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 */ 018 package org.apache.hadoop.net; 019 020 import static org.apache.hadoop.fs.CommonConfigurationKeysPublic.NET_TOPOLOGY_TABLE_MAPPING_FILE_KEY; 021 022 import java.io.BufferedReader; 023 import java.io.FileReader; 024 import java.io.IOException; 025 import java.util.ArrayList; 026 import java.util.HashMap; 027 import java.util.List; 028 import java.util.Map; 029 030 import org.apache.commons.lang.StringUtils; 031 import org.apache.commons.logging.Log; 032 import org.apache.commons.logging.LogFactory; 033 import org.apache.hadoop.classification.InterfaceAudience; 034 import org.apache.hadoop.classification.InterfaceStability; 035 import org.apache.hadoop.conf.Configuration; 036 import org.apache.hadoop.conf.Configured; 037 038 /** 039 * <p> 040 * Simple {@link DNSToSwitchMapping} implementation that reads a 2 column text 041 * file. The columns are separated by whitespace. The first column is a DNS or 042 * IP address and the second column specifies the rack where the address maps. 043 * </p> 044 * <p> 045 * This class uses the configuration parameter {@code 046 * net.topology.table.file.name} to locate the mapping file. 047 * </p> 048 * <p> 049 * Calls to {@link #resolve(List)} will look up the address as defined in the 050 * mapping file. If no entry corresponding to the address is found, the value 051 * {@code /default-rack} is returned. 052 * </p> 053 */ 054 @InterfaceAudience.Public 055 @InterfaceStability.Evolving 056 public class TableMapping extends CachedDNSToSwitchMapping { 057 058 private static final Log LOG = LogFactory.getLog(TableMapping.class); 059 060 public TableMapping() { 061 super(new RawTableMapping()); 062 } 063 064 private RawTableMapping getRawMapping() { 065 return (RawTableMapping) rawMapping; 066 } 067 068 @Override 069 public Configuration getConf() { 070 return getRawMapping().getConf(); 071 } 072 073 @Override 074 public void setConf(Configuration conf) { 075 super.setConf(conf); 076 getRawMapping().setConf(conf); 077 } 078 079 @Override 080 public void reloadCachedMappings() { 081 super.reloadCachedMappings(); 082 getRawMapping().reloadCachedMappings(); 083 } 084 085 private static final class RawTableMapping extends Configured 086 implements DNSToSwitchMapping { 087 088 private Map<String, String> map; 089 090 private Map<String, String> load() { 091 Map<String, String> loadMap = new HashMap<String, String>(); 092 093 String filename = getConf().get(NET_TOPOLOGY_TABLE_MAPPING_FILE_KEY, null); 094 if (StringUtils.isBlank(filename)) { 095 LOG.warn(NET_TOPOLOGY_TABLE_MAPPING_FILE_KEY + " not configured. "); 096 return null; 097 } 098 099 BufferedReader reader = null; 100 try { 101 reader = new BufferedReader(new FileReader(filename)); 102 String line = reader.readLine(); 103 while (line != null) { 104 line = line.trim(); 105 if (line.length() != 0 && line.charAt(0) != '#') { 106 String[] columns = line.split("\\s+"); 107 if (columns.length == 2) { 108 loadMap.put(columns[0], columns[1]); 109 } else { 110 LOG.warn("Line does not have two columns. Ignoring. " + line); 111 } 112 } 113 line = reader.readLine(); 114 } 115 } catch (Exception e) { 116 LOG.warn(filename + " cannot be read.", e); 117 return null; 118 } finally { 119 if (reader != null) { 120 try { 121 reader.close(); 122 } catch (IOException e) { 123 LOG.warn(filename + " cannot be read.", e); 124 return null; 125 } 126 } 127 } 128 return loadMap; 129 } 130 131 @Override 132 public synchronized List<String> resolve(List<String> names) { 133 if (map == null) { 134 map = load(); 135 if (map == null) { 136 LOG.warn("Failed to read topology table. " + 137 NetworkTopology.DEFAULT_RACK + " will be used for all nodes."); 138 map = new HashMap<String, String>(); 139 } 140 } 141 List<String> results = new ArrayList<String>(names.size()); 142 for (String name : names) { 143 String result = map.get(name); 144 if (result != null) { 145 results.add(result); 146 } else { 147 results.add(NetworkTopology.DEFAULT_RACK); 148 } 149 } 150 return results; 151 } 152 153 @Override 154 public void reloadCachedMappings() { 155 Map<String, String> newMap = load(); 156 if (newMap == null) { 157 LOG.error("Failed to reload the topology table. The cached " + 158 "mappings will not be cleared."); 159 } else { 160 synchronized(this) { 161 map = newMap; 162 } 163 } 164 } 165 166 @Override 167 public void reloadCachedMappings(List<String> names) { 168 // TableMapping has to reload all mappings at once, so no chance to 169 // reload mappings on specific nodes 170 reloadCachedMappings(); 171 } 172 } 173 }