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