hadoop Reporter 源码

haddop Reporter 代码

文件路径：/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/Reporter.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 org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.mapred.Counters.Counter;
import org.apache.hadoop.util.Progressable;

/** 
 * A facility for Map-Reduce applications to report progress and update 
 * counters, status information etc.
 * 
 * <p>{@link Mapper} and {@link Reducer} can use the <code>Reporter</code>
 * provided to report progress or just indicate that they are alive. In 
 * scenarios where the application takes significant amount of time to
 * process individual key/value pairs, this is crucial since the framework 
 * might assume that the task has timed-out and kill that task.
 *
 * <p>Applications can also update {@link Counters} via the provided 
 * <code>Reporter</code> .</p>
 * 
 * @see Progressable
 * @see Counters
 */
@InterfaceAudience.Public
@InterfaceStability.Stable
public interface Reporter extends Progressable {
  
  /**
   * A constant of Reporter type that does nothing.
   */
  public static final Reporter NULL = new Reporter() {
      public void setStatus(String s) {
      }
      public void progress() {
      }
      public Counter getCounter(Enum<?> name) {
        return null;
      }
      public Counter getCounter(String group, String name) {
        return null;
      }
      public void incrCounter(Enum<?> key, long amount) {
      }
      public void incrCounter(String group, String counter, long amount) {
      }
      public InputSplit getInputSplit() throws UnsupportedOperationException {
        throw new UnsupportedOperationException("NULL reporter has no input");
      }
      @Override
      public float getProgress() {
        return 0;
      }
    };

  /**
   * Set the status description for the task.
   * 
   * @param status brief description of the current status.
   */
  public abstract void setStatus(String status);
  
  /**
   * Get the {@link Counter} of the given group with the given name.
   * 
   * @param name counter name
   * @return the <code>Counter</code> of the given group/name.
   */
  public abstract Counter getCounter(Enum<?> name);

  /**
   * Get the {@link Counter} of the given group with the given name.
   * 
   * @param group counter group
   * @param name counter name
   * @return the <code>Counter</code> of the given group/name.
   */
  public abstract Counter getCounter(String group, String name);
  
  /**
   * Increments the counter identified by the key, which can be of
   * any {@link Enum} type, by the specified amount.
   * 
   * @param key key to identify the counter to be incremented. The key can be
   *            be any <code>Enum</code>. 
   * @param amount A non-negative amount by which the counter is to 
   *               be incremented.
   */
  public abstract void incrCounter(Enum<?> key, long amount);
  
  /**
   * Increments the counter identified by the group and counter name
   * by the specified amount.
   * 
   * @param group name to identify the group of the counter to be incremented.
   * @param counter name to identify the counter within the group.
   * @param amount A non-negative amount by which the counter is to 
   *               be incremented.
   */
  public abstract void incrCounter(String group, String counter, long amount);
  
  /**
   * Get the {@link InputSplit} object for a map.
   * 
   * @return the <code>InputSplit</code> that the map is reading from.
   * @throws UnsupportedOperationException if called outside a mapper
   */
  public abstract InputSplit getInputSplit() 
    throws UnsupportedOperationException;
  
  /**
   * Get the progress of the task. Progress is represented as a number between
   * 0 and 1 (inclusive).
   */
  public float getProgress();
}

相关信息

hadoop 源码目录

相关文章

hadoop AMFeedback 源码

hadoop BackupStore 源码

hadoop BasicTypeSorterBase 源码

hadoop BufferSorter 源码

hadoop CleanupQueue 源码

hadoop Clock 源码

hadoop ClusterStatus 源码

hadoop Counters 源码

hadoop CumulativePeriodicStats 源码

hadoop DeprecatedQueueConfigurationParser 源码