SubscriberRegistry.java 文件源码

/**
 * Gets an iterator representing an immutable snapshot of all subscribers to the given event at
 * the time this method is called.
 */
Iterator<Subscriber> getSubscribers(Object event) {
  ImmutableSet<Class<?>> eventTypes = flattenHierarchy(event.getClass());

  List<Iterator<Subscriber>> subscriberIterators =
      Lists.newArrayListWithCapacity(eventTypes.size());

  for (Class<?> eventType : eventTypes) {
    CopyOnWriteArraySet<Subscriber> eventSubscribers = subscribers.get(eventType);
    if (eventSubscribers != null) {
      // eager no-copy snapshot
      subscriberIterators.add(eventSubscribers.iterator());
    }
  }

  return Iterators.concat(subscriberIterators.iterator());
}