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 private static final class RawTableMapping extends Configured
080 implements DNSToSwitchMapping {
081
082 private final Map<String, String> map = new HashMap<String, String>();
083 private boolean initialized = false;
084
085 private synchronized void load() {
086 map.clear();
087
088 String filename = getConf().get(NET_TOPOLOGY_TABLE_MAPPING_FILE_KEY, null);
089 if (StringUtils.isBlank(filename)) {
090 LOG.warn(NET_TOPOLOGY_TABLE_MAPPING_FILE_KEY + " not configured. "
091 + NetworkTopology.DEFAULT_RACK + " will be returned.");
092 return;
093 }
094
095 BufferedReader reader = null;
096 try {
097 reader = new BufferedReader(new FileReader(filename));
098 String line = reader.readLine();
099 while (line != null) {
100 line = line.trim();
101 if (line.length() != 0 && line.charAt(0) != '#') {
102 String[] columns = line.split("\\s+");
103 if (columns.length == 2) {
104 map.put(columns[0], columns[1]);
105 } else {
106 LOG.warn("Line does not have two columns. Ignoring. " + line);
107 }
108 }
109 line = reader.readLine();
110 }
111 } catch (Exception e) {
112 LOG.warn(filename + " cannot be read. " + NetworkTopology.DEFAULT_RACK
113 + " will be returned.", e);
114 map.clear();
115 } finally {
116 if (reader != null) {
117 try {
118 reader.close();
119 } catch (IOException e) {
120 LOG.warn(filename + " cannot be read. "
121 + NetworkTopology.DEFAULT_RACK + " will be returned.", e);
122 map.clear();
123 }
124 }
125 }
126 }
127
128 @Override
129 public synchronized List<String> resolve(List<String> names) {
130 if (!initialized) {
131 initialized = true;
132 load();
133 }
134
135 List<String> results = new ArrayList<String>(names.size());
136 for (String name : names) {
137 String result = map.get(name);
138 if (result != null) {
139 results.add(result);
140 } else {
141 results.add(NetworkTopology.DEFAULT_RACK);
142 }
143 }
144 return results;
145 }
146
147 }
148 }