/*
* Copyright 2014-2016 CyberVision, Inc.
*
* Licensed 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.kaaproject.kaa.server.common.log.shared;
import org.apache.avro.io.BinaryDecoder;
import org.apache.avro.io.DecoderFactory;
import org.apache.avro.specific.SpecificDatumReader;
import org.apache.avro.specific.SpecificRecordBase;
import org.kaaproject.kaa.server.common.log.shared.avro.gen.RecordData;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.List;
/**
* Utility class to decode Avro records from Apache Flume events generated by Kaa Flume appender.
*
* @param <T> the type T
* @author Andrew Shvayka
*/
public class KaaFlumeEventReader<T extends SpecificRecordBase> {
private static final Logger LOG = LoggerFactory.getLogger(KaaFlumeEventReader.class);
// Datum reader for generic Kaa Flume object
private SpecificDatumReader<RecordData> recordDataReader;
// Datum reader for user-defined object
private SpecificDatumReader<T> recordReader;
public KaaFlumeEventReader(Class<T> clazz) {
recordDataReader = new SpecificDatumReader<>(RecordData.class);
recordReader = new SpecificDatumReader<>(clazz);
}
// Extracts byte array from byte buffer
private static final byte[] toByteArray(ByteBuffer buffer) {
byte[] data = new byte[buffer.remaining()];
buffer.get(data);
return data;
}
/**
* Decode records from <code>ByteBuffer</code> and return <code>Iterable</code>.
*
* @param bb the <code>ByteBuffer</code> which decode
* @return decoded <code>Iterable</code>
*/
public Iterable<T> decodeRecords(ByteBuffer bb) throws IOException {
byte[] recordDataBody = toByteArray(bb);
BinaryDecoder recordDataDecoder = DecoderFactory.get().binaryDecoder(recordDataBody, null);
RecordData recordData = recordDataReader.read(null, recordDataDecoder);
LOG.debug("Avro event header: {}", recordData.getRecordHeader());
LOG.debug("Avro event data.size: {}", recordData.getEventRecords().size());
List<T> results = new ArrayList<T>();
BinaryDecoder recordDecoder = null;
for (ByteBuffer eventBuf : recordData.getEventRecords()) {
byte[] recordBody = toByteArray(eventBuf);
recordDecoder = DecoderFactory.get().binaryDecoder(recordBody, recordDecoder);
T record = recordReader.read(null, recordDecoder);
results.add(record);
LOG.trace("Parsed record: {}", record);
}
return results;
}
}