/**
* 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.io.avro;
import java.io.IOException;
import java.util.Iterator;
import org.apache.avro.Schema;
import org.apache.avro.file.DataFileReader;
import org.apache.avro.generic.GenericDatumReader;
import org.apache.avro.io.DatumReader;
import org.apache.avro.mapred.FsInput;
import org.apache.avro.reflect.ReflectDatumReader;
import org.apache.avro.specific.SpecificDatumReader;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.crunch.MapFn;
import org.apache.crunch.fn.IdentityFn;
import org.apache.crunch.io.FileReaderFactory;
import org.apache.crunch.io.impl.AutoClosingIterator;
import org.apache.crunch.types.avro.AvroType;
import org.apache.crunch.types.avro.Avros;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import com.google.common.collect.Iterators;
import com.google.common.collect.UnmodifiableIterator;
public class AvroFileReaderFactory<T> implements FileReaderFactory<T> {
private static final Log LOG = LogFactory.getLog(AvroFileReaderFactory.class);
private final DatumReader<T> recordReader;
private final MapFn<T, T> mapFn;
public AvroFileReaderFactory(AvroType<T> atype) {
this.recordReader = createDatumReader(atype);
this.mapFn = (MapFn<T, T>) atype.getInputMapFn();
}
public AvroFileReaderFactory(Schema schema) {
this.recordReader = new GenericDatumReader<T>(schema);
this.mapFn = IdentityFn.<T>getInstance();
}
static <T> DatumReader<T> createDatumReader(AvroType<T> avroType) {
if (avroType.hasReflect()) {
if (avroType.hasSpecific()) {
Avros.checkCombiningSpecificAndReflectionSchemas();
}
return new ReflectDatumReader<T>(avroType.getSchema());
} else if (avroType.hasSpecific()) {
return new SpecificDatumReader<T>(avroType.getSchema());
} else {
return new GenericDatumReader<T>(avroType.getSchema());
}
}
@Override
public Iterator<T> read(FileSystem fs, final Path path) {
this.mapFn.initialize();
try {
FsInput fsi = new FsInput(path, fs.getConf());
final DataFileReader<T> reader = new DataFileReader<T>(fsi, recordReader);
return new AutoClosingIterator<T>(reader, new UnmodifiableIterator<T>() {
@Override
public boolean hasNext() {
return reader.hasNext();
}
@Override
public T next() {
return mapFn.map(reader.next());
}
});
} catch (IOException e) {
LOG.info("Could not read avro file at path: " + path, e);
return Iterators.emptyIterator();
}
}
}