Refactor out calculateAndSetState to decrease cyclomatic complexity

src/github.com/matrix-org/dendrite/roomserver/input/events.go

@@ -105,6 +105,30 @@ func processRoomEvent(
 	if stateAtEvent.BeforeStateSnapshotNID == 0 {
 		// We haven't calculated a state for this event yet.
 		// Lets calculate one.
+		err = calculateAndSetState(ctx, db, input, roomNID, &stateAtEvent, event)
+		if err != nil {
+			return err
+		}
+	}
+
+	if input.Kind == api.KindBackfill {
+		// Backfill is not implemented.
+		panic("Not implemented")
+	}
+
+	// Update the extremities of the event graph for the room
+	return updateLatestEvents(ctx, db, ow, roomNID, stateAtEvent, event, input.SendAsServer, input.TransactionID)
+}
+
+func calculateAndSetState(
+	ctx context.Context,
+	db RoomEventDatabase,
+	input api.InputRoomEvent,
+	roomNID types.RoomNID,
+	stateAtEvent *types.StateAtEvent,
+	event gomatrixserverlib.Event,
+) error {
+	var err error
 	if input.HasState {
 		// We've been told what the state at the event is so we don't need to calculate it.
 		// Check that those state events are in the database and store the state.
@@ -122,19 +146,7 @@ func processRoomEvent(
 			return err
 		}
 	}
-		err = db.SetState(ctx, stateAtEvent.EventNID, stateAtEvent.BeforeStateSnapshotNID)
+	return db.SetState(ctx, stateAtEvent.EventNID, stateAtEvent.BeforeStateSnapshotNID)
-		if err != nil {
-			return err
-		}
-	}
-
-	if input.Kind == api.KindBackfill {
-		// Backfill is not implemented.
-		panic("Not implemented")
-	}
-
-	// Update the extremities of the event graph for the room
-	return updateLatestEvents(ctx, db, ow, roomNID, stateAtEvent, event, input.SendAsServer, input.TransactionID)
 }
 
 func processInviteEvent(