Add `event.internal_metadata.instance_name` (#17300)

Add `event.internal_metadata.instance_name` (the worker instance that persisted the event) to go alongside the existing `event.internal_metadata.stream_ordering`.

`instance_name` is useful to properly compare and query for events with a token since you need to compare both the `stream_ordering` and `instance_name` against the vector clock/`instance_map` in the `RoomStreamToken`.

This is pre-requisite work and may be used in https://github.com/element-hq/synapse/pull/17293

Adding `event.internal_metadata.instance_name` was first mentioned in the initial Sliding Sync PR while pairing with @erikjohnston, see https://github.com/element-hq/synapse/pull/17187/commits/09609cb0dbca3a4cfd9fbf90cc962e765ec469c0#diff-5cd773fb307aa754bd3948871ba118b1ef0303f4d72d42a2d21e38242bf4e096R405-R410

1 files changed, 3 insertions, 0 deletions

diff --git a/tests/events/test_utils.py b/tests/events/test_utils.py

index d5ac66a6ed..30f8787758 100644
--- a/tests/events/test_utils.py
+++ b/tests/events/test_utils.py
@@ -625,6 +625,8 @@ class CloneEventTestCase(stdlib_unittest.TestCase):
         )
         original.internal_metadata.stream_ordering = 1234
         self.assertEqual(original.internal_metadata.stream_ordering, 1234)
+        original.internal_metadata.instance_name = "worker1"
+        self.assertEqual(original.internal_metadata.instance_name, "worker1")
 
         cloned = clone_event(original)
         cloned.unsigned["b"] = 3
@@ -632,6 +634,7 @@ class CloneEventTestCase(stdlib_unittest.TestCase):
         self.assertEqual(original.unsigned, {"a": 1, "b": 2})
         self.assertEqual(cloned.unsigned, {"a": 1, "b": 3})
         self.assertEqual(cloned.internal_metadata.stream_ordering, 1234)
+        self.assertEqual(cloned.internal_metadata.instance_name, "worker1")
         self.assertEqual(cloned.internal_metadata.txn_id, "txn")