/** {@inheritDoc} */
  @Nullable
  @Override
  public Map<? extends GridComputeJob, GridNode> map(
      List<GridNode> subgrid, @Nullable GridBiTuple<Set<UUID>, A> arg) throws GridException {
    assert arg != null;
    assert arg.get1() != null;

    start = U.currentTimeMillis();

    boolean debug = debugState(g);

    if (debug) logStart(g.log(), getClass(), start);

    Set<UUID> nodeIds = arg.get1();

    Map<GridComputeJob, GridNode> map = U.newHashMap(nodeIds.size());

    try {
      taskArg = arg.get2();

      for (GridNode node : subgrid) if (nodeIds.contains(node.id())) map.put(job(taskArg), node);

      return map;
    } finally {
      if (debug) logMapped(g.log(), getClass(), map.values());
    }
  }
  /**
   * Maps list by node ID.
   *
   * @param subgrid Subgrid.
   * @return Map.
   */
  private Map<UUID, GridNode> mapSubgrid(Collection<GridNode> subgrid) {
    Map<UUID, GridNode> res = U.newHashMap(subgrid.size());

    for (GridNode node : subgrid) res.put(node.id(), node);

    return res;
  }
    void onNodeLeft() {
      assert !isLocNode;
      assert bufMappings.get(node.id()) != this;

      if (log.isDebugEnabled())
        log.debug("Forcibly completing futures (node has left): " + node.id());

      Exception e =
          new GridTopologyException(
              "Failed to wait for request completion " + "(node has left): " + node.id());

      for (GridFutureAdapter<Object> f : reqs.values()) f.onDone(e);

      // Make sure to complete current future.
      GridFutureAdapter<Object> curFut0;

      synchronized (this) {
        curFut0 = curFut;
      }

      curFut0.onDone(e);
    }
    /** @param node Node. */
    Buffer(GridNode node) {
      assert node != null;

      this.node = node;

      locFuts = new GridConcurrentHashSet<>();
      reqs = new ConcurrentHashMap8<>();

      // Cache local node flag.
      isLocNode = node.equals(ctx.discovery().localNode());

      entries = newEntries();
      curFut = new GridFutureAdapter<>(ctx);
      curFut.listenAsync(signalC);

      sem = new Semaphore(parallelOps);
    }
    /**
     * @param entries Entries to submit.
     * @param curFut Current future.
     * @throws GridInterruptedException If interrupted.
     */
    private void submit(final List<Map.Entry<K, V>> entries, final GridFutureAdapter<Object> curFut)
        throws GridInterruptedException {
      assert entries != null;
      assert !entries.isEmpty();
      assert curFut != null;

      incrementActiveTasks();

      GridFuture<Object> fut;
      if (isLocNode) {
        fut =
            ctx.closure()
                .callLocalSafe(
                    new GridDataLoadUpdateJob<>(ctx, log, cacheName, entries, false, updater),
                    false);

        locFuts.add(fut);

        fut.listenAsync(
            new GridInClosure<GridFuture<Object>>() {
              @Override
              public void apply(GridFuture<Object> t) {
                try {
                  boolean rmv = locFuts.remove(t);

                  assert rmv;

                  curFut.onDone(t.get());
                } catch (GridException e) {
                  curFut.onDone(e);
                }
              }
            });
      } else {
        byte[] entriesBytes;

        try {
          entriesBytes = ctx.config().getMarshaller().marshal(entries);

          if (updaterBytes == null) {
            assert updater != null;

            updaterBytes = ctx.config().getMarshaller().marshal(updater);
          }

          if (topicBytes == null) topicBytes = ctx.config().getMarshaller().marshal(topic);
        } catch (GridException e) {
          U.error(log, "Failed to marshal (request will not be sent).", e);

          return;
        }

        GridDeployment dep = null;
        GridPeerDeployAware jobPda0 = null;

        if (ctx.deploy().enabled()) {
          try {
            jobPda0 = jobPda;

            assert jobPda0 != null;

            dep = ctx.deploy().deploy(jobPda0.deployClass(), jobPda0.classLoader());
          } catch (GridException e) {
            U.error(
                log,
                "Failed to deploy class (request will not be sent): " + jobPda0.deployClass(),
                e);

            return;
          }

          if (dep == null)
            U.warn(log, "Failed to deploy class (request will be sent): " + jobPda0.deployClass());
        }

        long reqId = idGen.incrementAndGet();

        fut = curFut;

        reqs.put(reqId, (GridFutureAdapter<Object>) fut);

        GridDataLoadRequest<Object, Object> req =
            new GridDataLoadRequest<>(
                reqId,
                topicBytes,
                cacheName,
                updaterBytes,
                entriesBytes,
                true,
                dep != null ? dep.deployMode() : null,
                dep != null ? jobPda0.deployClass().getName() : null,
                dep != null ? dep.userVersion() : null,
                dep != null ? dep.participants() : null,
                dep != null ? dep.classLoaderId() : null,
                dep == null);

        try {
          ctx.io().send(node, TOPIC_DATALOAD, req, PUBLIC_POOL);

          if (log.isDebugEnabled())
            log.debug("Sent request to node [nodeId=" + node.id() + ", req=" + req + ']');
        } catch (GridException e) {
          if (ctx.discovery().alive(node) && ctx.discovery().pingNode(node.id()))
            ((GridFutureAdapter<Object>) fut).onDone(e);
          else
            ((GridFutureAdapter<Object>) fut)
                .onDone(
                    new GridTopologyException(
                        "Failed to send " + "request (node has left): " + node.id()));
        }
      }
    }