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Apache Hadoop MapReduce Streaming
/**
* 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.streaming;
import java.io.DataOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.FileUtil;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.mapred.FileSplit;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.RecordReader;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.typedbytes.TypedBytesOutput;
import org.apache.hadoop.typedbytes.TypedBytesWritableOutput;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
/**
* Utility program that fetches all files that match a given pattern and dumps
* their content to stdout as typed bytes. This works for all files that can be
* handled by {@link org.apache.hadoop.streaming.AutoInputFormat}.
*/
public class DumpTypedBytes implements Tool {
private Configuration conf;
public DumpTypedBytes(Configuration conf) {
this.conf = conf;
}
public DumpTypedBytes() {
this(new Configuration());
}
public Configuration getConf() {
return conf;
}
public void setConf(Configuration conf) {
this.conf = conf;
}
/**
* The main driver for DumpTypedBytes
.
*/
public int run(String[] args) throws Exception {
if (args.length == 0) {
System.err.println("Too few arguments!");
printUsage();
return 1;
}
Path pattern = new Path(args[0]);
FileSystem fs = pattern.getFileSystem(getConf());
fs.setVerifyChecksum(true);
for (Path p : FileUtil.stat2Paths(fs.globStatus(pattern), pattern)) {
List inputFiles = new ArrayList();
FileStatus status = fs.getFileStatus(p);
if (status.isDirectory()) {
FileStatus[] files = fs.listStatus(p);
Collections.addAll(inputFiles, files);
} else {
inputFiles.add(status);
}
return dumpTypedBytes(inputFiles);
}
return -1;
}
private void printUsage() {
System.out.println("Usage: mapred streaming dumptb ");
System.out.println(" Dumps all files that match the given pattern to " +
"standard output as typed bytes.");
System.out.println(" The files can be text or sequence files");
}
/**
* Dump given list of files to standard output as typed bytes.
*/
@SuppressWarnings("unchecked")
private int dumpTypedBytes(List files) throws IOException {
JobConf job = new JobConf(getConf());
DataOutputStream dout = new DataOutputStream(System.out);
AutoInputFormat autoInputFormat = new AutoInputFormat();
for (FileStatus fileStatus : files) {
FileSplit split = new FileSplit(fileStatus.getPath(), 0,
fileStatus.getLen() * fileStatus.getBlockSize(),
(String[]) null);
RecordReader recReader = null;
try {
recReader = autoInputFormat.getRecordReader(split, job, Reporter.NULL);
Object key = recReader.createKey();
Object value = recReader.createValue();
while (recReader.next(key, value)) {
if (key instanceof Writable) {
TypedBytesWritableOutput.get(dout).write((Writable) key);
} else {
TypedBytesOutput.get(dout).write(key);
}
if (value instanceof Writable) {
TypedBytesWritableOutput.get(dout).write((Writable) value);
} else {
TypedBytesOutput.get(dout).write(value);
}
}
} finally {
if (recReader != null) {
recReader.close();
}
}
}
dout.flush();
return 0;
}
public static void main(String[] args) throws Exception {
DumpTypedBytes dumptb = new DumpTypedBytes();
int res = ToolRunner.run(dumptb, args);
System.exit(res);
}
}