rreddy-22 commented on code in PR #13637: URL: https://github.com/apache/kafka/pull/13637#discussion_r1177412216
########## group-coordinator/src/main/java/org/apache/kafka/coordinator/group/consumer/TargetAssignmentBuilder.java: ########## @@ -0,0 +1,327 @@ +/* + * 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.consumer; + +import org.apache.kafka.common.Uuid; +import org.apache.kafka.coordinator.group.Record; +import org.apache.kafka.coordinator.group.assignor.AssignmentMemberSpec; +import org.apache.kafka.coordinator.group.assignor.AssignmentSpec; +import org.apache.kafka.coordinator.group.assignor.AssignmentTopicMetadata; +import org.apache.kafka.coordinator.group.assignor.GroupAssignment; +import org.apache.kafka.coordinator.group.assignor.MemberAssignment; +import org.apache.kafka.coordinator.group.assignor.PartitionAssignor; +import org.apache.kafka.coordinator.group.assignor.PartitionAssignorException; + +import java.util.ArrayList; +import java.util.Collections; +import java.util.HashMap; +import java.util.HashSet; +import java.util.List; +import java.util.Map; +import java.util.Objects; +import java.util.Optional; +import java.util.Set; + +import static org.apache.kafka.coordinator.group.RecordHelpers.newTargetAssignmentEpochRecord; +import static org.apache.kafka.coordinator.group.RecordHelpers.newTargetAssignmentRecord; + +/** + * Build a new Target Assignment based on the provided parameters. As a result, + * it yields the records that must be persisted to the log and the new member + * assignments as a map. + * + * Records are only created for members which have a new target assignment. If + * their assignment did not change, no new record is needed. + * + * When a member is deleted, it is assumed that its target assignment record + * is deleted as part of the member deletion process. In other words, this class + * does not yield a tombstone for remove members. + */ +public class TargetAssignmentBuilder { + /** + * The assignment result returned by {{@link TargetAssignmentBuilder#build()}}. + */ + public static class TargetAssignmentResult { + /** + * The records that must be applied to the __consumer_offsets + * topics to persist the new target assignment. + */ + private final List<Record> records; + + /** + * The new target assignment for all members. + */ + private final Map<String, Assignment> assignments; + + TargetAssignmentResult( + List<org.apache.kafka.coordinator.group.Record> records, + Map<String, Assignment> assignments + ) { + Objects.requireNonNull(records); + Objects.requireNonNull(assignments); + this.records = records; + this.assignments = assignments; + } + + /** + * @return The records. + */ + public List<Record> records() { + return records; + } + + /** + * @return The assignment. + */ + public Map<String, Assignment> assignments() { + return assignments; + } + } + + /** + * The group id. + */ + private final String groupId; + + /** + * The group epoch. + */ + private final int groupEpoch; + + /** + * The partition assignor to compute the assignment. + */ + private final PartitionAssignor assignor; + + /** + * The members in the group. + */ + private Map<String, ConsumerGroupMember> members = Collections.emptyMap(); + + /** + * The subscription metadata. + */ + private Map<String, TopicMetadata> subscriptionMetadata = Collections.emptyMap(); + + /** + * The current target assignment. + */ + private Map<String, Assignment> assignments = Collections.emptyMap(); + + /** + * The members which have been updated or deleted. Deleted members + * are signaled by a null value. + */ + private Map<String, ConsumerGroupMember> updatedMembers = new HashMap<>(); + + /** + * Constructs the object. + * + * @param groupId The group id. + * @param groupEpoch The group epoch to compute a target assignment for. + * @param assignor The assignor to use to compute the target assignment. + */ + public TargetAssignmentBuilder( + String groupId, + int groupEpoch, + PartitionAssignor assignor + ) { + this.groupId = Objects.requireNonNull(groupId); + this.groupEpoch = groupEpoch; + this.assignor = Objects.requireNonNull(assignor); + } + + /** + * Adds all the current members. + * + * @param members The current members in the consumer groups. + * @return This object. + */ + public TargetAssignmentBuilder withMembers( + Map<String, ConsumerGroupMember> members + ) { + this.members = members; + return this; + } + + /** + * Adds the subscription metadata to use. + * + * @param subscriptionMetadata The subscription metadata. + * @return This object. + */ + public TargetAssignmentBuilder withSubscriptionMetadata( + Map<String, TopicMetadata> subscriptionMetadata + ) { + this.subscriptionMetadata = subscriptionMetadata; + return this; + } + + /** + * Adds the current target assignments. + * + * @param assignments The current assignments. + * @return This object. + */ + public TargetAssignmentBuilder withTargetAssignments( + Map<String, Assignment> assignments + ) { + this.assignments = assignments; + return this; + } + + /** + * Updates a member. This is useful when the updated member is + * not yet materialized in memory. + * + * @param memberId The member id. + * @param updatedMember The updated member. + * @return This object. + */ + public TargetAssignmentBuilder withUpdatedMember( + String memberId, + ConsumerGroupMember updatedMember + ) { + this.updatedMembers.put(memberId, updatedMember); + return this; + } + + /** + * Removes a member. This is useful when the removed member + * is not yet materialized in memory. + * + * @param memberId The member id. + * @return This object. + */ + public TargetAssignmentBuilder withRemoveMembers( + String memberId + ) { + return withUpdatedMember(memberId, null); + } + + /** + * Builds the new target assignment. + * + * @return A TargetAssignmentResult which contains the records to update + * the current target assignment. + * @throws PartitionAssignorException if the assignment can not be computed. + */ + public TargetAssignmentResult build() throws PartitionAssignorException { + Map<String, AssignmentMemberSpec> memberSpecs = new HashMap<>(); + + // Prepare the member spec for all members. + members.forEach((memberId, member) -> addMemberSpec( + memberSpecs, + member, + assignments.getOrDefault(memberId, Assignment.EMPTY) + )); + + // Update the member spec if updated or deleted members. + updatedMembers.forEach((memberId, updatedMemberOrNull) -> { + if (updatedMemberOrNull == null) { + memberSpecs.remove(memberId); + } else { + addMemberSpec( + memberSpecs, + updatedMemberOrNull, + assignments.getOrDefault(memberId, Assignment.EMPTY) + ); + } + }); + + // Prepare the topic metadata. + Map<Uuid, AssignmentTopicMetadata> topics = new HashMap<>(); + subscriptionMetadata.forEach((topicName, topicMetadata) -> + topics.put(topicMetadata.id(), new AssignmentTopicMetadata(topicMetadata.numPartitions())) + ); + + // Compute the assignment. + GroupAssignment newGroupAssignment = assignor.assign(new AssignmentSpec( + Collections.unmodifiableMap(memberSpecs), + Collections.unmodifiableMap(topics) + )); + + // Compute delta from previous to new assignment and create the + // relevant records. + List<Record> records = new ArrayList<>(); + Map<String, Assignment> newTargetAssignment = new HashMap<>(); + + memberSpecs.keySet().forEach(memberId -> { + Assignment oldMemberAssignment = assignments.get(memberId); + Assignment newMemberAssignment = newMemberAssignment(newGroupAssignment, memberId); + + newTargetAssignment.put(memberId, newMemberAssignment); + + if (oldMemberAssignment == null) { + // If the member had no assignment, we always create a record for him. Review Comment: nit : we always create a record for it* -- 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
