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;
019
020import java.io.IOException;
021import org.apache.hadoop.conf.Configuration;
022import org.apache.hadoop.fs.FileSystem;
023import org.apache.hadoop.hbase.client.ClusterConnection;
024import org.apache.hadoop.hbase.client.Connection;
025import org.apache.hadoop.hbase.zookeeper.ZKWatcher;
026import org.apache.yetus.audience.InterfaceAudience;
027
028/**
029 * Defines a curated set of shared functions implemented by HBase servers (Masters
030 * and RegionServers). For use internally only. Be judicious adding API. Changes cause ripples
031 * through the code base.
032 */
033@InterfaceAudience.Private
034public interface Server extends Abortable, Stoppable {
035  /**
036   * Gets the configuration object for this server.
037   */
038  Configuration getConfiguration();
039
040  /**
041   * Gets the ZooKeeper instance for this server.
042   */
043  ZKWatcher getZooKeeper();
044
045  /**
046   * Returns a reference to the servers' connection.
047   *
048   * Important note: this method returns a reference to Connection which is managed
049   * by Server itself, so callers must NOT attempt to close connection obtained.
050   */
051  Connection getConnection();
052
053  Connection createConnection(Configuration conf) throws IOException;
054
055  /**
056   * Returns a reference to the servers' cluster connection. Prefer {@link #getConnection()}.
057   *
058   * Important note: this method returns a reference to Connection which is managed
059   * by Server itself, so callers must NOT attempt to close connection obtained.
060   */
061  ClusterConnection getClusterConnection();
062
063  /**
064   * @return The unique server name for this server.
065   */
066  ServerName getServerName();
067
068  /**
069   * Get CoordinatedStateManager instance for this server.
070   */
071  CoordinatedStateManager getCoordinatedStateManager();
072
073  /**
074   * @return The {@link ChoreService} instance for this server
075   */
076  ChoreService getChoreService();
077
078  /**
079   * @return Return the FileSystem object used (can return null!).
080   */
081  // TODO: On Master, return Master's. On RegionServer, return RegionServers. The FileSystems
082  // may differ. TODO.
083  default FileSystem getFileSystem() {
084    // This default is pretty dodgy!
085    Configuration c = getConfiguration();
086    FileSystem fs = null;
087    try {
088      if (c != null) {
089        fs = FileSystem.get(c);
090      }
091    } catch (IOException e) {
092      // If an exception, just return null
093    }
094    return fs;
095  };
096
097  /**
098   * @return True is the server is Stopping
099   */
100  // Note: This method is not part of the Stoppable Interface.
101  default boolean isStopping() {
102    return false;
103  }
104}