/**
* 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.types.avro;
import java.io.IOException;
import org.apache.avro.Schema;
import org.apache.avro.file.DataFileReader;
import org.apache.avro.file.FileReader;
import org.apache.avro.file.SeekableInput;
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. */
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;
private Schema schema;
public AvroRecordReader(Schema schema) {
this.schema = schema;
}
@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 = AvroMode
.fromConfiguration(context.getConfiguration())
.getReader(schema);
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();
}
}