/**
* Copyright 2007 The Apache Software Foundation
*
* 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.hbase.mapred;
import java.io.IOException;
import java.util.Map;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.io.MapWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.mapred.FileAlreadyExistsException;
import org.apache.hadoop.mapred.InvalidJobConfException;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.OutputFormatBase;
import org.apache.hadoop.mapred.RecordWriter;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.util.Progressable;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.HTable;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.log4j.Logger;
/**
* Convert Map/Reduce output and write it to an HBase table
*/
public class TableOutputFormat
extends OutputFormatBase<Text, MapWritable> {
/** JobConf parameter that specifies the output table */
public static final String OUTPUT_TABLE = "hbase.mapred.outputtable";
static final Logger LOG = Logger.getLogger(TableOutputFormat.class.getName());
/** constructor */
public TableOutputFormat() {
super();
}
/**
* Convert Reduce output (key, value) to (HStoreKey, KeyedDataArrayWritable)
* and write to an HBase table
*/
protected class TableRecordWriter
implements RecordWriter<Text, MapWritable> {
private HTable m_table;
/**
* Instantiate a TableRecordWriter with the HBase HClient for writing.
*
* @param table
*/
public TableRecordWriter(HTable table) {
m_table = table;
}
/** {@inheritDoc} */
public void close(@SuppressWarnings("unused") Reporter reporter) {
// Nothing to do.
}
/** {@inheritDoc} */
public void write(Text key, MapWritable value) throws IOException {
long xid = m_table.startUpdate(key); // start transaction
for (Map.Entry<Writable, Writable> e: value.entrySet()) {
m_table.put(xid, (Text)e.getKey(),
((ImmutableBytesWritable)e.getValue()).get());
}
m_table.commit(xid); // end transaction
}
}
/** {@inheritDoc} */
@Override
@SuppressWarnings("unchecked")
public RecordWriter getRecordWriter(
@SuppressWarnings("unused") FileSystem ignored,
JobConf job,
@SuppressWarnings("unused") String name,
@SuppressWarnings("unused") Progressable progress) throws IOException {
// expecting exactly one path
Text tableName = new Text(job.get(OUTPUT_TABLE));
HTable table = null;
try {
table = new HTable(new HBaseConfiguration(job), tableName);
} catch(IOException e) {
LOG.error(e);
throw e;
}
return new TableRecordWriter(table);
}
/** {@inheritDoc} */
@Override
@SuppressWarnings("unused")
public void checkOutputSpecs(FileSystem ignored, JobConf job)
throws FileAlreadyExistsException, InvalidJobConfException, IOException {
String tableName = job.get(OUTPUT_TABLE);
if(tableName == null) {
throw new IOException("Must specify table name");
}
}
}