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.util;
019
020import java.lang.reflect.InvocationTargetException;
021import java.lang.reflect.Method;
022import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
023import org.apache.hadoop.hdfs.protocol.LocatedBlock;
024import org.apache.yetus.audience.InterfaceAudience;
025
026/**
027 * hadoop 3.3.1 changed the return value of this method from {@code DatanodeInfo[]} to
028 * {@code DatanodeInfoWithStorage[]}, which causes the JVM can not locate the method if we are
029 * compiled with hadoop 3.2 and then link with hadoop 3.3+, so here we need to use reflection to
030 * make it work for both hadoop versions, otherwise we need to publish more artifacts for different
031 * hadoop versions...
032 */
033@InterfaceAudience.Private
034public final class LocatedBlockHelper {
035
036  private static final Method GET_LOCATED_BLOCK_LOCATIONS_METHOD;
037
038  static {
039    try {
040      GET_LOCATED_BLOCK_LOCATIONS_METHOD = LocatedBlock.class.getMethod("getLocations");
041    } catch (Exception e) {
042      throw new Error("Can not initialize access to HDFS LocatedBlock.getLocations method", e);
043    }
044  }
045
046  private LocatedBlockHelper() {
047  }
048
049  public static DatanodeInfo[] getLocatedBlockLocations(LocatedBlock block) {
050    try {
051      // DatanodeInfoWithStorage[] can be casted to DatanodeInfo[] directly
052      return (DatanodeInfo[]) GET_LOCATED_BLOCK_LOCATIONS_METHOD.invoke(block);
053    } catch (IllegalAccessException | InvocationTargetException e) {
054      throw new RuntimeException(e);
055    }
056  }
057}