Sample increase(String metricName, Function2<Double, Long, Double> transform) {
        Tuple2<Long, Double> i = CounterWindow.INSTANCE.pop(metricName, labels, value, timestamp);
        double nv = transform.apply(i._2, i._1);
        return newValue(ignored -> nv);
    }
Sample represents the metric data point in a range of time.
oap-server/analyzer/meter-analyzer/src/main/java/org/apache/skywalking/oap/meter/analyzer/dsl/Sample.java