/**
* Copyright 2010 Nube Technologies
*
* Licensed 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 co.nubetech.hiho.mapreduce.lib.output;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.compress.CompressionCodec;
import org.apache.hadoop.io.compress.GzipCodec;
import org.apache.hadoop.mapreduce.RecordWriter;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.ReflectionUtils;
/**
* This class ignores the key and simply prints the value. However, new line is
* added
*
* @author sgoyal
*
*/
public class NoKeyOnlyValueOutputFormat<K, V> extends FileOutputFormat<K, V> {
protected static class NoKeyRecordWriter<K, V> extends RecordWriter<K, V> {
private static final String utf8 = "UTF-8";
private static final byte[] newline;
static {
try {
newline = "\n".getBytes(utf8);
} catch (UnsupportedEncodingException uee) {
throw new IllegalArgumentException("can't find " + utf8
+ " encoding");
}
}
protected DataOutputStream out;
public NoKeyRecordWriter(DataOutputStream out) {
this.out = out;
}
/**
* Write the object to the byte stream, handling Text as a special case.
*
* @param o
* the object to print
* @throws IOException
* if the write throws, we pass it on
*/
private void writeObject(Object o) throws IOException {
if (o instanceof Text) {
Text to = (Text) o;
out.write(to.getBytes(), 0, to.getLength());
} else {
out.write(o.toString().getBytes(utf8));
}
}
public synchronized void write(K key, V value) throws IOException {
writeObject(value);
out.write(newline);
}
public synchronized void close(TaskAttemptContext context)
throws IOException {
out.close();
}
}
public RecordWriter<K, V> getRecordWriter(TaskAttemptContext context)
throws IOException {
boolean isCompressed = getCompressOutput(context);
Configuration conf = context.getConfiguration();
String ext = "";
CompressionCodec codec = null;
if (isCompressed) {
// create the named codec
Class<? extends CompressionCodec> codecClass = getOutputCompressorClass(
context, GzipCodec.class);
codec = ReflectionUtils.newInstance(codecClass, conf);
ext = codec.getDefaultExtension();
}
Path file = getDefaultWorkFile(context, ext);
FileSystem fs = file.getFileSystem(conf);
FSDataOutputStream fileOut = fs.create(file, false);
DataOutputStream ostream = fileOut;
if (isCompressed) {
ostream = new DataOutputStream(codec.createOutputStream(fileOut));
}
return new NoKeyRecordWriter<K, V>(ostream);
}
}