/** {@inheritDoc} */
  @Override
  protected void beforeTestsStarted() throws Exception {
    chunk = new byte[128];

    for (int i = 0; i < chunk.length; i++) chunk[i] = (byte) i;

    Ignite igniteSecondary =
        startGridWithIgfs("grid-secondary", "igfs-secondary", PRIMARY, null, SECONDARY_REST_CFG);

    IgfsSecondaryFileSystem hadoopFs =
        new IgniteHadoopIgfsSecondaryFileSystem(SECONDARY_URI, SECONDARY_CFG);

    Ignite ignite = startGridWithIgfs("grid", "igfs", mode, hadoopFs, PRIMARY_REST_CFG);

    igfsSecondary = (IgfsImpl) igniteSecondary.fileSystem("igfs-secondary");
    igfs = (IgfsImpl) ignite.fileSystem("igfs");
  }
  /**
   * Checks for explicit events configuration.
   *
   * @param ignite Grid instance.
   * @return {@code true} if all task events explicitly specified in configuration.
   */
  public static boolean checkExplicitTaskMonitoring(Ignite ignite) {
    int[] evts = ignite.configuration().getIncludeEventTypes();

    if (F.isEmpty(evts)) return false;

    for (int evt : VISOR_TASK_EVTS) {
      if (!F.contains(evts, evt)) return false;
    }

    return true;
  }
  /**
   * Grabs local events and detects if events was lost since last poll.
   *
   * @param ignite Target grid.
   * @param evtOrderKey Unique key to take last order key from node local map.
   * @param evtThrottleCntrKey Unique key to take throttle count from node local map.
   * @param evtTypes Event types to collect.
   * @param evtMapper Closure to map grid events to Visor data transfer objects.
   * @return Collections of node events
   */
  public static Collection<VisorGridEvent> collectEvents(
      Ignite ignite,
      String evtOrderKey,
      String evtThrottleCntrKey,
      final int[] evtTypes,
      IgniteClosure<Event, VisorGridEvent> evtMapper) {
    assert ignite != null;
    assert evtTypes != null && evtTypes.length > 0;

    ConcurrentMap<String, Long> nl = ignite.cluster().nodeLocalMap();

    final long lastOrder = getOrElse(nl, evtOrderKey, -1L);
    final long throttle = getOrElse(nl, evtThrottleCntrKey, 0L);

    // When we first time arrive onto a node to get its local events,
    // we'll grab only last those events that not older than given period to make sure we are
    // not grabbing GBs of data accidentally.
    final long notOlderThan = System.currentTimeMillis() - EVENTS_COLLECT_TIME_WINDOW;

    // Flag for detecting gaps between events.
    final AtomicBoolean lastFound = new AtomicBoolean(lastOrder < 0);

    IgnitePredicate<Event> p =
        new IgnitePredicate<Event>() {
          /** */
          private static final long serialVersionUID = 0L;

          @Override
          public boolean apply(Event e) {
            // Detects that events were lost.
            if (!lastFound.get() && (lastOrder == e.localOrder())) lastFound.set(true);

            // Retains events by lastOrder, period and type.
            return e.localOrder() > lastOrder
                && e.timestamp() > notOlderThan
                && F.contains(evtTypes, e.type());
          }
        };

    Collection<Event> evts = ignite.events().localQuery(p);

    // Update latest order in node local, if not empty.
    if (!evts.isEmpty()) {
      Event maxEvt = Collections.max(evts, EVTS_ORDER_COMPARATOR);

      nl.put(evtOrderKey, maxEvt.localOrder());
    }

    // Update throttle counter.
    if (!lastFound.get())
      nl.put(evtThrottleCntrKey, throttle == 0 ? EVENTS_LOST_THROTTLE : throttle - 1);

    boolean lost = !lastFound.get() && throttle == 0;

    Collection<VisorGridEvent> res = new ArrayList<>(evts.size() + (lost ? 1 : 0));

    if (lost) res.add(new VisorGridEventsLost(ignite.cluster().localNode().id()));

    for (Event e : evts) {
      VisorGridEvent visorEvt = evtMapper.apply(e);

      if (visorEvt != null) res.add(visorEvt);
    }

    return res;
  }