Use stable identifiers for faster joins (#14832)

* Use new query param when requesting a partial join

* Read new query param when serving partial join

* Provide new field names when serving partial joins

* Read new field names from partial join response

* Changelog

1 files changed, 18 insertions, 0 deletions

diff --git a/synapse/federation/transport/client.py b/synapse/federation/transport/client.py
index 77f1f39cac..c8471d4cf7 100644
--- a/synapse/federation/transport/client.py
+++ b/synapse/federation/transport/client.py
@@ -357,6 +357,7 @@ class TransportLayerClient:
         if self._faster_joins_enabled:
             # lazy-load state on join
             query_params["org.matrix.msc3706.partial_state"] = "true"
+            query_params["omit_members"] = "true"
 
         return await self.client.put_json(
             destination=destination,
@@ -909,6 +910,14 @@ class SendJoinParser(ByteParser[SendJoinResponse]):
                     use_float="True",
                 )
             )
+            # The stable field name comes last, so it "wins" if the fields disagree
+            self._coros.append(
+                ijson.items_coro(
+                    _partial_state_parser(self._response),
+                    "members_omitted",
+                    use_float="True",
+                )
+            )
 
             self._coros.append(
                 ijson.items_coro(
@@ -918,6 +927,15 @@ class SendJoinParser(ByteParser[SendJoinResponse]):
                 )
             )
 
+            # Again, stable field name comes last
+            self._coros.append(
+                ijson.items_coro(
+                    _servers_in_room_parser(self._response),
+                    "servers_in_room",
+                    use_float="True",
+                )
+            )
+
     def write(self, data: bytes) -> int:
         for c in self._coros:
             c.send(data)