org.apache.sqoop.mapreduce.AvroRecordReader.java Source code

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Here is the source code for org.apache.sqoop.mapreduce.AvroRecordReader.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.sqoop.mapreduce;

import java.io.IOException;
import org.apache.avro.file.DataFileReader;
import org.apache.avro.file.FileReader;
import org.apache.avro.file.SeekableInput;
import org.apache.avro.generic.GenericDatumReader;
import org.apache.avro.io.DatumReader;
import org.apache.avro.mapred.AvroWrapper;
import org.apache.avro.mapred.FsInput;
import org.apache.hadoop.conf.Configuration;
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;

/** An {@link RecordReader} for Avro data files. */
public class AvroRecordReader<T> extends RecordReader<AvroWrapper<T>, NullWritable> {

    private FileReader<T> reader;
    private long start;
    private long end;
    private AvroWrapper<T> key;
    private NullWritable value;

    @Override
    public void initialize(InputSplit genericSplit, TaskAttemptContext context)
            throws IOException, InterruptedException {
        FileSplit split = (FileSplit) genericSplit;
        Configuration conf = context.getConfiguration();
        SeekableInput in = new FsInput(split.getPath(), conf);
        DatumReader<T> datumReader = new GenericDatumReader<T>();
        this.reader = DataFileReader.openReader(in, datumReader);
        reader.sync(split.getStart()); // sync to start
        this.start = reader.tell();
        this.end = split.getStart() + split.getLength();
    }

    @Override
    public boolean nextKeyValue() throws IOException, InterruptedException {
        if (!reader.hasNext() || reader.pastSync(end)) {
            key = null;
            value = null;
            return false;
        }
        if (key == null) {
            key = new AvroWrapper<T>();
        }
        if (value == null) {
            value = NullWritable.get();
        }
        key.datum(reader.next(key.datum()));
        return true;
    }

    @Override
    public AvroWrapper<T> getCurrentKey() throws IOException, InterruptedException {
        return key;
    }

    @Override
    public NullWritable getCurrentValue() throws IOException, InterruptedException {
        return value;
    }

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

    public long getPos() throws IOException {
        return reader.tell();
    }

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