org.apache.mahout.common.iterator.sequencefile.SequenceFileIterable.java Source code

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Here is the source code for org.apache.mahout.common.iterator.sequencefile.SequenceFileIterable.java

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/**
 * 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.mahout.common.iterator.sequencefile;

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

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.Writable;
import org.apache.mahout.common.Pair;

/**
 * <p>{@link Iterable} counterpart to {@link SequenceFileIterator}.</p>
 */
public final class SequenceFileIterable<K extends Writable, V extends Writable> implements Iterable<Pair<K, V>> {

    private final Path path;
    private final boolean reuseKeyValueInstances;
    private final Configuration conf;

    /**
     * Like {@link #SequenceFileIterable(Path, boolean, Configuration)} but key and value instances are not reused
     * by default.
     *
     * @param path file to iterate over
     */
    public SequenceFileIterable(Path path, Configuration conf) {
        this(path, false, conf);
    }

    /**
     * @param path file to iterate over
     * @param reuseKeyValueInstances if true, reuses instances of the key and value object instead of creating a new
     *  one for each read from the file
     */
    public SequenceFileIterable(Path path, boolean reuseKeyValueInstances, Configuration conf) {
        this.path = path;
        this.reuseKeyValueInstances = reuseKeyValueInstances;
        this.conf = conf;
    }

    @Override
    public Iterator<Pair<K, V>> iterator() {
        try {
            return new SequenceFileIterator<>(path, reuseKeyValueInstances, conf);
        } catch (IOException ioe) {
            throw new IllegalStateException(path.toString(), ioe);
        }
    }

}