* @return A Promise that will be resolved with the SuggestIndexResponse
     */
    public Deferred<SuggestIndexResponse>.Promise indexFromQueryLog(final ContentIndexingContext ctx, final QueryLogReader queryLogReader,
            final int docPerReq, final long requestInterval) {
        final Deferred<SuggestIndexResponse> deferred = new Deferred<>();
        threadPool.execute(() -> {
            final long start = System.currentTimeMillis();

                    deferred.reject(new SuggesterException("Search failure. Failed shards num:" + searchResponse.getFailedShards()));
                } else {
                    deferred.resolve(createResponse(searchResponse));
                }
            }

            @Override
            public void onFailure(final Exception e) {
                deferred.reject(new SuggesterException(e.getMessage(), e));

import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicReference;

import org.codelibs.fess.suggest.Suggester;
import org.codelibs.fess.suggest.concurrent.Deferred;
import org.codelibs.fess.suggest.constants.SuggestConstants;
import org.codelibs.fess.suggest.entity.SuggestItem;
import org.codelibs.fess.suggest.exception.SuggestIndexException;

// goroutine. When a function F calls panic, normal execution of F stops
// immediately. Any functions whose execution was deferred by F are run in
// the usual way, and then F returns to its caller. To the caller G, the
// invocation of F then behaves like a call to panic, terminating G's
// execution and running any deferred functions. This continues until all
// functions in the executing goroutine have stopped, in reverse order. At

├── concurrent/                 # Async patterns (Deferred/Promise)
└── util/                      # Utilities
```

### Key Design Patterns

- **Builder**: SuggesterBuilder, SuggestRequestBuilder
- **Facade**: Suggester (main entry point)
- **Composite**: NormalizerChain, ReadingConverterChain
- **Strategy**: Normalizer, ReadingConverter, ContentsParser
- **Deferred/Promise**: Async operations

### Index Alias Strategy

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.codelibs.core.lang.StringUtil;
import org.codelibs.fess.suggest.analysis.SuggestAnalyzer;
import org.codelibs.fess.suggest.concurrent.Deferred;
import org.codelibs.fess.suggest.converter.ReadingConverter;
import org.codelibs.fess.suggest.entity.ElevateWord;
import org.codelibs.fess.suggest.entity.SuggestItem;

and saved anew but the actual function is not invoked.
Instead, deferred functions are invoked immediately before
the surrounding function returns, in the reverse order
they were deferred. That is, if the surrounding function
returns through an explicit <a href="#Return_statements">return statement</a>,
deferred functions are executed <i>after</i> any result parameters are set

            logger.debug("[updateMemberOf] Default groups: {}, Default roles: {}", defaultGroups, defaultRoles);
        }

        // Retrieve direct groups synchronously (parent group lookup is deferred)
        processDirectMemberOf(user, groupList, roleList, groupIdsForParentLookup, "https://graph.microsoft.com/v1.0/me/memberOf");

        if (logger.isDebugEnabled()) {

          put(closeable, executor);
          return;
        }
      }
      closeQuietly(closeable, executor);
    }

    /**
     * Returns a latch that reaches zero when this objects' deferred closeables have been closed.
     */
    CountDownLatch whenClosedCountDown() {
      if (closed) {
        return new CountDownLatch(0);
      }
      synchronized (this) {
        if (closed) {

syncing a DaemonSet object when the controller has not yet observed daemonset or pod writes from the last time the object was synced. This prevents spurious creation of duplicate pods for nodes when the controller's cache is stale. When a sync is deferred for this reason, a `daemonset_controller_stale_sync_skips_total` metric is incremented and a message is logged by the daemonset controller. This behavior can be temporarily disabled by setting the `StaleControllerConsistencyDaemonSet` feature gate...