* allowing dispatch to occur asynchronously.
 *
 * @author Cliff Biffle
 * @since 10.0
 */
public class AsyncEventBus extends EventBus {

  /**
   * Creates a new AsyncEventBus that will use {@code executor} to dispatch events. Assigns {@code
   * identifier} as the bus's name for logging purposes.
   *

    return new PerThreadQueuedDispatcher();
  }

  /**
   * Returns a dispatcher that queues events that are posted in a single global queue. This behavior
   * matches the original behavior of AsyncEventBus exactly, but is otherwise not especially useful.
   * For async dispatch, an {@linkplain #immediate() immediate} dispatcher should generally be
   * preferable.
   */
  static Dispatcher legacyAsync() {

 * subscribers should be reasonably quick. If an event may trigger an extended process (such as a
 * database load), spawn a thread or queue it for later. (For a convenient way to do this, use an
 * {@link AsyncEventBus}.)
 *
 * <h2>Subscriber Methods</h2>
 *
 * <p>Event subscriber methods must accept only one argument: the event.
 *
 * <p>Subscribers should not, in general, throw. If they do, the EventBus will catch and log the