/** {@inheritDoc} */
  @Override
  public synchronized Iterable<String> getGroupNames() {
    Collection<String> res = new HashSet<>();

    for (HadoopCounter counter : cntrs.values()) res.add(counter.group());

    return res;
  }
  /**
   * Returns size of a group.
   *
   * @param grpName Name of the group.
   * @return amount of counters in the given group.
   */
  public int groupSize(String grpName) {
    int res = 0;

    for (HadoopCounter counter : cntrs.values()) {
      if (grpName.equals(counter.group())) res++;
    }

    return res;
  }
 /**
  * Creates new instance based on given counters.
  *
  * @param cntrs Counters to adapt.
  */
 public HadoopMapReduceCounters(
     org.apache.ignite.internal.processors.hadoop.counter.HadoopCounters cntrs) {
   for (HadoopCounter cntr : cntrs.all())
     if (cntr instanceof HadoopLongCounter)
       this.cntrs.put(new T2<>(cntr.group(), cntr.name()), (HadoopLongCounter) cntr);
 }