/*
* 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.consumer.internals;
import org.apache.kafka.common.Cluster;
import org.apache.kafka.common.TopicPartition;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
/**
* Abstract assignor implementation which does some common grunt work (in particular collecting
* partition counts which are always needed in assignors).
*/
public abstract class AbstractPartitionAssignor implements PartitionAssignor {
private static final Logger log = LoggerFactory.getLogger(AbstractPartitionAssignor.class);
private Map<String, Subscription> subscriptions = null;
/**
* Perform the group assignment given the partition counts and member subscriptions
* @param partitionsPerTopic The number of partitions for each subscribed topic. Topics not in metadata will be excluded
* from this map.
* @param subscriptions Map from the memberId to their respective topic subscription
* @return Map from each member to the list of partitions assigned to them.
*/
public abstract Map<String, List<TopicPartition>> assign(Map<String, Integer> partitionsPerTopic,
Map<String, List<String>> subscriptions);
@Override
public Subscription subscription(Set<String> topics) {
return new Subscription(new ArrayList<>(topics));
}
@Override
public Map<String, Assignment> assign(Cluster metadata, Map<String, Subscription> subscriptions) {
this.subscriptions = new HashMap<>(subscriptions);
Set<String> allSubscribedTopics = new HashSet<>();
Map<String, List<String>> topicSubscriptions = new HashMap<>();
for (Map.Entry<String, Subscription> subscriptionEntry : subscriptions.entrySet()) {
List<String> topics = subscriptionEntry.getValue().topics();
allSubscribedTopics.addAll(topics);
topicSubscriptions.put(subscriptionEntry.getKey(), topics);
}
Map<String, Integer> partitionsPerTopic = new HashMap<>();
for (String topic : allSubscribedTopics) {
Integer numPartitions = metadata.partitionCountForTopic(topic);
if (numPartitions != null && numPartitions > 0)
partitionsPerTopic.put(topic, numPartitions);
else
log.debug("Skipping assignment for topic {} since no metadata is available", topic);
}
Map<String, List<TopicPartition>> rawAssignments = assign(partitionsPerTopic, topicSubscriptions);
// this class maintains no user data, so just wrap the results
Map<String, Assignment> assignments = new HashMap<>();
for (Map.Entry<String, List<TopicPartition>> assignmentEntry : rawAssignments.entrySet())
assignments.put(assignmentEntry.getKey(), new Assignment(assignmentEntry.getValue()));
return assignments;
}
protected Map<String, Subscription> getSubscriptions() {
return subscriptions;
}
@Override
public void onAssignment(Assignment assignment) {
// this assignor maintains no internal state, so nothing to do
}
protected static <K, V> void put(Map<K, List<V>> map, K key, V value) {
List<V> list = map.get(key);
if (list == null) {
list = new ArrayList<>();
map.put(key, list);
}
list.add(value);
}
protected static List<TopicPartition> partitions(String topic, int numPartitions) {
List<TopicPartition> partitions = new ArrayList<>(numPartitions);
for (int i = 0; i < numPartitions; i++)
partitions.add(new TopicPartition(topic, i));
return partitions;
}
}