org.apache.kafka.streams.kstream.internals.WindowedStreamPartitioner Maven / Gradle / Ivy
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* (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
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package org.apache.kafka.streams.kstream.internals;
import org.apache.kafka.common.utils.Utils;
import org.apache.kafka.streams.kstream.Windowed;
import org.apache.kafka.streams.processor.StreamPartitioner;
import static org.apache.kafka.common.utils.Utils.toPositive;
public class WindowedStreamPartitioner implements StreamPartitioner, V> {
private final WindowedSerializer serializer;
public WindowedStreamPartitioner(final WindowedSerializer serializer) {
this.serializer = serializer;
}
/**
* WindowedStreamPartitioner determines the partition number for a record with the given windowed key and value
* and the current number of partitions. The partition number id determined by the original key of the windowed key
* using the same logic as DefaultPartitioner so that the topic is partitioned by the original key.
*
* @param topic the topic name this record is sent to
* @param windowedKey the key of the record
* @param value the value of the record
* @param numPartitions the total number of partitions
* @return an integer between 0 and {@code numPartitions-1}, or {@code null} if the default partitioning logic should be used
*/
@Override
public Integer partition(final String topic, final Windowed windowedKey, final V value, final int numPartitions) {
final byte[] keyBytes = serializer.serializeBaseKey(topic, windowedKey);
// hash the keyBytes to choose a partition
return toPositive(Utils.murmur2(keyBytes)) % numPartitions;
}
}