1 files changed, 42 insertions, 12 deletions
diff --git a/synapse/replication/tcp/streams/federation.py b/synapse/replication/tcp/streams/federation.py
index dc2484109d..9bcd13b009 100644
--- a/synapse/replication/tcp/streams/federation.py
+++ b/synapse/replication/tcp/streams/federation.py
@@ -15,14 +15,10 @@
 # limitations under the License.
 from collections import namedtuple
 
-from ._base import Stream
-
-FederationStreamRow = namedtuple(
-    "FederationStreamRow",
-    (
-        "type",  # str, the type of data as defined in the BaseFederationRows
-        "data",  # dict, serialization of a federation.send_queue.BaseFederationRow
-    ),
+from synapse.replication.tcp.streams._base import (
+    Stream,
+    current_token_without_instance,
+    make_http_update_function,
 )
 
 
@@ -31,13 +27,47 @@ class FederationStream(Stream):
     sending disabled.
     """
 
+    FederationStreamRow = namedtuple(
+        "FederationStreamRow",
+        (
+            "type",  # str, the type of data as defined in the BaseFederationRows
+            "data",  # dict, serialization of a federation.send_queue.BaseFederationRow
+        ),
+    )
+
     NAME = "federation"
     ROW_TYPE = FederationStreamRow
 
     def __init__(self, hs):
-        federation_sender = hs.get_federation_sender()
+        if hs.config.worker_app is None:
+            # master process: get updates from the FederationRemoteSendQueue.
+            # (if the master is configured to send federation itself, federation_sender
+            # will be a real FederationSender, which has stubs for current_token and
+            # get_replication_rows.)
+            federation_sender = hs.get_federation_sender()
+            current_token = current_token_without_instance(
+                federation_sender.get_current_token
+            )
+            update_function = federation_sender.get_replication_rows
+
+        elif hs.should_send_federation():
+            # federation sender: Query master process
+            update_function = make_http_update_function(hs, self.NAME)
+            current_token = self._stub_current_token
+
+        else:
+            # other worker: stub out the update function (we're not interested in
+            # any updates so when we get a POSITION we do nothing)
+            update_function = self._stub_update_function
+            current_token = self._stub_current_token
+
+        super().__init__(hs.get_instance_name(), current_token, update_function)
 
-        self.current_token = federation_sender.get_current_token
-        self.update_function = federation_sender.get_replication_rows
+    @staticmethod
+    def _stub_current_token(instance_name: str) -> int:
+        # dummy current-token method for use on workers
+        return 0
 
-        super(FederationStream, self).__init__(hs)
+    @staticmethod
+    async def _stub_update_function(instance_name, from_token, upto_token, limit):
+        return [], upto_token, False