/** {@inheritDoc} */
  @Override
  public Collection<ClusterNode> nodes(int p, AffinityTopologyVersion topVer) {
    Collection<ClusterNode> affNodes = cctx.affinity().nodes(p, topVer);

    lock.readLock().lock();

    try {
      assert node2part != null && node2part.valid()
          : "Invalid node-to-partitions map [topVer1="
              + topVer
              + ", topVer2="
              + this.topVer
              + ", cache="
              + cctx.name()
              + ", node2part="
              + node2part
              + ']';

      Collection<ClusterNode> nodes = null;

      Collection<UUID> nodeIds = part2node.get(p);

      if (!F.isEmpty(nodeIds)) {
        Collection<UUID> affIds = new HashSet<>(F.viewReadOnly(affNodes, F.node2id()));

        for (UUID nodeId : nodeIds) {
          if (!affIds.contains(nodeId) && hasState(p, nodeId, OWNING, MOVING, RENTING)) {
            ClusterNode n = cctx.discovery().node(nodeId);

            if (n != null
                && (topVer.topologyVersion() < 0 || n.order() <= topVer.topologyVersion())) {
              if (nodes == null) {
                nodes = new ArrayList<>(affNodes.size() + 2);

                nodes.addAll(affNodes);
              }

              nodes.add(n);
            }
          }
        }
      }

      return nodes != null ? nodes : affNodes;
    } finally {
      lock.readLock().unlock();
    }
  }
  /**
   * @param p Partition.
   * @param topVer Topology version ({@code -1} for all nodes).
   * @param state Partition state.
   * @param states Additional partition states.
   * @return List of nodes for the partition.
   */
  private List<ClusterNode> nodes(
      int p,
      AffinityTopologyVersion topVer,
      GridDhtPartitionState state,
      GridDhtPartitionState... states) {
    Collection<UUID> allIds =
        topVer.topologyVersion() > 0 ? F.nodeIds(CU.affinityNodes(cctx, topVer)) : null;

    lock.readLock().lock();

    try {
      assert node2part != null && node2part.valid()
          : "Invalid node-to-partitions map [topVer="
              + topVer
              + ", allIds="
              + allIds
              + ", node2part="
              + node2part
              + ", cache="
              + cctx.name()
              + ']';

      Collection<UUID> nodeIds = part2node.get(p);

      // Node IDs can be null if both, primary and backup, nodes disappear.
      int size = nodeIds == null ? 0 : nodeIds.size();

      if (size == 0) return Collections.emptyList();

      List<ClusterNode> nodes = new ArrayList<>(size);

      for (UUID id : nodeIds) {
        if (topVer.topologyVersion() > 0 && !allIds.contains(id)) continue;

        if (hasState(p, id, state, states)) {
          ClusterNode n = cctx.discovery().node(id);

          if (n != null && (topVer.topologyVersion() < 0 || n.order() <= topVer.topologyVersion()))
            nodes.add(n);
        }
      }

      return nodes;
    } finally {
      lock.readLock().unlock();
    }
  }
  /** {@inheritDoc} */
  @Override
  public String toString() {
    ClusterNode oldestNode = this.oldestNode.get();

    return S.toString(
        GridDhtPartitionsExchangeFuture.class,
        this,
        "oldest",
        oldestNode == null ? "null" : oldestNode.id(),
        "oldestOrder",
        oldestNode == null ? "null" : oldestNode.order(),
        "evtLatch",
        evtLatch == null ? "null" : evtLatch.getCount(),
        "remaining",
        remaining(),
        "super",
        super.toString());
  }
  /** @param nodeId Node to remove. */
  private void removeNode(UUID nodeId) {
    assert nodeId != null;
    assert lock.writeLock().isHeldByCurrentThread();

    ClusterNode oldest = CU.oldestAliveCacheServerNode(cctx.shared(), topVer);

    assert oldest != null;

    ClusterNode loc = cctx.localNode();

    if (node2part != null) {
      if (oldest.equals(loc) && !node2part.nodeId().equals(loc.id())) {
        updateSeq.setIfGreater(node2part.updateSequence());

        node2part =
            new GridDhtPartitionFullMap(
                loc.id(), loc.order(), updateSeq.incrementAndGet(), node2part, false);
      } else node2part = new GridDhtPartitionFullMap(node2part, node2part.updateSequence());

      part2node = new HashMap<>(part2node);

      GridDhtPartitionMap parts = node2part.remove(nodeId);

      if (parts != null) {
        for (Integer p : parts.keySet()) {
          Set<UUID> nodeIds = part2node.get(p);

          if (nodeIds != null) {
            nodeIds.remove(nodeId);

            if (nodeIds.isEmpty()) part2node.remove(p);
          }
        }
      }

      consistencyCheck();
    }
  }
  /** {@inheritDoc} */
  @Override
  public void beforeExchange(GridDhtPartitionsExchangeFuture exchFut)
      throws IgniteCheckedException {
    waitForRent();

    ClusterNode loc = cctx.localNode();

    int num = cctx.affinity().partitions();

    lock.writeLock().lock();

    try {
      GridDhtPartitionExchangeId exchId = exchFut.exchangeId();

      if (stopping) return;

      assert topVer.equals(exchId.topologyVersion())
          : "Invalid topology version [topVer=" + topVer + ", exchId=" + exchId + ']';

      if (exchId.isLeft()) removeNode(exchId.nodeId());

      // In case if node joins, get topology at the time of joining node.
      ClusterNode oldest = CU.oldestAliveCacheServerNode(cctx.shared(), topVer);

      assert oldest != null;

      if (log.isDebugEnabled())
        log.debug(
            "Partition map beforeExchange [exchId="
                + exchId
                + ", fullMap="
                + fullMapString()
                + ']');

      long updateSeq = this.updateSeq.incrementAndGet();

      // If this is the oldest node.
      if (oldest.id().equals(loc.id())
          || exchFut.isCacheAdded(cctx.cacheId(), exchId.topologyVersion())) {
        if (node2part == null) {
          node2part = new GridDhtPartitionFullMap(oldest.id(), oldest.order(), updateSeq);

          if (log.isDebugEnabled())
            log.debug(
                "Created brand new full topology map on oldest node [exchId="
                    + exchId
                    + ", fullMap="
                    + fullMapString()
                    + ']');
        } else if (!node2part.valid()) {
          node2part =
              new GridDhtPartitionFullMap(oldest.id(), oldest.order(), updateSeq, node2part, false);

          if (log.isDebugEnabled())
            log.debug(
                "Created new full topology map on oldest node [exchId="
                    + exchId
                    + ", fullMap="
                    + node2part
                    + ']');
        } else if (!node2part.nodeId().equals(loc.id())) {
          node2part =
              new GridDhtPartitionFullMap(oldest.id(), oldest.order(), updateSeq, node2part, false);

          if (log.isDebugEnabled())
            log.debug(
                "Copied old map into new map on oldest node (previous oldest node left) [exchId="
                    + exchId
                    + ", fullMap="
                    + fullMapString()
                    + ']');
        }
      }

      if (cctx.rebalanceEnabled()) {
        for (int p = 0; p < num; p++) {
          // If this is the first node in grid.
          boolean added = exchFut.isCacheAdded(cctx.cacheId(), exchId.topologyVersion());

          if ((oldest.id().equals(loc.id())
                  && oldest.id().equals(exchId.nodeId())
                  && exchId.isJoined())
              || added) {
            assert exchId.isJoined() || added;

            try {
              GridDhtLocalPartition locPart = localPartition(p, topVer, true, false);

              assert locPart != null;

              boolean owned = locPart.own();

              assert owned
                  : "Failed to own partition for oldest node [cacheName"
                      + cctx.name()
                      + ", part="
                      + locPart
                      + ']';

              if (log.isDebugEnabled()) log.debug("Owned partition for oldest node: " + locPart);

              updateLocal(p, loc.id(), locPart.state(), updateSeq);
            } catch (GridDhtInvalidPartitionException e) {
              if (log.isDebugEnabled())
                log.debug(
                    "Ignoring invalid partition on oldest node (no need to create a partition "
                        + "if it no longer belongs to local node: "
                        + e.partition());
            }
          }
          // If this is not the first node in grid.
          else {
            if (node2part != null && node2part.valid()) {
              if (cctx.affinity().localNode(p, topVer)) {
                try {
                  // This will make sure that all non-existing partitions
                  // will be created in MOVING state.
                  GridDhtLocalPartition locPart = localPartition(p, topVer, true, false);

                  updateLocal(p, loc.id(), locPart.state(), updateSeq);
                } catch (GridDhtInvalidPartitionException e) {
                  if (log.isDebugEnabled())
                    log.debug(
                        "Ignoring invalid partition (no need to create a partition if it "
                            + "no longer belongs to local node: "
                            + e.partition());
                }
              }
            }
            // If this node's map is empty, we pre-create local partitions,
            // so local map will be sent correctly during exchange.
            else if (cctx.affinity().localNode(p, topVer)) {
              try {
                localPartition(p, topVer, true, false);
              } catch (GridDhtInvalidPartitionException e) {
                if (log.isDebugEnabled())
                  log.debug(
                      "Ignoring invalid partition (no need to pre-create a partition if it "
                          + "no longer belongs to local node: "
                          + e.partition());
              }
            }
          }
        }
      } else {
        // If preloader is disabled, then we simply clear out
        // the partitions this node is not responsible for.
        for (int p = 0; p < num; p++) {
          GridDhtLocalPartition locPart = localPartition(p, topVer, false, false);

          boolean belongs = cctx.affinity().localNode(p, topVer);

          if (locPart != null) {
            if (!belongs) {
              GridDhtPartitionState state = locPart.state();

              if (state.active()) {
                locPart.rent(false);

                updateLocal(p, loc.id(), locPart.state(), updateSeq);

                if (log.isDebugEnabled())
                  log.debug(
                      "Evicting partition with rebalancing disabled "
                          + "(it does not belong to affinity): "
                          + locPart);
              }
            }
          } else if (belongs) {
            try {
              // Pre-create partitions.
              localPartition(p, topVer, true, false);
            } catch (GridDhtInvalidPartitionException e) {
              if (log.isDebugEnabled())
                log.debug(
                    "Ignoring invalid partition with disabled rebalancer (no need to "
                        + "pre-create a partition if it no longer belongs to local node: "
                        + e.partition());
            }
          }
        }
      }

      if (node2part != null && node2part.valid()) checkEvictions(updateSeq);

      consistencyCheck();

      if (log.isDebugEnabled())
        log.debug(
            "Partition map after beforeExchange [exchId="
                + exchId
                + ", fullMap="
                + fullMapString()
                + ']');
    } finally {
      lock.writeLock().unlock();
    }

    // Wait for evictions.
    waitForRent();
  }