1 /** 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the 7 * "License"); you may not use this file except in compliance 8 * with the License. You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 19 package org.apache.hadoop.mapreduce; 20 21 import java.io.DataInput; 22 import java.io.DataOutput; 23 import java.io.IOException; 24 25 /** 26 * TaskAttemptID represents the immutable and unique identifier for 27 * a task attempt. Each task attempt is one particular instance of a Map or 28 * Reduce Task identified by its TaskID. 29 * 30 * TaskAttemptID consists of 2 parts. First part is the 31 * {@link TaskID}, that this TaskAttemptID belongs to. 32 * Second part is the task attempt number. <br> 33 * An example TaskAttemptID is : 34 * <code>attempt_200707121733_0003_m_000005_0</code> , which represents the 35 * zeroth task attempt for the fifth map task in the third job 36 * running at the jobtracker started at <code>200707121733</code>. 37 * <p> 38 * Applications should never construct or parse TaskAttemptID strings 39 * , but rather use appropriate constructors or {@link #forName(String)} 40 * method. 41 * 42 * @see JobID 43 * @see TaskID 44 */ 45 public class TaskAttemptID extends org.apache.hadoop.mapred.ID { 46 protected static final String ATTEMPT = "attempt"; 47 private TaskID taskId; 48 49 /** 50 * Constructs a TaskAttemptID object from given {@link TaskID}. 51 * @param taskId TaskID that this task belongs to 52 * @param id the task attempt number 53 */ TaskAttemptID(TaskID taskId, int id)54 public TaskAttemptID(TaskID taskId, int id) { 55 super(id); 56 if(taskId == null) { 57 throw new IllegalArgumentException("taskId cannot be null"); 58 } 59 this.taskId = taskId; 60 } 61 62 /** 63 * Constructs a TaskId object from given parts. 64 * @param jtIdentifier jobTracker identifier 65 * @param jobId job number 66 * @param isMap whether the tip is a map 67 * @param taskId taskId number 68 * @param id the task attempt number 69 */ TaskAttemptID(String jtIdentifier, int jobId, boolean isMap, int taskId, int id)70 public TaskAttemptID(String jtIdentifier, int jobId, boolean isMap, 71 int taskId, int id) { 72 this(new TaskID(jtIdentifier, jobId, isMap, taskId), id); 73 } 74 TaskAttemptID()75 public TaskAttemptID() { 76 taskId = new TaskID(); 77 } 78 79 /** Returns the {@link JobID} object that this task attempt belongs to */ getJobID()80 public JobID getJobID() { 81 return taskId.getJobID(); 82 } 83 84 /** Returns the {@link TaskID} object that this task attempt belongs to */ getTaskID()85 public TaskID getTaskID() { 86 return taskId; 87 } 88 89 /**Returns whether this TaskAttemptID is a map ID */ isMap()90 public boolean isMap() { 91 return taskId.isMap(); 92 } 93 94 @Override equals(Object o)95 public boolean equals(Object o) { 96 if (!super.equals(o)) 97 return false; 98 99 TaskAttemptID that = (TaskAttemptID)o; 100 return this.taskId.equals(that.taskId); 101 } 102 103 /** 104 * Add the unique string to the StringBuilder 105 * @param builder the builder to append ot 106 * @return the builder that was passed in. 107 */ appendTo(StringBuilder builder)108 protected StringBuilder appendTo(StringBuilder builder) { 109 return taskId.appendTo(builder).append(SEPARATOR).append(id); 110 } 111 112 @Override readFields(DataInput in)113 public void readFields(DataInput in) throws IOException { 114 super.readFields(in); 115 taskId.readFields(in); 116 } 117 118 @Override write(DataOutput out)119 public void write(DataOutput out) throws IOException { 120 super.write(out); 121 taskId.write(out); 122 } 123 124 @Override hashCode()125 public int hashCode() { 126 return taskId.hashCode() * 5 + id; 127 } 128 129 /**Compare TaskIds by first tipIds, then by task numbers. */ 130 @Override compareTo(ID o)131 public int compareTo(ID o) { 132 TaskAttemptID that = (TaskAttemptID)o; 133 int tipComp = this.taskId.compareTo(that.taskId); 134 if(tipComp == 0) { 135 return this.id - that.id; 136 } 137 else return tipComp; 138 } 139 @Override toString()140 public String toString() { 141 return appendTo(new StringBuilder(ATTEMPT)).toString(); 142 } 143 144 /** Construct a TaskAttemptID object from given string 145 * @return constructed TaskAttemptID object or null if the given String is null 146 * @throws IllegalArgumentException if the given string is malformed 147 */ forName(String str )148 public static TaskAttemptID forName(String str 149 ) throws IllegalArgumentException { 150 if(str == null) 151 return null; 152 try { 153 String[] parts = str.split(Character.toString(SEPARATOR)); 154 if(parts.length == 6) { 155 if(parts[0].equals(ATTEMPT)) { 156 boolean isMap = false; 157 if(parts[3].equals("m")) isMap = true; 158 else if(parts[3].equals("r")) isMap = false; 159 else throw new Exception(); 160 return new org.apache.hadoop.mapred.TaskAttemptID 161 (parts[1], 162 Integer.parseInt(parts[2]), 163 isMap, Integer.parseInt(parts[4]), 164 Integer.parseInt(parts[5])); 165 } 166 } 167 } catch (Exception ex) { 168 //fall below 169 } 170 throw new IllegalArgumentException("TaskAttemptId string : " + str 171 + " is not properly formed"); 172 } 173 174 } 175