/**
* Copyright 2009 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.mapreduce;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
import java.util.TreeSet;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.filecache.DistributedCache;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.io.hfile.Compression;
import org.apache.hadoop.hbase.io.hfile.HFile;
import org.apache.hadoop.hbase.mapreduce.hadoopbackport.TotalOrderPartitioner;
import org.apache.hadoop.hbase.regionserver.StoreFile;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.SequenceFile;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.RecordWriter;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.lib.output.FileOutputCommitter;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* Writes HFiles. Passed KeyValues must arrive in order.
* Currently, can only write files to a single column family at a
* time. Multiple column families requires coordinating keys cross family.
* Writes current time as the sequence id for the file. Sets the major compacted
* attribute on created hfiles.
* @see KeyValueSortReducer
*/
public class HFileOutputFormat extends FileOutputFormat<ImmutableBytesWritable, KeyValue> {
static Log LOG = LogFactory.getLog(HFileOutputFormat.class);
public RecordWriter<ImmutableBytesWritable, KeyValue> getRecordWriter(final TaskAttemptContext context)
throws IOException, InterruptedException {
// Get the path of the temporary output file
final Path outputPath = FileOutputFormat.getOutputPath(context);
final Path outputdir = new FileOutputCommitter(outputPath, context).getWorkPath();
Configuration conf = context.getConfiguration();
final FileSystem fs = outputdir.getFileSystem(conf);
// These configs. are from hbase-*.xml
final long maxsize = conf.getLong("hbase.hregion.max.filesize", 268435456);
final int blocksize =
conf.getInt("hbase.mapreduce.hfileoutputformat.blocksize", 65536);
// Invented config. Add to hbase-*.xml if other than default compression.
final String compression = conf.get("hfile.compression",
Compression.Algorithm.NONE.getName());
return new RecordWriter<ImmutableBytesWritable, KeyValue>() {
// Map of families to writers and how much has been output on the writer.
private final Map<byte [], WriterLength> writers =
new TreeMap<byte [], WriterLength>(Bytes.BYTES_COMPARATOR);
private byte [] previousRow = HConstants.EMPTY_BYTE_ARRAY;
private final byte [] now = Bytes.toBytes(System.currentTimeMillis());
public void write(ImmutableBytesWritable row, KeyValue kv)
throws IOException {
long length = kv.getLength();
byte [] family = kv.getFamily();
WriterLength wl = this.writers.get(family);
if (wl == null || ((length + wl.written) >= maxsize) &&
Bytes.compareTo(this.previousRow, 0, this.previousRow.length,
kv.getBuffer(), kv.getRowOffset(), kv.getRowLength()) != 0) {
// Get a new writer.
Path basedir = new Path(outputdir, Bytes.toString(family));
if (wl == null) {
wl = new WriterLength();
this.writers.put(family, wl);
if (this.writers.size() > 1) throw new IOException("One family only");
// If wl == null, first file in family. Ensure family dir exits.
if (!fs.exists(basedir)) fs.mkdirs(basedir);
}
wl.writer = getNewWriter(wl.writer, basedir);
LOG.info("Writer=" + wl.writer.getPath() +
((wl.written == 0)? "": ", wrote=" + wl.written));
wl.written = 0;
}
kv.updateLatestStamp(this.now);
wl.writer.append(kv);
wl.written += length;
// Copy the row so we know when a row transition.
this.previousRow = kv.getRow();
}
/* Create a new HFile.Writer. Close current if there is one.
* @param writer
* @param familydir
* @return A new HFile.Writer.
* @throws IOException
*/
private HFile.Writer getNewWriter(final HFile.Writer writer,
final Path familydir)
throws IOException {
close(writer);
return new HFile.Writer(fs, StoreFile.getUniqueFile(fs, familydir),
blocksize, compression, KeyValue.KEY_COMPARATOR);
}
private void close(final HFile.Writer w) throws IOException {
if (w != null) {
w.appendFileInfo(StoreFile.BULKLOAD_TIME_KEY,
Bytes.toBytes(System.currentTimeMillis()));
w.appendFileInfo(StoreFile.BULKLOAD_TASK_KEY,
Bytes.toBytes(context.getTaskAttemptID().toString()));
w.appendFileInfo(StoreFile.MAJOR_COMPACTION_KEY,
Bytes.toBytes(true));
w.close();
}
}
public void close(TaskAttemptContext c)
throws IOException, InterruptedException {
for (Map.Entry<byte [], WriterLength> e: this.writers.entrySet()) {
close(e.getValue().writer);
}
}
};
}
/*
* Data structure to hold a Writer and amount of data written on it.
*/
static class WriterLength {
long written = 0;
HFile.Writer writer = null;
}
/**
* Return the start keys of all of the regions in this table,
* as a list of ImmutableBytesWritable.
*/
private static List<ImmutableBytesWritable> getRegionStartKeys(HTable table)
throws IOException {
byte[][] byteKeys = table.getStartKeys();
ArrayList<ImmutableBytesWritable> ret =
new ArrayList<ImmutableBytesWritable>(byteKeys.length);
for (byte[] byteKey : byteKeys) {
ret.add(new ImmutableBytesWritable(byteKey));
}
return ret;
}
/**
* Write out a SequenceFile that can be read by TotalOrderPartitioner
* that contains the split points in startKeys.
* @param partitionsPath output path for SequenceFile
* @param startKeys the region start keys
*/
private static void writePartitions(Configuration conf, Path partitionsPath,
List<ImmutableBytesWritable> startKeys) throws IOException {
if (startKeys.isEmpty()) {
throw new IllegalArgumentException("No regions passed");
}
// We're generating a list of split points, and we don't ever
// have keys < the first region (which has an empty start key)
// so we need to remove it. Otherwise we would end up with an
// empty reducer with index 0
TreeSet<ImmutableBytesWritable> sorted =
new TreeSet<ImmutableBytesWritable>(startKeys);
ImmutableBytesWritable first = sorted.first();
if (!first.equals(HConstants.EMPTY_BYTE_ARRAY)) {
throw new IllegalArgumentException(
"First region of table should have empty start key. Instead has: "
+ Bytes.toStringBinary(first.get()));
}
sorted.remove(first);
// Write the actual file
FileSystem fs = partitionsPath.getFileSystem(conf);
SequenceFile.Writer writer = SequenceFile.createWriter(fs,
conf, partitionsPath, ImmutableBytesWritable.class, NullWritable.class);
try {
for (ImmutableBytesWritable startKey : sorted) {
writer.append(startKey, NullWritable.get());
}
} finally {
writer.close();
}
}
/**
* Configure a MapReduce Job to perform an incremental load into the given
* table. This
* <ul>
* <li>Inspects the table to configure a total order partitioner</li>
* <li>Uploads the partitions file to the cluster and adds it to the DistributedCache</li>
* <li>Sets the number of reduce tasks to match the current number of regions</li>
* <li>Sets the output key/value class to match HFileOutputFormat's requirements</li>
* <li>Sets the reducer up to perform the appropriate sorting (either KeyValueSortReducer or
* PutSortReducer)</li>
* </ul>
* The user should be sure to set the map output value class to either KeyValue or Put before
* running this function.
*/
public static void configureIncrementalLoad(Job job, HTable table) throws IOException {
Configuration conf = job.getConfiguration();
job.setPartitionerClass(TotalOrderPartitioner.class);
job.setOutputKeyClass(ImmutableBytesWritable.class);
job.setOutputValueClass(KeyValue.class);
job.setOutputFormatClass(HFileOutputFormat.class);
// Based on the configured map output class, set the correct reducer to properly
// sort the incoming values.
// TODO it would be nice to pick one or the other of these formats.
if (KeyValue.class.equals(job.getMapOutputValueClass())) {
job.setReducerClass(KeyValueSortReducer.class);
} else if (Put.class.equals(job.getMapOutputValueClass())) {
job.setReducerClass(PutSortReducer.class);
} else {
LOG.warn("Unknown map output value type:" + job.getMapOutputValueClass());
}
LOG.info("Looking up current regions for table " + table);
List<ImmutableBytesWritable> startKeys = getRegionStartKeys(table);
LOG.info("Configuring " + startKeys.size() + " reduce partitions " +
"to match current region count");
job.setNumReduceTasks(startKeys.size());
Path partitionsPath = new Path(job.getWorkingDirectory(),
"partitions_" + System.currentTimeMillis());
LOG.info("Writing partition information to " + partitionsPath);
FileSystem fs = partitionsPath.getFileSystem(conf);
writePartitions(conf, partitionsPath, startKeys);
partitionsPath.makeQualified(fs);
URI cacheUri;
try {
cacheUri = new URI(partitionsPath.toString() + "#" +
TotalOrderPartitioner.DEFAULT_PATH);
} catch (URISyntaxException e) {
throw new IOException(e);
}
DistributedCache.addCacheFile(cacheUri, conf);
DistributedCache.createSymlink(conf);
LOG.info("Incremental table output configured.");
}
}