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.hive.service;
  
  /**
   * ServiceStateChangeListener.
   *
   */
  public interface ServiceStateChangeListener {
  
    /**
     * Callback to notify of a state change. The service will already
     * have changed state before this callback is invoked.
     *
     * This operation is invoked on the thread that initiated the state change,
     * while the service itself in in a synchronized section.
     * <ol>
     *   <li>Any long-lived operation here will prevent the service state
     *   change from completing in a timely manner.</li>
     *   <li>If another thread is somehow invoked from the listener, and
     *   that thread invokes the methods of the service (including
     *   subclass-specific methods), there is a risk of a deadlock.</li>
     * </ol>
     *
     *
     * @param service the service that has changed.
     */
    void stateChanged(Service service);
  
  }
  