From 70322699abcf69531fdb47a282561f19592b8dfd Mon Sep 17 00:00:00 2001
From: Till <2353100+S7evinK@users.noreply.github.com>
Date: Thu, 9 Mar 2023 09:52:13 +0100
Subject: [PATCH] Unset `RoomServerEvent`, since we can't be sure that `Set`
 actually updates the cached entry (#3002)

This should deflake UTs and be more correct in terms of getting
`Events`.
`Events` tries to fetch the event from the cache first and may get an
unredacted event from it, while it should already be redacted.
---
 internal/caching/cache_roomevents.go | 5 +++++
 roomserver/storage/shared/storage.go | 8 ++++++--
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/internal/caching/cache_roomevents.go b/internal/caching/cache_roomevents.go
index 9d5d3b912..14b6c3af8 100644
--- a/internal/caching/cache_roomevents.go
+++ b/internal/caching/cache_roomevents.go
@@ -10,6 +10,7 @@ import (
 type RoomServerEventsCache interface {
 	GetRoomServerEvent(eventNID types.EventNID) (*gomatrixserverlib.Event, bool)
 	StoreRoomServerEvent(eventNID types.EventNID, event *gomatrixserverlib.Event)
+	InvalidateRoomServerEvent(eventNID types.EventNID)
 }
 
 func (c Caches) GetRoomServerEvent(eventNID types.EventNID) (*gomatrixserverlib.Event, bool) {
@@ -19,3 +20,7 @@ func (c Caches) GetRoomServerEvent(eventNID types.EventNID) (*gomatrixserverlib.
 func (c Caches) StoreRoomServerEvent(eventNID types.EventNID, event *gomatrixserverlib.Event) {
 	c.RoomServerEvents.Set(int64(eventNID), event)
 }
+
+func (c Caches) InvalidateRoomServerEvent(eventNID types.EventNID) {
+	c.RoomServerEvents.Unset(int64(eventNID))
+}
diff --git a/roomserver/storage/shared/storage.go b/roomserver/storage/shared/storage.go
index 106a8244e..78bda95e5 100644
--- a/roomserver/storage/shared/storage.go
+++ b/roomserver/storage/shared/storage.go
@@ -567,6 +567,7 @@ func (d *EventDatabase) events(
 		if !redactionsArePermanent {
 			d.applyRedactions(results)
 		}
+		return results, nil
 	}
 	eventJSONs, err := d.EventJSONTable.BulkSelectEventJSON(ctx, txn, eventNIDs)
 	if err != nil {
@@ -578,8 +579,9 @@ func (d *EventDatabase) events(
 	}
 
 	for _, eventJSON := range eventJSONs {
+		redacted := gjson.GetBytes(eventJSON.EventJSON, "unsigned.redacted_because").Exists()
 		events[eventJSON.EventNID], err = gomatrixserverlib.NewEventFromTrustedJSONWithEventID(
-			eventIDs[eventJSON.EventNID], eventJSON.EventJSON, false, roomInfo.RoomVersion,
+			eventIDs[eventJSON.EventNID], eventJSON.EventJSON, redacted, roomInfo.RoomVersion,
 		)
 		if err != nil {
 			return nil, err
@@ -1020,7 +1022,9 @@ func (d *EventDatabase) MaybeRedactEvent(
 			return fmt.Errorf("d.RedactionsTable.MarkRedactionValidated: %w", err)
 		}
 
-		d.Cache.StoreRoomServerEvent(redactedEvent.EventNID, redactedEvent.Event)
+		// We remove the entry from the cache, as if we just "StoreRoomServerEvent", we can't be
+		// certain that the cached entry actually is updated, since ristretto is eventual-persistent.
+		d.Cache.InvalidateRoomServerEvent(redactedEvent.EventNID)
 
 		return nil
 	})