import java.util.Map;

/**
 * Interface for reading documents and extracting their contents into a map.
 * Implementations of this interface should provide the logic for reading
 * documents and converting them into a key-value structure.
 *
 * <p>This interface extends {@link java.io.Closeable}, so implementations
 * should also handle resource cleanup when the {@link #close()} method is called.</p>
 */
public interface DocumentReader extends Closeable {

import org.codelibs.fess.crawler.exception.CrawlerSystemException;
import org.codelibs.fess.crawler.interval.IntervalController;

/**
 * An abstract base class for implementing {@link IntervalController}.
 * Provides a common structure for handling delays at different stages of the crawling process.
 * It encapsulates the delay logic and exception handling, allowing subclasses to focus on
 * defining the specific delay behavior for each stage.
 *
 * <p>

/**
 * Abstract base class for CrawlerClient implementations.
 * Provides common functionality for handling initialization parameters,
 * content length checks, and default method implementations.
 * It defines the basic structure and configuration options for crawler clients.
 */
public abstract class AbstractCrawlerClient implements CrawlerClient {

    private static final Logger logger = LogManager.getLogger(AbstractCrawlerClient.class);

 *
 * <p>It uses {@code Map} and {@code Queue} data structures to hold the data. The class provides
 * methods to add, remove, clear, and retrieve data from these structures.
 *
 * <p>The class is thread-safe due to the use of {@code synchronized} keyword on methods that
 * modify the internal data structures. The internal maps are also declared as {@code volatile}
 * to ensure visibility of changes across threads.