rreddy-22 commented on code in PR #14416: URL: https://github.com/apache/kafka/pull/14416#discussion_r1378163455
########## group-coordinator/src/main/java/org/apache/kafka/coordinator/group/assignor/AbstractUniformAssignmentBuilder.java: ########## @@ -0,0 +1,260 @@ +/* + * 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.coordinator.group.assignor; + +import org.apache.kafka.common.Uuid; +import org.apache.kafka.server.common.TopicIdPartition; + +import java.util.ArrayList; +import java.util.Collection; +import java.util.Collections; +import java.util.Comparator; +import java.util.HashMap; +import java.util.HashSet; +import java.util.List; +import java.util.Map; +import java.util.Set; +import java.util.stream.Collectors; +import java.util.stream.IntStream; + +/** + * The assignment builder is used to construct the target assignment based on the members' subscriptions. + * + * This class contains common utility methods and a class for obtaining and storing rack information. + */ +public abstract class AbstractUniformAssignmentBuilder { + protected abstract GroupAssignment buildAssignment(); + + /** + * Determines if rack-aware assignment is appropriate based on the provided rack information. + * + * @param memberRacks Racks where members are located. + * @param allPartitionRacks Racks where partitions are located. + * @param racksPerPartition Map of partitions to their associated racks. + * + * @return {@code true} if rack-aware assignment should be applied; {@code false} otherwise. + */ + protected static boolean useRackAwareAssignment( + Set<String> memberRacks, + Set<String> allPartitionRacks, + Map<TopicIdPartition, Set<String>> racksPerPartition + ) { + if (memberRacks.isEmpty() || Collections.disjoint(memberRacks, allPartitionRacks)) + return false; + else { + return !racksPerPartition.values().stream().allMatch(allPartitionRacks::equals); + } + } + + /** + * Adds the topic's partition to the member's target assignment. + */ + protected static void addPartitionToAssignment( + Map<String, MemberAssignment> memberAssignments, + String memberId, + Uuid topicId, + int partition + ) { + memberAssignments.get(memberId) + .targetPartitions() + .computeIfAbsent(topicId, __ -> new HashSet<>()) + .add(partition); + } + + /** + * Constructs a list of {@code TopicIdPartition} for each topic Id based on its partition count. + * + * @param allTopicIds The subscribed topic Ids. + * @param subscribedTopicDescriber Utility to fetch the partition count for a given topic. + * + * @return List of sorted {@code TopicIdPartition} for all provided topic Ids. + */ + protected static List<TopicIdPartition> allTopicIdPartitions( + Collection<Uuid> allTopicIds, + SubscribedTopicDescriber subscribedTopicDescriber + ) { + List<TopicIdPartition> allTopicIdPartitions = new ArrayList<>(); + // Sorted so that partitions from each topic can be distributed amongst its subscribers equally. + allTopicIds.stream().sorted().forEach(topic -> + IntStream.range(0, subscribedTopicDescriber.numPartitions(topic)) + .forEach(i -> allTopicIdPartitions.add(new TopicIdPartition(topic, i))) + ); + + return allTopicIdPartitions; + } + + /** + * Represents the rack information of members and partitions along with utility methods + * to facilitate rack-aware assignment strategies for a given consumer group. + */ + protected static class RackInfo { + /** + * Map of every member to its rack. + */ + protected final Map<String, String> memberRacks; + + /** + * Map of every partition to a list of its racks. + */ + protected final Map<TopicIdPartition, Set<String>> partitionRacks; + + /** + * List of members with the same rack as the partition. + */ + protected final Map<TopicIdPartition, List<String>> membersWithSameRackAsPartition; + + /** + * Indicates if a rack aware assignment can be done. + * True if racks are defined for both members and partitions and there is an intersection between the sets. + */ + protected final boolean useRackStrategy; + + /** + * Constructs rack information based on the assignment specification and subscribed topics. + * + * @param assignmentSpec The current assignment specification. + * @param subscribedTopicDescriber Topic and partition metadata of the subscribed topics. + * @param topicIds List of topic Ids. + */ + public RackInfo( + AssignmentSpec assignmentSpec, + SubscribedTopicDescriber subscribedTopicDescriber, + Set<Uuid> topicIds + ) { + Map<String, List<String>> membersByRack = new HashMap<>(); + assignmentSpec.members().forEach((memberId, assignmentMemberSpec) -> + assignmentMemberSpec.rackId().filter(r -> !r.isEmpty()).ifPresent( + rackId -> membersByRack.computeIfAbsent(rackId, __ -> new ArrayList<>()).add(memberId) + ) + ); + + Set<String> allPartitionRacks; + Map<TopicIdPartition, Set<String>> racksPerPartition; + List<TopicIdPartition> topicIdPartitions = allTopicIdPartitions(topicIds, subscribedTopicDescriber); + + if (membersByRack.isEmpty()) { + allPartitionRacks = Collections.emptySet(); + racksPerPartition = Collections.emptyMap(); + } else { + racksPerPartition = new HashMap<>(); + allPartitionRacks = new HashSet<>(); + topicIdPartitions.forEach(tp -> { Review Comment: yes agreed, I changed it now, thanks! -- This is an automated message from the Apache Git Service. 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