/** {@inheritDoc} */
  @SuppressWarnings("BusyWait")
  @Override
  public Boolean reduce(List<GridComputeJobResult> results) throws GridException {
    assert taskSes != null;
    assert results != null;
    assert params != null;
    assert !params.isEmpty();
    assert results.size() == params.size();

    Map<String, Integer> receivedParams = new HashMap<>();

    boolean allAttrReceived = false;

    int cnt = 0;

    while (!allAttrReceived && cnt++ < 3) {
      allAttrReceived = true;

      for (Map.Entry<String, Integer> entry : params.entrySet()) {
        assert taskSes.getAttribute(entry.getKey()) != null;

        Integer newVal = (Integer) taskSes.getAttribute(entry.getKey());

        assert newVal != null;

        receivedParams.put(entry.getKey(), newVal);

        if (newVal != entry.getValue() + 1) allAttrReceived = false;
      }

      if (!allAttrReceived) {
        try {
          Thread.sleep(100);
        } catch (InterruptedException e) {
          throw new GridException("Thread interrupted.", e);
        }
      }
    }

    if (log.isDebugEnabled()) {
      for (Map.Entry<String, Integer> entry : receivedParams.entrySet()) {
        log.debug(
            "Received session attr value [name="
                + entry.getKey()
                + ", val="
                + entry.getValue()
                + ", expected="
                + (params.get(entry.getKey()) + 1)
                + ']');
      }
    }

    return allAttrReceived;
  }
  /**
   * Parses HTTP parameters in an appropriate format and return back map of values to predefined
   * list of names.
   *
   * @param req Request.
   * @return Map of parsed parameters.
   */
  @SuppressWarnings({"unchecked"})
  private Map<String, Object> parameters(ServletRequest req) {
    Map<String, String[]> params = req.getParameterMap();

    if (F.isEmpty(params)) return Collections.emptyMap();

    Map<String, Object> map = U.newHashMap(params.size());

    for (Map.Entry<String, String[]> entry : params.entrySet())
      map.put(entry.getKey(), parameter(entry.getValue()));

    return map;
  }
  /** {@inheritDoc} */
  @Override
  public GridFuture<?> addData(Map<K, V> entries) throws IllegalStateException {
    A.notNull(entries, "entries");

    return addData(entries.entrySet());
  }