com.cloudera.crunch.io.CompositePathIterable.java Source code

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Here is the source code for com.cloudera.crunch.io.CompositePathIterable.java

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/**
 * Copyright (c) 2011, Cloudera, Inc. All Rights Reserved.
 *
 * Cloudera, Inc. 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
 *
 * This software 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 com.cloudera.crunch.io;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.Iterator;

import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.PathFilter;

import com.google.common.collect.UnmodifiableIterator;

public class CompositePathIterable<T> implements Iterable<T> {

    private final FileStatus[] stati;
    private final FileSystem fs;
    private final FileReaderFactory<T> readerFactory;

    private static final PathFilter FILTER = new PathFilter() {
        @Override
        public boolean accept(Path path) {
            return !path.getName().startsWith("_");
        }
    };

    public static <S> Iterable<S> create(FileSystem fs, Path path, FileReaderFactory<S> readerFactory)
            throws IOException {
        FileStatus[] stati;
        try {
            stati = fs.listStatus(path, FILTER);
        } catch (FileNotFoundException fnfe) {
            stati = new FileStatus[0];
        }
        if (stati.length == 0) {
            throw new IOException("No files found to materialize at: " + path);
        }
        return new CompositePathIterable<S>(stati, fs, readerFactory);
    }

    private CompositePathIterable(FileStatus[] stati, FileSystem fs, FileReaderFactory<T> readerFactory) {
        this.stati = stati;
        this.fs = fs;
        this.readerFactory = readerFactory;
    }

    @Override
    public Iterator<T> iterator() {
        return new UnmodifiableIterator<T>() {
            private int index = 0;
            private Iterator<T> iter = readerFactory.read(fs, stati[index++].getPath());

            @Override
            public boolean hasNext() {
                if (!iter.hasNext()) {
                    while (index < stati.length) {
                        iter = readerFactory.read(fs, stati[index++].getPath());
                        if (iter.hasNext()) {
                            return true;
                        }
                    }
                    return false;
                }
                return true;
            }

            @Override
            public T next() {
                return iter.next();
            }
        };
    }
}