001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.master;
019
020import java.io.IOException;
021import java.util.Set;
022import org.apache.hadoop.hbase.ServerName;
023import org.apache.yetus.audience.InterfaceAudience;
024
025/**
026 * For storing the region server list.
027 * <p/>
028 * Mainly be used when restarting master, to load the previous active region server list.
029 */
030@InterfaceAudience.Private
031public interface RegionServerList {
032
033  /**
034   * Called when a region server join the cluster.
035   */
036  void started(ServerName sn);
037
038  /**
039   * Called when a region server is dead.
040   */
041  void expired(ServerName sn);
042
043  /**
044   * Get all live region servers.
045   */
046  Set<ServerName> getAll() throws IOException;
047}