org.apache.kafka.clients.consumer.CooperativeStickyAssignor Maven / Gradle / Ivy
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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.consumer;
import java.nio.ByteBuffer;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
import org.apache.kafka.clients.consumer.internals.AbstractStickyAssignor;
import org.apache.kafka.common.PartitionInfo;
import org.apache.kafka.common.TopicPartition;
import org.apache.kafka.common.protocol.types.Field;
import org.apache.kafka.common.protocol.types.Schema;
import org.apache.kafka.common.protocol.types.Struct;
import org.apache.kafka.common.protocol.types.Type;
/**
* A cooperative version of the {@link AbstractStickyAssignor AbstractStickyAssignor}. This follows the same (sticky)
* assignment logic as {@link StickyAssignor StickyAssignor} but allows for cooperative rebalancing while the
* {@link StickyAssignor StickyAssignor} follows the eager rebalancing protocol. See
* {@link ConsumerPartitionAssignor.RebalanceProtocol} for an explanation of the rebalancing protocols.
*
* Users should prefer this assignor for newer clusters.
*
* To turn on cooperative rebalancing you must set all your consumers to use this {@code PartitionAssignor},
* or implement a custom one that returns {@code RebalanceProtocol.COOPERATIVE} in
* {@link CooperativeStickyAssignor#supportedProtocols supportedProtocols()}.
*
* IMPORTANT: if upgrading from 2.3 or earlier, you must follow a specific upgrade path in order to safely turn on
* cooperative rebalancing. See the upgrade guide for details.
*/
public class CooperativeStickyAssignor extends AbstractStickyAssignor {
public static final String COOPERATIVE_STICKY_ASSIGNOR_NAME = "cooperative-sticky";
// these schemas are used for preserving useful metadata for the assignment, such as the last stable generation
private static final String GENERATION_KEY_NAME = "generation";
private static final Schema COOPERATIVE_STICKY_ASSIGNOR_USER_DATA_V0 = new Schema(
new Field(GENERATION_KEY_NAME, Type.INT32));
private int generation = DEFAULT_GENERATION; // consumer group generation
@Override
public String name() {
return COOPERATIVE_STICKY_ASSIGNOR_NAME;
}
@Override
public List supportedProtocols() {
return Arrays.asList(RebalanceProtocol.COOPERATIVE, RebalanceProtocol.EAGER);
}
@Override
public void onAssignment(Assignment assignment, ConsumerGroupMetadata metadata) {
this.generation = metadata.generationId();
}
@Override
public ByteBuffer subscriptionUserData(Set topics) {
Struct struct = new Struct(COOPERATIVE_STICKY_ASSIGNOR_USER_DATA_V0);
struct.set(GENERATION_KEY_NAME, generation);
ByteBuffer buffer = ByteBuffer.allocate(COOPERATIVE_STICKY_ASSIGNOR_USER_DATA_V0.sizeOf(struct));
COOPERATIVE_STICKY_ASSIGNOR_USER_DATA_V0.write(buffer, struct);
buffer.flip();
return buffer;
}
@Override
protected MemberData memberData(Subscription subscription) {
// In ConsumerProtocolSubscription v2 or higher, we can take member data from fields directly
if (subscription.generationId().isPresent()) {
return new MemberData(subscription.ownedPartitions(), subscription.generationId());
}
ByteBuffer buffer = subscription.userData();
Optional encodedGeneration;
if (buffer == null) {
encodedGeneration = Optional.empty();
} else {
try {
Struct struct = COOPERATIVE_STICKY_ASSIGNOR_USER_DATA_V0.read(buffer);
encodedGeneration = Optional.of(struct.getInt(GENERATION_KEY_NAME));
} catch (Exception e) {
encodedGeneration = Optional.of(DEFAULT_GENERATION);
}
}
return new MemberData(subscription.ownedPartitions(), encodedGeneration, subscription.rackId());
}
@Override
public Map> assignPartitions(Map> partitionsPerTopic,
Map subscriptions) {
Map> assignments = super.assignPartitions(partitionsPerTopic, subscriptions);
Map partitionsTransferringOwnership = super.partitionsTransferringOwnership == null ?
computePartitionsTransferringOwnership(subscriptions, assignments) :
super.partitionsTransferringOwnership;
adjustAssignment(assignments, partitionsTransferringOwnership);
return assignments;
}
// Following the cooperative rebalancing protocol requires removing partitions that must first be revoked from the assignment
private void adjustAssignment(Map> assignments,
Map partitionsTransferringOwnership) {
for (Map.Entry partitionEntry : partitionsTransferringOwnership.entrySet()) {
assignments.get(partitionEntry.getValue()).remove(partitionEntry.getKey());
}
}
private Map computePartitionsTransferringOwnership(Map subscriptions,
Map> assignments) {
Map allAddedPartitions = new HashMap<>();
Set allRevokedPartitions = new HashSet<>();
for (final Map.Entry> entry : assignments.entrySet()) {
String consumer = entry.getKey();
List ownedPartitions = subscriptions.get(consumer).ownedPartitions();
List assignedPartitions = entry.getValue();
Set ownedPartitionsSet = new HashSet<>(ownedPartitions);
for (TopicPartition tp : assignedPartitions) {
if (!ownedPartitionsSet.contains(tp))
allAddedPartitions.put(tp, consumer);
}
Set assignedPartitionsSet = new HashSet<>(assignedPartitions);
for (TopicPartition tp : ownedPartitions) {
if (!assignedPartitionsSet.contains(tp))
allRevokedPartitions.add(tp);
}
}
allAddedPartitions.keySet().retainAll(allRevokedPartitions);
return allAddedPartitions;
}
}