/**
   * Processes unlock request.
   *
   * @param nodeId Sender node ID.
   * @param req Unlock request.
   */
  @SuppressWarnings({"unchecked"})
  private void processUnlockRequest(UUID nodeId, GridDistributedUnlockRequest req) {
    assert nodeId != null;

    try {
      ClassLoader ldr = ctx.deploy().globalLoader();
      List<byte[]> keys = req.keyBytes();

      for (byte[] keyBytes : keys) {
        K key = (K) U.unmarshal(ctx.marshaller(), new ByteArrayInputStream(keyBytes), ldr);

        while (true) {
          boolean created = false;

          GridDistributedCacheEntry<K, V> entry = peekexx(key);

          if (entry == null) {
            entry = entryexx(key);

            created = true;
          }

          try {
            entry.doneRemote(
                req.version(), req.version(), req.committedVersions(), req.rolledbackVersions());

            // Note that we don't reorder completed versions here,
            // as there is no point to reorder relative to the version
            // we are about to remove.
            if (entry.removeLock(req.version())) {
              if (log.isDebugEnabled())
                log.debug("Removed lock [lockId=" + req.version() + ", key=" + key + ']');

              if (created && entry.markObsolete(req.version())) removeIfObsolete(entry.key());
            } else if (log.isDebugEnabled())
              log.debug(
                  "Received unlock request for unknown candidate "
                      + "(added to cancelled locks set): "
                      + req);

            break;
          } catch (GridCacheEntryRemovedException ignored) {
            if (log.isDebugEnabled())
              log.debug(
                  "Received remove lock request for removed entry (will retry) [entry="
                      + entry
                      + ", req="
                      + req
                      + ']');
          }
        }
      }
    } catch (GridException e) {
      U.error(log, "Failed to unmarshal unlock key (unlock will not be performed): " + req, e);
    }
  }
  /**
   * 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;

    Collection<GridRichNode> nodes = ctx.remoteNodes(keys);

    try {
      // Send request to remove from remote nodes.
      GridDistributedUnlockRequest<K, V> req = new GridDistributedUnlockRequest<K, V>(keys.size());

      req.version(ver);

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

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

              if (cand != null) {
                // Remove candidate from local node first.
                if (entry.removeLock(cand.version())) {
                  // If there is only local node in this lock's topology,
                  // then there is no reason to distribute the request.
                  if (nodes.isEmpty()) 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 (nodes.isEmpty()) return;

      req.completedVersions(ctx.tm().committedVersions(ver), ctx.tm().rolledbackVersions(ver));

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

    Collection<? extends GridNode> nodes = ctx.remoteNodes(keys);

    try {
      GridDistributedUnlockRequest<K, V> req = new GridDistributedUnlockRequest<K, V>(keys.size());

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

        if (!ctx.isAll(entry.wrap(false), filter)) continue;

        // Unlock local lock first.
        GridCacheMvccCandidate<K> rmv = entry.removeLock();

        if (rmv != null && !nodes.isEmpty()) {
          if (!rmv.reentry()) {
            req.addKey(entry.key(), entry.getOrMarshalKeyBytes(), ctx);

            // We are assuming that lock ID is the same for all keys.
            req.version(rmv.version());

            if (log.isDebugEnabled()) log.debug("Removed lock (will distribute): " + rmv);
          } else {
            if (log.isDebugEnabled())
              log.debug(
                  "Locally unlocked lock reentry without distributing to other nodes [removed="
                      + rmv
                      + ", entry="
                      + entry
                      + ']');
          }
        } else {
          if (log.isDebugEnabled())
            log.debug(
                "Current thread still owns lock (or there are no other nodes) [lock="
                    + rmv
                    + ", curThreadId="
                    + Thread.currentThread().getId()
                    + ']');
        }
      }

      // Don't proceed of no keys to unlock.
      if (req.keyBytes().isEmpty()) {
        if (log.isDebugEnabled())
          log.debug("No keys to unlock locally (was it reentry unlock?): " + keys);

        return;
      }

      // We don't wait for reply to this message. Receiving side will have
      // to make sure that unlock requests don't come before lock requests.
      ctx.io().safeSend(nodes, req, null);
    } catch (GridException e) {
      U.error(log, "Failed to unlock keys: " + keys, e);
    }
  }