/**
   * @param nodeId Sender node ID.
   * @param msg Response to prepare request.
   */
  private void processPrepareResponse(UUID nodeId, GridDistributedTxPrepareResponse<K, V> msg) {
    assert nodeId != null;
    assert msg != null;

    GridReplicatedTxLocal<K, V> tx = ctx.tm().tx(msg.version());

    if (tx == null) {
      if (log.isDebugEnabled())
        log.debug(
            "Received prepare response for non-existing transaction [senderNodeId="
                + nodeId
                + ", res="
                + msg
                + ']');

      return;
    }

    GridReplicatedTxPrepareFuture<K, V> future = (GridReplicatedTxPrepareFuture<K, V>) tx.future();

    if (future != null) future.onResult(nodeId, msg);
    else
      U.error(
          log,
          "Received prepare response for transaction with no future [res="
              + msg
              + ", tx="
              + tx
              + ']');
  }
  /**
   * 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);
    }
  }
  /** {@inheritDoc} */
  @SuppressWarnings({"unchecked", "ThrowableInstanceNeverThrown"})
  @Override
  protected GridFuture<Boolean> lockAllAsync(
      Collection<? extends K> keys,
      long timeout,
      GridCacheTxLocalEx<K, V> tx,
      boolean isInvalidate,
      boolean isRead,
      boolean retval,
      GridCacheTxIsolation isolation,
      GridPredicate<? super GridCacheEntry<K, V>>[] filter) {
    if (keys.isEmpty()) return new GridFinishedFuture<Boolean>(ctx.kernalContext(), true);

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

    final GridReplicatedLockFuture<K, V> fut =
        new GridReplicatedLockFuture<K, V>(ctx, keys, tx, this, nodes, timeout, filter);

    GridDistributedLockRequest<K, V> req =
        new GridDistributedLockRequest<K, V>(
            locNodeId,
            Thread.currentThread().getId(),
            fut.futureId(),
            fut.version(),
            tx != null,
            isRead,
            isolation,
            isInvalidate,
            timeout,
            keys.size());

    try {
      // Must add future before redying locks.
      if (!ctx.mvcc().addFuture(fut))
        throw new IllegalStateException("Duplicate future ID: " + fut);

      boolean distribute = false;

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

          try {
            entry = entryexx(key);

            if (!ctx.isAll(entry.wrap(false), filter)) {
              if (log.isDebugEnabled())
                log.debug("Entry being locked did not pass filter (will not lock): " + entry);

              fut.onDone(false);

              return fut;
            }

            // Removed exception may be thrown here.
            GridCacheMvccCandidate<K> cand = fut.addEntry(entry);

            if (cand != null) {
              req.addKeyBytes(
                  key,
                  cand.reentry() ? null : entry.getOrMarshalKeyBytes(),
                  retval,
                  entry.localCandidates(fut.version()),
                  ctx);

              req.completedVersions(
                  ctx.tm().committedVersions(fut.version()),
                  ctx.tm().rolledbackVersions(fut.version()));

              distribute = !cand.reentry();
            } else if (fut.isDone()) return fut;

            break;
          } catch (GridCacheEntryRemovedException ignored) {
            if (log.isDebugEnabled())
              log.debug("Got removed entry in lockAsync(..) method (will retry): " + entry);
          }
        }
      }

      // If nothing to distribute at this point,
      // then all locks are reentries.
      if (!distribute) fut.complete(true);

      if (nodes.isEmpty()) fut.readyLocks();

      // No reason to send request if all locks are locally re-entered,
      // or if timeout is negative and local locks could not be acquired.
      if (fut.isDone()) return fut;

      try {
        ctx.io()
            .safeSend(
                fut.nodes(),
                req,
                new P1<GridNode>() {
                  @Override
                  public boolean apply(GridNode node) {
                    fut.onNodeLeft(node.id());

                    return !fut.isDone();
                  }
                });
      } catch (GridException e) {
        U.error(
            log,
            "Failed to send lock request to node [nodes="
                + U.toShortString(nodes)
                + ", req="
                + req
                + ']',
            e);

        fut.onError(e);
      }

      return fut;
    } catch (GridException e) {
      Throwable err = new GridException("Failed to acquire asynchronous lock for keys: " + keys, e);

      // Clean-up.
      fut.onError(err);

      ctx.mvcc().removeFuture(fut);

      return fut;
    }
  }
  /**
   * @param nodeId Sender node ID.
   * @param req Finish transaction message.
   */
  @SuppressWarnings({"CatchGenericClass"})
  private void processFinishRequest(UUID nodeId, GridDistributedTxFinishRequest<K, V> req) {
    assert nodeId != null;
    assert req != null;

    GridReplicatedTxRemote<K, V> tx = ctx.tm().tx(req.version());

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

      if (req.commit()) {
        // If lock was acquired explicitly.
        if (tx == null) {
          // Create transaction and add entries.
          tx =
              ctx.tm()
                  .onCreated(
                      new GridReplicatedTxRemote<K, V>(
                          ldr,
                          nodeId,
                          req.threadId(),
                          req.version(),
                          req.commitVersion(),
                          PESSIMISTIC,
                          READ_COMMITTED,
                          req.isInvalidate(),
                          /*timeout */ 0,
                          /*read entries*/ null,
                          req.writes(),
                          ctx));

          if (tx == null || !ctx.tm().onStarted(tx))
            throw new GridCacheTxRollbackException(
                "Attempt to start a completed " + "transaction: " + req);
        } else {
          boolean set = tx.commitVersion(req.commitVersion());

          assert set;
        }

        Collection<GridCacheTxEntry<K, V>> writeEntries = req.writes();

        if (!F.isEmpty(writeEntries)) {
          // In OPTIMISTIC mode, we get the values at PREPARE stage.
          assert tx.concurrency() == PESSIMISTIC;

          for (GridCacheTxEntry<K, V> entry : writeEntries) {
            // Unmarshal write entries.
            entry.unmarshal(ctx, ldr);

            if (log.isDebugEnabled())
              log.debug(
                  "Unmarshalled transaction entry from pessimistic transaction [key="
                      + entry.key()
                      + ", value="
                      + entry.value()
                      + ", tx="
                      + tx
                      + ']');

            if (!tx.setWriteValue(entry))
              U.warn(
                  log,
                  "Received entry to commit that was not present in transaction [entry="
                      + entry
                      + ", tx="
                      + tx
                      + ']');
          }
        }

        // Add completed versions.
        tx.doneRemote(req.baseVersion(), req.committedVersions(), req.rolledbackVersions());

        if (tx.pessimistic()) tx.prepare();

        tx.commit();
      } else if (tx != null) {
        tx.doneRemote(req.baseVersion(), req.committedVersions(), req.rolledbackVersions());

        tx.rollback();
      }

      if (req.replyRequired()) {
        GridCacheMessage<K, V> res =
            new GridDistributedTxFinishResponse<K, V>(req.version(), req.futureId());

        try {
          ctx.io().send(nodeId, res);
        } catch (Throwable e) {
          // Double-check.
          if (ctx.discovery().node(nodeId) == null) {
            if (log.isDebugEnabled())
              log.debug(
                  "Node left while sending finish response [nodeId="
                      + nodeId
                      + ", res="
                      + res
                      + ']');
          } else
            U.error(
                log,
                "Failed to send finish response to node [nodeId=" + nodeId + ", res=" + res + ']',
                e);
        }
      }
    } catch (GridCacheTxRollbackException e) {
      if (log.isDebugEnabled())
        log.debug("Attempted to start a completed transaction (will ignore): " + e);
    } catch (Throwable e) {
      U.error(
          log,
          "Failed completing transaction [commit=" + req.commit() + ", tx=" + CU.txString(tx) + ']',
          e);

      if (tx != null) tx.rollback();
    }
  }
  /**
   * @param nodeId Sender node ID.
   * @param msg Prepare request.
   */
  @SuppressWarnings({"InstanceofCatchParameter"})
  private void processPrepareRequest(UUID nodeId, GridDistributedTxPrepareRequest<K, V> msg) {
    assert nodeId != null;
    assert msg != null;

    GridReplicatedTxRemote<K, V> tx = null;

    GridDistributedTxPrepareResponse<K, V> res;

    try {
      tx =
          new GridReplicatedTxRemote<K, V>(
              ctx.deploy().globalLoader(),
              nodeId,
              msg.threadId(),
              msg.version(),
              msg.commitVersion(),
              msg.concurrency(),
              msg.isolation(),
              msg.isInvalidate(),
              msg.timeout(),
              msg.reads(),
              msg.writes(),
              ctx);

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

      if (tx == null || !ctx.tm().onStarted(tx))
        throw new GridCacheTxRollbackException("Attempt to start a completed transaction: " + tx);

      // Prepare prior to reordering, so the pending locks added
      // in prepare phase will get properly ordered as well.
      tx.prepare();

      // Add remote candidates and reorder completed and uncompleted versions.
      tx.addRemoteCandidates(
          msg.candidatesByKey(), msg.committedVersions(), msg.rolledbackVersions());

      if (msg.concurrency() == EVENTUALLY_CONSISTENT) {
        if (log.isDebugEnabled()) log.debug("Committing transaction during remote prepare: " + tx);

        tx.commit();

        if (log.isDebugEnabled()) log.debug("Committed transaction during remote prepare: " + tx);

        // Don't send response.
        return;
      }

      res = new GridDistributedTxPrepareResponse<K, V>(msg.version());

      Map<K, Collection<GridCacheMvccCandidate<K>>> cands = tx.localCandidates();

      // Add local candidates (completed version must be set below).
      res.candidates(cands);
    } catch (GridException e) {
      if (e instanceof GridCacheTxRollbackException) {
        if (log.isDebugEnabled())
          log.debug("Transaction was rolled back before prepare completed: " + tx);
      } else if (e instanceof GridCacheTxOptimisticException) {
        if (log.isDebugEnabled())
          log.debug("Optimistic failure for remote transaction (will rollback): " + tx);
      } else {
        U.error(log, "Failed to process prepare request: " + msg, e);
      }

      if (tx != null)
        // Automatically rollback remote transactions.
        tx.rollback();

      // Don't send response.
      if (msg.concurrency() == EVENTUALLY_CONSISTENT) return;

      res = new GridDistributedTxPrepareResponse<K, V>(msg.version());

      res.error(e);
    }

    // Add completed versions.
    res.completedVersions(
        ctx.tm().committedVersions(msg.version()), ctx.tm().rolledbackVersions(msg.version()));

    assert msg.concurrency() != EVENTUALLY_CONSISTENT;

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

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

        if (tx != null) tx.rollback();
      }
    }
  }
  /**
   * 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).");
    }
  }