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.lib.aggregate;
020
021import java.util.ArrayList;
022
023import org.apache.hadoop.classification.InterfaceAudience;
024import org.apache.hadoop.classification.InterfaceStability;
025import org.apache.hadoop.conf.Configuration;
026import org.apache.hadoop.io.Writable;
027import org.apache.hadoop.io.WritableComparable;
028
029/**
030 * This abstract class implements some common functionalities of the
031 * the generic mapper, reducer and combiner classes of Aggregate.
032 */
033@InterfaceAudience.Public
034@InterfaceStability.Stable
035public class ValueAggregatorJobBase<K1 extends WritableComparable<?>,
036                                             V1 extends Writable>
037{
038  public static final String DESCRIPTOR = "mapreduce.aggregate.descriptor";
039  public static final String DESCRIPTOR_NUM = 
040    "mapreduce.aggregate.descriptor.num";
041  public static final String USER_JAR = "mapreduce.aggregate.user.jar.file";
042  
043  protected static ArrayList<ValueAggregatorDescriptor> aggregatorDescriptorList = null;
044
045  public static void setup(Configuration job) {
046    initializeMySpec(job);
047    logSpec();
048  }
049
050  protected static ValueAggregatorDescriptor getValueAggregatorDescriptor(
051      String spec, Configuration conf) {
052    if (spec == null)
053      return null;
054    String[] segments = spec.split(",", -1);
055    String type = segments[0];
056    if (type.compareToIgnoreCase("UserDefined") == 0) {
057      String className = segments[1];
058      return new UserDefinedValueAggregatorDescriptor(className, conf);
059    }
060    return null;
061  }
062
063  protected static ArrayList<ValueAggregatorDescriptor> getAggregatorDescriptors(
064      Configuration conf) {
065    int num = conf.getInt(DESCRIPTOR_NUM, 0);
066    ArrayList<ValueAggregatorDescriptor> retv = 
067      new ArrayList<ValueAggregatorDescriptor>(num);
068    for (int i = 0; i < num; i++) {
069      String spec = conf.get(DESCRIPTOR + "." + i);
070      ValueAggregatorDescriptor ad = getValueAggregatorDescriptor(spec, conf);
071      if (ad != null) {
072        retv.add(ad);
073      }
074    }
075    return retv;
076  }
077
078  private static void initializeMySpec(Configuration conf) {
079    aggregatorDescriptorList = getAggregatorDescriptors(conf);
080    if (aggregatorDescriptorList.size() == 0) {
081      aggregatorDescriptorList
082          .add(new UserDefinedValueAggregatorDescriptor(
083              ValueAggregatorBaseDescriptor.class.getCanonicalName(), conf));
084    }
085  }
086
087  protected static void logSpec() {
088  }
089}