/**
   * @param cancel {@code True} to close with cancellation.
   * @throws GridException If failed.
   */
  @Override
  public void close(boolean cancel) throws GridException {
    if (!closed.compareAndSet(false, true)) return;

    busyLock.block();

    if (log.isDebugEnabled())
      log.debug("Closing data loader [ldr=" + this + ", cancel=" + cancel + ']');

    GridException e = null;

    try {
      // Assuming that no methods are called on this loader after this method is called.
      if (cancel) {
        cancelled = true;

        for (Buffer buf : bufMappings.values()) buf.cancelAll();
      } else doFlush();

      ctx.event().removeLocalEventListener(discoLsnr);

      ctx.io().removeMessageListener(topic);
    } catch (GridException e0) {
      e = e0;
    }

    fut.onDone(null, e);

    if (e != null) throw e;
  }
  /** {@inheritDoc} */
  @Override
  public boolean heldcc() {
    if (ctx == null) return false;

    if (job == null) job = ctx.job().activeJob(jobId);

    return job != null && job.held();
  }
  /** {@inheritDoc} */
  @Override
  public void callcc() {
    if (ctx != null) {
      if (job == null) job = ctx.job().activeJob(jobId);

      if (job != null)
        // Execute in the same thread.
        job.execute();
    }
  }
  /** {@inheritDoc} */
  @Override
  public <T> T holdcc(long timeout) {
    if (ctx != null) {
      if (job == null) job = ctx.job().activeJob(jobId);

      // Completed?
      if (job != null) {
        if (timeout > 0 && !job.isDone()) {
          final long endTime = System.currentTimeMillis() + timeout;

          // Overflow.
          if (endTime > 0) {
            ctx.timeout()
                .addTimeoutObject(
                    new GridTimeoutObject() {
                      private final GridUuid id = GridUuid.randomUuid();

                      @Override
                      public GridUuid timeoutId() {
                        return id;
                      }

                      @Override
                      public long endTime() {
                        return endTime;
                      }

                      @Override
                      public void onTimeout() {
                        callcc();
                      }
                    });
          }
        }

        job.hold();
      }
    }

    return null;
  }
  /** {@inheritDoc} */
  @Override
  public void isolated(boolean isolated) throws GridException {
    if (isolated()) return;

    GridNode node = F.first(ctx.grid().forCache(cacheName).nodes());

    if (node == null) throw new GridException("Failed to get node for cache: " + cacheName);

    GridCacheAttributes a = U.cacheAttributes(node, cacheName);

    assert a != null;

    updater =
        a.atomicityMode() == GridCacheAtomicityMode.ATOMIC
            ? GridDataLoadCacheUpdaters.<K, V>batched()
            : GridDataLoadCacheUpdaters.<K, V>groupLocked();
  }
  /**
   * @param entries Entries.
   * @param resFut Result future.
   * @param activeKeys Active keys.
   * @param remaps Remaps count.
   */
  private void load0(
      Collection<? extends Map.Entry<K, V>> entries,
      final GridFutureAdapter<Object> resFut,
      final Collection<K> activeKeys,
      final int remaps) {
    assert entries != null;

    if (remaps >= MAX_REMAP_CNT) {
      resFut.onDone(new GridException("Failed to finish operation (too many remaps): " + remaps));

      return;
    }

    Map<GridNode, Collection<Map.Entry<K, V>>> mappings = new HashMap<>();

    boolean initPda = ctx.deploy().enabled() && jobPda == null;

    for (Map.Entry<K, V> entry : entries) {
      GridNode node;

      try {
        K key = entry.getKey();

        assert key != null;

        if (initPda) {
          jobPda = new DataLoaderPda(key, entry.getValue(), updater);

          initPda = false;
        }

        node = ctx.affinity().mapKeyToNode(cacheName, key);
      } catch (GridException e) {
        resFut.onDone(e);

        return;
      }

      if (node == null) {
        resFut.onDone(
            new GridTopologyException(
                "Failed to map key to node "
                    + "(no nodes with cache found in topology) [infos="
                    + entries.size()
                    + ", cacheName="
                    + cacheName
                    + ']'));

        return;
      }

      Collection<Map.Entry<K, V>> col = mappings.get(node);

      if (col == null) mappings.put(node, col = new ArrayList<>());

      col.add(entry);
    }

    for (final Map.Entry<GridNode, Collection<Map.Entry<K, V>>> e : mappings.entrySet()) {
      final UUID nodeId = e.getKey().id();

      Buffer buf = bufMappings.get(nodeId);

      if (buf == null) {
        Buffer old = bufMappings.putIfAbsent(nodeId, buf = new Buffer(e.getKey()));

        if (old != null) buf = old;
      }

      final Collection<Map.Entry<K, V>> entriesForNode = e.getValue();

      GridInClosure<GridFuture<?>> lsnr =
          new GridInClosure<GridFuture<?>>() {
            @Override
            public void apply(GridFuture<?> t) {
              try {
                t.get();

                for (Map.Entry<K, V> e : entriesForNode) activeKeys.remove(e.getKey());

                if (activeKeys.isEmpty()) resFut.onDone();
              } catch (GridException e1) {
                if (log.isDebugEnabled())
                  log.debug("Future finished with error [nodeId=" + nodeId + ", err=" + e1 + ']');

                if (cancelled) {
                  resFut.onDone(
                      new GridException(
                          "Data loader has been cancelled: " + GridDataLoaderImpl.this, e1));
                } else load0(entriesForNode, resFut, activeKeys, remaps + 1);
              }
            }
          };

      GridFutureAdapter<?> f;

      try {
        f = buf.update(entriesForNode, lsnr);
      } catch (GridInterruptedException e1) {
        resFut.onDone(e1);

        return;
      }

      if (ctx.discovery().node(nodeId) == null) {
        if (bufMappings.remove(nodeId, buf)) buf.onNodeLeft();

        if (f != null)
          f.onDone(
              new GridTopologyException(
                  "Failed to wait for request completion " + "(node has left): " + nodeId));
      }
    }
  }
  /**
   * @param ctx Grid kernal context.
   * @param cacheName Cache name.
   * @param flushQ Flush queue.
   */
  public GridDataLoaderImpl(
      final GridKernalContext ctx,
      @Nullable final String cacheName,
      DelayQueue<GridDataLoaderImpl<K, V>> flushQ) {
    assert ctx != null;

    this.ctx = ctx;
    this.cacheName = cacheName;
    this.flushQ = flushQ;

    log = U.logger(ctx, logRef, GridDataLoaderImpl.class);

    discoLsnr =
        new GridLocalEventListener() {
          @Override
          public void onEvent(GridEvent evt) {
            assert evt.type() == EVT_NODE_FAILED || evt.type() == EVT_NODE_LEFT;

            GridDiscoveryEvent discoEvt = (GridDiscoveryEvent) evt;

            UUID id = discoEvt.eventNodeId();

            // Remap regular mappings.
            final Buffer buf = bufMappings.remove(id);

            if (buf != null) {
              // Only async notification is possible since
              // discovery thread may be trapped otherwise.
              ctx.closure()
                  .callLocalSafe(
                      new Callable<Object>() {
                        @Override
                        public Object call() throws Exception {
                          buf.onNodeLeft();

                          return null;
                        }
                      },
                      true /* system pool */);
            }
          }
        };

    ctx.event().addLocalEventListener(discoLsnr, EVT_NODE_FAILED, EVT_NODE_LEFT);

    // Generate unique topic for this loader.
    topic = TOPIC_DATALOAD.topic(GridUuid.fromUuid(ctx.localNodeId()));

    ctx.io()
        .addMessageListener(
            topic,
            new GridMessageListener() {
              @Override
              public void onMessage(UUID nodeId, Object msg) {
                assert msg instanceof GridDataLoadResponse;

                GridDataLoadResponse res = (GridDataLoadResponse) msg;

                if (log.isDebugEnabled()) log.debug("Received data load response: " + res);

                Buffer buf = bufMappings.get(nodeId);

                if (buf != null) buf.onResponse(res);
                else if (log.isDebugEnabled())
                  log.debug("Ignoring response since node has left [nodeId=" + nodeId + ", ");
              }
            });

    if (log.isDebugEnabled()) log.debug("Added response listener within topic: " + topic);

    fut = new GridDataLoaderFuture(ctx, this);
  }