org.apache.avro.mapred.AvroRecordReader.java Source code

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Here is the source code for org.apache.avro.mapred.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.avro.mapred;

import java.io.IOException;

import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.FileSplit;
import org.apache.hadoop.mapred.RecordReader;

import org.apache.avro.file.FileReader;
import org.apache.avro.file.DataFileReader;

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

    private FileReader<T> reader;
    private long start;
    private long end;

    public AvroRecordReader(JobConf job, FileSplit split) throws IOException {
        this(DataFileReader.openReader(new FsInput(split.getPath(), job),
                AvroJob.createInputDataModel(job).createDatumReader(AvroJob.getInputSchema(job))), split);
    }

    protected AvroRecordReader(FileReader<T> reader, FileSplit split) throws IOException {
        this.reader = reader;
        reader.sync(split.getStart()); // sync to start
        this.start = reader.tell();
        this.end = split.getStart() + split.getLength();
    }

    public AvroWrapper<T> createKey() {
        return new AvroWrapper<T>(null);
    }

    public NullWritable createValue() {
        return NullWritable.get();
    }

    public boolean next(AvroWrapper<T> wrapper, NullWritable ignore) throws IOException {
        if (!reader.hasNext() || reader.pastSync(end))
            return false;
        wrapper.datum(reader.next(wrapper.datum()));
        return true;
    }

    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();
    }

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

}