/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.mapred;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.text.NumberFormat;
/**
* TaskID represents the immutable and unique identifier for
* a Map or Reduce Task. Each TaskID encompasses multiple attempts made to
* execute the Map or Reduce Task, each of which are uniquely indentified by
* their TaskAttemptID.
*
* TaskID consists of 3 parts. First part is the {@link JobID}, that this
* TaskInProgress belongs to. Second part of the TaskID is either 'm' or 'r'
* representing whether the task is a map task or a reduce task.
* And the third part is the task number. <br>
* An example TaskID is :
* <code>task_200707121733_0003_m_000005</code> , which represents the
* fifth map task in the third job running at the jobtracker
* started at <code>200707121733</code>.
* <p>
* Applications should never construct or parse TaskID strings
* , but rather use appropriate constructors or {@link #forName(String)}
* method.
*
* @see JobID
* @see TaskAttemptID
*/
public class TaskID extends ID {
private static final String TASK = "task";
private static char UNDERSCORE = '_';
private static NumberFormat idFormat = NumberFormat.getInstance();
static {
idFormat.setGroupingUsed(false);
idFormat.setMinimumIntegerDigits(6);
}
private JobID jobId;
private boolean isMap;
/**
* Constructs a TaskID object from given {@link JobID}.
* @param jobId JobID that this tip belongs to
* @param isMap whether the tip is a map
* @param id the tip number
*/
public TaskID(JobID jobId, boolean isMap, int id) {
super(id);
if(jobId == null) {
throw new IllegalArgumentException("jobId cannot be null");
}
this.jobId = jobId;
this.isMap = isMap;
}
/**
* Constructs a TaskInProgressId object from given parts.
* @param jtIdentifier jobTracker identifier
* @param jobId job number
* @param isMap whether the tip is a map
* @param id the tip number
*/
public TaskID(String jtIdentifier, int jobId, boolean isMap, int id) {
this(new JobID(jtIdentifier, jobId), isMap, id);
}
private TaskID() { }
/** Returns the {@link JobID} object that this tip belongs to */
public JobID getJobID() {
return jobId;
}
/**Returns whether this TaskID is a map ID */
public boolean isMap() {
return isMap;
}
@Override
public boolean equals(Object o) {
if(o == null)
return false;
if(o.getClass().equals(TaskID.class)) {
TaskID that = (TaskID)o;
return this.id==that.id
&& this.isMap == that.isMap
&& this.jobId.equals(that.jobId);
}
else return false;
}
/**Compare TaskInProgressIds by first jobIds, then by tip numbers. Reduces are
* defined as greater then maps.*/
@Override
public int compareTo(ID o) {
TaskID that = (TaskID)o;
int jobComp = this.jobId.compareTo(that.jobId);
if(jobComp == 0) {
if(this.isMap == that.isMap) {
return this.id - that.id;
}
else return this.isMap ? -1 : 1;
}
else return jobComp;
}
@Override
public String toString() {
StringBuilder builder = new StringBuilder();
return builder.append(TASK).append(UNDERSCORE)
.append(toStringWOPrefix()).toString();
}
StringBuilder toStringWOPrefix() {
StringBuilder builder = new StringBuilder();
builder.append(jobId.toStringWOPrefix())
.append(isMap ? "_m_" : "_r_");
return builder.append(idFormat.format(id));
}
@Override
public int hashCode() {
return toStringWOPrefix().toString().hashCode();
}
@Override
public void readFields(DataInput in) throws IOException {
super.readFields(in);
this.jobId = JobID.read(in);
this.isMap = in.readBoolean();
}
@Override
public void write(DataOutput out) throws IOException {
super.write(out);
jobId.write(out);
out.writeBoolean(isMap);
}
public static TaskID read(DataInput in) throws IOException {
TaskID tipId = new TaskID();
tipId.readFields(in);
return tipId;
}
/** Construct a TaskID object from given string
* @return constructed TaskID object or null if the given String is null
* @throws IllegalArgumentException if the given string is malformed
*/
public static TaskID forName(String str)
throws IllegalArgumentException {
if(str == null)
return null;
try {
String[] parts = str.split("_");
if(parts.length == 5) {
if(parts[0].equals(TASK)) {
boolean isMap = false;
if(parts[3].equals("m")) isMap = true;
else if(parts[3].equals("r")) isMap = false;
else throw new Exception();
return new TaskID(parts[1], Integer.parseInt(parts[2]),
isMap, Integer.parseInt(parts[4]));
}
}
}catch (Exception ex) {//fall below
}
throw new IllegalArgumentException("TaskId string : " + str
+ " is not properly formed");
}
/**
* Returns a regex pattern which matches task IDs. Arguments can
* be given null, in which case that part of the regex will be generic.
* For example to obtain a regex matching <i>the first map task</i>
* of <i>any jobtracker</i>, of <i>any job</i>, we would use :
* <pre>
* TaskID.getTaskIDsPattern(null, null, true, 1);
* </pre>
* which will return :
* <pre> "task_[^_]*_[0-9]*_m_000001*" </pre>
* @param jtIdentifier jobTracker identifier, or null
* @param jobId job number, or null
* @param isMap whether the tip is a map, or null
* @param taskId taskId number, or null
* @return a regex pattern matching TaskIDs
*/
public static String getTaskIDsPattern(String jtIdentifier, Integer jobId
, Boolean isMap, Integer taskId) {
StringBuilder builder = new StringBuilder(TASK).append(UNDERSCORE)
.append(getTaskIDsPatternWOPrefix(jtIdentifier, jobId, isMap, taskId));
return builder.toString();
}
static StringBuilder getTaskIDsPatternWOPrefix(String jtIdentifier
, Integer jobId, Boolean isMap, Integer taskId) {
StringBuilder builder = new StringBuilder();
builder.append(JobID.getJobIDsPatternWOPrefix(jtIdentifier, jobId))
.append(UNDERSCORE)
.append(isMap != null ? (isMap ? "m" : "r") : "(m|r)").append(UNDERSCORE)
.append(taskId != null ? idFormat.format(taskId) : "[0-9]*");
return builder;
}
}