*   <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 */

        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) {
            ClickLogCA ca = new ClickLogCA();
            aggsLambda.callback(ca);
            ca.getAggregationBuilderList().forEach(builder::subAggregation);

        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);

   * 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.

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

    dispatcher.maxRequests = 2
    client.newCall(newRequest("http://a/1")).enqueue(callback)
    client.newCall(newRequest("http://b/1")).enqueue(callback)
    client.newCall(newRequest("http://c/1")).enqueue(callback)
    client.newCall(newRequest("http://a/2")).enqueue(callback)
    client.newCall(newRequest("http://b/2")).enqueue(callback)
    dispatcher.maxRequests = 4

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

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