private void recheck() {
    // If this is the oldest node.
    if (oldestNode.get().id().equals(cctx.localNodeId())) {
      Collection<UUID> remaining = remaining();

      if (!remaining.isEmpty()) {
        try {
          cctx.io()
              .safeSend(
                  cctx.discovery().nodes(remaining),
                  new GridDhtPartitionsSingleRequest(exchId),
                  SYSTEM_POOL,
                  null);
        } catch (IgniteCheckedException e) {
          U.error(
              log,
              "Failed to request partitions from nodes [exchangeId="
                  + exchId
                  + ", nodes="
                  + remaining
                  + ']',
              e);
        }
      }
      // Resend full partition map because last attempt failed.
      else {
        if (spreadPartitions()) onDone(exchId.topologyVersion());
      }
    } else sendPartitions();

    // Schedule another send.
    scheduleRecheck();
  }
  /**
   * @param cacheCtx Cache context.
   * @return {@code True} if local node can calculate affinity on it's own for this partition map
   *     exchange.
   */
  private boolean canCalculateAffinity(GridCacheContext cacheCtx) {
    AffinityFunction affFunc = cacheCtx.config().getAffinity();

    // Do not request affinity from remote nodes if affinity function is not centralized.
    if (!U.hasAnnotation(affFunc, AffinityCentralizedFunction.class)) return true;

    // If local node did not initiate exchange or local node is the only cache node in grid.
    Collection<ClusterNode> affNodes = CU.affinityNodes(cacheCtx, exchId.topologyVersion());

    return !exchId.nodeId().equals(cctx.localNodeId())
        || (affNodes.size() == 1 && affNodes.contains(cctx.localNode()));
  }
  /** Cleans up resources to avoid excessive memory usage. */
  public void cleanUp() {
    topSnapshot.set(null);
    singleMsgs.clear();
    fullMsgs.clear();
    rcvdIds.clear();
    oldestNode.set(null);
    partReleaseFut = null;

    Collection<ClusterNode> rmtNodes = this.rmtNodes;

    if (rmtNodes != null) rmtNodes.clear();
  }
  /** @return {@code True} if all replies are received. */
  private boolean allReceived() {
    Collection<UUID> rmtIds = this.rmtIds;

    assert rmtIds != null : "Remote Ids can't be null: " + this;

    synchronized (rcvdIds) {
      return rcvdIds.containsAll(rmtIds);
    }
  }