kafka RoundRobinPartitioner 源码
kafka RoundRobinPartitioner 代码
文件路径：/clients/src/main/java/org/apache/kafka/clients/producer/RoundRobinPartitioner.java
/*
* 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;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.atomic.AtomicInteger;
import org.apache.kafka.common.Cluster;
import org.apache.kafka.common.PartitionInfo;
import org.apache.kafka.common.utils.Utils;
/**
* The "Round-Robin" partitioner
*
* This partitioning strategy can be used when user wants
* to distribute the writes to all partitions equally. This
* is the behaviour regardless of record key hash.
*
*/
public class RoundRobinPartitioner implements Partitioner {
private final ConcurrentMap<String, AtomicInteger> topicCounterMap = new ConcurrentHashMap<>();
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
*/
@Override
public int partition(String topic, Object key, byte[] keyBytes, Object value, byte[] valueBytes, Cluster cluster) {
List<PartitionInfo> partitions = cluster.partitionsForTopic(topic);
int numPartitions = partitions.size();
int nextValue = nextValue(topic);
List<PartitionInfo> availablePartitions = cluster.availablePartitionsForTopic(topic);
if (!availablePartitions.isEmpty()) {
int part = Utils.toPositive(nextValue) % availablePartitions.size();
return availablePartitions.get(part).partition();
} else {
// no partitions are available, give a non-available partition
return Utils.toPositive(nextValue) % numPartitions;
}
}
private int nextValue(String topic) {
AtomicInteger counter = topicCounterMap.computeIfAbsent(topic, k -> new AtomicInteger(0));
return counter.getAndIncrement();
}
public void close() {}
}
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