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 }