hdfs.jsr203.HadoopDirectoryStream Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of jsr203hadoop Show documentation
A Java NIO file system provider for HDFS
There is a newer version: 1.0.3
/*
 * Copyright 2016 Damien Carol 
 *
 * Licensed 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 hdfs.jsr203;

import java.io.IOException;
import java.net.URISyntaxException;
import java.nio.file.ClosedDirectoryStreamException;
import java.nio.file.DirectoryStream;
import java.nio.file.NotDirectoryException;
import java.nio.file.Path;
import java.util.Iterator;
import java.util.NoSuchElementException;

import org.apache.hadoop.fs.FileStatus;

public class HadoopDirectoryStream implements DirectoryStream 
{
    private final HadoopFileSystem hadoopfs;
    //private final byte[] path;
	private final HadoopPath path;
    private final DirectoryStream.Filter filter;
    private volatile boolean isClosed;
    private volatile Iterator itr;

    HadoopDirectoryStream(HadoopPath hadoopPath,
                       DirectoryStream.Filter filter)
        throws IOException
    {
        this.hadoopfs = hadoopPath.getFileSystem();
        //this.path = hadoopPath.getResolvedPath();
    	this.path = hadoopPath;
        this.filter = filter;
        
        // sanity check
        FileStatus stat = hadoopPath.getFileSystem().getHDFS().getFileStatus(hadoopPath.getRawResolvedPath());
        if (!stat.isDirectory())
            throw new NotDirectoryException(hadoopPath.toString());
    }

    @Override
    public synchronized Iterator iterator() {
        if (isClosed)
            throw new ClosedDirectoryStreamException();
        if (itr != null)
            throw new IllegalStateException("Iterator has already been returned");

        try {
        	itr = hadoopfs.iteratorOf(path, filter);
        } catch (IOException e) {
            throw new IllegalStateException(e);
        } catch (URISyntaxException e) {
            throw new IllegalStateException(e);
		}
        return new Iterator() {
            //private Path next;
            @Override
            public boolean hasNext() {
                if (isClosed)
                    return false;
                return itr.hasNext();
            }

            @Override
            public synchronized Path next() {
                if (isClosed)
                    throw new NoSuchElementException();
                return itr.next();
            }

            @Override
            public void remove() {
                throw new UnsupportedOperationException();
            }
        };
    }

    @Override
    public synchronized void close() throws IOException {
        isClosed = true;
    }
}