content: /*
   * Copyright 1999-2018 Alibaba Group Holding Ltd.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.alibaba.nacos.common.notify;
  
  import com.alibaba.nacos.common.lifecycle.Closeable;
  import com.alibaba.nacos.common.notify.listener.Subscriber;
  
  /**
   * Event publisher.
   *
   * @author <a href="mailto:liaochuntao@live.com">liaochuntao</a>
   * @author zongtanghu
   */
  public interface EventPublisher extends Closeable {
      
      /**
       * Initializes the event publisher.
       *
       * @param type       {@link Event >}
       * @param bufferSize Message staging queue size
       */
      void init(Class<? extends Event> type, int bufferSize);
      
      /**
       * The number of currently staged events.
       *
       * @return event size
       */
      long currentEventSize();
      
      /**
       * Add listener.
       *
       * @param subscriber {@link Subscriber}
       */
      void addSubscriber(Subscriber subscriber);
      
      /**
       * Remove listener.
       *
       * @param subscriber {@link Subscriber}
       */
      void removeSubscriber(Subscriber subscriber);
      
      /**
       * publish event.
       *
       * @param event {@link Event}
       * @return publish event is success
       */
      boolean publish(Event event);
      
      /**
       * Notify listener.
       *
       * @param subscriber {@link Subscriber}
       * @param event      {@link Event}
       */
      void notifySubscriber(Subscriber subscriber, Event event);
      
  }
  