@Override
    public void postGetOp(ObserverContext<? extends RegionCoprocessorEnvironment> e, Get get,
      List<Cell> results) throws IOException {
      // do a costly (high latency) operation which we want to measure how long it takes by
      // using a Timer (which is a Meter and a Histogram).
      long start = System.nanoTime();
      try {
        performCostlyOperation();
      } finally {
        costlyOperationTimer.updateNanos(System.nanoTime() - start);
      }
    }
An example coprocessor that collects some metrics to demonstrate the usage of exporting custom
metrics from the coprocessor.
<p>
These metrics will be available through the regular Hadoop metrics2 sinks (ganglia, opentsdb,
etc) as well as JMX output. You can view a snapshot of the metrics by going to the http web UI of
the regionserver page, something like http://myregionserverhost:16030/jmx
</p>
@see ExampleMasterObserverWithMetrics
hbase-examples/src/main/java/org/apache/hadoop/hbase/coprocessor/example/ExampleRegionObserverWithMetrics.java