001/**
002 * Copyright (c) 2011, The University of Southampton and the individual contributors.
003 * All rights reserved.
004 *
005 * Redistribution and use in source and binary forms, with or without modification,
006 * are permitted provided that the following conditions are met:
007 *
008 *   *  Redistributions of source code must retain the above copyright notice,
009 *      this list of conditions and the following disclaimer.
010 *
011 *   *  Redistributions in binary form must reproduce the above copyright notice,
012 *      this list of conditions and the following disclaimer in the documentation
013 *      and/or other materials provided with the distribution.
014 *
015 *   *  Neither the name of the University of Southampton nor the names of its
016 *      contributors may be used to endorse or promote products derived from this
017 *      software without specific prior written permission.
018 *
019 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
020 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
021 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
022 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
023 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
024 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
025 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
026 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
027 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
028 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
029 */
030package org.openimaj.hadoop.sequencefile;
031
032import java.io.IOException;
033
034import org.apache.hadoop.conf.Configuration;
035import org.apache.hadoop.fs.FileSystem;
036import org.apache.hadoop.fs.Path;
037import org.apache.hadoop.io.SequenceFile;
038import org.apache.hadoop.io.SequenceFile.CompressionType;
039import org.apache.hadoop.io.SequenceFile.Metadata;
040import org.apache.hadoop.io.compress.CompressionCodec;
041import org.apache.hadoop.io.compress.DefaultCodec;
042import org.apache.hadoop.mapreduce.RecordWriter;
043import org.apache.hadoop.mapreduce.TaskAttemptContext;
044import org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat;
045import org.apache.hadoop.util.ReflectionUtils;
046
047
048/**
049 * Output format for a extended {@link SequenceFile} that includes
050 * additional metadata in the file header. The metadata is provided
051 * though a {@link MetadataConfiguration} object which is constructed
052 * using information stored in the Hadoop {@link Configuration}.
053 * 
054 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
055 *
056 * @param <K> Key type of {@link SequenceFile}
057 * @param <V> Value type of {@link SequenceFile}
058 */
059public class MetadataSequenceFileOutputFormat<K, V> extends SequenceFileOutputFormat<K, V> {
060        @Override
061        public RecordWriter<K, V> getRecordWriter(TaskAttemptContext context ) throws IOException, InterruptedException {
062                Configuration conf = context.getConfiguration();
063
064                CompressionCodec codec = null;
065                CompressionType compressionType = CompressionType.NONE;
066                if (getCompressOutput(context)) {
067                        // find the kind of compression to do
068                        compressionType = getOutputCompressionType(context);
069
070                        // find the right codec
071                        Class<?> codecClass = getOutputCompressorClass(context, DefaultCodec.class);
072                        codec = (CompressionCodec) ReflectionUtils.newInstance(codecClass, conf);
073                }
074                // get the path of the temporary output file 
075                Path file = getDefaultWorkFile(context, "");
076                FileSystem fs = file.getFileSystem(conf);
077                
078                Metadata md = MetadataConfiguration.getMetadata(conf);
079                
080                final SequenceFile.Writer out = 
081                        SequenceFile.createWriter(fs, conf, file,
082                                        context.getOutputKeyClass(),
083                                        context.getOutputValueClass(),
084                                        compressionType,
085                                        codec,
086                                        context, md);
087
088                return new RecordWriter<K, V>() {
089
090                        @Override
091                        public void write(K key, V value)
092                        throws IOException {
093
094                                out.append(key, value);
095                        }
096
097                        @Override
098                        public void close(TaskAttemptContext context) throws IOException { 
099                                out.close();
100                        }
101                };
102        }
103}