rreddy-22 commented on code in PR #13663: URL: https://github.com/apache/kafka/pull/13663#discussion_r1190358529
########## group-coordinator/src/main/java/org/apache/kafka/coordinator/group/generic/GenericGroup.java: ########## @@ -0,0 +1,958 @@ +/* + * 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.generic; + +import org.apache.kafka.clients.consumer.internals.ConsumerProtocol; +import org.apache.kafka.common.message.JoinGroupResponseData; +import org.apache.kafka.common.message.ListGroupsResponseData; +import org.apache.kafka.common.message.SyncGroupResponseData; +import org.apache.kafka.common.message.JoinGroupResponseData.JoinGroupResponseMember; +import org.apache.kafka.common.protocol.Errors; +import org.apache.kafka.common.protocol.types.SchemaException; +import org.apache.kafka.common.utils.LogContext; +import org.apache.kafka.common.utils.Time; +import org.slf4j.Logger; + +import java.nio.ByteBuffer; +import java.util.Collection; +import java.util.Collections; +import java.util.Comparator; +import java.util.HashMap; +import java.util.HashSet; +import java.util.Iterator; +import java.util.List; +import java.util.Map; +import java.util.Objects; +import java.util.Optional; +import java.util.Set; +import java.util.UUID; +import java.util.concurrent.CompletableFuture; +import java.util.stream.Collectors; + +import static org.apache.kafka.coordinator.group.generic.GenericGroupState.COMPLETING_REBALANCE; +import static org.apache.kafka.coordinator.group.generic.GenericGroupState.DEAD; +import static org.apache.kafka.coordinator.group.generic.GenericGroupState.EMPTY; +import static org.apache.kafka.coordinator.group.generic.GenericGroupState.PREPARING_REBALANCE; + +/** + * + * This class holds metadata for a generic group. + */ +public class GenericGroup { + + /** + * Empty generation. + */ + public static final int NO_GENERATION = -1; + + /** + * Protocol with empty name. + */ + public static final String NO_PROTOCOL_NAME = ""; + + /** + * No leader. + */ + public static final String NO_LEADER = ""; + + /** + * Delimiter used to join a randomly generated UUID + * with client id or group instance id. + */ + private static final String MEMBER_ID_DELIMITER = "-"; + + /** + * The slf4j log context, used to create new loggers. + */ + private final LogContext logContext; + + /** + * The slf4j logger. + */ + private final Logger log; + + /** + * The group id. + */ + private final String groupId; + + /** + * The time. + */ + private final Time time; + + /** + * The current group state. + */ + private GenericGroupState state; + + /** + * The timestamp of when the group transitioned + * to its current state. + */ + private Optional<Long> currentStateTimestamp; + + /** + * The protocol type used for rebalance. + */ + private Optional<String> protocolType = Optional.empty(); + + /** + * The protocol name used for rebalance. + */ + private Optional<String> protocolName = Optional.empty(); + + /** + * The generation id. + */ + private int generationId = 0; + + /** + * The id of the group's leader. + */ + private Optional<String> leaderId = Optional.empty(); + + /** + * The members of the group. + */ + private final Map<String, GenericGroupMember> members = new HashMap<>(); + + /** + * The static members of the group. + */ + private final Map<String, String> staticMembers = new HashMap<>(); + + /** + * Members who have yet to (re)join the group + * during the join group phase. + */ + private final Set<String> pendingJoinMembers = new HashSet<>(); + + /** + * The number of members waiting to hear back a join response. + */ + private int numMembersAwaitingJoinResponse = 0; + + /** + * Map of protocol names to how many members support them. + */ + private final Map<String, Integer> supportedProtocols = new HashMap<>(); + + /** + * Members who have yet to sync with the group + * during the sync group phase. + */ + private final Set<String> pendingSyncMembers = new HashSet<>(); + + /** + * The list of topics the group members are subscribed to. + */ + private Optional<Set<String>> subscribedTopics = Optional.empty(); + + /** + * A flag to indiciate whether a new member was added. Used + * to further delay initial joins (new group). + */ + private boolean newMemberAdded = false; + + public GenericGroup( + LogContext logContext, + String groupId, + GenericGroupState initialState, + Time time + ) { + this.logContext = Objects.requireNonNull(logContext); + this.log = logContext.logger(GenericGroup.class); + this.groupId = Objects.requireNonNull(groupId); + this.state = Objects.requireNonNull(initialState); + this.time = Objects.requireNonNull(time); + this.currentStateTimestamp = Optional.of(time.milliseconds()); + } + + /** + * @return the generation id. + */ + public int generationId() { + return this.generationId; + } + + /** + * @return the protocol name. + */ + public Optional<String> protocolName() { + return this.protocolName; + } + + /** + * @return the current group state. + */ + public GenericGroupState currentState() { + return state; + } + + /** + * Compares the group's current state with the given state. + * + * @param groupState the state to match against. + * @return true if matches, false otherwise. + */ + public boolean isState(GenericGroupState groupState) { + return this.state == groupState; + } + + /** + * To identify whether the given member id is part of this group. + * + * @param memberId the given member id. + * @return true if the member is part of this group, false otherwise. + */ + public boolean hasMemberId(String memberId) { + return members.containsKey(memberId); + } + + /** + * Get the member metadata with the provided member id. + * + * @param memberId the member id. + * @return the member metadata if it exists, null otherwise. + */ + public GenericGroupMember member(String memberId) { + return members.get(memberId); + } + + /** + * @return the total number of members in this group. + */ + public int size() { + return members.size(); + } + + /** + * Used to identify whether the given member is the leader of this group. + * + * @param memberId the member id. + * @return true if the member is the leader, false otherwise. + */ + public boolean isLeader(String memberId) { + return leaderId.map(id -> id.equals(memberId)).orElse(false); + } + + /** + * @return the leader id or null if a leader does not exist. + */ + public String leaderOrNull() { + return leaderId.orElse(null); + } + + /** + * @return the current state timestamp. + */ + public long currentStateTimestampOrDefault() { + return currentStateTimestamp.orElse(-1L); + } + + /** + * @return whether the group is using the consumer protocol. + */ + public boolean isGenericGroup() { + return protocolType.map(type -> + type.equals(ConsumerProtocol.PROTOCOL_TYPE) + ).orElse(false); + } + + public void add(GenericGroupMember member) { + add(member, null); + } + + /** + * Add a member to this group. + * + * @param member the member to add. + * @param future the future to complete once the join group phase completes. + */ + public void add(GenericGroupMember member, CompletableFuture<JoinGroupResponseData> future) { + member.groupInstanceId().ifPresent(instanceId -> { + if (staticMembers.containsKey(instanceId)) { + throw new IllegalStateException("Static member with groupInstanceId=" + + instanceId + " cannot be added to group " + groupId + " since" + + " it is already a member."); + } + staticMembers.put(instanceId, member.memberId()); + }); + + if (members.isEmpty()) { + this.protocolType = Optional.of(member.protocolType()); + } + + if (!Objects.equals(this.protocolType.orElse(null), member.protocolType())) { + throw new IllegalStateException("The group and member's protocol type must be the same."); + } + + if (!supportsProtocols( + member.protocolType(), + GenericGroupMember.plainProtocolSet(member.supportedProtocols()))) { + + throw new IllegalStateException("None of the member's protocols can be supported."); + } + + if (!leaderId.isPresent()) { + leaderId = Optional.of(member.memberId()); + } + + members.put(member.memberId(), member); + incrementSupportedProtocols(member); + member.setAwaitingJoinFuture(future); + + if (member.isAwaitingJoin()) { + numMembersAwaitingJoinResponse++; + } + + pendingJoinMembers.remove(member.memberId()); + } + + /** + * Remove a member from the group. + * + * @param memberId the member id to remove. + */ + public void remove(String memberId) { + GenericGroupMember removedMember = members.remove(memberId); + if (removedMember != null) { + decrementSupportedProtocols(removedMember); + if (removedMember.isAwaitingJoin()) { + numMembersAwaitingJoinResponse--; + } + + removedMember.groupInstanceId().ifPresent(staticMembers::remove); + } + + if (isLeader(memberId)) { + Iterator<String> iter = members.keySet().iterator(); + String newLeader = iter.hasNext() ? iter.next() : null; + leaderId = Optional.ofNullable(newLeader); + } + + pendingJoinMembers.remove(memberId); + pendingSyncMembers.remove(memberId); + } + + /** + * Check whether current leader has rejoined. If not, try to find another joined member to be + * new leader. Return false if + * 1. the group is currently empty (has no designated leader) + * 2. no member rejoined + * + * @return whether a new leader was elected. + */ + public boolean maybeElectNewJoinedLeader() { + if (leaderId.isPresent()) { + GenericGroupMember currentLeader = member(leaderId.get()); + if (!currentLeader.isAwaitingJoin()) { + for (GenericGroupMember member : members.values()) { + if (member.isAwaitingJoin()) { + leaderId = Optional.of(member.memberId()); + log.info("Group leader [memberId: {}, groupInstanceId: {}] " + + "failed to join before the rebalance timeout. Member {} " + + "was elected as the new leader.", + currentLeader.memberId(), + currentLeader.groupInstanceId().orElse("None"), + member + ); + return true; + } + } + log.info("Group leader [memberId: {}, groupInstanceId: {}] " + + "failed to join before the rebalance timeout and the " + + "group couldn't proceed to the next generation because " + + "no member joined.", + currentLeader.memberId(), + currentLeader.groupInstanceId().orElse("None") + ); + return false; + } + return false; + } + return false; + } + + /** + * [For static members only]: Replace the old member id with the new one, + * keep everything else unchanged and return the updated member. + * + * @param groupInstanceId the group instance id. + * @param oldMemberId the old member id. + * @param newMemberId the new member id that will replace the old member id. + * @return the old member. + */ + public GenericGroupMember replaceStaticMember( + String groupInstanceId, + String oldMemberId, + String newMemberId + ) { + GenericGroupMember removedMember = members.remove(oldMemberId); + if (removedMember == null) { + throw new IllegalArgumentException("Cannot replace non-existing member id " + oldMemberId); + } + + // Fence potential duplicate member immediately if someone awaits join/sync future. + JoinGroupResponseData joinGroupResponse = new JoinGroupResponseData() + .setMembers(Collections.emptyList()) + .setMemberId(oldMemberId) + .setGenerationId(NO_GENERATION) + .setProtocolName(null) + .setProtocolType(null) + .setLeader(NO_LEADER) + .setSkipAssignment(false) + .setErrorCode(Errors.FENCED_INSTANCE_ID.code()); + completeJoinFuture(removedMember, joinGroupResponse); + + SyncGroupResponseData syncGroupResponse = new SyncGroupResponseData() + .setAssignment(new byte[0]) + .setProtocolName(null) + .setProtocolType(null) + .setErrorCode(Errors.FENCED_INSTANCE_ID.code()); + completeSyncFuture(removedMember, syncGroupResponse); + + GenericGroupMember newMember = new GenericGroupMember( + newMemberId, + removedMember.groupInstanceId(), + removedMember.clientId(), + removedMember.clientHost(), + removedMember.rebalanceTimeoutMs(), + removedMember.sessionTimeoutMs(), + removedMember.protocolType(), + removedMember.supportedProtocols(), + removedMember.assignment() + ); + + members.put(newMemberId, newMember); + + if (isLeader(oldMemberId)) { + leaderId = Optional.of(newMemberId); + } + + staticMembers.put(groupInstanceId, newMemberId); + return removedMember; + } + + /** + * Check whether a member has joined the group. + * + * @param memberId the member id. + * @return true if the member has yet to join, false otherwise. + */ + public boolean isPendingMember(String memberId) { + return pendingJoinMembers.contains(memberId); + } + + /** + * Add a pending member. + * + * @param memberId the member id. + * @return true if the group did not already have the pending member, + * false otherwise. + */ + public boolean addPendingMember(String memberId) { + if (hasMemberId(memberId)) { + throw new IllegalStateException("Attept to add pending member " + memberId + + " which is already a stable member of the group."); + } + return pendingJoinMembers.add(memberId); + } + + /** + * @return number of members that are pending join. + */ + public int numPending() { + return pendingJoinMembers.size(); + } + + /** + * Add a pending sync member. + * + * @param memberId the member id. + * @return true if the group did not already have the pending sync member, + * false otherwise. + */ + public boolean addPendingSyncMember(String memberId) { + if (!hasMemberId(memberId)) { + throw new IllegalStateException("Attept to add pending sync member " + memberId + + " which is already a stable member of the group."); + } + + return pendingSyncMembers.add(memberId); + } + + /** + * Remove a member that has not yet synced. + * + * @param memberId the member id. + * @return true if the group did store this member, false otherwise. + */ + public boolean removePendingSyncMember(String memberId) { + if (!hasMemberId(memberId)) { + throw new IllegalStateException("Attept to add pending member " + memberId + + " which is already a stable member of the group."); + } + return pendingSyncMembers.remove(memberId); + } + + /** + * @return true if all members have sent sync group requests, + * false otherwise. + */ + public boolean hasReceivedSyncFromAllMembers() { + return pendingSyncMembers.isEmpty(); + } + + /** + * @return members that have yet to sync. + */ + public Set<String> allPendingSyncMembers() { + return pendingSyncMembers; + } + + /** + * Clear members pending sync. + */ + public void clearPendingSyncMembers() { + pendingSyncMembers.clear(); + } + + /** + * Checks whether the given group instance id exists as + * a static member. + * + * @param groupInstanceId the group instance id. + * @return true if a static member with the group instance id exists, + * false otherwise. + */ + public boolean hasStaticMember(String groupInstanceId) { + return staticMembers.containsKey(groupInstanceId); + } + + /** + * Get member id of a static member that matches the given group + * instance id. + * + * @param groupInstanceId the group instance id. + * @return the static member if it exists. + */ + public String staticMemberId(String groupInstanceId) { + return staticMembers.get(groupInstanceId); + } + + /** + * @return members who have yet to rejoin during the + * join group phase. + */ + public Map<String, GenericGroupMember> notYetRejoinedMembers() { + Map<String, GenericGroupMember> notYetRejoinedMembers = new HashMap<>(); + members.values().forEach(member -> { + if (!member.isAwaitingJoin()) { + notYetRejoinedMembers.put(member.memberId(), member); + } + }); + return notYetRejoinedMembers; + } + + /** + * @return whether all members have joined. + */ + public boolean hasAllMembersJoined() { + return members.size() == numMembersAwaitingJoinResponse && pendingJoinMembers.isEmpty(); + } + + /** + * @return the ids of all members in the group. + */ + public Set<String> allMemberIds() { + return members.keySet(); + } + + /** + * @return all static members in the group. + */ + public Set<String> allStaticMemberIds() { + return staticMembers.keySet(); + } + + // For testing only. + Set<String> allDynamicMemberIds() { + Set<String> dynamicMemberSet = new HashSet<>(allMemberIds()); + staticMembers.values().forEach(dynamicMemberSet::remove); + return dynamicMemberSet; + } + + /** + * @return number of members waiting for a join group response. + */ + public int numAwaiting() { + return numMembersAwaitingJoinResponse; + } + + /** + * @return all members. + */ + public Collection<GenericGroupMember> allMembers() { + return members.values(); + } + + /** + * @return the group's rebalance timeout in milliseconds. + * It is the max of all member's rebalance timeout. + */ + public int rebalanceTimeoutMs() { + int maxRebalanceTimeoutMs = 0; + for (GenericGroupMember member : members.values()) { + maxRebalanceTimeoutMs = Math.max(maxRebalanceTimeoutMs, member.rebalanceTimeoutMs()); + } + return maxRebalanceTimeoutMs; + } + + /** + * Generate a member id from the given client and group instance ids. + * + * @param clientId the client id. + * @param groupInstanceId the group instance id. + * @return the generated id. + */ Review Comment: Should we indent this better? -- This is an automated message from the Apache Git Service. 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