com.cloudera.crunch.io.avro.AvroFileReaderFactory.java Source code

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Here is the source code for com.cloudera.crunch.io.avro.AvroFileReaderFactory.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.avro;

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

import org.apache.avro.file.DataFileReader;
import org.apache.avro.generic.GenericDatumReader;
import org.apache.avro.io.DatumReader;
import org.apache.avro.mapred.FsInput;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

import com.cloudera.crunch.MapFn;
import com.cloudera.crunch.io.FileReaderFactory;
import com.cloudera.crunch.type.avro.AvroType;
import com.google.common.collect.Iterators;
import com.google.common.collect.UnmodifiableIterator;

public class AvroFileReaderFactory<T> implements FileReaderFactory<T> {

    private static final Log LOG = LogFactory.getLog(AvroFileReaderFactory.class);

    private final DatumReader<T> recordReader;
    private final MapFn<T, T> mapFn;

    public AvroFileReaderFactory(AvroType<T> atype) {
        //TODO: fix this to handle specific records as well as generic.
        this.recordReader = new GenericDatumReader<T>(atype.getSchema());
        this.mapFn = (MapFn<T, T>) atype.getInputMapFn();
    }

    @Override
    public Iterator<T> read(FileSystem fs, final Path path) {
        this.mapFn.initialize();
        try {
            FsInput fsi = new FsInput(path, fs.getConf());
            final DataFileReader<T> reader = new DataFileReader<T>(fsi, recordReader);
            return new UnmodifiableIterator<T>() {
                @Override
                public boolean hasNext() {
                    return reader.hasNext();
                }

                @Override
                public T next() {
                    return mapFn.map(reader.next());
                }
            };
        } catch (IOException e) {
            LOG.info("Could not read avro file at path: " + path, e);
            return Iterators.emptyIterator();
        }
    }

}