hive/service/ServiceStateChangeListener.java

0001 /**
0002  * Licensed to the Apache Software Foundation (ASF) under one
0003  * or more contributor license agreements.  See the NOTICE file
0004  * distributed with this work for additional information
0005  * regarding copyright ownership.  The ASF licenses this file
0006  * to you under the Apache License, Version 2.0 (the
0007  * "License"); you may not use this file except in compliance
0008  * with the License.  You may obtain a copy of the License at
0009  *
0010  *     http://www.apache.org/licenses/LICENSE-2.0
0011  *
0012  * Unless required by applicable law or agreed to in writing, software
0013  * distributed under the License is distributed on an "AS IS" BASIS,
0014  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
0015  * See the License for the specific language governing permissions and
0016  * limitations under the License.
0017  */
0018
0019 package org.apache.hive.service;
0020
0021 /**
0022  * ServiceStateChangeListener.
0023  *
0024  */
0025 public interface ServiceStateChangeListener {
0026
0027   /**
0028    * Callback to notify of a state change. The service will already
0029    * have changed state before this callback is invoked.
0030    *
0031    * This operation is invoked on the thread that initiated the state change,
0032    * while the service itself in a synchronized section.
0033    * <ol>
0034    *   <li>Any long-lived operation here will prevent the service state
0035    *   change from completing in a timely manner.</li>
0036    *   <li>If another thread is somehow invoked from the listener, and
0037    *   that thread invokes the methods of the service (including
0038    *   subclass-specific methods), there is a risk of a deadlock.</li>
0039    * </ol>
0040    *
0041    *
0042    * @param service the service that has changed.
0043    */
0044   void stateChanged(Service service);
0045
0046 }