/*
* 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;
/**
* RecordReader for Avro files
*/
public final class AvroRecordReader
extends RecordReader<NullWritable, GenericData.Record> {
private FileReader<GenericData.Record> reader;
private long start;
private long end;
private Schema schema;
private GenericData.Record currentRecord;
/**
* Creates new instance of AvroRecordReader.
* @param s The input schema.
*/
public AvroRecordReader(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 (currentRecord != null) {
return currentRecord;
} 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.Record> datumReader
= new GenericDatumReader<GenericData.Record>(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 {
currentRecord = reader.next(new GenericData.Record(schema));
} catch (NoSuchElementException e) {
return false;
} catch (IOException ioe) {
reader.sync(reader.tell()+1);
throw ioe;
}
return true;
}
}