/**
   * @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();
      }
    }
  }