output.cancel(false);
        throw new SomeUncheckedException();
      }
    }
    Fallback fallback = new Fallback();
    SettableFuture<Object> input = SettableFuture.create();

    ListenableFuture<Object> output = catching(input, Throwable.class, fallback, directExecutor());
    fallback.output = output;

    input.setException(new MyException());
    assertTrue(output.isCancelled());
  }

     *   <li>Index update operations through callbacks</li>
     *   <li>Error handling and failure logging</li>
     *   <li>Cleanup of old documents after successful crawling</li>
     * </ul>
     */
    protected static class DataCrawlingThread extends Thread {

        /** Configuration for the data store being crawled */
        private final DataConfig dataConfig;

        /** Callback for handling document indexing operations */

                notifyStarted();
                // We need to wait for the main thread to leave the ServiceManager.startAsync call
                // to
                // ensure that the thread running the failure callbacks is not the main thread.
                Uninterruptibles.awaitUninterruptibly(afterStarted);
                notifyFailed(new Exception("boom"));
              }
            }.start();
          }

   * across calls to multiple listeners. Specifically, a given listener will have its callbacks
   * invoked in the same order as the underlying service enters those states. Additionally, at most
   * one of the listener's callbacks will execute at once. However, multiple listeners' callbacks
   * may execute concurrently, and listeners may execute in an order different from the one in which
   * they were registered.

   *     exception itself.
   * @param executor the executor that runs {@code fallback} if the input fails
   */
  public <X extends Throwable> ClosingFuture<V> catching(
      Class<X> exceptionType, ClosingFunction<? super X, ? extends V> fallback, Executor executor) {
    return catchingMoreGeneric(exceptionType, fallback, executor);
  }

  companion object {
    /**
     * A network that resolves only one IP address per host. Use this when testing route selection
     * fallbacks to prevent the host machine's various IP addresses from interfering.
     */
    private val SINGLE_INET_ADDRESS_DNS =
      Dns { hostname ->
        val addresses = Dns.SYSTEM.lookup(hostname)

        if (queryLambda != null) {
            queryLambda.callback(cq);
        }
        FilterAggregationBuilder builder = regFilterA(name, cq.getQuery());
        if (opLambda != null) {
            opLambda.callback(builder);
        }
        if (aggsLambda != null) {
            SearchLogCA ca = new SearchLogCA();
            aggsLambda.callback(ca);
            ca.getAggregationBuilderList().forEach(builder::subAggregation);

        KeyMatchCQ cq = new KeyMatchCQ();
        queryLambda.callback(cq);
        final Collection<FilterFunctionBuilder> list = new ArrayList<>();
        if (functionsLambda != null) {
            functionsLambda.callback((cqLambda, scoreFunctionBuilder) -> {
                KeyMatchCQ cf = new KeyMatchCQ();
                cqLambda.callback(cf);

        if (queryLambda != null) {
            queryLambda.callback(cq);
        }
        FilterAggregationBuilder builder = regFilterA(name, cq.getQuery());
        if (opLambda != null) {
            opLambda.callback(builder);
        }
        if (aggsLambda != null) {
            FailureUrlCA ca = new FailureUrlCA();
            aggsLambda.callback(ca);

        if (queryLambda != null) {
            queryLambda.callback(cq);
        }
        FilterAggregationBuilder builder = regFilterA(name, cq.getQuery());
        if (opLambda != null) {
            opLambda.callback(builder);
        }
        if (aggsLambda != null) {
            ClickLogCA ca = new ClickLogCA();
            aggsLambda.callback(ca);
            ca.getAggregationBuilderList().forEach(builder::subAggregation);