@Override
    public void mutateRows(RpcController controller, MutateRowsRequest request,
      RpcCallback<MutateRowsResponse> done) {
      long start = System.nanoTime();
      super.mutateRows(controller, request, done);
      endpointExecution.updateNanos(System.nanoTime() - start);
    }
RegionEndpoint to test metrics from endpoint calls
hbase-server/src/test/java/org/apache/hadoop/hbase/coprocessor/TestCoprocessorMetrics.java