Expand comments around different replication process methods

matrix-org · Jan 3, 2023 · 537cb40 · 537cb40
1 parent 427972f
commit 537cb40
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diff --git a/synapse/replication/tcp/client.py b/synapse/replication/tcp/client.py
@@ -152,6 +152,8 @@ async def on_rdata(
             rows: a list of Stream.ROW_TYPE objects as returned by Stream.parse_row.
         """
         self.store.process_replication_rows(stream_name, instance_name, token, rows)
+        # NOTE: this must be called after process_replication_rows to ensure any
+        # cache invalidations are first handled before any stream ID advances.
         self.store.process_replication_position(stream_name, instance_name, token)
 
         if self.send_handler:

diff --git a/synapse/storage/_base.py b/synapse/storage/_base.py
@@ -58,7 +58,8 @@ def process_replication_rows(  # noqa: B027 (no-op by design)
         rows: Iterable[Any],
     ) -> None:
         """
-        Used by storage classes to invalidate caches based on incoming replication data.
+        Used by storage classes to invalidate caches based on incoming replication data. These
+        must not update any ID generators, use `process_replication_position`.
         """
 
     def process_replication_position(  # noqa: B027 (no-op by design)