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.mapred.lib;
020
021import java.io.IOException;
022
023import org.apache.hadoop.classification.InterfaceAudience;
024import org.apache.hadoop.classification.InterfaceStability;
025import org.apache.hadoop.fs.FileSystem;
026import org.apache.hadoop.mapred.JobConf;
027import org.apache.hadoop.mapred.OutputFormat;
028import org.apache.hadoop.mapred.RecordWriter;
029import org.apache.hadoop.mapred.Reporter;
030import org.apache.hadoop.util.Progressable;
031
032/**
033 * FilterOutputFormat is a convenience class that wraps OutputFormat. 
034 */
035@InterfaceAudience.Public
036@InterfaceStability.Stable
037public class FilterOutputFormat<K, V> implements OutputFormat<K, V> {
038
039  protected OutputFormat<K,V> baseOut;
040
041  public FilterOutputFormat () {
042    this.baseOut = null;
043  }
044
045  /**
046   * Create a FilterOutputFormat based on the supplied output format.
047   * @param out the underlying OutputFormat
048   */
049  public FilterOutputFormat (OutputFormat<K,V> out) {
050    this.baseOut = out;
051  }
052
053  public RecordWriter<K, V> getRecordWriter(FileSystem ignored, JobConf job, 
054      String name, Progressable progress) throws IOException {
055    return getBaseOut().getRecordWriter(ignored, job, name, progress);
056  }
057
058  public void checkOutputSpecs(FileSystem ignored, JobConf job) 
059  throws IOException {
060    getBaseOut().checkOutputSpecs(ignored, job);
061  }
062  
063  private OutputFormat<K,V> getBaseOut() throws IOException {
064    if (baseOut == null) {
065      throw new IOException("Outputformat not set for FilterOutputFormat");
066    }
067    return baseOut;
068  }
069
070  /**
071   * <code>FilterRecordWriter</code> is a convenience wrapper
072   * class that implements  {@link RecordWriter}.
073   */
074
075  public static class FilterRecordWriter<K,V> implements RecordWriter<K,V> {
076
077    protected RecordWriter<K,V> rawWriter = null;
078
079    public FilterRecordWriter() throws IOException {
080      rawWriter = null;
081    }
082
083    public FilterRecordWriter(RecordWriter<K,V> rawWriter)  throws IOException {
084      this.rawWriter = rawWriter;
085    }
086
087    public void close(Reporter reporter) throws IOException {
088      getRawWriter().close(reporter);
089    }
090
091    public void write(K key, V value) throws IOException {
092      getRawWriter().write(key, value);
093    }
094    
095    private RecordWriter<K,V> getRawWriter() throws IOException {
096      if (rawWriter == null) {
097        throw new IOException ("Record Writer not set for FilterRecordWriter");
098      }
099      return rawWriter;
100    }
101  }
102
103}