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