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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.DataInputStream;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.SequenceFile;
import org.apache.hadoop.typedbytes.TypedBytesInput;
import org.apache.hadoop.typedbytes.TypedBytesWritable;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
/**
* Utility program that reads typed bytes from standard input and stores them in
* a sequence file for which the path is given as an argument.
*/
public class LoadTypedBytes implements Tool {
private Configuration conf;
public LoadTypedBytes(Configuration conf) {
this.conf = conf;
}
public LoadTypedBytes() {
this(new Configuration());
}
public Configuration getConf() {
return conf;
}
public void setConf(Configuration conf) {
this.conf = conf;
}
/**
* The main driver for LoadTypedBytes
.
*/
public int run(String[] args) throws Exception {
if (args.length == 0) {
System.err.println("Too few arguments!");
printUsage();
return 1;
}
Path path = new Path(args[0]);
FileSystem fs = path.getFileSystem(getConf());
if (fs.exists(path)) {
System.err.println("given path exists already!");
return -1;
}
TypedBytesInput tbinput = new TypedBytesInput(new DataInputStream(System.in));
SequenceFile.Writer writer = SequenceFile.createWriter(fs, conf, path,
TypedBytesWritable.class, TypedBytesWritable.class);
try {
TypedBytesWritable key = new TypedBytesWritable();
TypedBytesWritable value = new TypedBytesWritable();
byte[] rawKey = tbinput.readRaw();
while (rawKey != null) {
byte[] rawValue = tbinput.readRaw();
key.set(rawKey, 0, rawKey.length);
value.set(rawValue, 0, rawValue.length);
writer.append(key, value);
rawKey = tbinput.readRaw();
}
} finally {
writer.close();
}
return 0;
}
private void printUsage() {
System.out.println("Usage: mapred streaming loadtb ");
System.out.println(" Reads typed bytes from standard input" +
" and stores them in a sequence file in");
System.out.println(" the specified path");
}
public static void main(String[] args) throws Exception {
LoadTypedBytes loadtb = new LoadTypedBytes();
int res = ToolRunner.run(loadtb, args);
System.exit(res);
}
}