public MutableGaugeLong newGauge(MetricsInfo info, long iVal) {
    MutableGaugeLong ret = new MutableGaugeLong(info, iVal);
    return addNewMetricIfAbsent(info.name(), ret, MutableGaugeLong.class);
  }
Create a mutable long integer gauge
@param info metadata of the metric
@param iVal initial value
@return a new gauge object
hbase-hadoop-compat/src/main/java/org/apache/hadoop/metrics2/lib/DynamicMetricsRegistry.java