content: /*
   * Copyright 1999-2023 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.client.selector;
  
  /**
   * Listener invoker.
   *
   * @param <E> the type of event received by the listener
   * @author lideyou
   */
  public interface ListenerInvoker<E> {
      
      /**
       * Invoke inner listener.
       *
       * @param event event
       */
      void invoke(E event);
      
      /**
       * Mark the listener whether invoked once. It should return {@code true} after {@link #invoke(E)} called at lease once.
       *
       * @return {@code true} if this listener has invoked at least once, {@code false} otherwise
       */
      boolean isInvoked();
  }
  