittest.HomeserverTestCase):
             }
         )
 
+        federation_event_handler = self.homeserver.get_federation_event_handler()
         with LoggingContext("test-context"):
             failure = self.get_failure(
-                self.handler.on_receive_pdu("test.serv", lying_event),
+                federation_event_handler.on_receive_pdu("test.serv", lying_event),
                 FederationError,
             )