geode-core/src/main/java/org/apache/geode/internal/cache/RegionListener.java

/*
 * 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.geode.internal.cache;

import org.apache.geode.cache.Region;
import org.apache.geode.cache.RegionAttributes;

/**
 * Callback on a cache that receives notifications about region creates.
 *
 * If there are multiple listeners added to a cache they are invoked in a random order. See
 * {@link GemFireCacheImpl#addRegionListener(RegionListener)}
 *
 * If any of these callbacks throw an exception, that exception will get thrown out to the user
 * creating the region and the region creation will fail.
 */
public interface RegionListener {

  /**
   * Invoked before a region is created. This callback is allowed to modify the region attributes
   * before the region is created. Note that it's generally a bad idea to modify the
   * RegionAttributes in place; a new set of RegionAttributes should be returned that contain the
   * modifications. InternalRegionArguments *may* be modified, but only if you are sure the caller
   * is not going to reuse the InternalRegionArguments for something else.
   */
  default RegionAttributes beforeCreate(Region parent, String regionName, RegionAttributes attrs,
      InternalRegionArguments internalRegionArgs) {
    return attrs;
  };

  /**
   * Invoked after a region is created.
   */
  default void afterCreate(Region region) {};

  /**
   * Invoked before a region is destroyed. This callback is currently only invoked in the initiator
   * of destroyRegion.
   *
   * @param region The region being destroyed
   */
  default void beforeDestroyed(Region region) {};

  /**
   * Invoked when a region has failed initialization.
   *
   * @param region The region that has failed initialization
   */
  default void cleanupFailedInitialization(Region region) {};
}