org.apache.kafka.clients.producer.internals.StickyPartitionCache Maven / Gradle / Ivy
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* 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,
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* See the License for the specific language governing permissions and
* limitations under the License.
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package org.apache.kafka.clients.producer.internals;
import org.apache.kafka.common.Cluster;
import org.apache.kafka.common.PartitionInfo;
import java.util.List;
import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ConcurrentHashMap;
import org.apache.kafka.common.utils.Utils;
/**
* An internal class that implements a cache used for sticky partitioning behavior. The cache tracks the current sticky
* partition for any given topic. This class should not be used externally.
*/
public class StickyPartitionCache {
private final ConcurrentMap indexCache;
public StickyPartitionCache() {
this.indexCache = new ConcurrentHashMap<>();
}
public int partition(String topic, Cluster cluster) {
Integer part = indexCache.get(topic);
if (part == null) {
return nextPartition(topic, cluster, -1);
}
return part;
}
public int nextPartition(String topic, Cluster cluster, int prevPartition) {
List partitions = cluster.partitionsForTopic(topic);
Integer oldPart = indexCache.get(topic);
Integer newPart = oldPart;
// Check that the current sticky partition for the topic is either not set or that the partition that
// triggered the new batch matches the sticky partition that needs to be changed.
if (oldPart == null || oldPart == prevPartition) {
List availablePartitions = cluster.availablePartitionsForTopic(topic);
if (availablePartitions.size() < 1) {
Integer random = Utils.toPositive(ThreadLocalRandom.current().nextInt());
newPart = random % partitions.size();
} else if (availablePartitions.size() == 1) {
newPart = availablePartitions.get(0).partition();
} else {
while (newPart == null || newPart.equals(oldPart)) {
int random = Utils.toPositive(ThreadLocalRandom.current().nextInt());
newPart = availablePartitions.get(random % availablePartitions.size()).partition();
}
}
// Only change the sticky partition if it is null or prevPartition matches the current sticky partition.
if (oldPart == null) {
indexCache.putIfAbsent(topic, newPart);
} else {
indexCache.replace(topic, prevPartition, newPart);
}
return indexCache.get(topic);
}
return indexCache.get(topic);
}
}