TaskID.java
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上传日期:2018-01-08
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- /**
- * 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.mapreduce;
- 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 org.apache.hadoop.mapred.ID {
- protected static final String TASK = "task";
- protected static final 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);
- }
-
- public TaskID() {
- jobId = new JobID();
- }
-
- /** 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 (!super.equals(o))
- return false;
- TaskID that = (TaskID)o;
- return this.isMap == that.isMap && this.jobId.equals(that.jobId);
- }
- /**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() {
- return appendTo(new StringBuilder(TASK)).toString();
- }
- /**
- * Add the unique string to the given builder.
- * @param builder the builder to append to
- * @return the builder that was passed in
- */
- protected StringBuilder appendTo(StringBuilder builder) {
- return jobId.appendTo(builder).
- append(SEPARATOR).
- append(isMap ? 'm' : 'r').
- append(SEPARATOR).
- append(idFormat.format(id));
- }
-
- @Override
- public int hashCode() {
- return jobId.hashCode() * 524287 + id;
- }
-
- @Override
- public void readFields(DataInput in) throws IOException {
- super.readFields(in);
- jobId.readFields(in);
- isMap = in.readBoolean();
- }
- @Override
- public void write(DataOutput out) throws IOException {
- super.write(out);
- jobId.write(out);
- out.writeBoolean(isMap);
- }
-
- /** 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 org.apache.hadoop.mapred.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");
- }
-
- }