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}