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Apache Hadoop Distributed Copy
/**
* 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.tools;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.security.Credentials;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;
/**
* FileBasedCopyListing implements the CopyListing interface,
* to create the copy-listing for DistCp,
* by iterating over all source paths mentioned in a specified input-file.
*/
public class FileBasedCopyListing extends CopyListing {
private final CopyListing globbedListing;
/**
* Constructor, to initialize base-class.
* @param configuration The input Configuration object.
* @param credentials - Credentials object on which the FS delegation tokens are cached. If null
* delegation token caching is skipped
*/
public FileBasedCopyListing(Configuration configuration, Credentials credentials) {
super(configuration, credentials);
globbedListing = new GlobbedCopyListing(getConf(), credentials);
}
/** {@inheritDoc} */
@Override
protected void validatePaths(DistCpContext context)
throws IOException, InvalidInputException {
}
/**
* Implementation of CopyListing::buildListing().
* Iterates over all source paths mentioned in the input-file.
* @param pathToListFile Path on HDFS where the listing file is written.
* @param context Distcp context with associated input options.
* @throws IOException
*/
@Override
public void doBuildListing(Path pathToListFile, DistCpContext context)
throws IOException {
context.setSourcePaths(fetchFileList(context.getSourceFileListing()));
globbedListing.buildListing(pathToListFile, context);
}
private List fetchFileList(Path sourceListing) throws IOException {
List result = new ArrayList();
FileSystem fs = sourceListing.getFileSystem(getConf());
BufferedReader input = null;
try {
input = new BufferedReader(new InputStreamReader(fs.open(sourceListing),
Charset.forName("UTF-8")));
String line = input.readLine();
while (line != null) {
result.add(new Path(line));
line = input.readLine();
}
} finally {
IOUtils.closeStream(input);
}
return result;
}
/** {@inheritDoc} */
@Override
protected long getBytesToCopy() {
return globbedListing.getBytesToCopy();
}
/** {@inheritDoc} */
@Override
protected long getNumberOfPaths() {
return globbedListing.getNumberOfPaths();
}
}