content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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 org.apache.cassandra.tcm.listeners;
  
  import org.apache.cassandra.tcm.ClusterMetadata;
  
  /**
   * Invoked when cluster metadata changes
   *
   * `next` epoch is not guaranteed to directly follow `prev` epoch
   */
  public interface ChangeListener
  {
      /**
       * Called before updating ClusterMetadata.current() - it is still `prev` here.
       */
      default void notifyPreCommit(ClusterMetadata prev, ClusterMetadata next, boolean fromSnapshot) {}
  
      /**
       * Called after updating ClusterMetadata.current() - it is now `next`
       */
      default void notifyPostCommit(ClusterMetadata prev, ClusterMetadata next, boolean fromSnapshot) {}
  
      interface Async extends ChangeListener {}
  
  }
  