/**
   * @param reads Read entries.
   * @param writes Write entries.
   */
  @SuppressWarnings({"unchecked"})
  private void prepare(
      Iterable<GridCacheTxEntry<K, V>> reads, Iterable<GridCacheTxEntry<K, V>> writes) {
    Collection<GridRichNode> nodes = CU.allNodes(cctx);

    // Assign keys to primary nodes.
    for (GridCacheTxEntry<K, V> read : reads) map(read, nodes);

    for (GridCacheTxEntry<K, V> write : writes) map(write, nodes);

    // Create mini futures.
    for (GridDistributedTxMapping<K, V> m : mappings.values()) finish(m);
  }
  /**
   * @param cctx Context.
   * @param tx Transaction.
   * @param failedNodeId ID of failed node started transaction.
   */
  @SuppressWarnings("ConstantConditions")
  public GridCachePessimisticCheckCommittedTxFuture(
      GridCacheContext<K, V> cctx, GridCacheTxEx<K, V> tx, UUID failedNodeId) {
    super(cctx.kernalContext(), new SingleReducer<K, V>());

    this.cctx = cctx;
    this.tx = tx;
    this.failedNodeId = failedNodeId;

    log = U.logger(ctx, logRef, GridCacheOptimisticCheckPreparedTxFuture.class);

    nodes = new GridLeanMap<>();

    for (GridNode node : CU.allNodes(cctx, tx.topologyVersion())) nodes.put(node.id(), node);
  }
  /**
   * @param cctx Cache context.
   * @param prj Projection (optional).
   * @return Collection of data nodes in provided projection (if any).
   */
  private static Collection<GridNode> nodes(
      final GridCacheContext<?, ?> cctx, @Nullable final GridProjection prj) {
    assert cctx != null;

    return F.view(
        CU.allNodes(cctx),
        new P1<GridNode>() {
          @Override
          public boolean apply(GridNode n) {
            GridCacheDistributionMode mode = U.distributionMode(n, cctx.name());

            return (mode == PARTITIONED_ONLY || mode == NEAR_PARTITIONED)
                && (prj == null || prj.node(n.id()) != null);
          }
        });
  }
  /**
   * Removes locks regardless of whether they are owned or not for given version and keys.
   *
   * @param ver Lock version.
   * @param keys Keys.
   */
  @SuppressWarnings({"unchecked"})
  public void removeLocks(GridCacheVersion ver, Collection<? extends K> keys) {
    if (keys.isEmpty()) return;

    try {
      Collection<GridRichNode> affNodes = null;

      int keyCnt = -1;

      Map<GridNode, GridNearUnlockRequest<K, V>> map = null;

      for (K key : keys) {
        // Send request to remove from remote nodes.
        GridNearUnlockRequest<K, V> req = null;

        while (true) {
          GridDistributedCacheEntry<K, V> entry = peekExx(key);

          try {
            if (entry != null) {
              GridCacheMvccCandidate<K> cand = entry.candidate(ver);

              if (cand != null) {
                if (affNodes == null) {
                  affNodes = CU.allNodes(ctx, cand.topologyVersion());

                  keyCnt = (int) Math.ceil((double) keys.size() / affNodes.size());

                  map = new HashMap<GridNode, GridNearUnlockRequest<K, V>>(affNodes.size());
                }

                GridRichNode primary = CU.primary0(ctx.affinity(key, affNodes));

                if (!primary.isLocal()) {
                  req = map.get(primary);

                  if (req == null) {
                    map.put(primary, req = new GridNearUnlockRequest<K, V>(keyCnt));

                    req.version(ver);
                  }
                }

                // Remove candidate from local node first.
                if (entry.removeLock(cand.version())) {
                  if (primary.isLocal()) {
                    dht.removeLocks(primary.id(), ver, F.asList(key), true);

                    assert req == null;

                    continue;
                  }

                  req.addKey(entry.key(), entry.getOrMarshalKeyBytes(), ctx);
                }
              }
            }

            break;
          } catch (GridCacheEntryRemovedException ignored) {
            if (log.isDebugEnabled())
              log.debug(
                  "Attempted to remove lock from removed entry (will retry) [rmvVer="
                      + ver
                      + ", entry="
                      + entry
                      + ']');
          }
        }
      }

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

      Collection<GridCacheVersion> committed = ctx.tm().committedVersions(ver);
      Collection<GridCacheVersion> rolledback = ctx.tm().rolledbackVersions(ver);

      for (Map.Entry<GridNode, GridNearUnlockRequest<K, V>> mapping : map.entrySet()) {
        GridNode n = mapping.getKey();

        GridDistributedUnlockRequest<K, V> req = mapping.getValue();

        if (!req.keyBytes().isEmpty()) {
          req.completedVersions(committed, rolledback);

          // We don't wait for reply to this message.
          ctx.io().send(n, req);
        }
      }
    } catch (GridException ex) {
      U.error(log, "Failed to unlock the lock for keys: " + keys, ex);
    }
  }
  /** {@inheritDoc} */
  @Override
  public void unlockAll(
      Collection<? extends K> keys, GridPredicate<? super GridCacheEntry<K, V>>[] filter) {
    if (keys.isEmpty()) return;

    try {
      GridCacheVersion ver = null;

      Collection<GridRichNode> affNodes = null;

      int keyCnt = -1;

      Map<GridRichNode, GridNearUnlockRequest<K, V>> map = null;

      Collection<K> locKeys = new LinkedList<K>();

      GridCacheVersion obsoleteVer = ctx.versions().next();

      for (K key : keys) {
        while (true) {
          GridDistributedCacheEntry<K, V> entry = peekExx(key);

          if (entry == null || !ctx.isAll(entry.wrap(false), filter)) break; // While.

          try {
            GridCacheMvccCandidate<K> cand =
                entry.candidate(ctx.nodeId(), Thread.currentThread().getId());

            if (cand != null) {
              ver = cand.version();

              if (affNodes == null) {
                affNodes = CU.allNodes(ctx, cand.topologyVersion());

                keyCnt = (int) Math.ceil((double) keys.size() / affNodes.size());

                map = new HashMap<GridRichNode, GridNearUnlockRequest<K, V>>(affNodes.size());
              }

              // Send request to remove from remote nodes.
              GridRichNode primary = CU.primary0(ctx.affinity(key, affNodes));

              GridNearUnlockRequest<K, V> req = map.get(primary);

              if (req == null) {
                map.put(primary, req = new GridNearUnlockRequest<K, V>(keyCnt));

                req.version(ver);
              }

              // Remove candidate from local node first.
              GridCacheMvccCandidate<K> rmv = entry.removeLock();

              if (rmv != null) {
                if (!rmv.reentry()) {
                  if (ver != null && !ver.equals(rmv.version()))
                    throw new GridException(
                        "Failed to unlock (if keys were locked separately, "
                            + "then they need to be unlocked separately): "
                            + keys);

                  if (!primary.isLocal()) {
                    assert req != null;

                    req.addKey(entry.key(), entry.getOrMarshalKeyBytes(), ctx);
                  } else locKeys.add(key);

                  if (log.isDebugEnabled()) log.debug("Removed lock (will distribute): " + rmv);
                } else if (log.isDebugEnabled())
                  log.debug(
                      "Current thread still owns lock (or there are no other nodes)"
                          + " [lock="
                          + rmv
                          + ", curThreadId="
                          + Thread.currentThread().getId()
                          + ']');
              }

              // Try to evict near entry if it's dht-mapped locally.
              evictNearEntry(entry, obsoleteVer);
            }

            break;
          } catch (GridCacheEntryRemovedException ignore) {
            if (log.isDebugEnabled())
              log.debug("Attempted to unlock removed entry (will retry): " + entry);
          }
        }
      }

      if (ver == null) return;

      for (Map.Entry<GridRichNode, GridNearUnlockRequest<K, V>> mapping : map.entrySet()) {
        GridRichNode n = mapping.getKey();

        GridDistributedUnlockRequest<K, V> req = mapping.getValue();

        if (n.isLocal()) dht.removeLocks(ctx.nodeId(), req.version(), locKeys, true);
        else if (!req.keyBytes().isEmpty())
          // We don't wait for reply to this message.
          ctx.io().send(n, req);
      }
    } catch (GridException ex) {
      U.error(log, "Failed to unlock the lock for keys: " + keys, ex);
    }
  }
 /**
  * @param e Transaction entry.
  * @return {@code True} if entry is locally mapped as a primary or back up node.
  */
 protected boolean isNearLocallyMapped(GridCacheEntryEx<K, V> e) {
   return F.contains(ctx.affinity(e.key(), CU.allNodes(ctx)), ctx.localNode());
 }
  /**
   * @param nodeId Reader to add.
   * @param msgId Message ID.
   * @return Future for all relevant transactions that were active at the time of adding reader, or
   *     {@code null} if reader was added
   * @throws GridCacheEntryRemovedException If entry was removed.
   */
  @Nullable
  public GridFuture<Boolean> addReader(UUID nodeId, long msgId)
      throws GridCacheEntryRemovedException {
    // Don't add local node as reader.
    if (cctx.nodeId().equals(nodeId)) return null;

    GridNode node = cctx.discovery().node(nodeId);

    // If remote node has no near cache, don't add it.
    if (node == null || !U.hasNearCache(node, cctx.dht().near().name())) return null;

    // If remote node is (primary?) or back up, don't add it as a reader.
    if (U.nodeIds(cctx.affinity(partition(), CU.allNodes(cctx))).contains(nodeId)) return null;

    boolean ret = false;

    GridCacheMultiTxFuture<K, V> txFut;

    Collection<GridCacheMvccCandidate<K>> cands = null;

    synchronized (mux) {
      checkObsolete();

      txFut = this.txFut;

      ReaderId reader = readerId(nodeId);

      if (reader == null) {
        reader = new ReaderId(nodeId, msgId);

        readers = new LinkedList<ReaderId>(readers);

        readers.add(reader);

        // Seal.
        readers = Collections.unmodifiableList(readers);

        txFut = this.txFut = new GridCacheMultiTxFuture<K, V>(cctx);

        cands = localCandidates();

        ret = true;
      } else {
        long id = reader.messageId();

        if (id < msgId) reader.messageId(msgId);
      }
    }

    if (ret) {
      assert txFut != null;

      if (!F.isEmpty(cands)) {
        for (GridCacheMvccCandidate<K> c : cands) {
          GridCacheTxEx<K, V> tx = cctx.tm().<GridCacheTxEx<K, V>>tx(c.version());

          if (tx != null) {
            assert tx.local();

            txFut.addTx(tx);
          }
        }
      }

      txFut.init();

      if (!txFut.isDone()) {
        txFut.listenAsync(
            new CI1<GridFuture<?>>() {
              @Override
              public void apply(GridFuture<?> f) {
                synchronized (mux) {
                  // Release memory.
                  GridDhtCacheEntry.this.txFut = null;
                }
              }
            });
      } else
        // Release memory.
        txFut = this.txFut = null;
    }

    return txFut;
  }