Make logging output for state deletions a bit better

roomserver/internal/input/input_latest_events.go

@@ -102,8 +102,8 @@ type latestEventsUpdater struct {
 	// The eventID of the event that was processed before this one.
 	lastEventIDSent string
 	// The latest events in the room after processing this event.
-	oldLatest []types.StateAtEventAndReference
-	latest    []types.StateAtEventAndReference
+	oldLatest types.StateAtEventAndReferences
+	latest    types.StateAtEventAndReferences
 	// The state entries removed from and added to the current state of the
 	// room as a result of processing this event. They are sorted lists.
 	removed []types.StateEntry
@@ -126,7 +126,7 @@ func (u *latestEventsUpdater) doUpdateLatestEvents() error {
 	// state snapshot from somewhere else, e.g. a federated room join,
 	// then start with an empty set - none of the forward extremities
 	// that we knew about before matter anymore.
-	u.oldLatest = []types.StateAtEventAndReference{}
+	u.oldLatest = types.StateAtEventAndReferences{}
 	if !u.rewritesState {
 		u.oldStateNID = u.updater.CurrentStateSnapshotNID()
 		u.oldLatest = u.updater.LatestEvents()
@@ -277,8 +277,8 @@ func (u *latestEventsUpdater) latestState() error {
 			"room_id":       u.event.RoomID(),
 			"old_state_nid": u.oldStateNID,
 			"new_state_nid": u.newStateNID,
-			"old_latest":    u.oldLatest,
-			"new_latest":    u.latest,
+			"old_latest":    u.oldLatest.EventIDs(),
+			"new_latest":    u.latest.EventIDs(),
 		}).Errorf("Unexpected state deletion (removing %d events)", removed)
 	}
 

roomserver/types/types.go

@@ -210,6 +210,14 @@ func (s StateAtEventAndReferences) Swap(a, b int) {
 	s[a], s[b] = s[b], s[a]
 }
 
+func (s StateAtEventAndReferences) EventIDs() string {
+	strs := make([]string, 0, len(s))
+	for _, r := range s {
+		strs = append(strs, r.EventID)
+	}
+	return "[" + strings.Join(strs, " ") + "]"
+}
+
 // An Event is a gomatrixserverlib.Event with the numeric event ID attached.
 // It is when performing bulk event lookup in the database.
 type Event struct {