geode-core/src/main/java/org/apache/geode/internal/cache/persistence/PersistenceObserverHolder.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.persistence;

import org.apache.geode.annotations.internal.MutableForTesting;

/**
 * Used for test hooks to during the persistence process.
 *
 */

public class PersistenceObserverHolder {
  @MutableForTesting
  private static PersistenceObserver INSTANCE = new PersistenceObserverAdapter();

  public static void setInstance(PersistenceObserver instance) {
    if (instance == null) {
      INSTANCE = new PersistenceObserverAdapter();
    }
    INSTANCE = instance;
  }

  public static PersistenceObserver getInstance() {
    return INSTANCE;
  }

  private PersistenceObserverHolder() {

  }

  public interface PersistenceObserver {
    /**
     * Fired just before we persist that a member is offline. Returning false indicates that we
     * should not persist the change.
     */
    boolean memberOffline(String regionName, PersistentMemberID persistentID);

    /**
     * Fired after we persist that a member is offline.
     */
    void afterPersistedOffline(String fullPath, PersistentMemberID persistentID);

    /**
     * Fired just before we persist that a member is online. Returning false indicates that we
     * should not persist the change.
     */
    boolean memberOnline(String regionName, PersistentMemberID persistentID);

    /**
     * Fired after we persist that a member is online.
     */
    void afterPersistedOnline(String fullPath, PersistentMemberID persistentID);

    /**
     * Fired just before we persist that a member no longer hosts a region. Returning false
     * indicates that we should not persist the change.
     */
    boolean memberRemoved(String regionName, PersistentMemberID persistentID);

    /**
     * Fired after we persist that a member no longer hosts the region.
     */
    void afterRemovePersisted(String fullPath, PersistentMemberID persistentID);

  }

  public static class PersistenceObserverAdapter implements PersistenceObserver {

    @Override
    public boolean memberOffline(String region, PersistentMemberID persistentID) {
      return true;
    }

    @Override
    public boolean memberOnline(String region, PersistentMemberID persistentID) {
      return true;
    }

    @Override
    public boolean memberRemoved(String region, PersistentMemberID persistentID) {
      return true;
    }

    @Override
    public void afterPersistedOffline(String fullPath, PersistentMemberID persistentID) {}

    @Override
    public void afterPersistedOnline(String fullPath, PersistentMemberID persistentID) {}

    @Override
    public void afterRemovePersisted(String fullPath, PersistentMemberID persistentID) {}
  }
}