/** {@inheritDoc} */
  @Override
  public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
    jobName = U.readString(in);
    user = U.readString(in);

    hasCombiner = in.readBoolean();
    numReduces = in.readInt();

    props = U.readStringMap(in);
  }
  /** {@inheritDoc} */
  @Override
  public void writeExternal(ObjectOutput out) throws IOException {
    U.writeString(out, jobName);
    U.writeString(out, user);

    out.writeBoolean(hasCombiner);
    out.writeInt(numReduces);

    U.writeStringMap(out, props);
  }
  /** {@inheritDoc} */
  @Override
  public void onDiscoveryDataReceived(UUID nodeId, UUID rmtNodeId, Serializable data) {
    Map<String, Serializable> discData = (Map<String, Serializable>) data;

    if (discData != null) {
      for (Map.Entry<String, Serializable> e : discData.entrySet()) {
        PluginProvider provider = plugins.get(e.getKey());

        if (provider != null) provider.receiveDiscoveryData(nodeId, e.getValue());
        else U.warn(log, "Received discovery data for unknown plugin: " + e.getKey());
      }
    }
  }
  /** Print plugins information. */
  private void ackPluginsInfo() {
    U.quietAndInfo(log, "Configured plugins:");

    if (plugins.isEmpty()) {
      U.quietAndInfo(log, "  ^-- None");
      U.quietAndInfo(log, "");
    } else {
      for (PluginProvider plugin : plugins.values()) {
        U.quietAndInfo(log, "  ^-- " + plugin.name() + " " + plugin.version());
        U.quietAndInfo(log, "  ^-- " + plugin.copyright());
        U.quietAndInfo(log, "");
      }
    }
  }
  /**
   * Test how IPC cache map works.
   *
   * @throws Exception If failed.
   */
  @SuppressWarnings("unchecked")
  public void testIpcCache() throws Exception {
    Field cacheField = GridGgfsHadoopIpcIo.class.getDeclaredField("ipcCache");

    cacheField.setAccessible(true);

    Field activeCntField = GridGgfsHadoopIpcIo.class.getDeclaredField("activeCnt");

    activeCntField.setAccessible(true);

    Map<String, GridGgfsHadoopIpcIo> cache =
        (Map<String, GridGgfsHadoopIpcIo>) cacheField.get(null);

    String name = "ggfs:" + getTestGridName(0) + "@";

    Configuration cfg = new Configuration();

    cfg.addResource(U.resolveGridGainUrl(HADOOP_FS_CFG));
    cfg.setBoolean("fs.ggfs.impl.disable.cache", true);
    cfg.setBoolean(String.format(GridGgfsHadoopUtils.PARAM_GGFS_ENDPOINT_NO_EMBED, name), true);

    // Ensure that existing IO is reused.
    FileSystem fs1 = FileSystem.get(new URI("ggfs://" + name + "/"), cfg);

    assertEquals(1, cache.size());

    GridGgfsHadoopIpcIo io = null;

    System.out.println("CACHE: " + cache);

    for (String key : cache.keySet()) {
      if (key.contains("10500")) {
        io = cache.get(key);

        break;
      }
    }

    assert io != null;

    assertEquals(1, ((AtomicInteger) activeCntField.get(io)).get());

    // Ensure that when IO is used by multiple file systems and one of them is closed, IO is not
    // stopped.
    FileSystem fs2 = FileSystem.get(new URI("ggfs://" + name + "/abc"), cfg);

    assertEquals(1, cache.size());
    assertEquals(2, ((AtomicInteger) activeCntField.get(io)).get());

    fs2.close();

    assertEquals(1, cache.size());
    assertEquals(1, ((AtomicInteger) activeCntField.get(io)).get());

    Field stopField = GridGgfsHadoopIpcIo.class.getDeclaredField("stopping");

    stopField.setAccessible(true);

    assert !(Boolean) stopField.get(io);

    // Ensure that IO is stopped when nobody else is need it.
    fs1.close();

    assert cache.isEmpty();

    assert (Boolean) stopField.get(io);
  }