dajac commented on code in PR #22487: URL: https://github.com/apache/kafka/pull/22487#discussion_r4081171636
########## group-coordinator/src/main/java/org/apache/kafka/coordinator/group/TargetAssignmentRecordsBuilder.java: ########## @@ -0,0 +1,459 @@ +/* + * 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; + +import org.apache.kafka.coordinator.common.runtime.CoordinatorRecord; +import org.apache.kafka.coordinator.group.modern.Assignment; +import org.apache.kafka.coordinator.group.streams.StreamsCoordinatorRecordHelpers; +import org.apache.kafka.coordinator.group.streams.TasksTuple; + +import org.slf4j.Logger; + +import java.util.ArrayList; +import java.util.HashMap; +import java.util.List; +import java.util.Map; +import java.util.Objects; +import java.util.Set; + +/** + * Builds the records to persist a new target assignment for a group. + * + * 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 removed members. + * + * @param <A> The member's target assignment type. + */ +public abstract class TargetAssignmentRecordsBuilder<A> { + + /** + * The logger. + */ + private final Logger log; + + /** + * The group id. + */ + private final String groupId; + + /** + * The target assignment metadata. + */ + private TargetAssignmentMetadata targetAssignmentMetadata; + + /** + * The static members in the group at the time the new target assignment was computed. + */ + private Map<String, String> previousStaticMembers; + + /** + * The current member ids in the group. + */ + private Set<String> currentMemberIds; + + /** + * The current static members in the group. + */ + private Map<String, String> currentStaticMembers; + + /** + * The current target assignment. + */ + private Map<String, A> currentTargetAssignment; + + /** + * The new target assignment. + */ + private Map<String, A> newTargetAssignment; + + /** + * Constructs the object. + * + * @param log The logger. + * @param groupId The group id. + */ + public TargetAssignmentRecordsBuilder( + Logger log, + String groupId + ) { + this.log = log; + this.groupId = Objects.requireNonNull(groupId); + } + + /** + * Sets the target assignment metadata. + * + * @param targetAssignmentMetadata The target assignment metadata. + * @return This object. + */ + public TargetAssignmentRecordsBuilder<A> withTargetAssignmentMetadata(TargetAssignmentMetadata targetAssignmentMetadata) { + this.targetAssignmentMetadata = Objects.requireNonNull(targetAssignmentMetadata); + return this; + } + + /** + * Sets the static members in the group at the time the new target assignment was computed. + * + * @param previousStaticMembers The static members in the group at the time the new target assignment was computed. + * @return This object. + */ + public TargetAssignmentRecordsBuilder<A> withPreviousStaticMembers(Map<String, String> previousStaticMembers) { + this.previousStaticMembers = Objects.requireNonNull(previousStaticMembers); + return this; + } + + /** + * Sets the current member ids in the group. + * + * @param currentMemberIds The current member ids in the group. + * @return This object. + */ + public TargetAssignmentRecordsBuilder<A> withCurrentMemberIds(Set<String> currentMemberIds) { + this.currentMemberIds = Objects.requireNonNull(currentMemberIds); + return this; + } + + /** + * Sets the current static members in the group. + * + * @param currentStaticMembers The current static members in the group. + * @return This object. + */ + public TargetAssignmentRecordsBuilder<A> withCurrentStaticMembers(Map<String, String> currentStaticMembers) { + this.currentStaticMembers = Objects.requireNonNull(currentStaticMembers); + return this; + } + + /** + * Sets the current target assignment. + * + * @param currentTargetAssignment The current target assignment. + * @return This object. + */ + public TargetAssignmentRecordsBuilder<A> withCurrentTargetAssignment(Map<String, A> currentTargetAssignment) { + this.currentTargetAssignment = Objects.requireNonNull(currentTargetAssignment); + return this; + } + + /** + * Sets the new target assignment. + * + * @param newTargetAssignment The new target assignment. + * @return This object. + */ + public TargetAssignmentRecordsBuilder<A> withNewTargetAssignment(Map<String, A> newTargetAssignment) { + this.newTargetAssignment = Objects.requireNonNull(newTargetAssignment); + return this; + } + + /** + * Builds the records for the new target assignment. + * + * @return The records for the new target assignment. + */ + public List<CoordinatorRecord> build() { + List<CoordinatorRecord> records = new ArrayList<>(); + build(records); + return records; + } + + /** + * Builds the records for the new target assignment. + * + * @param records The list to accumulate records. + */ + @SuppressWarnings({"CyclomaticComplexity", "NPathComplexity"}) + public void build(List<CoordinatorRecord> records) { + if (targetAssignmentMetadata == null) + throw new IllegalArgumentException("Target assignment metadata must be set."); + if (previousStaticMembers == null) + throw new IllegalArgumentException("Previous static members must be set."); + if (currentMemberIds == null) + throw new IllegalArgumentException("Current member ids must be set."); + if (currentStaticMembers == null) + throw new IllegalArgumentException("Current static members must be set."); + if (currentTargetAssignment == null) + throw new IllegalArgumentException("Current target assignment must be set."); + if (newTargetAssignment == null) + throw new IllegalArgumentException("New target assignment must be set."); + + // The members in the group may have changed while the target assignment was computed. + // We want to act as if concurrent member operations such as leaves and static member + // replacements happened *after* the target assignment was computed. + // + // * When members leave the group, the group coordinator tombstones their target + // assignment. + // * When static members are replaced, the group coordinator moves the assignment from the + // old member id to the new member id. + // + // Thus, when building the new target assignment records, + // * we should not emit records for members that have left the group + // * we should relabel records with the latest member id for static members + // + // It is allowed by the protocol, but extremely unlikely, for static members to fully leave + // the group and rejoin with the same member id but different instance ids. We choose to + // match up assignments using member ids first, then fall back to instance ids. + + // Build map of replacement member ids for static members that have churned. + Map<String, String> staticMemberIdRemapping = new HashMap<>(); + for (Map.Entry<String, String> entry : previousStaticMembers.entrySet()) { + String instanceId = entry.getKey(); + String oldMemberId = entry.getValue(); + String newMemberId = currentStaticMembers.get(instanceId); + + if (currentMemberIds.contains(oldMemberId)) { + // The old member id is still in the group. We must not create a remapping entry, + // otherwise we could give the same assignment to two different members. + continue; + } + + if (newMemberId != null) { + if (newTargetAssignment.containsKey(newMemberId)) { + // The new member id has been in the group since before the assignment was + // computed. We want to prioritize matching assignments up by member id, so + // avoid creating a remapping entry. Note that we can't detect this if the + // assignor omits an entry for the member but nothing bad happens in that case. + continue; + } + + staticMemberIdRemapping.put(newMemberId, oldMemberId); + } + } + + if (log.isDebugEnabled()) { + for (Map.Entry<String, String> entry : previousStaticMembers.entrySet()) { Review Comment: Sorry, I was not clear about this one. I was asking whether we could add sufficient debug logging in the loop at L217 and the one at L304 to achieve a similar result. Would it be possible? -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
