org.apache.pig.impl.util.avro.AvroArrayReader.java Source code

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Here is the source code for org.apache.pig.impl.util.avro.AvroArrayReader.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.pig.impl.util.avro;

import java.io.IOException;
import java.util.NoSuchElementException;

import org.apache.avro.Schema;
import org.apache.avro.file.DataFileReader;
import org.apache.avro.file.FileReader;
import org.apache.avro.generic.GenericData;
import org.apache.avro.generic.GenericDatumReader;
import org.apache.avro.io.DatumReader;
import org.apache.avro.mapred.FsInput;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.lib.input.FileSplit;

import com.google.common.collect.Lists;

/**
 * RecordReader for Avro files
 */
public final class AvroArrayReader extends RecordReader<NullWritable, GenericData.Record> {

    private FileReader<GenericData.Array<Object>> reader;
    private long start;
    private long end;
    private Schema schema;
    private GenericData.Array<Object> currentArray;

    /**
     * Creates new instance of AvroRecordReader.
     * @param s The input schema.
     */
    public AvroArrayReader(final Schema s) {
        schema = s;
    }

    @Override
    public void close() throws IOException {
        reader.close();
    }

    /**
     * Returns current value.
     * @return the current value
     * @throws IOException when an IO error occurs
     * @throws InterruptedException when interrupted
     */
    @Override
    public GenericData.Record getCurrentValue() throws IOException, InterruptedException {
        if (currentArray != null) {
            GenericData.Record r = new GenericData.Record(Schema
                    .createRecord(Lists.newArrayList(new Schema.Field(schema.getName(), schema, null, null))));
            r.put(0, currentArray);
            return r;
        } else {
            return null;
        }
    }

    @Override
    public NullWritable getCurrentKey() throws IOException, InterruptedException {
        return NullWritable.get();
    }

    @Override
    public float getProgress() throws IOException, InterruptedException {
        if (start == end) {
            return 0.0f;
        } else {
            return Math.min(1.0f, ((float) (reader.tell() - start)) / ((float) (end - start)));
        }
    }

    @Override
    public void initialize(final InputSplit isplit, final TaskAttemptContext tc)
            throws IOException, InterruptedException {

        FileSplit fsplit = (FileSplit) isplit;
        start = fsplit.getStart();
        end = fsplit.getStart() + fsplit.getLength();
        DatumReader<GenericData.Array<Object>> datumReader = new GenericDatumReader<GenericData.Array<Object>>(
                schema);
        reader = DataFileReader.openReader(new FsInput(fsplit.getPath(), tc.getConfiguration()), datumReader);
        reader.sync(start);
    }

    @Override
    public boolean nextKeyValue() throws IOException, InterruptedException {

        if (reader.pastSync(end)) {
            return false;
        }
        try {
            currentArray = reader.next();
        } catch (NoSuchElementException e) {
            return false;
        }
        return true;
    }

}