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.net; 019 020import static org.apache.hadoop.fs.CommonConfigurationKeysPublic.NET_TOPOLOGY_TABLE_MAPPING_FILE_KEY; 021 022import java.io.BufferedReader; 023import java.io.FileInputStream; 024import java.io.FileReader; 025import java.io.IOException; 026import java.io.InputStreamReader; 027import java.util.ArrayList; 028import java.util.HashMap; 029import java.util.List; 030import java.util.Map; 031 032import org.apache.commons.io.Charsets; 033import org.apache.commons.lang.StringUtils; 034import org.apache.commons.logging.Log; 035import org.apache.commons.logging.LogFactory; 036import org.apache.hadoop.classification.InterfaceAudience; 037import org.apache.hadoop.classification.InterfaceStability; 038import org.apache.hadoop.conf.Configuration; 039import org.apache.hadoop.conf.Configured; 040 041/** 042 * <p> 043 * Simple {@link DNSToSwitchMapping} implementation that reads a 2 column text 044 * file. The columns are separated by whitespace. The first column is a DNS or 045 * IP address and the second column specifies the rack where the address maps. 046 * </p> 047 * <p> 048 * This class uses the configuration parameter {@code 049 * net.topology.table.file.name} to locate the mapping file. 050 * </p> 051 * <p> 052 * Calls to {@link #resolve(List)} will look up the address as defined in the 053 * mapping file. If no entry corresponding to the address is found, the value 054 * {@code /default-rack} is returned. 055 * </p> 056 */ 057@InterfaceAudience.Public 058@InterfaceStability.Evolving 059public class TableMapping extends CachedDNSToSwitchMapping { 060 061 private static final Log LOG = LogFactory.getLog(TableMapping.class); 062 063 public TableMapping() { 064 super(new RawTableMapping()); 065 } 066 067 private RawTableMapping getRawMapping() { 068 return (RawTableMapping) rawMapping; 069 } 070 071 @Override 072 public Configuration getConf() { 073 return getRawMapping().getConf(); 074 } 075 076 @Override 077 public void setConf(Configuration conf) { 078 super.setConf(conf); 079 getRawMapping().setConf(conf); 080 } 081 082 @Override 083 public void reloadCachedMappings() { 084 super.reloadCachedMappings(); 085 getRawMapping().reloadCachedMappings(); 086 } 087 088 private static final class RawTableMapping extends Configured 089 implements DNSToSwitchMapping { 090 091 private Map<String, String> map; 092 093 private Map<String, String> load() { 094 Map<String, String> loadMap = new HashMap<String, String>(); 095 096 String filename = getConf().get(NET_TOPOLOGY_TABLE_MAPPING_FILE_KEY, null); 097 if (StringUtils.isBlank(filename)) { 098 LOG.warn(NET_TOPOLOGY_TABLE_MAPPING_FILE_KEY + " not configured. "); 099 return null; 100 } 101 102 103 try (BufferedReader reader = 104 new BufferedReader(new InputStreamReader( 105 new FileInputStream(filename), Charsets.UTF_8))) { 106 String line = reader.readLine(); 107 while (line != null) { 108 line = line.trim(); 109 if (line.length() != 0 && line.charAt(0) != '#') { 110 String[] columns = line.split("\\s+"); 111 if (columns.length == 2) { 112 loadMap.put(columns[0], columns[1]); 113 } else { 114 LOG.warn("Line does not have two columns. Ignoring. " + line); 115 } 116 } 117 line = reader.readLine(); 118 } 119 } catch (Exception e) { 120 LOG.warn(filename + " cannot be read.", e); 121 return null; 122 } 123 return loadMap; 124 } 125 126 @Override 127 public synchronized List<String> resolve(List<String> names) { 128 if (map == null) { 129 map = load(); 130 if (map == null) { 131 LOG.warn("Failed to read topology table. " + 132 NetworkTopology.DEFAULT_RACK + " will be used for all nodes."); 133 map = new HashMap<String, String>(); 134 } 135 } 136 List<String> results = new ArrayList<String>(names.size()); 137 for (String name : names) { 138 String result = map.get(name); 139 if (result != null) { 140 results.add(result); 141 } else { 142 results.add(NetworkTopology.DEFAULT_RACK); 143 } 144 } 145 return results; 146 } 147 148 @Override 149 public void reloadCachedMappings() { 150 Map<String, String> newMap = load(); 151 if (newMap == null) { 152 LOG.error("Failed to reload the topology table. The cached " + 153 "mappings will not be cleared."); 154 } else { 155 synchronized(this) { 156 map = newMap; 157 } 158 } 159 } 160 161 @Override 162 public void reloadCachedMappings(List<String> names) { 163 // TableMapping has to reload all mappings at once, so no chance to 164 // reload mappings on specific nodes 165 reloadCachedMappings(); 166 } 167 } 168}