/**
   * Sends query request.
   *
   * @param fut Distributed future.
   * @param req Request.
   * @param nodes Nodes.
   * @throws IgniteCheckedException In case of error.
   */
  @SuppressWarnings("unchecked")
  private void sendRequest(
      final GridCacheDistributedQueryFuture<?, ?, ?> fut,
      final GridCacheQueryRequest req,
      Collection<ClusterNode> nodes)
      throws IgniteCheckedException {
    assert fut != null;
    assert req != null;
    assert nodes != null;

    final UUID locNodeId = cctx.localNodeId();

    ClusterNode locNode = null;

    Collection<ClusterNode> rmtNodes = null;

    for (ClusterNode n : nodes) {
      if (n.id().equals(locNodeId)) locNode = n;
      else {
        if (rmtNodes == null) rmtNodes = new ArrayList<>(nodes.size());

        rmtNodes.add(n);
      }
    }

    // Request should be sent to remote nodes before the query is processed on the local node.
    // For example, a remote reducer has a state, we should not serialize and then send
    // the reducer changed by the local node.
    if (!F.isEmpty(rmtNodes)) {
      cctx.io()
          .safeSend(
              rmtNodes,
              req,
              cctx.ioPolicy(),
              new P1<ClusterNode>() {
                @Override
                public boolean apply(ClusterNode node) {
                  fut.onNodeLeft(node.id());

                  return !fut.isDone();
                }
              });
    }

    if (locNode != null) {
      cctx.closures()
          .callLocalSafe(
              new Callable<Object>() {
                @Override
                public Object call() throws Exception {
                  req.beforeLocalExecution(cctx);

                  processQueryRequest(locNodeId, req);

                  return null;
                }
              });
    }
  }
  /**
   * Processes cache query request.
   *
   * @param sndId Sender node id.
   * @param req Query request.
   */
  @SuppressWarnings("unchecked")
  @Override
  void processQueryRequest(UUID sndId, GridCacheQueryRequest req) {
    if (req.cancel()) {
      cancelIds.add(new CancelMessageId(req.id(), sndId));

      if (req.fields()) removeFieldsQueryResult(sndId, req.id());
      else removeQueryResult(sndId, req.id());
    } else {
      if (!cancelIds.contains(new CancelMessageId(req.id(), sndId))) {
        if (!F.eq(req.cacheName(), cctx.name())) {
          GridCacheQueryResponse res =
              new GridCacheQueryResponse(
                  cctx.cacheId(),
                  req.id(),
                  new IgniteCheckedException(
                      "Received request for incorrect cache [expected="
                          + cctx.name()
                          + ", actual="
                          + req.cacheName()));

          sendQueryResponse(sndId, res, 0);
        } else {
          threads.put(req.id(), Thread.currentThread());

          try {
            GridCacheQueryInfo info = distributedQueryInfo(sndId, req);

            if (info == null) return;

            if (req.fields()) runFieldsQuery(info);
            else runQuery(info);
          } catch (Throwable e) {
            U.error(log(), "Failed to run query.", e);

            sendQueryResponse(
                sndId, new GridCacheQueryResponse(cctx.cacheId(), req.id(), e.getCause()), 0);

            if (e instanceof Error) throw (Error) e;
          } finally {
            threads.remove(req.id());
          }
        }
      }
    }
  }
  /**
   * Decode file charset.
   *
   * @param f File to process.
   * @return File charset.
   * @throws IOException in case of error.
   */
  public static Charset decode(File f) throws IOException {
    SortedMap<String, Charset> charsets = Charset.availableCharsets();

    String[] firstCharsets = {
      Charset.defaultCharset().name(), "US-ASCII", "UTF-8", "UTF-16BE", "UTF-16LE"
    };

    Collection<Charset> orderedCharsets = U.newLinkedHashSet(charsets.size());

    for (String c : firstCharsets)
      if (charsets.containsKey(c)) orderedCharsets.add(charsets.get(c));

    orderedCharsets.addAll(charsets.values());

    try (RandomAccessFile raf = new RandomAccessFile(f, "r")) {
      FileChannel ch = raf.getChannel();

      ByteBuffer buf = ByteBuffer.allocate(4096);

      ch.read(buf);

      buf.flip();

      for (Charset charset : orderedCharsets) {
        CharsetDecoder decoder = charset.newDecoder();

        decoder.reset();

        try {
          decoder.decode(buf);

          return charset;
        } catch (CharacterCodingException ignored) {
        }
      }
    }

    return Charset.defaultCharset();
  }
 /** {@inheritDoc} */
 @Override
 void onQueryFutureCanceled(long reqId) {
   cancelled.add(reqId);
 }
  /**
   * 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;
  }