/**
   * Gets values referenced by sequential keys, e.g. {@code key1...keyN}.
   *
   * @param keyPrefix Key prefix, e.g. {@code key} for {@code key1...keyN}.
   * @param params Parameters map.
   * @return Values.
   */
  @Nullable
  protected List<Object> values(String keyPrefix, Map<String, Object> params) {
    assert keyPrefix != null;

    List<Object> vals = new LinkedList<>();

    for (int i = 1; ; i++) {
      String key = keyPrefix + i;

      if (params.containsKey(key)) vals.add(params.get(key));
      else break;
    }

    return vals;
  }
  /**
   * Performs flush.
   *
   * @throws GridException If failed.
   */
  private void doFlush() throws GridException {
    lastFlushTime = U.currentTimeMillis();

    List<GridFuture> activeFuts0 = null;

    int doneCnt = 0;

    for (GridFuture<?> f : activeFuts) {
      if (!f.isDone()) {
        if (activeFuts0 == null) activeFuts0 = new ArrayList<>((int) (activeFuts.size() * 1.2));

        activeFuts0.add(f);
      } else {
        f.get();

        doneCnt++;
      }
    }

    if (activeFuts0 == null || activeFuts0.isEmpty()) return;

    while (true) {
      Queue<GridFuture<?>> q = null;

      for (Buffer buf : bufMappings.values()) {
        GridFuture<?> flushFut = buf.flush();

        if (flushFut != null) {
          if (q == null) q = new ArrayDeque<>(bufMappings.size() * 2);

          q.add(flushFut);
        }
      }

      if (q != null) {
        assert !q.isEmpty();

        boolean err = false;

        for (GridFuture fut = q.poll(); fut != null; fut = q.poll()) {
          try {
            fut.get();
          } catch (GridException e) {
            if (log.isDebugEnabled()) log.debug("Failed to flush buffer: " + e);

            err = true;
          }
        }

        if (err)
          // Remaps needed - flush buffers.
          continue;
      }

      doneCnt = 0;

      for (int i = 0; i < activeFuts0.size(); i++) {
        GridFuture f = activeFuts0.get(i);

        if (f == null) doneCnt++;
        else if (f.isDone()) {
          f.get();

          doneCnt++;

          activeFuts0.set(i, null);
        } else break;
      }

      if (doneCnt == activeFuts0.size()) return;
    }
  }