org.apache.crunch.io.parquet.AvroParquetFileReaderFactory.java Source code

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Here is the source code for org.apache.crunch.io.parquet.AvroParquetFileReaderFactory.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.crunch.io.parquet;

import com.google.common.collect.UnmodifiableIterator;
import java.io.IOException;
import java.util.Iterator;
import java.util.Map;
import java.util.NoSuchElementException;
import org.apache.avro.generic.IndexedRecord;
import org.apache.crunch.CrunchRuntimeException;
import org.apache.crunch.io.FileReaderFactory;
import org.apache.crunch.io.impl.AutoClosingIterator;
import org.apache.crunch.types.avro.AvroType;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import parquet.avro.AvroReadSupport;
import parquet.hadoop.ParquetReader;
import parquet.schema.MessageType;

class AvroParquetFileReaderFactory<T> implements FileReaderFactory<T> {

    private AvroType<T> avroType;

    public AvroParquetFileReaderFactory(AvroType<T> avroType) {
        this.avroType = avroType;
    }

    @Override
    @SuppressWarnings("unchecked")
    public Iterator<T> read(FileSystem fs, Path path) {
        Path p = fs.makeQualified(path);
        final ParquetReader reader;
        try {
            reader = new ParquetReader(p, new CrunchAvroReadSupport(avroType));
        } catch (IOException e) {
            throw new CrunchRuntimeException(e);
        }
        return new AutoClosingIterator<T>(reader, new UnmodifiableIterator<T>() {

            private T next;

            @Override
            public boolean hasNext() {
                if (next != null) {
                    return true;
                }
                try {
                    next = (T) reader.read();
                } catch (IOException e) {
                    throw new CrunchRuntimeException(e);
                }
                return next != null;
            }

            @Override
            public T next() {
                if (hasNext()) {
                    T ret = next;
                    next = null;
                    return ret;
                }
                throw new NoSuchElementException();
            }
        });

    }

    static class CrunchAvroReadSupport<T extends IndexedRecord> extends AvroReadSupport<T> {
        private AvroType<T> avroType;

        public CrunchAvroReadSupport(AvroType<T> avroType) {
            this.avroType = avroType;
        }

        @Override
        public ReadContext init(Configuration configuration, Map<String, String> keyValueMetaData,
                MessageType fileSchema) {
            if (avroType != null) {
                setRequestedProjection(configuration, avroType.getSchema());
            }
            return super.init(configuration, keyValueMetaData, fileSchema);
        }
    }
}