Java tutorial
/** * 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; /** * TaskAttemptID represents the immutable and unique identifier for * a task attempt. Each task attempt is one particular instance of a Map or * Reduce Task identified by its TaskID. * * TaskAttemptID consists of 2 parts. First part is the * {@link TaskID}, that this TaskAttemptID belongs to. * Second part is the task attempt number. <br> * An example TaskAttemptID is : * <code>attempt_200707121733_0003_m_000005_0</code> , which represents the * zeroth task attempt for the fifth map task in the third job * running at the jobtracker started at <code>200707121733</code>. * <p> * Applications should never construct or parse TaskAttemptID strings * , but rather use appropriate constructors or {@link #forName(String)} * method. * * @see JobID * @see TaskID */ @InterfaceAudience.Public @InterfaceStability.Stable public class TaskAttemptID extends org.apache.hadoop.mapreduce.TaskAttemptID { /** * Constructs a TaskAttemptID object from given {@link TaskID}. * @param taskId TaskID that this task belongs to * @param id the task attempt number */ public TaskAttemptID(TaskID taskId, int id) { super(taskId, id); } /** * Constructs a TaskId object from given parts. * @param jtIdentifier jobTracker identifier * @param jobId job number * @param isMap whether the tip is a map * @param taskId taskId number * @param id the task attempt number * @deprecated Use {@link #TaskAttemptID(String, int, TaskType, int, int)}. */ @Deprecated public TaskAttemptID(String jtIdentifier, int jobId, boolean isMap, int taskId, int id) { this(jtIdentifier, jobId, isMap ? TaskType.MAP : TaskType.REDUCE, taskId, id); } /** * Constructs a TaskId object from given parts. * @param jtIdentifier jobTracker identifier * @param jobId job number * @param type the TaskType * @param taskId taskId number * @param id the task attempt number */ public TaskAttemptID(String jtIdentifier, int jobId, TaskType type, int taskId, int id) { this(new TaskID(jtIdentifier, jobId, type, taskId), id); } public TaskAttemptID() { super(new TaskID(), 0); } /** * Downgrade a new TaskAttemptID to an old one * @param old the new id * @return either old or a new TaskAttemptID constructed to match old */ public static TaskAttemptID downgrade(org.apache.hadoop.mapreduce.TaskAttemptID old) { if (old instanceof TaskAttemptID) { return (TaskAttemptID) old; } else { return new TaskAttemptID(TaskID.downgrade(old.getTaskID()), old.getId()); } } public TaskID getTaskID() { return (TaskID) super.getTaskID(); } public JobID getJobID() { return (JobID) super.getJobID(); } @Deprecated public static TaskAttemptID read(DataInput in) throws IOException { TaskAttemptID taskId = new TaskAttemptID(); taskId.readFields(in); return taskId; } /** Construct a TaskAttemptID object from given string * @return constructed TaskAttemptID object or null if the given String is null * @throws IllegalArgumentException if the given string is malformed */ public static TaskAttemptID forName(String str) throws IllegalArgumentException { return (TaskAttemptID) org.apache.hadoop.mapreduce.TaskAttemptID.forName(str); } /** * Returns a regex pattern which matches task attempt 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>all task attempt IDs</i> * of <i>any jobtracker</i>, in <i>any job</i>, of the <i>first * map task</i>, we would use : * <pre> * TaskAttemptID.getTaskAttemptIDsPattern(null, null, true, 1, null); * </pre> * which will return : * <pre> "attempt_[^_]*_[0-9]*_m_000001_[0-9]*" </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 * @param attemptId the task attempt number, or null * @return a regex pattern matching TaskAttemptIDs */ @Deprecated public static String getTaskAttemptIDsPattern(String jtIdentifier, Integer jobId, Boolean isMap, Integer taskId, Integer attemptId) { return getTaskAttemptIDsPattern(jtIdentifier, jobId, isMap ? TaskType.MAP : TaskType.REDUCE, taskId, attemptId); } /** * Returns a regex pattern which matches task attempt 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>all task attempt IDs</i> * of <i>any jobtracker</i>, in <i>any job</i>, of the <i>first * map task</i>, we would use : * <pre> * TaskAttemptID.getTaskAttemptIDsPattern(null, null, TaskType.MAP, 1, null); * </pre> * which will return : * <pre> "attempt_[^_]*_[0-9]*_m_000001_[0-9]*" </pre> * @param jtIdentifier jobTracker identifier, or null * @param jobId job number, or null * @param type the {@link TaskType} * @param taskId taskId number, or null * @param attemptId the task attempt number, or null * @return a regex pattern matching TaskAttemptIDs */ @Deprecated public static String getTaskAttemptIDsPattern(String jtIdentifier, Integer jobId, TaskType type, Integer taskId, Integer attemptId) { StringBuilder builder = new StringBuilder(ATTEMPT).append(SEPARATOR); builder.append(getTaskAttemptIDsPatternWOPrefix(jtIdentifier, jobId, type, taskId, attemptId)); return builder.toString(); } @Deprecated static StringBuilder getTaskAttemptIDsPatternWOPrefix(String jtIdentifier, Integer jobId, TaskType type, Integer taskId, Integer attemptId) { StringBuilder builder = new StringBuilder(); builder.append(TaskID.getTaskIDsPatternWOPrefix(jtIdentifier, jobId, type, taskId)).append(SEPARATOR) .append(attemptId != null ? attemptId : "[0-9]*"); return builder; } }