/**
   * 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);
    }
  }
  /**
   * Processes lock request.
   *
   * @param nodeId Sender node ID.
   * @param msg Lock request.
   */
  @SuppressWarnings({"unchecked", "ThrowableInstanceNeverThrown"})
  private void processLockRequest(UUID nodeId, GridDistributedLockRequest<K, V> msg) {
    assert !nodeId.equals(locNodeId);

    List<byte[]> keys = msg.keyBytes();

    int cnt = keys.size();

    GridReplicatedTxRemote<K, V> tx = null;

    GridDistributedLockResponse res;

    ClassLoader ldr = null;

    try {
      ldr = ctx.deploy().globalLoader();

      if (ldr != null) {
        res = new GridDistributedLockResponse(msg.version(), msg.futureId(), cnt);

        for (int i = 0; i < keys.size(); i++) {
          byte[] bytes = keys.get(i);
          K key = msg.keys().get(i);

          Collection<GridCacheMvccCandidate<K>> cands = msg.candidatesByIndex(i);

          if (bytes == null) continue;

          if (log.isDebugEnabled()) log.debug("Unmarshalled key: " + key);

          GridDistributedCacheEntry<K, V> entry = null;

          while (true) {
            try {
              entry = entryexx(key);

              // Handle implicit locks for pessimistic transactions.
              if (msg.inTx()) {
                tx = ctx.tm().tx(msg.version());

                if (tx != null) {
                  if (msg.txRead()) tx.addRead(key, bytes);
                  else tx.addWrite(key, bytes);
                } else {
                  tx =
                      new GridReplicatedTxRemote<K, V>(
                          nodeId,
                          msg.threadId(),
                          msg.version(),
                          null,
                          PESSIMISTIC,
                          msg.isolation(),
                          msg.isInvalidate(),
                          msg.timeout(),
                          key,
                          bytes,
                          msg.txRead(),
                          ctx);

                  tx = ctx.tm().onCreated(tx);

                  if (tx == null || !ctx.tm().onStarted(tx))
                    throw new GridCacheTxRollbackException(
                        "Failed to acquire lock "
                            + "(transaction has been completed): "
                            + msg.version());
                }
              }

              // Add remote candidate before reordering.
              entry.addRemote(
                  msg.nodeId(),
                  null,
                  msg.threadId(),
                  msg.version(),
                  msg.timeout(),
                  tx != null && tx.ec(),
                  tx != null,
                  tx != null && tx.implicitSingle());

              // Remote candidates for ordered lock queuing.
              entry.addRemoteCandidates(
                  cands, msg.version(), msg.committedVersions(), msg.rolledbackVersions());

              // Double-check in case if sender node left the grid.
              if (ctx.discovery().node(msg.nodeId()) == null) {
                if (log.isDebugEnabled())
                  log.debug(
                      "Node requesting lock left grid (lock request will be ignored): " + msg);

                if (tx != null) tx.rollback();

                return;
              }

              res.setCandidates(
                  i,
                  entry.localCandidates(),
                  ctx.tm().committedVersions(msg.version()),
                  ctx.tm().rolledbackVersions(msg.version()));

              res.addValueBytes(
                  entry.rawGet(), msg.returnValue(i) ? entry.valueBytes(null) : null, ctx);

              // Entry is legit.
              break;
            } catch (GridCacheEntryRemovedException ignored) {
              assert entry.obsoleteVersion() != null
                  : "Obsolete flag not set on removed entry: " + entry;

              if (log.isDebugEnabled())
                log.debug(
                    "Received entry removed exception (will retry on renewed entry): " + entry);

              if (tx != null) {
                tx.clearEntry(entry.key());

                if (log.isDebugEnabled())
                  log.debug(
                      "Cleared removed entry from remote transaction (will retry) [entry="
                          + entry
                          + ", tx="
                          + tx
                          + ']');
              }
            }
          }
        }
      } else {
        String err = "Failed to acquire deployment class for message: " + msg;

        U.warn(log, err);

        res =
            new GridDistributedLockResponse(msg.version(), msg.futureId(), new GridException(err));
      }
    } catch (GridCacheTxRollbackException e) {
      if (log.isDebugEnabled())
        log.debug("Received lock request for completed transaction (will ignore): " + e);

      res = new GridDistributedLockResponse(msg.version(), msg.futureId(), e);
    } catch (GridException e) {
      String err = "Failed to unmarshal at least one of the keys for lock request message: " + msg;

      log.error(err, e);

      res =
          new GridDistributedLockResponse(msg.version(), msg.futureId(), new GridException(err, e));

      if (tx != null) tx.rollback();
    } catch (GridDistributedLockCancelledException ignored) {
      // Received lock request for cancelled lock.
      if (log.isDebugEnabled())
        log.debug("Received lock request for canceled lock (will ignore): " + msg);

      if (tx != null) tx.rollback();

      // Don't send response back.
      return;
    }

    GridNode node = ctx.discovery().node(msg.nodeId());

    boolean releaseAll = false;

    if (node != null) {
      try {
        // Reply back to sender.
        ctx.io().send(node, res);
      } catch (GridException e) {
        U.error(log, "Failed to send message to node (did the node leave grid?): " + node.id(), e);

        releaseAll = ldr != null;
      }
    }
    // If sender left grid, release all locks acquired so far.
    else releaseAll = ldr != null;

    // Release all locks because sender node left grid.
    if (releaseAll) {
      for (K key : msg.keys()) {
        while (true) {
          GridDistributedCacheEntry<K, V> entry = peekexx(key);

          try {
            if (entry != null) entry.removeExplicitNodeLocks(msg.nodeId());

            break;
          } catch (GridCacheEntryRemovedException ignore) {
            if (log.isDebugEnabled())
              log.debug(
                  "Attempted to remove lock on removed entity during failure "
                      + "of replicated lock request handling (will retry): "
                      + entry);
          }
        }
      }

      U.warn(
          log, "Sender node left grid in the midst of lock acquisition (locks will be released).");
    }
  }