From 8e56a1b73c9819ea4bddbe6a4734966e70b3b92c Mon Sep 17 00:00:00 2001
From: lukasdenk <63459921+lukasdenk@users.noreply.github.com>
Date: Wed, 2 Mar 2022 11:35:34 +0100
Subject: [PATCH] Make get_room_version use cached get_room_version_id.
 (#11808)

---
 changelog.d/11808.misc                  |  1 +
 synapse/storage/databases/main/state.py | 27 ++++++++++++-------------
 tests/handlers/test_room_summary.py     |  5 ++++-
 3 files changed, 18 insertions(+), 15 deletions(-)
 create mode 100644 changelog.d/11808.misc

diff --git a/changelog.d/11808.misc b/changelog.d/11808.misc
new file mode 100644
index 000000000..cdc5fc75b
--- /dev/null
+++ b/changelog.d/11808.misc
@@ -0,0 +1 @@
+Make method `get_room_version` use cached `get_room_version_id`.
diff --git a/synapse/storage/databases/main/state.py b/synapse/storage/databases/main/state.py
index 2fb3e6519..417aef1db 100644
--- a/synapse/storage/databases/main/state.py
+++ b/synapse/storage/databases/main/state.py
@@ -42,6 +42,16 @@ logger = logging.getLogger(__name__)
 MAX_STATE_DELTA_HOPS = 100
 
 
+def _retrieve_and_check_room_version(room_id: str, room_version_id: str) -> RoomVersion:
+    v = KNOWN_ROOM_VERSIONS.get(room_version_id)
+    if not v:
+        raise UnsupportedRoomVersionError(
+            "Room %s uses a room version %s which is no longer supported"
+            % (room_id, room_version_id)
+        )
+    return v
+
+
 # this inherits from EventsWorkerStore because it calls self.get_events
 class StateGroupWorkerStore(EventsWorkerStore, SQLBaseStore):
     """The parts of StateGroupStore that can be called from workers."""
@@ -62,11 +72,8 @@ class StateGroupWorkerStore(EventsWorkerStore, SQLBaseStore):
                 Typically this happens if support for the room's version has been
                 removed from Synapse.
         """
-        return await self.db_pool.runInteraction(
-            "get_room_version_txn",
-            self.get_room_version_txn,
-            room_id,
-        )
+        room_version_id = await self.get_room_version_id(room_id)
+        return _retrieve_and_check_room_version(room_id, room_version_id)
 
     def get_room_version_txn(
         self, txn: LoggingTransaction, room_id: str
@@ -82,15 +89,7 @@ class StateGroupWorkerStore(EventsWorkerStore, SQLBaseStore):
                 removed from Synapse.
         """
         room_version_id = self.get_room_version_id_txn(txn, room_id)
-        v = KNOWN_ROOM_VERSIONS.get(room_version_id)
-
-        if not v:
-            raise UnsupportedRoomVersionError(
-                "Room %s uses a room version %s which is no longer supported"
-                % (room_id, room_version_id)
-            )
-
-        return v
+        return _retrieve_and_check_room_version(room_id, room_version_id)
 
     @cached(max_entries=10000)
     async def get_room_version_id(self, room_id: str) -> str:
diff --git a/tests/handlers/test_room_summary.py b/tests/handlers/test_room_summary.py
index b33ff94a3..cff07a897 100644
--- a/tests/handlers/test_room_summary.py
+++ b/tests/handlers/test_room_summary.py
@@ -658,7 +658,7 @@ class SpaceSummaryTestCase(unittest.HomeserverTestCase):
 
     def test_unknown_room_version(self):
         """
-        If an room with an unknown room version is encountered it should not cause
+        If a room with an unknown room version is encountered it should not cause
         the entire summary to skip.
         """
         # Poke the database and update the room version to an unknown one.
@@ -670,6 +670,9 @@ class SpaceSummaryTestCase(unittest.HomeserverTestCase):
                 desc="updated-room-version",
             )
         )
+        # Invalidate method so that it returns the currently updated version
+        # instead of the cached version.
+        self.hs.get_datastores().main.get_room_version_id.invalidate((self.room,))
 
         # The result should have only the space, along with a link from space -> room.
         expected = [(self.space, [self.room])]