mapreduce/src/java/org/apache/hadoop/mapred/TaskID.java

/**
 * 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.IOException;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.mapreduce.TaskType;

/**
 * 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
 */
@InterfaceAudience.Public
@InterfaceStability.Stable
public class TaskID extends org.apache.hadoop.mapreduce.TaskID {

  /**
   * 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
   * @deprecated Use {@link #TaskID(String, int, TaskType, int)}
   */
  @Deprecated
  public TaskID(org.apache.hadoop.mapreduce.JobID jobId, boolean isMap,int id) {
    this(jobId, isMap ? TaskType.MAP : TaskType.REDUCE, id);
  }
   
  /**
   * 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
   * @deprecated Use {@link #TaskID(org.apache.hadoop.mapreduce.JobID, TaskType,
   * int)}
   */
  @Deprecated
  public TaskID(String jtIdentifier, int jobId, boolean isMap, int id) {
    this(jtIdentifier, jobId, isMap ? TaskType.MAP : TaskType.REDUCE, id);
  }
    
  /**
   * Constructs a TaskID object from given {@link JobID}.  
   * @param jobId JobID that this tip belongs to 
   * @param type the {@link TaskType} 
   * @param id the tip number
   */
  public TaskID(org.apache.hadoop.mapreduce.JobID jobId, TaskType type,int id) {
    super(jobId, type, id);
  }
  
  /**
   * Constructs a TaskInProgressId object from given parts.
   * @param jtIdentifier jobTracker identifier
   * @param jobId job number 
   * @param type the {@link TaskType} 
   * @param id the tip number
   */
  public TaskID(String jtIdentifier, int jobId, TaskType type, int id) {
    this(new JobID(jtIdentifier, jobId), type, id);
  }
  
  public TaskID() {
    super(new JobID(), TaskType.REDUCE, 0);
  }
  
  /**
   * Downgrade a new TaskID to an old one
   * @param old a new or old TaskID
   * @return either old or a new TaskID build to match old
   */
  public static TaskID downgrade(org.apache.hadoop.mapreduce.TaskID old) {
    if (old instanceof TaskID) {
      return (TaskID) old;
    } else {
      return new TaskID(JobID.downgrade(old.getJobID()), old.getTaskType(), 
                        old.getId());
    }
  }

  @Deprecated
  public static TaskID read(DataInput in) throws IOException {
    TaskID tipId = new TaskID();
    tipId.readFields(in);
    return tipId;
  }
  
  public JobID getJobID() {
    return (JobID) super.getJobID();
  }

  /** 
   * 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
   * @deprecated Use {@link TaskID#getTaskIDsPattern(String, Integer, TaskType,
   * Integer)}
   */
  @Deprecated
  public static String getTaskIDsPattern(String jtIdentifier, Integer jobId
      , Boolean isMap, Integer taskId) {
    return getTaskIDsPattern(jtIdentifier, jobId,
	isMap ? TaskType.MAP : TaskType.REDUCE, taskId);
  }
  
  /** 
   * 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 type the {@link TaskType}, or null 
   * @param taskId taskId number, or null
   * @return a regex pattern matching TaskIDs
   */
  @Deprecated
  public static String getTaskIDsPattern(String jtIdentifier, Integer jobId
      , TaskType type, Integer taskId) {
    StringBuilder builder = new StringBuilder(TASK).append(SEPARATOR)
      .append(getTaskIDsPatternWOPrefix(jtIdentifier, jobId, type, taskId));
    return builder.toString();
  }
  
  @Deprecated
  static StringBuilder getTaskIDsPatternWOPrefix(String jtIdentifier
      , Integer jobId, TaskType type, Integer taskId) {
    StringBuilder builder = new StringBuilder();
    builder.append(JobID.getJobIDsPatternWOPrefix(jtIdentifier, jobId))
      .append(SEPARATOR)
      .append(type != null ? 
          (org.apache.hadoop.mapreduce.TaskID.getRepresentingCharacter(type)) : 
            org.apache.hadoop.mapreduce.TaskID.getAllTaskTypes()).
            append(SEPARATOR)
      .append(taskId != null ? idFormat.format(taskId) : "[0-9]*");
    return builder;
  }

  public static TaskID forName(String str
                               ) throws IllegalArgumentException {
    return (TaskID) org.apache.hadoop.mapreduce.TaskID.forName(str);
  }

}