rreddy-22 commented on code in PR #14182: URL: https://github.com/apache/kafka/pull/14182#discussion_r1316792230
########## group-coordinator/src/main/java/org/apache/kafka/coordinator/group/assignor/UniformAssignor.java: ########## @@ -0,0 +1,288 @@ +/* + * 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.coordinator.group.common.TopicIdPartition; +import org.apache.kafka.common.Uuid; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.util.ArrayList; +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 Uniform Assignor distributes Kafka topic partitions among group members for balanced assignment. + * The assignor employs two different strategies based on the nature of topic + * subscriptions across the group members: + * <ul> + * <li> + * <b> Optimized Uniform Assignment Builder: </b> This strategy is used when all members have subscribed + * to the same set of topics. + * </li> + * <li> + * <b> General Uniform Assignment Builder: </b> This strategy is used when members have varied topic + * subscriptions. + * </li> + * </ul> + * + * The appropriate strategy is automatically chosen based on the current members' topic subscriptions. + * + * @see OptimizedUniformAssignmentBuilder + * @see GeneralUniformAssignmentBuilder + */ +public class UniformAssignor implements PartitionAssignor { + private static final Logger log = LoggerFactory.getLogger(UniformAssignor.class); + public static final String UNIFORM_ASSIGNOR_NAME = "uniform"; + + @Override + public String name() { + return UNIFORM_ASSIGNOR_NAME; + } + + /** + * Perform the group assignment given the current members and + * topic metadata. + * + * @param assignmentSpec The member assignment spec. + * @param subscribedTopicDescriber The topic and cluster metadata describer {@link SubscribedTopicDescriber}. + * @return The new assignment for the group. + */ + @Override + public GroupAssignment assign( + AssignmentSpec assignmentSpec, + SubscribedTopicDescriber subscribedTopicDescriber + ) throws PartitionAssignorException { + AbstractAssignmentBuilder assignmentBuilder; + if (assignmentSpec.members().isEmpty()) + return new GroupAssignment(Collections.emptyMap()); + + if (allSubscriptionsEqual(assignmentSpec.members())) { + log.debug("Detected that all members are subscribed to the same set of topics, invoking the " + + "optimized assignment algorithm"); + assignmentBuilder = new OptimizedUniformAssignmentBuilder(assignmentSpec, subscribedTopicDescriber); + } else { + assignmentBuilder = new GeneralUniformAssignmentBuilder(); + log.debug("Detected that all members are subscribed to a different set of topics, invoking the " + + "general assignment algorithm"); + } + + return assignmentBuilder.buildAssignment(); + } + + /** + * Determines if all members are subscribed to the same list of topic IDs. + * + * @param members A map of member identifiers to their respective {@code AssignmentMemberSpec}. + * Assumes the map is non-empty. + * @return true if all members have the same subscription list of topic IDs, + * false otherwise. + */ + private boolean allSubscriptionsEqual(Map<String, AssignmentMemberSpec> members) { + Set<Uuid> firstSubscriptionSet = new HashSet<>(members.values().iterator().next().subscribedTopicIds()); + for (AssignmentMemberSpec memberSpec : members.values()) { + Set<Uuid> currentSubscriptionSet = new HashSet<>(memberSpec.subscribedTopicIds()); + if (!firstSubscriptionSet.equals(currentSubscriptionSet)) { + return false; + } + } + return true; + } + + /** + * The assignment builder is used to construct the final assignment in a series of steps that + * are determined by the type of subscriptions. + * + * There are common methods present that are used by any type of assignment strategy. + */ + protected static abstract class AbstractAssignmentBuilder { Review Comment: Which concrete classes? We made it abstract so that any builder that implements this class would need to implement buildAssignment which is the main function called within assign -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: jira-unsubscr...@kafka.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
