/** {@inheritDoc} */
  @Override
  public GridDiscoveryTopologySnapshot topologySnapshot() throws IgniteCheckedException {
    get();

    if (topSnapshot.get() == null)
      topSnapshot.compareAndSet(
          null,
          new GridDiscoveryTopologySnapshot(discoEvt.topologyVersion(), discoEvt.topologyNodes()));

    return topSnapshot.get();
  }
  /** {@inheritDoc} */
  @Override
  public boolean onDone(AffinityTopologyVersion res, Throwable err) {
    Map<Integer, Boolean> m = null;

    for (GridCacheContext cacheCtx : cctx.cacheContexts()) {
      if (cacheCtx.config().getTopologyValidator() != null && !CU.isSystemCache(cacheCtx.name())) {
        if (m == null) m = new HashMap<>();

        m.put(
            cacheCtx.cacheId(),
            cacheCtx.config().getTopologyValidator().validate(discoEvt.topologyNodes()));
      }
    }

    cacheValidRes = m != null ? m : Collections.<Integer, Boolean>emptyMap();

    cctx.cache().onExchangeDone(exchId.topologyVersion(), reqs, err);

    cctx.exchange().onExchangeDone(this, err);

    if (super.onDone(res, err) && !dummy && !forcePreload) {
      if (log.isDebugEnabled())
        log.debug(
            "Completed partition exchange [localNode="
                + cctx.localNodeId()
                + ", exchange= "
                + this
                + ']');

      initFut.onDone(err == null);

      GridTimeoutObject timeoutObj = this.timeoutObj;

      // Deschedule timeout object.
      if (timeoutObj != null) cctx.kernalContext().timeout().removeTimeoutObject(timeoutObj);

      if (exchId.isLeft()) {
        for (GridCacheContext cacheCtx : cctx.cacheContexts())
          cacheCtx.config().getAffinity().removeNode(exchId.nodeId());
      }

      return true;
    }

    return dummy;
  }