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TimeSeriesKeySerde.java
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TimeSeriesKeySerde.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.samza.operators.impl.store;
import org.apache.samza.serializers.Serde;
import java.nio.ByteBuffer;
/**
* A {@link Serde} for {@link TimeSeriesKey}s.
*
* <p> This wraps the actual key's serde with serializers for timestamp and sequence number.
*
* A {@link TimeSeriesKeySerde} serializes a key as follows:
* +-------------------------+------------------+------------+
* | serialized-key bytes | timestamp | seq num |
* |(serialized by keySerde) | | |
* +-------------------------+------------------+------------+
* +---serialized key len----+-------8 bytes----+---4 bytes--+
*
* @param <K> the type of the wrapped key
*/
public class TimeSeriesKeySerde<K> implements Serde<TimeSeriesKey<K>> {
private static final int TIMESTAMP_SIZE = 8;
private static final int SEQNUM_SIZE = 4;
private final Serde<K> keySerde;
public TimeSeriesKeySerde(Serde<K> keySerde) {
this.keySerde = keySerde;
}
@Override
public byte[] toBytes(TimeSeriesKey<K> timeSeriesKey) {
K key = timeSeriesKey.getKey();
long timestamp = timeSeriesKey.getTimestamp();
int seqNum = timeSeriesKey.getSeqNum();
byte[] serializedKey = keySerde.toBytes(key);
int keySize = serializedKey == null ? 0 : serializedKey.length;
// append the timestamp and sequence number to the serialized key bytes
ByteBuffer buf = ByteBuffer.allocate(keySize + TIMESTAMP_SIZE + SEQNUM_SIZE);
if (serializedKey != null) {
buf.put(serializedKey);
}
buf.putLong(timestamp);
buf.putInt(seqNum);
return buf.array();
}
@Override
public TimeSeriesKey<K> fromBytes(byte[] timeSeriesKeyBytes) {
// First obtain the key bytes, and deserialize them. Later de-serialize the timestamp and sequence number
ByteBuffer buf = ByteBuffer.wrap(timeSeriesKeyBytes);
int keySize = timeSeriesKeyBytes.length - TIMESTAMP_SIZE - SEQNUM_SIZE;
K key = null;
if (keySize != 0) {
byte[] keyBytes = new byte[keySize];
buf.get(keyBytes);
key = keySerde.fromBytes(keyBytes);
}
long timeStamp = buf.getLong();
int seqNum = buf.getInt();
return new TimeSeriesKey(key, timeStamp, seqNum);
}
}