@Override
    public void in(Metrics metrics) {
        if (metrics instanceof WithMetadata) {
            entrance.forward(metrics);
        }
    }
Alarm notify worker, do a simple route to alarm core after the aggregation persistence.
oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/worker/AlarmNotifyWorker.java