| /** |
| * 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.mapreduce.lib.output; |
| |
| import java.io.IOException; |
| import java.util.Arrays; |
| |
| import org.apache.hadoop.fs.FileSystem; |
| import org.apache.hadoop.fs.Path; |
| import org.apache.hadoop.fs.FileUtil; |
| import org.apache.hadoop.fs.PathFilter; |
| |
| import org.apache.hadoop.io.MapFile; |
| import org.apache.hadoop.io.WritableComparable; |
| import org.apache.hadoop.io.Writable; |
| import org.apache.hadoop.io.SequenceFile.CompressionType; |
| import org.apache.hadoop.io.compress.CompressionCodec; |
| import org.apache.hadoop.io.compress.DefaultCodec; |
| import org.apache.hadoop.mapreduce.Partitioner; |
| import org.apache.hadoop.mapreduce.RecordWriter; |
| import org.apache.hadoop.mapreduce.TaskAttemptContext; |
| import org.apache.hadoop.util.ReflectionUtils; |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.conf.Configuration; |
| |
| /** |
| * An {@link org.apache.hadoop.mapreduce.OutputFormat} that writes |
| * {@link MapFile}s. |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Stable |
| public class MapFileOutputFormat |
| extends FileOutputFormat<WritableComparable<?>, Writable> { |
| |
| public RecordWriter<WritableComparable<?>, Writable> getRecordWriter( |
| TaskAttemptContext context) throws IOException { |
| Configuration conf = context.getConfiguration(); |
| CompressionCodec codec = null; |
| CompressionType compressionType = CompressionType.NONE; |
| if (getCompressOutput(context)) { |
| // find the kind of compression to do |
| compressionType = SequenceFileOutputFormat.getOutputCompressionType(context); |
| |
| // find the right codec |
| Class<?> codecClass = getOutputCompressorClass(context, |
| DefaultCodec.class); |
| codec = (CompressionCodec) ReflectionUtils.newInstance(codecClass, conf); |
| } |
| |
| Path file = getDefaultWorkFile(context, ""); |
| FileSystem fs = file.getFileSystem(conf); |
| // ignore the progress parameter, since MapFile is local |
| final MapFile.Writer out = |
| new MapFile.Writer(conf, fs, file.toString(), |
| context.getOutputKeyClass().asSubclass(WritableComparable.class), |
| context.getOutputValueClass().asSubclass(Writable.class), |
| compressionType, codec, context); |
| |
| return new RecordWriter<WritableComparable<?>, Writable>() { |
| public void write(WritableComparable<?> key, Writable value) |
| throws IOException { |
| out.append(key, value); |
| } |
| |
| public void close(TaskAttemptContext context) throws IOException { |
| out.close(); |
| } |
| }; |
| } |
| |
| /** Open the output generated by this format. */ |
| public static MapFile.Reader[] getReaders(Path dir, |
| Configuration conf) throws IOException { |
| FileSystem fs = dir.getFileSystem(conf); |
| PathFilter filter = new PathFilter() { |
| @Override |
| public boolean accept(Path path) { |
| String name = path.getName(); |
| if (name.startsWith("_") || name.startsWith(".")) |
| return false; |
| return true; |
| } |
| }; |
| Path[] names = FileUtil.stat2Paths(fs.listStatus(dir, filter)); |
| |
| // sort names, so that hash partitioning works |
| Arrays.sort(names); |
| |
| MapFile.Reader[] parts = new MapFile.Reader[names.length]; |
| for (int i = 0; i < names.length; i++) { |
| parts[i] = new MapFile.Reader(fs, names[i].toString(), conf); |
| } |
| return parts; |
| } |
| |
| /** Get an entry from output generated by this class. */ |
| public static <K extends WritableComparable<?>, V extends Writable> |
| Writable getEntry(MapFile.Reader[] readers, |
| Partitioner<K, V> partitioner, K key, V value) throws IOException { |
| int part = partitioner.getPartition(key, value, readers.length); |
| return readers[part].get(key, value); |
| } |
| } |
| |