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DefaultPartitioner.java
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DefaultPartitioner.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.kafka.clients.producer.internals;
import org.apache.kafka.clients.producer.Partitioner;
import org.apache.kafka.common.Cluster;
import org.apache.kafka.common.utils.Utils;
import java.util.Map;
/**
* The default partitioning strategy:
* <ul>
* <li>If a partition is specified in the record, use it
* <li>If no partition is specified but a key is present choose a partition based on a hash of the key
* <li>If no partition or key is present choose the sticky partition that changes when the batch is full.
*
* See KIP-480 for details about sticky partitioning.
*/
public class DefaultPartitioner implements Partitioner {
private final StickyPartitionCache stickyPartitionCache = new StickyPartitionCache();
public void configure(Map<String, ?> configs) {}
/**
* Compute the partition for the given record.
*
* @param topic The topic name
* @param key The key to partition on (or null if no key)
* @param keyBytes serialized key to partition on (or null if no key)
* @param value The value to partition on or null
* @param valueBytes serialized value to partition on or null
* @param cluster The current cluster metadata
*/
public int partition(String topic, Object key, byte[] keyBytes, Object value, byte[] valueBytes, Cluster cluster) {
return partition(topic, key, keyBytes, value, valueBytes, cluster, cluster.partitionsForTopic(topic).size());
}
/**
* Compute the partition for the given record.
*
* @param topic The topic name
* @param numPartitions The number of partitions of the given {@code topic}
* @param key The key to partition on (or null if no key)
* @param keyBytes serialized key to partition on (or null if no key)
* @param value The value to partition on or null
* @param valueBytes serialized value to partition on or null
* @param cluster The current cluster metadata
*/
public int partition(String topic, Object key, byte[] keyBytes, Object value, byte[] valueBytes, Cluster cluster,
int numPartitions) {
if (keyBytes == null) {
return stickyPartitionCache.partition(topic, cluster);
}
// hash the keyBytes to choose a partition
return Utils.toPositive(Utils.murmur2(keyBytes)) % numPartitions;
}
public void close() {}
/**
* If a batch completed for the current sticky partition, change the sticky partition.
* Alternately, if no sticky partition has been determined, set one.
*/
public void onNewBatch(String topic, Cluster cluster, int prevPartition) {
stickyPartitionCache.nextPartition(topic, cluster, prevPartition);
}
}