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 019package org.apache.hadoop.mapreduce; 020 021import java.io.DataInput; 022import java.io.DataOutput; 023import java.io.IOException; 024import java.text.NumberFormat; 025import java.util.EnumMap; 026import java.util.HashMap; 027import java.util.Map; 028 029import org.apache.hadoop.classification.InterfaceAudience; 030import org.apache.hadoop.classification.InterfaceStability; 031import org.apache.hadoop.io.WritableUtils; 032 033 034/** 035 * TaskID represents the immutable and unique identifier for 036 * a Map or Reduce Task. Each TaskID encompasses multiple attempts made to 037 * execute the Map or Reduce Task, each of which are uniquely indentified by 038 * their TaskAttemptID. 039 * 040 * TaskID consists of 3 parts. First part is the {@link JobID}, that this 041 * TaskInProgress belongs to. Second part of the TaskID is either 'm' or 'r' 042 * representing whether the task is a map task or a reduce task. 043 * And the third part is the task number. <br> 044 * An example TaskID is : 045 * <code>task_200707121733_0003_m_000005</code> , which represents the 046 * fifth map task in the third job running at the jobtracker 047 * started at <code>200707121733</code>. 048 * <p> 049 * Applications should never construct or parse TaskID strings 050 * , but rather use appropriate constructors or {@link #forName(String)} 051 * method. 052 * 053 * @see JobID 054 * @see TaskAttemptID 055 */ 056@InterfaceAudience.Public 057@InterfaceStability.Stable 058public class TaskID extends org.apache.hadoop.mapred.ID { 059 protected static final String TASK = "task"; 060 protected static final NumberFormat idFormat = NumberFormat.getInstance(); 061 static { 062 idFormat.setGroupingUsed(false); 063 idFormat.setMinimumIntegerDigits(6); 064 } 065 066 private JobID jobId; 067 private TaskType type; 068 069 /** 070 * Constructs a TaskID object from given {@link JobID}. 071 * @param jobId JobID that this tip belongs to 072 * @param type the {@link TaskType} of the task 073 * @param id the tip number 074 */ 075 public TaskID(JobID jobId, TaskType type, int id) { 076 super(id); 077 if(jobId == null) { 078 throw new IllegalArgumentException("jobId cannot be null"); 079 } 080 this.jobId = jobId; 081 this.type = type; 082 } 083 084 /** 085 * Constructs a TaskInProgressId object from given parts. 086 * @param jtIdentifier jobTracker identifier 087 * @param jobId job number 088 * @param type the TaskType 089 * @param id the tip number 090 */ 091 public TaskID(String jtIdentifier, int jobId, TaskType type, int id) { 092 this(new JobID(jtIdentifier, jobId), type, id); 093 } 094 095 /** 096 * Constructs a TaskID object from given {@link JobID}. 097 * @param jobId JobID that this tip belongs to 098 * @param isMap whether the tip is a map 099 * @param id the tip number 100 */ 101 @Deprecated 102 public TaskID(JobID jobId, boolean isMap, int id) { 103 this(jobId, isMap ? TaskType.MAP : TaskType.REDUCE, id); 104 } 105 106 /** 107 * Constructs a TaskInProgressId object from given parts. 108 * @param jtIdentifier jobTracker identifier 109 * @param jobId job number 110 * @param isMap whether the tip is a map 111 * @param id the tip number 112 */ 113 @Deprecated 114 public TaskID(String jtIdentifier, int jobId, boolean isMap, int id) { 115 this(new JobID(jtIdentifier, jobId), isMap, id); 116 } 117 118 public TaskID() { 119 jobId = new JobID(); 120 } 121 122 /** Returns the {@link JobID} object that this tip belongs to */ 123 public JobID getJobID() { 124 return jobId; 125 } 126 127 /**Returns whether this TaskID is a map ID */ 128 @Deprecated 129 public boolean isMap() { 130 return type == TaskType.MAP; 131 } 132 133 /** 134 * Get the type of the task 135 */ 136 public TaskType getTaskType() { 137 return type; 138 } 139 140 @Override 141 public boolean equals(Object o) { 142 if (!super.equals(o)) 143 return false; 144 145 TaskID that = (TaskID)o; 146 return this.type == that.type && this.jobId.equals(that.jobId); 147 } 148 149 /**Compare TaskInProgressIds by first jobIds, then by tip numbers. Reduces are 150 * defined as greater then maps.*/ 151 @Override 152 public int compareTo(ID o) { 153 TaskID that = (TaskID)o; 154 int jobComp = this.jobId.compareTo(that.jobId); 155 if(jobComp == 0) { 156 if(this.type == that.type) { 157 return this.id - that.id; 158 } 159 else { 160 return this.type.compareTo(that.type); 161 } 162 } 163 else return jobComp; 164 } 165 @Override 166 public String toString() { 167 return appendTo(new StringBuilder(TASK)).toString(); 168 } 169 170 /** 171 * Add the unique string to the given builder. 172 * @param builder the builder to append to 173 * @return the builder that was passed in 174 */ 175 protected StringBuilder appendTo(StringBuilder builder) { 176 return jobId.appendTo(builder). 177 append(SEPARATOR). 178 append(CharTaskTypeMaps.getRepresentingCharacter(type)). 179 append(SEPARATOR). 180 append(idFormat.format(id)); 181 } 182 183 @Override 184 public int hashCode() { 185 return jobId.hashCode() * 524287 + id; 186 } 187 188 @Override 189 public void readFields(DataInput in) throws IOException { 190 super.readFields(in); 191 jobId.readFields(in); 192 type = WritableUtils.readEnum(in, TaskType.class); 193 } 194 195 @Override 196 public void write(DataOutput out) throws IOException { 197 super.write(out); 198 jobId.write(out); 199 WritableUtils.writeEnum(out, type); 200 } 201 202 /** Construct a TaskID object from given string 203 * @return constructed TaskID object or null if the given String is null 204 * @throws IllegalArgumentException if the given string is malformed 205 */ 206 public static TaskID forName(String str) 207 throws IllegalArgumentException { 208 if(str == null) 209 return null; 210 String exceptionMsg = null; 211 try { 212 String[] parts = str.split("_"); 213 if(parts.length == 5) { 214 if(parts[0].equals(TASK)) { 215 String type = parts[3]; 216 TaskType t = CharTaskTypeMaps.getTaskType(type.charAt(0)); 217 if(t != null) { 218 219 return new org.apache.hadoop.mapred.TaskID(parts[1], 220 Integer.parseInt(parts[2]), 221 t, 222 Integer.parseInt(parts[4])); 223 } else 224 exceptionMsg = "Bad TaskType identifier. TaskId string : " + str 225 + " is not properly formed."; 226 } 227 } 228 }catch (Exception ex) {//fall below 229 } 230 if (exceptionMsg == null) { 231 exceptionMsg = "TaskId string : " + str + " is not properly formed"; 232 } 233 throw new IllegalArgumentException(exceptionMsg); 234 } 235 /** 236 * Gets the character representing the {@link TaskType} 237 * @param type the TaskType 238 * @return the character 239 */ 240 public static char getRepresentingCharacter(TaskType type) { 241 return CharTaskTypeMaps.getRepresentingCharacter(type); 242 } 243 /** 244 * Gets the {@link TaskType} corresponding to the character 245 * @param c the character 246 * @return the TaskType 247 */ 248 public static TaskType getTaskType(char c) { 249 return CharTaskTypeMaps.getTaskType(c); 250 } 251 252 public static String getAllTaskTypes() { 253 return CharTaskTypeMaps.allTaskTypes; 254 } 255 256 /** 257 * Maintains the mapping from the character representation of a task type to 258 * the enum class TaskType constants 259 */ 260 static class CharTaskTypeMaps { 261 private static EnumMap<TaskType, Character> typeToCharMap = 262 new EnumMap<TaskType,Character>(TaskType.class); 263 private static Map<Character, TaskType> charToTypeMap = 264 new HashMap<Character, TaskType>(); 265 static String allTaskTypes = "(m|r|s|c|t)"; 266 static { 267 setupTaskTypeToCharMapping(); 268 setupCharToTaskTypeMapping(); 269 } 270 271 private static void setupTaskTypeToCharMapping() { 272 typeToCharMap.put(TaskType.MAP, 'm'); 273 typeToCharMap.put(TaskType.REDUCE, 'r'); 274 typeToCharMap.put(TaskType.JOB_SETUP, 's'); 275 typeToCharMap.put(TaskType.JOB_CLEANUP, 'c'); 276 typeToCharMap.put(TaskType.TASK_CLEANUP, 't'); 277 } 278 279 private static void setupCharToTaskTypeMapping() { 280 charToTypeMap.put('m', TaskType.MAP); 281 charToTypeMap.put('r', TaskType.REDUCE); 282 charToTypeMap.put('s', TaskType.JOB_SETUP); 283 charToTypeMap.put('c', TaskType.JOB_CLEANUP); 284 charToTypeMap.put('t', TaskType.TASK_CLEANUP); 285 } 286 287 static char getRepresentingCharacter(TaskType type) { 288 return typeToCharMap.get(type); 289 } 290 static TaskType getTaskType(char c) { 291 return charToTypeMap.get(c); 292 } 293 } 294 295}