lianetm commented on code in PR #14323: URL: https://github.com/apache/kafka/pull/14323#discussion_r1319075024
########## clients/src/main/java/org/apache/kafka/clients/consumer/internals/MembershipManagerImpl.java: ########## @@ -0,0 +1,168 @@ +/* + * 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.internals; + +import org.apache.kafka.common.message.ConsumerGroupHeartbeatResponseData; +import org.apache.kafka.common.protocol.Errors; + +import java.util.ArrayList; +import java.util.List; +import java.util.Optional; + +/** + * Membership manager that maintains group membership for a single member following the new + * consumer group protocol. + * <p/> + * This keeps membership state and assignment updated in-memory, based on the heartbeat responses + * the member receives. It is also responsible for computing assignment for the group based on + * the metadata, if the member has been selected by the broker to do so. + */ +public class MembershipManagerImpl implements MembershipManager { + + private final String groupId; + private Optional<String> groupInstanceId; + private String memberId; + private int memberEpoch; + private MemberState state; + private AssignorSelection assignorSelection; + + /** + * Assignment that the member received from the server and successfully processed + */ + private ConsumerGroupHeartbeatResponseData.Assignment currentAssignment; + + /** + * List of assignments that the member received from the server but hasn't processed yet + */ + private final List<ConsumerGroupHeartbeatResponseData.Assignment> targetAssignments; + + public MembershipManagerImpl(String groupId) { + this.groupId = groupId; + this.state = MemberState.UNJOINED; + this.assignorSelection = AssignorSelection.defaultAssignor(); + this.targetAssignments = new ArrayList<>(); + } + + public MembershipManagerImpl(String groupId, String groupInstanceId, AssignorSelection assignorSelection) { + this(groupId); + this.groupInstanceId = Optional.ofNullable(groupInstanceId); + setAssignorSelection(assignorSelection); + } + + /** + * Update assignor selection for the member. + * + * @param assignorSelection New assignor selection + * @throws IllegalArgumentException If the provided assignor selection is null + */ + public void setAssignorSelection(AssignorSelection assignorSelection) { + if (assignorSelection == null) { + throw new IllegalArgumentException("Assignor selection cannot be null"); + } + this.assignorSelection = assignorSelection; + } + + private void transitionTo(MemberState nextState) { + if (!nextState.getPreviousValidStates().contains(state)) { + // TODO: handle invalid state transition + throw new RuntimeException(String.format("Invalid state transition from %s to %s", + state, nextState)); + } + this.state = nextState; + } + + @Override + public String groupId() { + return groupId; + } + + @Override + public String groupInstanceId() { + // TODO: review empty vs null instance id + return groupInstanceId.orElse(null); + } + + @Override + public String memberId() { + return memberId; + } + + @Override + public int memberEpoch() { + return memberEpoch; + } + + @Override + public void updateState(ConsumerGroupHeartbeatResponseData response) { + if (response.errorCode() == Errors.NONE.code()) { + this.memberId = response.memberId(); + this.memberEpoch = response.memberEpoch(); + targetAssignments.add(response.assignment()); + transitionTo(MemberState.PROCESSING_ASSIGNMENT); + } else { + if (response.errorCode() == Errors.FENCED_MEMBER_EPOCH.code() || response.errorCode() == Errors.UNKNOWN_MEMBER_ID.code()) { + resetMemberIdAndEpoch(); + transitionTo(MemberState.UNJOINED); + } else if (response.errorCode() == Errors.UNRELEASED_INSTANCE_ID.code()) { + transitionTo(MemberState.FAILED); + } + } + } + + public void onAssignmentProcessSuccess(ConsumerGroupHeartbeatResponseData.Assignment assignment) { + currentAssignment = assignment; + targetAssignments.remove(assignment); + transitionTo(MemberState.STABLE); + } + + public void onAssignmentProcessFailure(Throwable error) { + // TODO: handle failure scenario when the member was not able to process the assignment + } + + private void resetMemberIdAndEpoch() { + this.memberId = ""; Review Comment: Yes, I know it's not written like that but we had conversations saying that sending epoch 0 would be enough (that's why I want to double check) -- This is an automated message from the Apache Git Service. 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