Thread through instance name to replication client. (#7369)

For in memory streams when fetching updates on workers we need to query the source of the stream, which currently is hard coded to be master. This PR threads through the source instance we received via `POSITION` through to the update function in each stream, which can then be passed to the replication client for in memory streams.

1 files changed, 8 insertions, 2 deletions

diff --git a/synapse/replication/tcp/streams/events.py b/synapse/replication/tcp/streams/events.py
index 52df81b1bd..890e75d827 100644
--- a/synapse/replication/tcp/streams/events.py
+++ b/synapse/replication/tcp/streams/events.py
@@ -118,11 +118,17 @@ class EventsStream(Stream):
     def __init__(self, hs):
         self._store = hs.get_datastore()
         super().__init__(
-            self._store.get_current_events_token, self._update_function,
+            hs.get_instance_name(),
+            self._store.get_current_events_token,
+            self._update_function,
         )
 
     async def _update_function(
-        self, from_token: Token, current_token: Token, target_row_count: int
+        self,
+        instance_name: str,
+        from_token: Token,
+        current_token: Token,
+        target_row_count: int,
     ) -> StreamUpdateResult:
 
         # the events stream merges together three separate sources: