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.ambari.server.events.jpa;
  
  import jakarta.persistence.EntityManagerFactory;
  
  import org.apache.ambari.server.events.AmbariEvent;
  
  /**
   * The {@link JPAEvent} class is the base for all JPA events in Ambari. Although
   * this class could inherit from {@link AmbariEvent}, the publishers for
   * {@link AmbariEvent} instances use an asynchronous model. With JPA, we want a
   * synchronous publication model in order to ensure that events are handled
   * within the scope of the method invoking them.
   */
  public abstract class JPAEvent {
  
    /**
     * The {@link JPAEventType} defines the type of JPA event.
     */
    public enum JPAEventType {
  
      /**
       * An event which instructs an {@link EntityManagerFactory} to evict
       * instances of a particular class.
       */
      CACHE_INVALIDATION;
    }
  
    /**
     * The concrete event's type.
     */
    protected final JPAEventType m_eventType;
  
    /**
     * Constructor.
     *
     * @param eventType
     *          the type of event (not {@code null}).
     */
    public JPAEvent(JPAEventType eventType) {
      m_eventType = eventType;
    }
  
    /**
     * Gets the type of {@link JPAEvent}.
     *
     * @return the event type (never {@code null}).
     */
    public JPAEventType getType() {
      return m_eventType;
    }
  
    /**
     * {@inheritDoc}
     */
    @Override
    public String toString() {
      StringBuilder buffer = new StringBuilder(getClass().getSimpleName());
      buffer.append("{eventType=").append(m_eventType);
      buffer.append("}");
      return buffer.toString();
    }
  }
  