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Posted to jira@kafka.apache.org by "dajac (via GitHub)" <gi...@apache.org> on 2023/06/20 14:43:24 UTC
[GitHub] [kafka] dajac commented on a diff in pull request #13870: KAFKA-14500; [5/N] Implement JoinGroup protocol in new GroupCoordinator
dajac commented on code in PR #13870:
URL: https://github.com/apache/kafka/pull/13870#discussion_r1235169801
##########
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/GroupMetadataManager.java:
##########
@@ -171,70 +260,152 @@ GroupMetadataManager build() {
/**
* The maximum number of members allowed in a single consumer group.
*/
- private final int consumerGroupMaxSize;
+ private final int groupMaxSize;
/**
* The heartbeat interval for consumer groups.
*/
private final int consumerGroupHeartbeatIntervalMs;
/**
- * The topics metadata (or image).
+ * The metadata image.
+ */
+ private MetadataImage metadataImage;
+
+ // Rest of the fields are used for the generic group APIs.
+
+ /**
+ * An empty result returned to the state machine. This means that
+ * there are no records to append to the log.
+ *
+ * Package private for testing.
+ */
+ static final CoordinatorResult<CompletableFuture<Errors>, Record> EMPTY_RESULT =
+ new CoordinatorResult<>(Collections.emptyList(), CompletableFuture.completedFuture(null));
+
+ /**
+ * Initial rebalance delay for members joining a generic group.
+ */
+ private final int initialRebalanceDelayMs;
Review Comment:
nit: Could we prefix all those attributes with `genericGroup`?
##########
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/GroupMetadataManager.java:
##########
@@ -171,70 +260,152 @@ GroupMetadataManager build() {
/**
* The maximum number of members allowed in a single consumer group.
*/
- private final int consumerGroupMaxSize;
+ private final int groupMaxSize;
Review Comment:
We can't use the same config both both the consumer and the generic group because we have two configs for each.
##########
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/GroupMetadataManager.java:
##########
@@ -874,4 +1045,1265 @@ public void replay(
consumerGroup.updateMember(newMember);
}
}
+
+ // Below stores all methods to handle generic group APIs.
+
+ /**
+ * Handle a JoinGroupRequest.
+ *
+ * @param context The request context.
+ * @param request The actual JoinGroup request.
+ *
+ * @return The result that contains records to append if the join group phase completes.
+ */
+ public CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoin(
+ RequestContext context,
+ JoinGroupRequestData request,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ CoordinatorResult<CompletableFuture<Errors>, Record> result = EMPTY_RESULT;
Review Comment:
Should we have a method helper to validate the request?
##########
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/GroupMetadataManager.java:
##########
@@ -874,4 +1045,1265 @@ public void replay(
consumerGroup.updateMember(newMember);
}
}
+
+ // Below stores all methods to handle generic group APIs.
Review Comment:
I would remove this because it will be outdated extremely quickly.
##########
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/GroupMetadataManager.java:
##########
@@ -874,4 +1045,1265 @@ public void replay(
consumerGroup.updateMember(newMember);
}
}
+
+ // Below stores all methods to handle generic group APIs.
+
+ /**
+ * Handle a JoinGroupRequest.
+ *
+ * @param context The request context.
+ * @param request The actual JoinGroup request.
+ *
+ * @return The result that contains records to append if the join group phase completes.
+ */
+ public CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoin(
+ RequestContext context,
+ JoinGroupRequestData request,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ CoordinatorResult<CompletableFuture<Errors>, Record> result = EMPTY_RESULT;
+ String groupId = request.groupId();
+ String memberId = request.memberId();
+ int sessionTimeoutMs = request.sessionTimeoutMs();
+
+ if (sessionTimeoutMs < groupMinSessionTimeoutMs ||
+ sessionTimeoutMs > groupMaxSessionTimeoutMs
+ ) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.INVALID_SESSION_TIMEOUT.code())
+ );
+ } else {
+ boolean isUnknownMember = memberId.equals(UNKNOWN_MEMBER_ID);
+ // Group is created if it does not exist and the member id is UNKNOWN. if member
+ // is specified but group does not exist, request is rejected with GROUP_ID_NOT_FOUND
+ GenericGroup group;
+ try {
+ group = (GenericGroup) getOrMaybeCreateGroup(groupId, GENERIC, isUnknownMember);
Review Comment:
When the group is created to the first time, I think that we need to write a record to the log; the group could be reverted in the timeline hash map otherwise.
##########
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/GroupMetadataManager.java:
##########
@@ -874,4 +1045,1265 @@ public void replay(
consumerGroup.updateMember(newMember);
}
}
+
+ // Below stores all methods to handle generic group APIs.
+
+ /**
+ * Handle a JoinGroupRequest.
+ *
+ * @param context The request context.
+ * @param request The actual JoinGroup request.
+ *
+ * @return The result that contains records to append if the join group phase completes.
+ */
+ public CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoin(
+ RequestContext context,
+ JoinGroupRequestData request,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ CoordinatorResult<CompletableFuture<Errors>, Record> result = EMPTY_RESULT;
+ String groupId = request.groupId();
+ String memberId = request.memberId();
+ int sessionTimeoutMs = request.sessionTimeoutMs();
+
+ if (sessionTimeoutMs < groupMinSessionTimeoutMs ||
+ sessionTimeoutMs > groupMaxSessionTimeoutMs
+ ) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.INVALID_SESSION_TIMEOUT.code())
+ );
+ } else {
+ boolean isUnknownMember = memberId.equals(UNKNOWN_MEMBER_ID);
+ // Group is created if it does not exist and the member id is UNKNOWN. if member
+ // is specified but group does not exist, request is rejected with GROUP_ID_NOT_FOUND
+ GenericGroup group;
+ try {
+ group = (GenericGroup) getOrMaybeCreateGroup(groupId, GENERIC, isUnknownMember);
+ } catch (Throwable t) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.forException(t).code())
+ );
+ return EMPTY_RESULT;
+ }
+
+ String joinReason = request.reason();
+ if (joinReason == null || joinReason.isEmpty()) {
+ joinReason = "not provided";
+ }
+
+ if (!acceptJoiningMember(group, memberId)) {
+ group.remove(memberId);
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.GROUP_MAX_SIZE_REACHED.code())
+ );
+
+ } else if (isUnknownMember) {
+ result = genericGroupJoinNewMember(
+ context,
+ request,
+ group,
+ joinReason,
+ responseFuture
+ );
+ } else {
+ result = genericGroupJoinExistingMember(
+ context,
+ request,
+ group,
+ joinReason,
+ responseFuture
+ );
+ }
+
+ // Attempt to complete join group phase. We do not complete
+ // the join group phase if this is the initial rebalance.
+ if (group.isInState(PREPARING_REBALANCE) &&
+ group.hasAllMembersJoined() &&
+ group.generationId() != 0
+ ) {
+ completeGenericGroupJoin(group);
+ }
+ }
+
+ return result;
+ }
+
+ /**
+ * Handle a new member generic group join.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinNewMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ List<Protocol> protocols = new ArrayList<>();
+ request.protocols().forEach(protocol -> protocols.add(new Protocol(protocol.name(), protocol.metadata())));
+ if (group.isInState(DEAD)) {
+ // if the group is marked as dead, it means some other thread has just removed the group
+ // from the coordinator metadata; it is likely that the group has migrated to some other
+ // coordinator OR the group is in a transient unstable phase. Let the member retry
+ // finding the correct coordinator and rejoin.
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.COORDINATOR_NOT_AVAILABLE.code())
+ );
+ } else if (!group.supportsProtocols(request.protocolType(), GenericGroupMember.plainProtocolSet(protocols))) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.INCONSISTENT_GROUP_PROTOCOL.code())
+ );
+ } else {
+ Optional<String> groupInstanceId = Optional.ofNullable(request.groupInstanceId());
+ String newMemberId = group.generateMemberId(context.clientId(), groupInstanceId);
+
+ if (groupInstanceId.isPresent()) {
+ return genericGroupJoinNewStaticMember(
+ context,
+ request,
+ group,
+ newMemberId,
+ joinReason,
+ responseFuture
+ );
+ } else {
+ return genericGroupJoinNewDynamicMember(
+ context,
+ request,
+ group,
+ newMemberId,
+ joinReason,
+ responseFuture
+ );
+ }
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Handle new static member join. If there was an existing member id for the group instance id,
+ * replace that member. Otherwise, add the member and rebalance.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param newMemberId The newly generated member id.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinNewStaticMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String newMemberId,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ String groupInstanceId = request.groupInstanceId();
+ String existingMemberId = group.staticMemberId(groupInstanceId);
+ if (existingMemberId != null) {
+ log.info("Static member with groupInstanceId={} and unknown member id joins " +
+ "group {} in {} state. Replacing previously mapped member {} with this groupInstanceId.",
+ groupInstanceId, group.groupId(), group.currentState(), existingMemberId);
+
+ return updateStaticMemberAndRebalance(
+ context,
+ request,
+ group,
+ existingMemberId,
+ newMemberId,
+ joinReason,
+ responseFuture
+ );
+
+ } else {
+ log.info("Static member with groupInstanceId={} and unknown member id joins " +
+ "group {} in {} state. Created a new member id {} for this member and added to the group.",
+ groupInstanceId, group.groupId(), group.currentState(), newMemberId);
+
+ return addMemberAndRebalance(context, request, group, newMemberId, joinReason, responseFuture);
+ }
+ }
+
+ /**
+ * Handle a new dynamic member join. If the member id field is required, the group metadata manager
+ * will add the new member id to the pending members and respond with MEMBER_ID_REQUIRED along with
+ * the new member id for the client to join with.
+ *
+ * Otherwise, add the new member to the group and rebalance.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param newMemberId The newly generated member id.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinNewDynamicMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String newMemberId,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ boolean requireKnownMemberId = context.apiVersion() >= 4
+ && (request.groupInstanceId() == null || request.groupInstanceId().isEmpty());
+
+ if (requireKnownMemberId) {
+ // If member id required, register the member in the pending member list and send
+ // back a response to call for another join group request with allocated member id.
+ log.info("Dynamic member with unknown member id joins group {} in {} state. " +
+ "Created a new member id {} and requesting the member to rejoin with this id.",
+ group.groupId(), group.currentState(), newMemberId);
+
+ group.addPendingMember(newMemberId);
+ String heartbeatKey = heartbeatKey(group.groupId(), newMemberId);
+
+ timer.schedule(
+ heartbeatKey,
+ request.sessionTimeoutMs(),
+ TimeUnit.MILLISECONDS,
+ () -> expireGenericGroupMemberHeartbeat(group, newMemberId)
+ );
+
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(newMemberId)
+ .setErrorCode(Errors.MEMBER_ID_REQUIRED.code())
+ );
+
+ } else {
+ log.info("Dynamic member with unknown member id joins group {} in state {}. " +
+ "Created a new member id {} and added the member to the group.",
+ group.groupId(), group.currentState(), newMemberId);
+
+ return addMemberAndRebalance(context, request, group, newMemberId, joinReason, responseFuture);
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Handle a join group request for an existing member.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinExistingMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ List<Protocol> protocols = request.protocols().stream()
+ .map(protocol -> new Protocol(protocol.name(), protocol.metadata())).collect(Collectors.toList());
+
+ String memberId = request.memberId();
+ String groupInstanceId = request.groupInstanceId();
+
+ if (group.isInState(DEAD)) {
+ // If the group is marked as dead, it means the group was recently removed the group
+ // from the coordinator metadata; it is likely that the group has migrated to some other
+ // coordinator OR the group is in a transient unstable phase. Let the member retry
+ // finding the correct coordinator and rejoin.
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.COORDINATOR_NOT_AVAILABLE.code())
+ );
+ } else if (!group.supportsProtocols(
+ request.protocolType(),
+ GenericGroupMember.plainProtocolSet(protocols))
+ ) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.INCONSISTENT_GROUP_PROTOCOL.code())
+ );
+ } else if (group.isPendingMember(memberId)) {
+ // A rejoining pending member will be accepted. Note that pending member cannot be a static member.
+ if (groupInstanceId != null) {
+ throw new IllegalStateException("Received unexpected JoinGroup with groupInstanceId=" +
+ groupInstanceId + " for pending member with memberId=" + memberId);
+ }
+
+ log.debug("Pending dynamic member with id {} joins group {} in {} state. Adding to the group now.",
+ memberId, group.groupId(), group.currentState());
+
+ return addMemberAndRebalance(
+ context,
+ request,
+ group,
+ memberId,
+ joinReason,
+ responseFuture
+ );
+ } else {
+ Optional<Errors> memberError = validateExistingMember(
+ group,
+ memberId,
+ groupInstanceId,
+ "join-group"
+ );
+
+ if (memberError.isPresent()) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(memberError.get().code())
+ );
+ } else {
+ GenericGroupMember member = group.member(memberId);
+ if (group.isInState(PREPARING_REBALANCE)) {
+ return updateMemberAndRebalance(
+ request,
+ group,
+ member,
+ "Member " + member.memberId() + " is joining group during " +
+ group.stateAsString() + "; client reason: " + joinReason,
+ responseFuture
+ );
+ } else if (group.isInState(COMPLETING_REBALANCE)) {
+ if (member.matches(protocols)) {
+ // Member is joining with the same metadata (which could be because it failed to
+ // receive the initial JoinGroup response), so just return current group information
+ // for the current generation.
+ List<JoinGroupResponseData.JoinGroupResponseMember> members = Collections.emptyList();
+ if (group.isLeader(memberId)) {
+ members = group.currentGenericGroupMembers();
+ }
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMembers(members)
+ .setMemberId(memberId)
+ .setGenerationId(group.generationId())
+ .setProtocolName(group.protocolName().orElse(null))
+ .setProtocolType(group.protocolType().orElse(null))
+ .setLeader(group.leaderOrNull())
+ .setSkipAssignment(false)
+ .setErrorCode(Errors.NONE.code())
+ );
+ } else {
+ // Member has changed metadata, so force a rebalance
+ return updateMemberAndRebalance(
+ request,
+ group,
+ member,
+ "Updating metadata for member " + memberId + " during " +
+ group.stateAsString() + "; client reason: " + joinReason,
+ responseFuture
+ );
+ }
+ } else if (group.isInState(STABLE)) {
+ if (group.isLeader(memberId)) {
+ // Force a rebalance if the leader sends JoinGroup;
+ // This allows the leader to trigger rebalances for changes affecting assignment
+ // which do not affect the member metadata (such as topic metadata changes for the consumer)
+ return updateMemberAndRebalance(
+ request,
+ group,
+ member,
+ "Leader " + memberId + " re-joining group during " +
+ group.stateAsString() + "; client reason: " + joinReason,
+ responseFuture
+ );
+ } else if (!member.matches(protocols)) {
+ return updateMemberAndRebalance(
+ request,
+ group,
+ member,
+ "Updating metadata for member " + memberId + " during " +
+ group.stateAsString() + "; client reason: " + joinReason,
+ responseFuture
+ );
+ } else {
+ // For followers with no actual change to their metadata, just return group information
+ // for the current generation which will allow them to issue SyncGroup.
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMembers(Collections.emptyList())
+ .setMemberId(memberId)
+ .setGenerationId(group.generationId())
+ .setProtocolName(group.protocolName().orElse(null))
+ .setProtocolType(group.protocolType().orElse(null))
+ .setLeader(group.leaderOrNull())
+ .setSkipAssignment(false)
+ .setErrorCode(Errors.NONE.code())
+ );
+ }
+ } else {
+ // Group reached unexpected (Empty) state. Let the joining member reset their generation and rejoin.
+ log.warn("Attempt to add rejoining member {} of group {} in unexpected group state {}",
+ memberId, group.groupId(), group.stateAsString());
+
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.UNKNOWN_MEMBER_ID.code())
+ );
+ }
+ }
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Complete the join group phase. Remove all dynamic members that have not rejoined
+ * during this stage and proceed with the next generation for this group. The generation id
+ * is incremented and the group transitions to CompletingRebalance state if there is at least
+ * one member.
+ *
+ * If the group is in Empty state, append a new group metadata record to the log. Otherwise,
+ * complete all members' join group response futures and wait for sync requests from members.
+ *
+ * @param group The group that is completing the join group phase.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> completeGenericGroupJoin(
+ GenericGroup group
+ ) {
+ timer.cancel(joinKey(group.groupId()));
+ String groupId = group.groupId();
+
+ Map<String, GenericGroupMember> notYetRejoinedDynamicMembers =
+ group.notYetRejoinedMembers().entrySet().stream()
+ .filter(entry -> !entry.getValue().isStaticMember())
+ .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
+
+ if (!notYetRejoinedDynamicMembers.isEmpty()) {
+ notYetRejoinedDynamicMembers.values().forEach(failedMember -> {
+ group.remove(failedMember.memberId());
+ timer.cancel(heartbeatKey(group.groupId(), failedMember.memberId()));
+ });
+
+ log.info("Group {} removed dynamic members who haven't joined: {}",
+ groupId, notYetRejoinedDynamicMembers.keySet());
+ }
+
+ if (group.isInState(DEAD)) {
+ log.info("Group {} is dead, skipping rebalance stage.", groupId);
+ } else if (!group.maybeElectNewJoinedLeader() && !group.allMembers().isEmpty()) {
+ // If all members are not rejoining, we will postpone the completion
+ // of rebalance preparing stage, and send out another delayed operation
+ // until session timeout removes all the non-responsive members.
+ log.error("Group {} could not complete rebalance because no members rejoined.", groupId);
+
+ return tryCompleteJoinElseSchedule(group);
+ } else {
+ group.initNextGeneration();
+ if (group.isInState(EMPTY)) {
+ log.info("Group {} with generation {} is now empty ({}-{})",
+ groupId, group.generationId(), topicPartition.topic(), topicPartition.partition());
+
+ CompletableFuture<Errors> appendFuture = new CompletableFuture<>();
+ appendFuture.whenComplete((error, t) -> {
+ if (t != null || error != Errors.NONE) {
+ // We failed to write the empty group metadata. If the broker fails before another rebalance,
+ // the previous generation written to the log will become active again (and most likely timeout).
+ // This should be safe since there are no active members in an empty generation, so we just warn.
+ String message = t != null ? t.getMessage() : error.message();
+ log.warn("Failed to write empty metadata for group {}: {}", group.groupId(), message);
+ }
+ });
+
+ List<Record> records = Collections.singletonList(
+ RecordHelpers.newGroupMetadataRecord(group, metadataImage.features().metadataVersion())
+ );
+
+ return new CoordinatorResult<>(records, appendFuture);
+
+ } else {
+ log.info("Stabilized group {} generation {} ({}-{}) with {} members",
+ groupId, group.generationId(), topicPartition.topic(),
+ topicPartition.partition(), group.size());
+
+ // Complete the awaiting join group response future for all the members after rebalancing
+ group.allMembers().forEach(member -> {
+
+ List<JoinGroupResponseData.JoinGroupResponseMember> members = Collections.emptyList();
+ if (group.isLeader(member.memberId())) {
+ members = group.currentGenericGroupMembers();
+ }
+
+ JoinGroupResponseData response = new JoinGroupResponseData()
+ .setMembers(members)
+ .setMemberId(member.memberId())
+ .setGenerationId(group.generationId())
+ .setProtocolName(group.protocolName().orElse(null))
+ .setProtocolType(group.protocolType().orElse(null))
+ .setLeader(group.leaderOrNull())
+ .setSkipAssignment(false)
+ .setErrorCode(Errors.NONE.code());
+
+ group.completeJoinFuture(member, response);
+ rescheduleGenericGroupMemberHeartbeat(group, member);
Review Comment:
We need to discuss whether we want to start the heartbeat timer here or not. See [KAFKA-13766](https://issues.apache.org/jira/browse/KAFKA-13766).
##########
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/GroupMetadataManager.java:
##########
@@ -874,4 +1045,1265 @@ public void replay(
consumerGroup.updateMember(newMember);
}
}
+
+ // Below stores all methods to handle generic group APIs.
+
+ /**
+ * Handle a JoinGroupRequest.
+ *
+ * @param context The request context.
+ * @param request The actual JoinGroup request.
+ *
+ * @return The result that contains records to append if the join group phase completes.
+ */
+ public CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoin(
+ RequestContext context,
+ JoinGroupRequestData request,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ CoordinatorResult<CompletableFuture<Errors>, Record> result = EMPTY_RESULT;
+ String groupId = request.groupId();
+ String memberId = request.memberId();
+ int sessionTimeoutMs = request.sessionTimeoutMs();
+
+ if (sessionTimeoutMs < groupMinSessionTimeoutMs ||
+ sessionTimeoutMs > groupMaxSessionTimeoutMs
+ ) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.INVALID_SESSION_TIMEOUT.code())
+ );
+ } else {
+ boolean isUnknownMember = memberId.equals(UNKNOWN_MEMBER_ID);
+ // Group is created if it does not exist and the member id is UNKNOWN. if member
+ // is specified but group does not exist, request is rejected with GROUP_ID_NOT_FOUND
+ GenericGroup group;
+ try {
+ group = (GenericGroup) getOrMaybeCreateGroup(groupId, GENERIC, isUnknownMember);
+ } catch (Throwable t) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.forException(t).code())
+ );
+ return EMPTY_RESULT;
+ }
+
+ String joinReason = request.reason();
+ if (joinReason == null || joinReason.isEmpty()) {
+ joinReason = "not provided";
+ }
+
+ if (!acceptJoiningMember(group, memberId)) {
+ group.remove(memberId);
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.GROUP_MAX_SIZE_REACHED.code())
+ );
+
+ } else if (isUnknownMember) {
+ result = genericGroupJoinNewMember(
+ context,
+ request,
+ group,
+ joinReason,
+ responseFuture
+ );
+ } else {
+ result = genericGroupJoinExistingMember(
+ context,
+ request,
+ group,
+ joinReason,
+ responseFuture
+ );
+ }
+
+ // Attempt to complete join group phase. We do not complete
+ // the join group phase if this is the initial rebalance.
+ if (group.isInState(PREPARING_REBALANCE) &&
+ group.hasAllMembersJoined() &&
+ group.generationId() != 0
+ ) {
+ completeGenericGroupJoin(group);
+ }
+ }
+
+ return result;
+ }
+
+ /**
+ * Handle a new member generic group join.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinNewMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ List<Protocol> protocols = new ArrayList<>();
+ request.protocols().forEach(protocol -> protocols.add(new Protocol(protocol.name(), protocol.metadata())));
+ if (group.isInState(DEAD)) {
+ // if the group is marked as dead, it means some other thread has just removed the group
+ // from the coordinator metadata; it is likely that the group has migrated to some other
+ // coordinator OR the group is in a transient unstable phase. Let the member retry
+ // finding the correct coordinator and rejoin.
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.COORDINATOR_NOT_AVAILABLE.code())
+ );
+ } else if (!group.supportsProtocols(request.protocolType(), GenericGroupMember.plainProtocolSet(protocols))) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.INCONSISTENT_GROUP_PROTOCOL.code())
+ );
+ } else {
+ Optional<String> groupInstanceId = Optional.ofNullable(request.groupInstanceId());
+ String newMemberId = group.generateMemberId(context.clientId(), groupInstanceId);
+
+ if (groupInstanceId.isPresent()) {
+ return genericGroupJoinNewStaticMember(
+ context,
+ request,
+ group,
+ newMemberId,
+ joinReason,
+ responseFuture
+ );
+ } else {
+ return genericGroupJoinNewDynamicMember(
+ context,
+ request,
+ group,
+ newMemberId,
+ joinReason,
+ responseFuture
+ );
+ }
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Handle new static member join. If there was an existing member id for the group instance id,
+ * replace that member. Otherwise, add the member and rebalance.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param newMemberId The newly generated member id.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinNewStaticMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String newMemberId,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ String groupInstanceId = request.groupInstanceId();
+ String existingMemberId = group.staticMemberId(groupInstanceId);
+ if (existingMemberId != null) {
+ log.info("Static member with groupInstanceId={} and unknown member id joins " +
+ "group {} in {} state. Replacing previously mapped member {} with this groupInstanceId.",
+ groupInstanceId, group.groupId(), group.currentState(), existingMemberId);
+
+ return updateStaticMemberAndRebalance(
+ context,
+ request,
+ group,
+ existingMemberId,
+ newMemberId,
+ joinReason,
+ responseFuture
+ );
+
+ } else {
+ log.info("Static member with groupInstanceId={} and unknown member id joins " +
+ "group {} in {} state. Created a new member id {} for this member and added to the group.",
+ groupInstanceId, group.groupId(), group.currentState(), newMemberId);
+
+ return addMemberAndRebalance(context, request, group, newMemberId, joinReason, responseFuture);
+ }
+ }
+
+ /**
+ * Handle a new dynamic member join. If the member id field is required, the group metadata manager
+ * will add the new member id to the pending members and respond with MEMBER_ID_REQUIRED along with
+ * the new member id for the client to join with.
+ *
+ * Otherwise, add the new member to the group and rebalance.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param newMemberId The newly generated member id.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinNewDynamicMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String newMemberId,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ boolean requireKnownMemberId = context.apiVersion() >= 4
+ && (request.groupInstanceId() == null || request.groupInstanceId().isEmpty());
+
+ if (requireKnownMemberId) {
+ // If member id required, register the member in the pending member list and send
+ // back a response to call for another join group request with allocated member id.
+ log.info("Dynamic member with unknown member id joins group {} in {} state. " +
+ "Created a new member id {} and requesting the member to rejoin with this id.",
+ group.groupId(), group.currentState(), newMemberId);
+
+ group.addPendingMember(newMemberId);
+ String heartbeatKey = heartbeatKey(group.groupId(), newMemberId);
+
+ timer.schedule(
+ heartbeatKey,
+ request.sessionTimeoutMs(),
+ TimeUnit.MILLISECONDS,
+ () -> expireGenericGroupMemberHeartbeat(group, newMemberId)
+ );
+
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(newMemberId)
+ .setErrorCode(Errors.MEMBER_ID_REQUIRED.code())
+ );
+
+ } else {
+ log.info("Dynamic member with unknown member id joins group {} in state {}. " +
+ "Created a new member id {} and added the member to the group.",
+ group.groupId(), group.currentState(), newMemberId);
+
+ return addMemberAndRebalance(context, request, group, newMemberId, joinReason, responseFuture);
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Handle a join group request for an existing member.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinExistingMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ List<Protocol> protocols = request.protocols().stream()
+ .map(protocol -> new Protocol(protocol.name(), protocol.metadata())).collect(Collectors.toList());
+
+ String memberId = request.memberId();
+ String groupInstanceId = request.groupInstanceId();
+
+ if (group.isInState(DEAD)) {
+ // If the group is marked as dead, it means the group was recently removed the group
+ // from the coordinator metadata; it is likely that the group has migrated to some other
+ // coordinator OR the group is in a transient unstable phase. Let the member retry
+ // finding the correct coordinator and rejoin.
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.COORDINATOR_NOT_AVAILABLE.code())
+ );
+ } else if (!group.supportsProtocols(
+ request.protocolType(),
+ GenericGroupMember.plainProtocolSet(protocols))
+ ) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.INCONSISTENT_GROUP_PROTOCOL.code())
+ );
+ } else if (group.isPendingMember(memberId)) {
+ // A rejoining pending member will be accepted. Note that pending member cannot be a static member.
+ if (groupInstanceId != null) {
+ throw new IllegalStateException("Received unexpected JoinGroup with groupInstanceId=" +
+ groupInstanceId + " for pending member with memberId=" + memberId);
+ }
+
+ log.debug("Pending dynamic member with id {} joins group {} in {} state. Adding to the group now.",
+ memberId, group.groupId(), group.currentState());
+
+ return addMemberAndRebalance(
+ context,
+ request,
+ group,
+ memberId,
+ joinReason,
+ responseFuture
+ );
+ } else {
+ Optional<Errors> memberError = validateExistingMember(
+ group,
+ memberId,
+ groupInstanceId,
+ "join-group"
+ );
+
+ if (memberError.isPresent()) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(memberError.get().code())
+ );
+ } else {
+ GenericGroupMember member = group.member(memberId);
+ if (group.isInState(PREPARING_REBALANCE)) {
+ return updateMemberAndRebalance(
+ request,
+ group,
+ member,
+ "Member " + member.memberId() + " is joining group during " +
+ group.stateAsString() + "; client reason: " + joinReason,
+ responseFuture
+ );
+ } else if (group.isInState(COMPLETING_REBALANCE)) {
+ if (member.matches(protocols)) {
+ // Member is joining with the same metadata (which could be because it failed to
+ // receive the initial JoinGroup response), so just return current group information
+ // for the current generation.
+ List<JoinGroupResponseData.JoinGroupResponseMember> members = Collections.emptyList();
+ if (group.isLeader(memberId)) {
+ members = group.currentGenericGroupMembers();
+ }
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMembers(members)
+ .setMemberId(memberId)
+ .setGenerationId(group.generationId())
+ .setProtocolName(group.protocolName().orElse(null))
+ .setProtocolType(group.protocolType().orElse(null))
+ .setLeader(group.leaderOrNull())
+ .setSkipAssignment(false)
+ .setErrorCode(Errors.NONE.code())
+ );
+ } else {
+ // Member has changed metadata, so force a rebalance
+ return updateMemberAndRebalance(
+ request,
+ group,
+ member,
+ "Updating metadata for member " + memberId + " during " +
+ group.stateAsString() + "; client reason: " + joinReason,
+ responseFuture
+ );
+ }
+ } else if (group.isInState(STABLE)) {
+ if (group.isLeader(memberId)) {
+ // Force a rebalance if the leader sends JoinGroup;
+ // This allows the leader to trigger rebalances for changes affecting assignment
+ // which do not affect the member metadata (such as topic metadata changes for the consumer)
+ return updateMemberAndRebalance(
+ request,
+ group,
+ member,
+ "Leader " + memberId + " re-joining group during " +
+ group.stateAsString() + "; client reason: " + joinReason,
+ responseFuture
+ );
+ } else if (!member.matches(protocols)) {
+ return updateMemberAndRebalance(
+ request,
+ group,
+ member,
+ "Updating metadata for member " + memberId + " during " +
+ group.stateAsString() + "; client reason: " + joinReason,
+ responseFuture
+ );
+ } else {
+ // For followers with no actual change to their metadata, just return group information
+ // for the current generation which will allow them to issue SyncGroup.
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMembers(Collections.emptyList())
+ .setMemberId(memberId)
+ .setGenerationId(group.generationId())
+ .setProtocolName(group.protocolName().orElse(null))
+ .setProtocolType(group.protocolType().orElse(null))
+ .setLeader(group.leaderOrNull())
+ .setSkipAssignment(false)
+ .setErrorCode(Errors.NONE.code())
+ );
+ }
+ } else {
+ // Group reached unexpected (Empty) state. Let the joining member reset their generation and rejoin.
+ log.warn("Attempt to add rejoining member {} of group {} in unexpected group state {}",
+ memberId, group.groupId(), group.stateAsString());
+
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.UNKNOWN_MEMBER_ID.code())
+ );
+ }
+ }
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Complete the join group phase. Remove all dynamic members that have not rejoined
+ * during this stage and proceed with the next generation for this group. The generation id
+ * is incremented and the group transitions to CompletingRebalance state if there is at least
+ * one member.
+ *
+ * If the group is in Empty state, append a new group metadata record to the log. Otherwise,
+ * complete all members' join group response futures and wait for sync requests from members.
+ *
+ * @param group The group that is completing the join group phase.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> completeGenericGroupJoin(
+ GenericGroup group
+ ) {
+ timer.cancel(joinKey(group.groupId()));
+ String groupId = group.groupId();
+
+ Map<String, GenericGroupMember> notYetRejoinedDynamicMembers =
+ group.notYetRejoinedMembers().entrySet().stream()
+ .filter(entry -> !entry.getValue().isStaticMember())
+ .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
+
+ if (!notYetRejoinedDynamicMembers.isEmpty()) {
+ notYetRejoinedDynamicMembers.values().forEach(failedMember -> {
+ group.remove(failedMember.memberId());
+ timer.cancel(heartbeatKey(group.groupId(), failedMember.memberId()));
+ });
+
+ log.info("Group {} removed dynamic members who haven't joined: {}",
+ groupId, notYetRejoinedDynamicMembers.keySet());
+ }
+
+ if (group.isInState(DEAD)) {
+ log.info("Group {} is dead, skipping rebalance stage.", groupId);
+ } else if (!group.maybeElectNewJoinedLeader() && !group.allMembers().isEmpty()) {
+ // If all members are not rejoining, we will postpone the completion
+ // of rebalance preparing stage, and send out another delayed operation
+ // until session timeout removes all the non-responsive members.
+ log.error("Group {} could not complete rebalance because no members rejoined.", groupId);
+
+ return tryCompleteJoinElseSchedule(group);
+ } else {
+ group.initNextGeneration();
+ if (group.isInState(EMPTY)) {
+ log.info("Group {} with generation {} is now empty ({}-{})",
+ groupId, group.generationId(), topicPartition.topic(), topicPartition.partition());
+
+ CompletableFuture<Errors> appendFuture = new CompletableFuture<>();
+ appendFuture.whenComplete((error, t) -> {
+ if (t != null || error != Errors.NONE) {
+ // We failed to write the empty group metadata. If the broker fails before another rebalance,
+ // the previous generation written to the log will become active again (and most likely timeout).
+ // This should be safe since there are no active members in an empty generation, so we just warn.
+ String message = t != null ? t.getMessage() : error.message();
+ log.warn("Failed to write empty metadata for group {}: {}", group.groupId(), message);
+ }
+ });
+
+ List<Record> records = Collections.singletonList(
+ RecordHelpers.newGroupMetadataRecord(group, metadataImage.features().metadataVersion())
+ );
+
+ return new CoordinatorResult<>(records, appendFuture);
+
+ } else {
+ log.info("Stabilized group {} generation {} ({}-{}) with {} members",
+ groupId, group.generationId(), topicPartition.topic(),
+ topicPartition.partition(), group.size());
+
+ // Complete the awaiting join group response future for all the members after rebalancing
+ group.allMembers().forEach(member -> {
+
+ List<JoinGroupResponseData.JoinGroupResponseMember> members = Collections.emptyList();
+ if (group.isLeader(member.memberId())) {
+ members = group.currentGenericGroupMembers();
+ }
+
+ JoinGroupResponseData response = new JoinGroupResponseData()
+ .setMembers(members)
+ .setMemberId(member.memberId())
+ .setGenerationId(group.generationId())
+ .setProtocolName(group.protocolName().orElse(null))
+ .setProtocolType(group.protocolType().orElse(null))
+ .setLeader(group.leaderOrNull())
+ .setSkipAssignment(false)
+ .setErrorCode(Errors.NONE.code());
+
+ group.completeJoinFuture(member, response);
+ rescheduleGenericGroupMemberHeartbeat(group, member);
+ member.setIsNew(false);
+
+ group.addPendingSyncMember(member.memberId());
+ });
+
+ schedulePendingSync(group);
+ }
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Wait for sync requests for the group.
+ *
+ * @param group The group.
+ */
+ private void schedulePendingSync(GenericGroup group) {
+ timer.schedule(syncKey(group.groupId()),
+ group.rebalanceTimeoutMs(),
+ TimeUnit.MILLISECONDS,
+ () -> expirePendingSync(group, group.generationId()));
+ }
+
+ /**
+ * Invoked when the heartbeat operation is expired from the timer. Possibly remove the member and
+ * try complete the join phase.
+ *
+ * @param group The group.
+ * @param memberId The member id.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> expireGenericGroupMemberHeartbeat(
+ GenericGroup group,
+ String memberId
+ ) {
+ if (group.isInState(DEAD)) {
+ log.info("Received notification of heartbeat expiration for member {} after group {} " +
+ "had already been unloaded or deleted.",
+ memberId, group.groupId());
+
+ } else if (group.isPendingMember(memberId)) {
+ log.info("Pending member {} in group {} has been removed after session timeout expiration.",
+ memberId, group.groupId());
+
+ return removePendingMemberAndUpdateGenericGroup(group, memberId);
+ } else if (!group.hasMemberId(memberId)) {
+ log.debug("Member {} has already been removed from the group.", memberId);
+ } else {
+ GenericGroupMember member = group.member(memberId);
+ if (!member.hasSatisfiedHeartbeat()) {
+ log.info("Member {} in group {} has failed, removing it from the group.",
+ member.memberId(), group.groupId());
+
+ return removeMemberAndUpdateGenericGroup(
+ group,
+ member,
+ "removing member " + member.memberId() + " on heartbeat expiration."
+ );
+ }
+ }
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Invoked when the heartbeat key is expired from the timer. Possibly remove the member
+ * from the group and try to complete the join phase.
+ *
+ * @param group The group.
+ * @param member The member.
+ * @param reason The reason for removing the member.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> removeMemberAndUpdateGenericGroup(
+ GenericGroup group,
+ GenericGroupMember member,
+ String reason
+ ) {
+ // New members may timeout with a pending JoinGroup while the group is still rebalancing, so we have
+ // to invoke the response future before removing the member. We return UNKNOWN_MEMBER_ID so
+ // that the consumer will retry the JoinGroup request if it is still active.
+ group.completeJoinFuture(member, new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.UNKNOWN_MEMBER_ID.code())
+ );
+ group.remove(member.memberId());
+
+ if (group.isInState(STABLE) || group.isInState(COMPLETING_REBALANCE)) {
+ return maybePrepareRebalance(group, reason);
+ } else if (group.isInState(PREPARING_REBALANCE) && group.hasAllMembersJoined()) {
+ return completeGenericGroupJoin(group);
+ } // Do nothing if state is DEAD or EMPTY.
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Remove a pending member from the group and possibly complete the join phase.
+ *
+ * @param group The group.
+ * @param memberId The member id.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> removePendingMemberAndUpdateGenericGroup(
+ GenericGroup group,
+ String memberId
+ ) {
+ group.remove(memberId);
+
+ if (group.isInState(PREPARING_REBALANCE) && group.hasAllMembersJoined()) {
+ return completeGenericGroupJoin(group);
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Update an existing member and rebalance.
+ *
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param member The member.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> updateMemberAndRebalance(
+ JoinGroupRequestData request,
+ GenericGroup group,
+ GenericGroupMember member,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ List<Protocol> protocols = request.protocols().stream()
+ .map(protocol -> new Protocol(protocol.name(), protocol.metadata()))
+ .collect(Collectors.toList());
+
+ group.updateMember(member, protocols, request.rebalanceTimeoutMs(), request.sessionTimeoutMs(), responseFuture);
+ return maybePrepareRebalance(group, joinReason);
+ }
+
+ /**
+ * We are validating two things:
+ * 1. If `groupInstanceId` is present, then it exists and is mapped to `memberId`
+ * 2. The `memberId` exists in the group
+ *
+ * @param group The generic group.
+ * @param memberId The member id.
+ * @param groupInstanceId The group instance id.
+ * @param operation The API operation.
+ *
+ * @return the error.
+ */
+ private Optional<Errors> validateExistingMember(
+ GenericGroup group,
+ String memberId,
+ String groupInstanceId,
+ String operation
+ ) {
+ if (groupInstanceId == null) {
+ if (!group.hasMemberId(memberId)) {
+ return Optional.of(Errors.UNKNOWN_MEMBER_ID);
+ } else {
+ return Optional.empty();
+ }
+ }
+
+ String existingMemberId = group.staticMemberId(groupInstanceId);
+ if (existingMemberId == null) {
+ return Optional.of(Errors.UNKNOWN_MEMBER_ID);
+ }
+
+ if (!existingMemberId.equals(memberId)) {
+ log.info("Request memberId={} for static member with groupInstanceId={} " +
+ "is fenced by existing memberId={} during operation {}",
+ memberId, groupInstanceId, existingMemberId, operation);
+
+ return Optional.of(Errors.FENCED_INSTANCE_ID);
+ }
+
+ return Optional.empty();
+ }
+
+ /**
+ * Add a member and rebalance.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param memberId The member id.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> addMemberAndRebalance(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String memberId,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ List<Protocol> protocols = new ArrayList<>();
+ request.protocols().forEach(protocol -> protocols.add(new Protocol(protocol.name(), protocol.metadata())));
+ Optional<String> groupInstanceId = Optional.ofNullable(request.groupInstanceId());
+ GenericGroupMember member = new GenericGroupMember(
+ memberId,
+ groupInstanceId,
+ context.clientId(),
+ context.clientAddress().toString(),
+ request.rebalanceTimeoutMs(),
+ request.sessionTimeoutMs(),
+ request.protocolType(),
+ protocols
+ );
+
+ member.setIsNew(true);
+
+ // Update the newMemberAdded flag to indicate that the initial rebalance can be further delayed
+ if (group.isInState(PREPARING_REBALANCE) && group.generationId() == 0) {
+ group.setNewMemberAdded(true);
+ }
+
+ group.add(member, responseFuture);
+
+ // The session timeout does not affect new members since they do not have their memberId and
+ // cannot send heartbeats. Furthermore, we cannot detect disconnects because sockets are muted
+ // while the JoinGroup request is parked. If the client does disconnect (e.g. because of a request
+ // timeout during a long rebalance), they may simply retry which will lead to a lot of defunct
+ // members in the rebalance. To prevent this going on indefinitely, we time out JoinGroup requests
+ // for new members. If the new member is still there, we expect it to retry.
+ rescheduleGenericGroupMemberHeartbeat(group, member, newMemberJoinTimeoutMs);
Review Comment:
I wonder if we should use a different timer for this case. Have you considered it?
##########
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/GroupMetadataManager.java:
##########
@@ -874,4 +1045,1265 @@ public void replay(
consumerGroup.updateMember(newMember);
}
}
+
+ // Below stores all methods to handle generic group APIs.
+
+ /**
+ * Handle a JoinGroupRequest.
+ *
+ * @param context The request context.
+ * @param request The actual JoinGroup request.
+ *
+ * @return The result that contains records to append if the join group phase completes.
+ */
+ public CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoin(
+ RequestContext context,
+ JoinGroupRequestData request,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ CoordinatorResult<CompletableFuture<Errors>, Record> result = EMPTY_RESULT;
+ String groupId = request.groupId();
+ String memberId = request.memberId();
+ int sessionTimeoutMs = request.sessionTimeoutMs();
+
+ if (sessionTimeoutMs < groupMinSessionTimeoutMs ||
+ sessionTimeoutMs > groupMaxSessionTimeoutMs
+ ) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.INVALID_SESSION_TIMEOUT.code())
+ );
+ } else {
+ boolean isUnknownMember = memberId.equals(UNKNOWN_MEMBER_ID);
+ // Group is created if it does not exist and the member id is UNKNOWN. if member
+ // is specified but group does not exist, request is rejected with GROUP_ID_NOT_FOUND
+ GenericGroup group;
+ try {
+ group = (GenericGroup) getOrMaybeCreateGroup(groupId, GENERIC, isUnknownMember);
+ } catch (Throwable t) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.forException(t).code())
+ );
+ return EMPTY_RESULT;
+ }
+
+ String joinReason = request.reason();
+ if (joinReason == null || joinReason.isEmpty()) {
+ joinReason = "not provided";
+ }
+
+ if (!acceptJoiningMember(group, memberId)) {
+ group.remove(memberId);
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.GROUP_MAX_SIZE_REACHED.code())
+ );
+
+ } else if (isUnknownMember) {
+ result = genericGroupJoinNewMember(
+ context,
+ request,
+ group,
+ joinReason,
+ responseFuture
+ );
+ } else {
+ result = genericGroupJoinExistingMember(
+ context,
+ request,
+ group,
+ joinReason,
+ responseFuture
+ );
+ }
+
+ // Attempt to complete join group phase. We do not complete
+ // the join group phase if this is the initial rebalance.
+ if (group.isInState(PREPARING_REBALANCE) &&
+ group.hasAllMembersJoined() &&
+ group.generationId() != 0
+ ) {
+ completeGenericGroupJoin(group);
+ }
+ }
+
+ return result;
+ }
+
+ /**
+ * Handle a new member generic group join.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinNewMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ List<Protocol> protocols = new ArrayList<>();
+ request.protocols().forEach(protocol -> protocols.add(new Protocol(protocol.name(), protocol.metadata())));
+ if (group.isInState(DEAD)) {
+ // if the group is marked as dead, it means some other thread has just removed the group
+ // from the coordinator metadata; it is likely that the group has migrated to some other
+ // coordinator OR the group is in a transient unstable phase. Let the member retry
+ // finding the correct coordinator and rejoin.
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.COORDINATOR_NOT_AVAILABLE.code())
+ );
+ } else if (!group.supportsProtocols(request.protocolType(), GenericGroupMember.plainProtocolSet(protocols))) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.INCONSISTENT_GROUP_PROTOCOL.code())
+ );
+ } else {
+ Optional<String> groupInstanceId = Optional.ofNullable(request.groupInstanceId());
+ String newMemberId = group.generateMemberId(context.clientId(), groupInstanceId);
+
+ if (groupInstanceId.isPresent()) {
+ return genericGroupJoinNewStaticMember(
+ context,
+ request,
+ group,
+ newMemberId,
+ joinReason,
+ responseFuture
+ );
+ } else {
+ return genericGroupJoinNewDynamicMember(
+ context,
+ request,
+ group,
+ newMemberId,
+ joinReason,
+ responseFuture
+ );
+ }
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Handle new static member join. If there was an existing member id for the group instance id,
+ * replace that member. Otherwise, add the member and rebalance.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param newMemberId The newly generated member id.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinNewStaticMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String newMemberId,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ String groupInstanceId = request.groupInstanceId();
+ String existingMemberId = group.staticMemberId(groupInstanceId);
+ if (existingMemberId != null) {
+ log.info("Static member with groupInstanceId={} and unknown member id joins " +
+ "group {} in {} state. Replacing previously mapped member {} with this groupInstanceId.",
+ groupInstanceId, group.groupId(), group.currentState(), existingMemberId);
+
+ return updateStaticMemberAndRebalance(
+ context,
+ request,
+ group,
+ existingMemberId,
+ newMemberId,
+ joinReason,
+ responseFuture
+ );
+
+ } else {
+ log.info("Static member with groupInstanceId={} and unknown member id joins " +
+ "group {} in {} state. Created a new member id {} for this member and added to the group.",
+ groupInstanceId, group.groupId(), group.currentState(), newMemberId);
+
+ return addMemberAndRebalance(context, request, group, newMemberId, joinReason, responseFuture);
+ }
+ }
+
+ /**
+ * Handle a new dynamic member join. If the member id field is required, the group metadata manager
+ * will add the new member id to the pending members and respond with MEMBER_ID_REQUIRED along with
+ * the new member id for the client to join with.
+ *
+ * Otherwise, add the new member to the group and rebalance.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param newMemberId The newly generated member id.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinNewDynamicMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String newMemberId,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ boolean requireKnownMemberId = context.apiVersion() >= 4
+ && (request.groupInstanceId() == null || request.groupInstanceId().isEmpty());
+
+ if (requireKnownMemberId) {
+ // If member id required, register the member in the pending member list and send
+ // back a response to call for another join group request with allocated member id.
+ log.info("Dynamic member with unknown member id joins group {} in {} state. " +
+ "Created a new member id {} and requesting the member to rejoin with this id.",
+ group.groupId(), group.currentState(), newMemberId);
+
+ group.addPendingMember(newMemberId);
+ String heartbeatKey = heartbeatKey(group.groupId(), newMemberId);
+
+ timer.schedule(
+ heartbeatKey,
+ request.sessionTimeoutMs(),
+ TimeUnit.MILLISECONDS,
+ () -> expireGenericGroupMemberHeartbeat(group, newMemberId)
+ );
+
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(newMemberId)
+ .setErrorCode(Errors.MEMBER_ID_REQUIRED.code())
+ );
+
+ } else {
+ log.info("Dynamic member with unknown member id joins group {} in state {}. " +
+ "Created a new member id {} and added the member to the group.",
+ group.groupId(), group.currentState(), newMemberId);
+
+ return addMemberAndRebalance(context, request, group, newMemberId, joinReason, responseFuture);
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Handle a join group request for an existing member.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinExistingMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ List<Protocol> protocols = request.protocols().stream()
+ .map(protocol -> new Protocol(protocol.name(), protocol.metadata())).collect(Collectors.toList());
+
+ String memberId = request.memberId();
+ String groupInstanceId = request.groupInstanceId();
+
+ if (group.isInState(DEAD)) {
+ // If the group is marked as dead, it means the group was recently removed the group
+ // from the coordinator metadata; it is likely that the group has migrated to some other
+ // coordinator OR the group is in a transient unstable phase. Let the member retry
+ // finding the correct coordinator and rejoin.
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.COORDINATOR_NOT_AVAILABLE.code())
+ );
+ } else if (!group.supportsProtocols(
+ request.protocolType(),
+ GenericGroupMember.plainProtocolSet(protocols))
+ ) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.INCONSISTENT_GROUP_PROTOCOL.code())
+ );
+ } else if (group.isPendingMember(memberId)) {
+ // A rejoining pending member will be accepted. Note that pending member cannot be a static member.
+ if (groupInstanceId != null) {
+ throw new IllegalStateException("Received unexpected JoinGroup with groupInstanceId=" +
+ groupInstanceId + " for pending member with memberId=" + memberId);
+ }
+
+ log.debug("Pending dynamic member with id {} joins group {} in {} state. Adding to the group now.",
+ memberId, group.groupId(), group.currentState());
+
+ return addMemberAndRebalance(
+ context,
+ request,
+ group,
+ memberId,
+ joinReason,
+ responseFuture
+ );
+ } else {
+ Optional<Errors> memberError = validateExistingMember(
+ group,
+ memberId,
+ groupInstanceId,
+ "join-group"
+ );
+
+ if (memberError.isPresent()) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(memberError.get().code())
+ );
+ } else {
+ GenericGroupMember member = group.member(memberId);
+ if (group.isInState(PREPARING_REBALANCE)) {
+ return updateMemberAndRebalance(
+ request,
+ group,
+ member,
+ "Member " + member.memberId() + " is joining group during " +
+ group.stateAsString() + "; client reason: " + joinReason,
+ responseFuture
+ );
+ } else if (group.isInState(COMPLETING_REBALANCE)) {
+ if (member.matches(protocols)) {
+ // Member is joining with the same metadata (which could be because it failed to
+ // receive the initial JoinGroup response), so just return current group information
+ // for the current generation.
+ List<JoinGroupResponseData.JoinGroupResponseMember> members = Collections.emptyList();
+ if (group.isLeader(memberId)) {
+ members = group.currentGenericGroupMembers();
+ }
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMembers(members)
+ .setMemberId(memberId)
+ .setGenerationId(group.generationId())
+ .setProtocolName(group.protocolName().orElse(null))
+ .setProtocolType(group.protocolType().orElse(null))
+ .setLeader(group.leaderOrNull())
+ .setSkipAssignment(false)
+ .setErrorCode(Errors.NONE.code())
+ );
+ } else {
+ // Member has changed metadata, so force a rebalance
+ return updateMemberAndRebalance(
+ request,
+ group,
+ member,
+ "Updating metadata for member " + memberId + " during " +
+ group.stateAsString() + "; client reason: " + joinReason,
+ responseFuture
+ );
+ }
+ } else if (group.isInState(STABLE)) {
+ if (group.isLeader(memberId)) {
+ // Force a rebalance if the leader sends JoinGroup;
+ // This allows the leader to trigger rebalances for changes affecting assignment
+ // which do not affect the member metadata (such as topic metadata changes for the consumer)
+ return updateMemberAndRebalance(
+ request,
+ group,
+ member,
+ "Leader " + memberId + " re-joining group during " +
+ group.stateAsString() + "; client reason: " + joinReason,
+ responseFuture
+ );
+ } else if (!member.matches(protocols)) {
+ return updateMemberAndRebalance(
+ request,
+ group,
+ member,
+ "Updating metadata for member " + memberId + " during " +
+ group.stateAsString() + "; client reason: " + joinReason,
+ responseFuture
+ );
+ } else {
+ // For followers with no actual change to their metadata, just return group information
+ // for the current generation which will allow them to issue SyncGroup.
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMembers(Collections.emptyList())
+ .setMemberId(memberId)
+ .setGenerationId(group.generationId())
+ .setProtocolName(group.protocolName().orElse(null))
+ .setProtocolType(group.protocolType().orElse(null))
+ .setLeader(group.leaderOrNull())
+ .setSkipAssignment(false)
+ .setErrorCode(Errors.NONE.code())
+ );
+ }
+ } else {
+ // Group reached unexpected (Empty) state. Let the joining member reset their generation and rejoin.
+ log.warn("Attempt to add rejoining member {} of group {} in unexpected group state {}",
+ memberId, group.groupId(), group.stateAsString());
+
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.UNKNOWN_MEMBER_ID.code())
+ );
+ }
+ }
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Complete the join group phase. Remove all dynamic members that have not rejoined
+ * during this stage and proceed with the next generation for this group. The generation id
+ * is incremented and the group transitions to CompletingRebalance state if there is at least
+ * one member.
+ *
+ * If the group is in Empty state, append a new group metadata record to the log. Otherwise,
+ * complete all members' join group response futures and wait for sync requests from members.
+ *
+ * @param group The group that is completing the join group phase.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> completeGenericGroupJoin(
+ GenericGroup group
+ ) {
+ timer.cancel(joinKey(group.groupId()));
+ String groupId = group.groupId();
+
+ Map<String, GenericGroupMember> notYetRejoinedDynamicMembers =
+ group.notYetRejoinedMembers().entrySet().stream()
+ .filter(entry -> !entry.getValue().isStaticMember())
+ .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
+
+ if (!notYetRejoinedDynamicMembers.isEmpty()) {
+ notYetRejoinedDynamicMembers.values().forEach(failedMember -> {
+ group.remove(failedMember.memberId());
+ timer.cancel(heartbeatKey(group.groupId(), failedMember.memberId()));
+ });
+
+ log.info("Group {} removed dynamic members who haven't joined: {}",
+ groupId, notYetRejoinedDynamicMembers.keySet());
+ }
+
+ if (group.isInState(DEAD)) {
+ log.info("Group {} is dead, skipping rebalance stage.", groupId);
+ } else if (!group.maybeElectNewJoinedLeader() && !group.allMembers().isEmpty()) {
+ // If all members are not rejoining, we will postpone the completion
+ // of rebalance preparing stage, and send out another delayed operation
+ // until session timeout removes all the non-responsive members.
+ log.error("Group {} could not complete rebalance because no members rejoined.", groupId);
+
+ return tryCompleteJoinElseSchedule(group);
+ } else {
+ group.initNextGeneration();
+ if (group.isInState(EMPTY)) {
+ log.info("Group {} with generation {} is now empty ({}-{})",
+ groupId, group.generationId(), topicPartition.topic(), topicPartition.partition());
+
+ CompletableFuture<Errors> appendFuture = new CompletableFuture<>();
+ appendFuture.whenComplete((error, t) -> {
+ if (t != null || error != Errors.NONE) {
+ // We failed to write the empty group metadata. If the broker fails before another rebalance,
+ // the previous generation written to the log will become active again (and most likely timeout).
+ // This should be safe since there are no active members in an empty generation, so we just warn.
+ String message = t != null ? t.getMessage() : error.message();
+ log.warn("Failed to write empty metadata for group {}: {}", group.groupId(), message);
+ }
+ });
+
+ List<Record> records = Collections.singletonList(
+ RecordHelpers.newGroupMetadataRecord(group, metadataImage.features().metadataVersion())
+ );
+
+ return new CoordinatorResult<>(records, appendFuture);
+
+ } else {
+ log.info("Stabilized group {} generation {} ({}-{}) with {} members",
+ groupId, group.generationId(), topicPartition.topic(),
+ topicPartition.partition(), group.size());
+
+ // Complete the awaiting join group response future for all the members after rebalancing
+ group.allMembers().forEach(member -> {
+
+ List<JoinGroupResponseData.JoinGroupResponseMember> members = Collections.emptyList();
+ if (group.isLeader(member.memberId())) {
+ members = group.currentGenericGroupMembers();
+ }
+
+ JoinGroupResponseData response = new JoinGroupResponseData()
+ .setMembers(members)
+ .setMemberId(member.memberId())
+ .setGenerationId(group.generationId())
+ .setProtocolName(group.protocolName().orElse(null))
+ .setProtocolType(group.protocolType().orElse(null))
+ .setLeader(group.leaderOrNull())
+ .setSkipAssignment(false)
+ .setErrorCode(Errors.NONE.code());
+
+ group.completeJoinFuture(member, response);
+ rescheduleGenericGroupMemberHeartbeat(group, member);
+ member.setIsNew(false);
+
+ group.addPendingSyncMember(member.memberId());
+ });
+
+ schedulePendingSync(group);
+ }
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Wait for sync requests for the group.
+ *
+ * @param group The group.
+ */
+ private void schedulePendingSync(GenericGroup group) {
+ timer.schedule(syncKey(group.groupId()),
+ group.rebalanceTimeoutMs(),
+ TimeUnit.MILLISECONDS,
+ () -> expirePendingSync(group, group.generationId()));
+ }
+
+ /**
+ * Invoked when the heartbeat operation is expired from the timer. Possibly remove the member and
+ * try complete the join phase.
+ *
+ * @param group The group.
+ * @param memberId The member id.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> expireGenericGroupMemberHeartbeat(
+ GenericGroup group,
+ String memberId
+ ) {
+ if (group.isInState(DEAD)) {
+ log.info("Received notification of heartbeat expiration for member {} after group {} " +
+ "had already been unloaded or deleted.",
+ memberId, group.groupId());
+
+ } else if (group.isPendingMember(memberId)) {
+ log.info("Pending member {} in group {} has been removed after session timeout expiration.",
+ memberId, group.groupId());
+
+ return removePendingMemberAndUpdateGenericGroup(group, memberId);
+ } else if (!group.hasMemberId(memberId)) {
+ log.debug("Member {} has already been removed from the group.", memberId);
+ } else {
+ GenericGroupMember member = group.member(memberId);
+ if (!member.hasSatisfiedHeartbeat()) {
+ log.info("Member {} in group {} has failed, removing it from the group.",
+ member.memberId(), group.groupId());
+
+ return removeMemberAndUpdateGenericGroup(
+ group,
+ member,
+ "removing member " + member.memberId() + " on heartbeat expiration."
+ );
+ }
+ }
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Invoked when the heartbeat key is expired from the timer. Possibly remove the member
+ * from the group and try to complete the join phase.
+ *
+ * @param group The group.
+ * @param member The member.
+ * @param reason The reason for removing the member.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> removeMemberAndUpdateGenericGroup(
+ GenericGroup group,
+ GenericGroupMember member,
+ String reason
+ ) {
+ // New members may timeout with a pending JoinGroup while the group is still rebalancing, so we have
+ // to invoke the response future before removing the member. We return UNKNOWN_MEMBER_ID so
+ // that the consumer will retry the JoinGroup request if it is still active.
+ group.completeJoinFuture(member, new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.UNKNOWN_MEMBER_ID.code())
+ );
+ group.remove(member.memberId());
+
+ if (group.isInState(STABLE) || group.isInState(COMPLETING_REBALANCE)) {
+ return maybePrepareRebalance(group, reason);
+ } else if (group.isInState(PREPARING_REBALANCE) && group.hasAllMembersJoined()) {
+ return completeGenericGroupJoin(group);
+ } // Do nothing if state is DEAD or EMPTY.
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Remove a pending member from the group and possibly complete the join phase.
+ *
+ * @param group The group.
+ * @param memberId The member id.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> removePendingMemberAndUpdateGenericGroup(
+ GenericGroup group,
+ String memberId
+ ) {
+ group.remove(memberId);
+
+ if (group.isInState(PREPARING_REBALANCE) && group.hasAllMembersJoined()) {
+ return completeGenericGroupJoin(group);
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Update an existing member and rebalance.
+ *
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param member The member.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> updateMemberAndRebalance(
+ JoinGroupRequestData request,
+ GenericGroup group,
+ GenericGroupMember member,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ List<Protocol> protocols = request.protocols().stream()
+ .map(protocol -> new Protocol(protocol.name(), protocol.metadata()))
+ .collect(Collectors.toList());
+
+ group.updateMember(member, protocols, request.rebalanceTimeoutMs(), request.sessionTimeoutMs(), responseFuture);
+ return maybePrepareRebalance(group, joinReason);
+ }
+
+ /**
+ * We are validating two things:
+ * 1. If `groupInstanceId` is present, then it exists and is mapped to `memberId`
+ * 2. The `memberId` exists in the group
+ *
+ * @param group The generic group.
+ * @param memberId The member id.
+ * @param groupInstanceId The group instance id.
+ * @param operation The API operation.
+ *
+ * @return the error.
+ */
+ private Optional<Errors> validateExistingMember(
+ GenericGroup group,
+ String memberId,
+ String groupInstanceId,
+ String operation
+ ) {
+ if (groupInstanceId == null) {
+ if (!group.hasMemberId(memberId)) {
+ return Optional.of(Errors.UNKNOWN_MEMBER_ID);
+ } else {
+ return Optional.empty();
+ }
+ }
+
+ String existingMemberId = group.staticMemberId(groupInstanceId);
+ if (existingMemberId == null) {
+ return Optional.of(Errors.UNKNOWN_MEMBER_ID);
+ }
+
+ if (!existingMemberId.equals(memberId)) {
+ log.info("Request memberId={} for static member with groupInstanceId={} " +
+ "is fenced by existing memberId={} during operation {}",
+ memberId, groupInstanceId, existingMemberId, operation);
+
+ return Optional.of(Errors.FENCED_INSTANCE_ID);
+ }
+
+ return Optional.empty();
+ }
+
+ /**
+ * Add a member and rebalance.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param memberId The member id.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> addMemberAndRebalance(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String memberId,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ List<Protocol> protocols = new ArrayList<>();
+ request.protocols().forEach(protocol -> protocols.add(new Protocol(protocol.name(), protocol.metadata())));
+ Optional<String> groupInstanceId = Optional.ofNullable(request.groupInstanceId());
+ GenericGroupMember member = new GenericGroupMember(
+ memberId,
+ groupInstanceId,
+ context.clientId(),
+ context.clientAddress().toString(),
+ request.rebalanceTimeoutMs(),
+ request.sessionTimeoutMs(),
+ request.protocolType(),
+ protocols
+ );
+
+ member.setIsNew(true);
+
+ // Update the newMemberAdded flag to indicate that the initial rebalance can be further delayed
+ if (group.isInState(PREPARING_REBALANCE) && group.generationId() == 0) {
+ group.setNewMemberAdded(true);
+ }
+
+ group.add(member, responseFuture);
+
+ // The session timeout does not affect new members since they do not have their memberId and
+ // cannot send heartbeats. Furthermore, we cannot detect disconnects because sockets are muted
+ // while the JoinGroup request is parked. If the client does disconnect (e.g. because of a request
+ // timeout during a long rebalance), they may simply retry which will lead to a lot of defunct
+ // members in the rebalance. To prevent this going on indefinitely, we time out JoinGroup requests
+ // for new members. If the new member is still there, we expect it to retry.
+ rescheduleGenericGroupMemberHeartbeat(group, member, newMemberJoinTimeoutMs);
+
+ return maybePrepareRebalance(group, "Adding new member " + memberId + " with group instance id " +
+ request.groupInstanceId() + "; client reason: " + joinReason);
+ }
+
+ /**
+ * Prepare a rebalance if the group is in a valid state.
+ *
+ * @param group The group to rebalance.
+ * @param reason The reason for the rebalance.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> maybePrepareRebalance(
+ GenericGroup group,
+ String reason
+ ) {
+ if (group.canRebalance()) {
+ return prepareRebalance(group, reason);
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Prepare a rebalance.
+ *
+ * @param group The group to rebalance.
+ * @param reason The reason for the rebalance.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ CoordinatorResult<CompletableFuture<Errors>, Record> prepareRebalance(
+ GenericGroup group,
+ String reason
+ ) {
+ // If any members are awaiting sync, cancel their request and have them rejoin.
+ if (group.isInState(COMPLETING_REBALANCE)) {
+ resetAndPropagateAssignmentWithError(group, Errors.REBALANCE_IN_PROGRESS);
+ }
+
+ // If a sync expiration is pending, cancel it.
+ removeSyncExpiration(group);
+
+ boolean isInitialRebalance = group.generationId() == 0;
+ if (isInitialRebalance) {
+ // The group is new. Provide more time for the members to join.
+ int delayMs = initialRebalanceDelayMs;
+ int remainingMs = Math.max(group.rebalanceTimeoutMs() - initialRebalanceDelayMs, 0);
+ group.setInitialRebalanceTimeoutMs(remainingMs);
+ group.setInitialRebalanceDelayMs(delayMs);
+
+ timer.schedule(
+ joinKey(group.groupId()),
+ delayMs,
+ TimeUnit.MILLISECONDS,
+ () -> tryCompleteInitialRebalanceElseSchedule(group)
+ );
+ }
+
+
+ group.transitionTo(PREPARING_REBALANCE);
+
+ log.info("Preparing to rebalance group {} in state {} with old generation {} ({}-{}) (reason: {})",
+ group.groupId(), group.currentState(), group.generationId(),
+ topicPartition.topic(), topicPartition.partition(), reason);
+
+ return isInitialRebalance ? EMPTY_RESULT : tryCompleteJoinElseSchedule(group);
+ }
+
+ /**
+ * Try to complete the join phase. Otherwise, schedule a new join operation.
+ *
+ * @param group The group.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> tryCompleteJoinElseSchedule(
+ GenericGroup group
+ ) {
+ String joinKey = joinKey(group.groupId());
+ if (group.hasAllMembersJoined()) {
+ // All members have joined. Proceed to sync phase.
+ return completeGenericGroupJoin(group);
+ } else {
+ timer.schedule(
+ joinKey,
+ group.rebalanceTimeoutMs(),
+ TimeUnit.MILLISECONDS,
+ () -> completeGenericGroupJoin(group)
+ );
+ return EMPTY_RESULT;
+ }
+ }
+
+ /**
+ * Try to complete the join phase of the initial rebalance.
+ * Otherwise, extend the rebalance.
+ *
+ * @param group The group under initial rebalance.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> tryCompleteInitialRebalanceElseSchedule(
+ GenericGroup group
+ ) {
+ int remainingMs = group.initialRebalanceTimeoutMs();
+ int delayMs = group.initialRebalanceDelayMs();
+ if (group.newMemberAdded() && remainingMs != 0) {
+ // A new member was added. Extend the delay.
+ group.setNewMemberAdded(false);
+ int newDelayMs = Math.min(initialRebalanceDelayMs, remainingMs);
+ int newRemainingMs = Math.max(remainingMs - delayMs, 0);
+
+ group.setInitialRebalanceTimeoutMs(newRemainingMs);
+ group.setInitialRebalanceDelayMs(newDelayMs);
+
+ timer.schedule(
+ joinKey(group.groupId()),
+ newDelayMs,
+ TimeUnit.MILLISECONDS,
+ () -> tryCompleteInitialRebalanceElseSchedule(group)
Review Comment:
Instead of storing the initial rebalance timeout and the initial rebalance delay in the group, could we imagine passing them as arguments to `tryCompleteInitialRebalanceElseSchedule`? That could simplify the logic as everything would be self contain here.
##########
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/GroupMetadataManager.java:
##########
@@ -171,70 +260,152 @@ GroupMetadataManager build() {
/**
* The maximum number of members allowed in a single consumer group.
*/
- private final int consumerGroupMaxSize;
+ private final int groupMaxSize;
/**
* The heartbeat interval for consumer groups.
*/
private final int consumerGroupHeartbeatIntervalMs;
/**
- * The topics metadata (or image).
+ * The metadata image.
+ */
+ private MetadataImage metadataImage;
+
+ // Rest of the fields are used for the generic group APIs.
+
+ /**
+ * An empty result returned to the state machine. This means that
+ * there are no records to append to the log.
+ *
+ * Package private for testing.
+ */
+ static final CoordinatorResult<CompletableFuture<Errors>, Record> EMPTY_RESULT =
+ new CoordinatorResult<>(Collections.emptyList(), CompletableFuture.completedFuture(null));
+
+ /**
+ * Initial rebalance delay for members joining a generic group.
+ */
+ private final int initialRebalanceDelayMs;
+
+ /**
+ * The timeout used to wait for a new member in milliseconds.
+ */
+ private final int newMemberJoinTimeoutMs;
+
+ /**
+ * The group minimum session timeout.
+ */
+ private final int groupMinSessionTimeoutMs;
+
+ /**
+ * The group maximum session timeout.
+ */
+ private final int groupMaxSessionTimeoutMs;
+
+ /**
+ * The timer to add and cancel group operations.
*/
- private TopicsImage topicsImage;
+ private final Timer<CompletableFuture<Errors>, Record> timer;
+
+ /**
+ * The time.
+ */
+ private final Time time;
private GroupMetadataManager(
SnapshotRegistry snapshotRegistry,
LogContext logContext,
List<PartitionAssignor> assignors,
- TopicsImage topicsImage,
- int consumerGroupMaxSize,
- int consumerGroupHeartbeatIntervalMs
+ MetadataImage metadataImage,
+ TopicPartition topicPartition,
+ int groupMaxSize,
+ int consumerGroupHeartbeatIntervalMs,
+ int initialRebalanceDelayMs,
+ int newMemberJoinTimeoutMs,
+ int groupMinSessionTimeoutMs,
+ int groupMaxSessionTimeoutMs,
+ Timer<CompletableFuture<Errors>, Record> timer,
+ Time time
) {
+ this.logContext = logContext;
this.log = logContext.logger(GroupMetadataManager.class);
this.snapshotRegistry = snapshotRegistry;
- this.topicsImage = topicsImage;
+ this.metadataImage = metadataImage;
this.assignors = assignors.stream().collect(Collectors.toMap(PartitionAssignor::name, Function.identity()));
+ this.topicPartition = topicPartition;
this.defaultAssignor = assignors.get(0);
this.groups = new TimelineHashMap<>(snapshotRegistry, 0);
- this.consumerGroupMaxSize = consumerGroupMaxSize;
+ this.groupMaxSize = groupMaxSize;
this.consumerGroupHeartbeatIntervalMs = consumerGroupHeartbeatIntervalMs;
+ this.initialRebalanceDelayMs = initialRebalanceDelayMs;
+ this.newMemberJoinTimeoutMs = newMemberJoinTimeoutMs;
+ this.groupMinSessionTimeoutMs = groupMinSessionTimeoutMs;
+ this.groupMaxSessionTimeoutMs = groupMaxSessionTimeoutMs;
+ this.timer = timer;
+ this.time = time;
+ }
+
+ /**
+ * When a new metadata image is pushed.
+ *
+ * @param metadataImage The new metadata image.
+ */
+ public void onNewMetadataImage(MetadataImage metadataImage) {
+ this.metadataImage = metadataImage;
}
/**
* Gets or maybe creates a consumer group.
*
* @param groupId The group id.
+ * @param groupType The group type (generic or consumer).
* @param createIfNotExists A boolean indicating whether the group should be
* created if it does not exist.
*
* @return A ConsumerGroup.
+ * @throws InvalidGroupIdException if the group id is invalid.
* @throws GroupIdNotFoundException if the group does not exist and createIfNotExists is false or
* if the group is not a consumer group.
*
* Package private for testing.
*/
- ConsumerGroup getOrMaybeCreateConsumerGroup(
+ // Package private for testing.
Review Comment:
nit: We can remove this one as there is the same phrase in the javadoc.
##########
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/GroupMetadataManager.java:
##########
@@ -171,70 +260,152 @@ GroupMetadataManager build() {
/**
* The maximum number of members allowed in a single consumer group.
*/
- private final int consumerGroupMaxSize;
+ private final int groupMaxSize;
/**
* The heartbeat interval for consumer groups.
*/
private final int consumerGroupHeartbeatIntervalMs;
/**
- * The topics metadata (or image).
+ * The metadata image.
+ */
+ private MetadataImage metadataImage;
+
+ // Rest of the fields are used for the generic group APIs.
+
+ /**
+ * An empty result returned to the state machine. This means that
+ * there are no records to append to the log.
+ *
+ * Package private for testing.
+ */
+ static final CoordinatorResult<CompletableFuture<Errors>, Record> EMPTY_RESULT =
+ new CoordinatorResult<>(Collections.emptyList(), CompletableFuture.completedFuture(null));
+
+ /**
+ * Initial rebalance delay for members joining a generic group.
+ */
+ private final int initialRebalanceDelayMs;
+
+ /**
+ * The timeout used to wait for a new member in milliseconds.
+ */
+ private final int newMemberJoinTimeoutMs;
+
+ /**
+ * The group minimum session timeout.
+ */
+ private final int groupMinSessionTimeoutMs;
+
+ /**
+ * The group maximum session timeout.
+ */
+ private final int groupMaxSessionTimeoutMs;
+
+ /**
+ * The timer to add and cancel group operations.
*/
- private TopicsImage topicsImage;
+ private final Timer<CompletableFuture<Errors>, Record> timer;
+
+ /**
+ * The time.
+ */
+ private final Time time;
private GroupMetadataManager(
SnapshotRegistry snapshotRegistry,
LogContext logContext,
List<PartitionAssignor> assignors,
- TopicsImage topicsImage,
- int consumerGroupMaxSize,
- int consumerGroupHeartbeatIntervalMs
+ MetadataImage metadataImage,
+ TopicPartition topicPartition,
+ int groupMaxSize,
+ int consumerGroupHeartbeatIntervalMs,
+ int initialRebalanceDelayMs,
+ int newMemberJoinTimeoutMs,
+ int groupMinSessionTimeoutMs,
+ int groupMaxSessionTimeoutMs,
+ Timer<CompletableFuture<Errors>, Record> timer,
+ Time time
) {
+ this.logContext = logContext;
this.log = logContext.logger(GroupMetadataManager.class);
this.snapshotRegistry = snapshotRegistry;
- this.topicsImage = topicsImage;
+ this.metadataImage = metadataImage;
this.assignors = assignors.stream().collect(Collectors.toMap(PartitionAssignor::name, Function.identity()));
+ this.topicPartition = topicPartition;
this.defaultAssignor = assignors.get(0);
this.groups = new TimelineHashMap<>(snapshotRegistry, 0);
- this.consumerGroupMaxSize = consumerGroupMaxSize;
+ this.groupMaxSize = groupMaxSize;
this.consumerGroupHeartbeatIntervalMs = consumerGroupHeartbeatIntervalMs;
+ this.initialRebalanceDelayMs = initialRebalanceDelayMs;
+ this.newMemberJoinTimeoutMs = newMemberJoinTimeoutMs;
+ this.groupMinSessionTimeoutMs = groupMinSessionTimeoutMs;
+ this.groupMaxSessionTimeoutMs = groupMaxSessionTimeoutMs;
+ this.timer = timer;
+ this.time = time;
+ }
+
+ /**
+ * When a new metadata image is pushed.
+ *
+ * @param metadataImage The new metadata image.
+ */
+ public void onNewMetadataImage(MetadataImage metadataImage) {
+ this.metadataImage = metadataImage;
}
/**
* Gets or maybe creates a consumer group.
*
* @param groupId The group id.
+ * @param groupType The group type (generic or consumer).
* @param createIfNotExists A boolean indicating whether the group should be
* created if it does not exist.
*
* @return A ConsumerGroup.
+ * @throws InvalidGroupIdException if the group id is invalid.
* @throws GroupIdNotFoundException if the group does not exist and createIfNotExists is false or
* if the group is not a consumer group.
*
* Package private for testing.
*/
- ConsumerGroup getOrMaybeCreateConsumerGroup(
+ // Package private for testing.
+ Group getOrMaybeCreateGroup(
Review Comment:
I am not a fan of returning a `Group` here because it means that the caller have to cast the returned value. Is it possible to avoid it?
##########
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/GroupMetadataManager.java:
##########
@@ -171,70 +260,152 @@ GroupMetadataManager build() {
/**
* The maximum number of members allowed in a single consumer group.
*/
- private final int consumerGroupMaxSize;
+ private final int groupMaxSize;
/**
* The heartbeat interval for consumer groups.
*/
private final int consumerGroupHeartbeatIntervalMs;
/**
- * The topics metadata (or image).
+ * The metadata image.
+ */
+ private MetadataImage metadataImage;
+
+ // Rest of the fields are used for the generic group APIs.
+
+ /**
+ * An empty result returned to the state machine. This means that
+ * there are no records to append to the log.
+ *
+ * Package private for testing.
+ */
+ static final CoordinatorResult<CompletableFuture<Errors>, Record> EMPTY_RESULT =
+ new CoordinatorResult<>(Collections.emptyList(), CompletableFuture.completedFuture(null));
+
+ /**
+ * Initial rebalance delay for members joining a generic group.
+ */
+ private final int initialRebalanceDelayMs;
+
+ /**
+ * The timeout used to wait for a new member in milliseconds.
+ */
+ private final int newMemberJoinTimeoutMs;
+
+ /**
+ * The group minimum session timeout.
+ */
+ private final int groupMinSessionTimeoutMs;
+
+ /**
+ * The group maximum session timeout.
+ */
+ private final int groupMaxSessionTimeoutMs;
+
+ /**
+ * The timer to add and cancel group operations.
*/
- private TopicsImage topicsImage;
+ private final Timer<CompletableFuture<Errors>, Record> timer;
+
+ /**
+ * The time.
+ */
+ private final Time time;
private GroupMetadataManager(
SnapshotRegistry snapshotRegistry,
LogContext logContext,
List<PartitionAssignor> assignors,
- TopicsImage topicsImage,
- int consumerGroupMaxSize,
- int consumerGroupHeartbeatIntervalMs
+ MetadataImage metadataImage,
+ TopicPartition topicPartition,
+ int groupMaxSize,
+ int consumerGroupHeartbeatIntervalMs,
+ int initialRebalanceDelayMs,
+ int newMemberJoinTimeoutMs,
+ int groupMinSessionTimeoutMs,
+ int groupMaxSessionTimeoutMs,
+ Timer<CompletableFuture<Errors>, Record> timer,
+ Time time
) {
+ this.logContext = logContext;
this.log = logContext.logger(GroupMetadataManager.class);
this.snapshotRegistry = snapshotRegistry;
- this.topicsImage = topicsImage;
+ this.metadataImage = metadataImage;
this.assignors = assignors.stream().collect(Collectors.toMap(PartitionAssignor::name, Function.identity()));
+ this.topicPartition = topicPartition;
this.defaultAssignor = assignors.get(0);
this.groups = new TimelineHashMap<>(snapshotRegistry, 0);
- this.consumerGroupMaxSize = consumerGroupMaxSize;
+ this.groupMaxSize = groupMaxSize;
this.consumerGroupHeartbeatIntervalMs = consumerGroupHeartbeatIntervalMs;
+ this.initialRebalanceDelayMs = initialRebalanceDelayMs;
+ this.newMemberJoinTimeoutMs = newMemberJoinTimeoutMs;
+ this.groupMinSessionTimeoutMs = groupMinSessionTimeoutMs;
+ this.groupMaxSessionTimeoutMs = groupMaxSessionTimeoutMs;
+ this.timer = timer;
+ this.time = time;
+ }
+
+ /**
+ * When a new metadata image is pushed.
+ *
+ * @param metadataImage The new metadata image.
+ */
+ public void onNewMetadataImage(MetadataImage metadataImage) {
+ this.metadataImage = metadataImage;
}
/**
* Gets or maybe creates a consumer group.
*
* @param groupId The group id.
+ * @param groupType The group type (generic or consumer).
* @param createIfNotExists A boolean indicating whether the group should be
* created if it does not exist.
*
* @return A ConsumerGroup.
+ * @throws InvalidGroupIdException if the group id is invalid.
* @throws GroupIdNotFoundException if the group does not exist and createIfNotExists is false or
* if the group is not a consumer group.
*
* Package private for testing.
*/
- ConsumerGroup getOrMaybeCreateConsumerGroup(
+ // Package private for testing.
+ Group getOrMaybeCreateGroup(
String groupId,
+ Group.GroupType groupType,
boolean createIfNotExists
- ) throws GroupIdNotFoundException {
+ ) throws InvalidGroupIdException, GroupIdNotFoundException {
+ if (groupId == null || groupId.isEmpty()) {
+ throw new InvalidGroupIdException(String.format("Group id %s is invalid.", groupId));
+ }
Review Comment:
Should we move this to the request validation?
##########
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/GroupMetadataManager.java:
##########
@@ -874,4 +1045,1265 @@ public void replay(
consumerGroup.updateMember(newMember);
}
}
+
+ // Below stores all methods to handle generic group APIs.
+
+ /**
+ * Handle a JoinGroupRequest.
+ *
+ * @param context The request context.
+ * @param request The actual JoinGroup request.
+ *
+ * @return The result that contains records to append if the join group phase completes.
+ */
+ public CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoin(
+ RequestContext context,
+ JoinGroupRequestData request,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ CoordinatorResult<CompletableFuture<Errors>, Record> result = EMPTY_RESULT;
+ String groupId = request.groupId();
+ String memberId = request.memberId();
+ int sessionTimeoutMs = request.sessionTimeoutMs();
+
+ if (sessionTimeoutMs < groupMinSessionTimeoutMs ||
+ sessionTimeoutMs > groupMaxSessionTimeoutMs
+ ) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.INVALID_SESSION_TIMEOUT.code())
+ );
+ } else {
+ boolean isUnknownMember = memberId.equals(UNKNOWN_MEMBER_ID);
+ // Group is created if it does not exist and the member id is UNKNOWN. if member
+ // is specified but group does not exist, request is rejected with GROUP_ID_NOT_FOUND
+ GenericGroup group;
+ try {
+ group = (GenericGroup) getOrMaybeCreateGroup(groupId, GENERIC, isUnknownMember);
+ } catch (Throwable t) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.forException(t).code())
+ );
+ return EMPTY_RESULT;
+ }
+
+ String joinReason = request.reason();
+ if (joinReason == null || joinReason.isEmpty()) {
+ joinReason = "not provided";
+ }
+
+ if (!acceptJoiningMember(group, memberId)) {
+ group.remove(memberId);
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.GROUP_MAX_SIZE_REACHED.code())
+ );
+
+ } else if (isUnknownMember) {
+ result = genericGroupJoinNewMember(
+ context,
+ request,
+ group,
+ joinReason,
+ responseFuture
+ );
+ } else {
+ result = genericGroupJoinExistingMember(
+ context,
+ request,
+ group,
+ joinReason,
+ responseFuture
+ );
+ }
+
+ // Attempt to complete join group phase. We do not complete
+ // the join group phase if this is the initial rebalance.
+ if (group.isInState(PREPARING_REBALANCE) &&
+ group.hasAllMembersJoined() &&
+ group.generationId() != 0
+ ) {
+ completeGenericGroupJoin(group);
+ }
+ }
+
+ return result;
+ }
+
+ /**
+ * Handle a new member generic group join.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinNewMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ List<Protocol> protocols = new ArrayList<>();
+ request.protocols().forEach(protocol -> protocols.add(new Protocol(protocol.name(), protocol.metadata())));
+ if (group.isInState(DEAD)) {
+ // if the group is marked as dead, it means some other thread has just removed the group
+ // from the coordinator metadata; it is likely that the group has migrated to some other
+ // coordinator OR the group is in a transient unstable phase. Let the member retry
+ // finding the correct coordinator and rejoin.
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.COORDINATOR_NOT_AVAILABLE.code())
+ );
+ } else if (!group.supportsProtocols(request.protocolType(), GenericGroupMember.plainProtocolSet(protocols))) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.INCONSISTENT_GROUP_PROTOCOL.code())
+ );
+ } else {
+ Optional<String> groupInstanceId = Optional.ofNullable(request.groupInstanceId());
+ String newMemberId = group.generateMemberId(context.clientId(), groupInstanceId);
+
+ if (groupInstanceId.isPresent()) {
+ return genericGroupJoinNewStaticMember(
+ context,
+ request,
+ group,
+ newMemberId,
+ joinReason,
+ responseFuture
+ );
+ } else {
+ return genericGroupJoinNewDynamicMember(
+ context,
+ request,
+ group,
+ newMemberId,
+ joinReason,
+ responseFuture
+ );
+ }
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Handle new static member join. If there was an existing member id for the group instance id,
+ * replace that member. Otherwise, add the member and rebalance.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param newMemberId The newly generated member id.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinNewStaticMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String newMemberId,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ String groupInstanceId = request.groupInstanceId();
+ String existingMemberId = group.staticMemberId(groupInstanceId);
+ if (existingMemberId != null) {
+ log.info("Static member with groupInstanceId={} and unknown member id joins " +
+ "group {} in {} state. Replacing previously mapped member {} with this groupInstanceId.",
+ groupInstanceId, group.groupId(), group.currentState(), existingMemberId);
+
+ return updateStaticMemberAndRebalance(
+ context,
+ request,
+ group,
+ existingMemberId,
+ newMemberId,
+ joinReason,
+ responseFuture
+ );
+
+ } else {
+ log.info("Static member with groupInstanceId={} and unknown member id joins " +
+ "group {} in {} state. Created a new member id {} for this member and added to the group.",
+ groupInstanceId, group.groupId(), group.currentState(), newMemberId);
+
+ return addMemberAndRebalance(context, request, group, newMemberId, joinReason, responseFuture);
+ }
+ }
+
+ /**
+ * Handle a new dynamic member join. If the member id field is required, the group metadata manager
+ * will add the new member id to the pending members and respond with MEMBER_ID_REQUIRED along with
+ * the new member id for the client to join with.
+ *
+ * Otherwise, add the new member to the group and rebalance.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param newMemberId The newly generated member id.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinNewDynamicMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String newMemberId,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ boolean requireKnownMemberId = context.apiVersion() >= 4
+ && (request.groupInstanceId() == null || request.groupInstanceId().isEmpty());
Review Comment:
I suppose that being here means that group instance id is null.
##########
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/GroupMetadataManager.java:
##########
@@ -874,4 +1045,1265 @@ public void replay(
consumerGroup.updateMember(newMember);
}
}
+
+ // Below stores all methods to handle generic group APIs.
+
+ /**
+ * Handle a JoinGroupRequest.
+ *
+ * @param context The request context.
+ * @param request The actual JoinGroup request.
+ *
+ * @return The result that contains records to append if the join group phase completes.
+ */
+ public CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoin(
+ RequestContext context,
+ JoinGroupRequestData request,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ CoordinatorResult<CompletableFuture<Errors>, Record> result = EMPTY_RESULT;
+ String groupId = request.groupId();
+ String memberId = request.memberId();
+ int sessionTimeoutMs = request.sessionTimeoutMs();
+
+ if (sessionTimeoutMs < groupMinSessionTimeoutMs ||
+ sessionTimeoutMs > groupMaxSessionTimeoutMs
+ ) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.INVALID_SESSION_TIMEOUT.code())
+ );
+ } else {
+ boolean isUnknownMember = memberId.equals(UNKNOWN_MEMBER_ID);
+ // Group is created if it does not exist and the member id is UNKNOWN. if member
+ // is specified but group does not exist, request is rejected with GROUP_ID_NOT_FOUND
+ GenericGroup group;
+ try {
+ group = (GenericGroup) getOrMaybeCreateGroup(groupId, GENERIC, isUnknownMember);
+ } catch (Throwable t) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.forException(t).code())
+ );
+ return EMPTY_RESULT;
+ }
+
+ String joinReason = request.reason();
+ if (joinReason == null || joinReason.isEmpty()) {
+ joinReason = "not provided";
+ }
+
+ if (!acceptJoiningMember(group, memberId)) {
+ group.remove(memberId);
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.GROUP_MAX_SIZE_REACHED.code())
+ );
+
+ } else if (isUnknownMember) {
+ result = genericGroupJoinNewMember(
+ context,
+ request,
+ group,
+ joinReason,
+ responseFuture
+ );
+ } else {
+ result = genericGroupJoinExistingMember(
+ context,
+ request,
+ group,
+ joinReason,
+ responseFuture
+ );
+ }
+
+ // Attempt to complete join group phase. We do not complete
+ // the join group phase if this is the initial rebalance.
+ if (group.isInState(PREPARING_REBALANCE) &&
+ group.hasAllMembersJoined() &&
+ group.generationId() != 0
+ ) {
+ completeGenericGroupJoin(group);
+ }
+ }
+
+ return result;
+ }
+
+ /**
+ * Handle a new member generic group join.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinNewMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ List<Protocol> protocols = new ArrayList<>();
+ request.protocols().forEach(protocol -> protocols.add(new Protocol(protocol.name(), protocol.metadata())));
+ if (group.isInState(DEAD)) {
+ // if the group is marked as dead, it means some other thread has just removed the group
+ // from the coordinator metadata; it is likely that the group has migrated to some other
+ // coordinator OR the group is in a transient unstable phase. Let the member retry
+ // finding the correct coordinator and rejoin.
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.COORDINATOR_NOT_AVAILABLE.code())
+ );
+ } else if (!group.supportsProtocols(request.protocolType(), GenericGroupMember.plainProtocolSet(protocols))) {
Review Comment:
nit: Would it make sense to update `plainProtocolSet` to take `request.protocols()`?
##########
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/GroupMetadataManager.java:
##########
@@ -874,4 +1045,1265 @@ public void replay(
consumerGroup.updateMember(newMember);
}
}
+
+ // Below stores all methods to handle generic group APIs.
+
+ /**
+ * Handle a JoinGroupRequest.
+ *
+ * @param context The request context.
+ * @param request The actual JoinGroup request.
+ *
+ * @return The result that contains records to append if the join group phase completes.
+ */
+ public CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoin(
+ RequestContext context,
+ JoinGroupRequestData request,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ CoordinatorResult<CompletableFuture<Errors>, Record> result = EMPTY_RESULT;
+ String groupId = request.groupId();
+ String memberId = request.memberId();
+ int sessionTimeoutMs = request.sessionTimeoutMs();
+
+ if (sessionTimeoutMs < groupMinSessionTimeoutMs ||
+ sessionTimeoutMs > groupMaxSessionTimeoutMs
+ ) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.INVALID_SESSION_TIMEOUT.code())
+ );
+ } else {
+ boolean isUnknownMember = memberId.equals(UNKNOWN_MEMBER_ID);
+ // Group is created if it does not exist and the member id is UNKNOWN. if member
+ // is specified but group does not exist, request is rejected with GROUP_ID_NOT_FOUND
+ GenericGroup group;
+ try {
+ group = (GenericGroup) getOrMaybeCreateGroup(groupId, GENERIC, isUnknownMember);
+ } catch (Throwable t) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.forException(t).code())
+ );
+ return EMPTY_RESULT;
+ }
+
+ String joinReason = request.reason();
+ if (joinReason == null || joinReason.isEmpty()) {
+ joinReason = "not provided";
+ }
+
+ if (!acceptJoiningMember(group, memberId)) {
+ group.remove(memberId);
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.GROUP_MAX_SIZE_REACHED.code())
+ );
+
+ } else if (isUnknownMember) {
+ result = genericGroupJoinNewMember(
+ context,
+ request,
+ group,
+ joinReason,
+ responseFuture
+ );
+ } else {
+ result = genericGroupJoinExistingMember(
+ context,
+ request,
+ group,
+ joinReason,
+ responseFuture
+ );
+ }
+
+ // Attempt to complete join group phase. We do not complete
+ // the join group phase if this is the initial rebalance.
+ if (group.isInState(PREPARING_REBALANCE) &&
+ group.hasAllMembersJoined() &&
+ group.generationId() != 0
+ ) {
+ completeGenericGroupJoin(group);
+ }
+ }
+
+ return result;
+ }
+
+ /**
+ * Handle a new member generic group join.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinNewMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ List<Protocol> protocols = new ArrayList<>();
+ request.protocols().forEach(protocol -> protocols.add(new Protocol(protocol.name(), protocol.metadata())));
+ if (group.isInState(DEAD)) {
+ // if the group is marked as dead, it means some other thread has just removed the group
+ // from the coordinator metadata; it is likely that the group has migrated to some other
+ // coordinator OR the group is in a transient unstable phase. Let the member retry
+ // finding the correct coordinator and rejoin.
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.COORDINATOR_NOT_AVAILABLE.code())
+ );
+ } else if (!group.supportsProtocols(request.protocolType(), GenericGroupMember.plainProtocolSet(protocols))) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.INCONSISTENT_GROUP_PROTOCOL.code())
+ );
+ } else {
+ Optional<String> groupInstanceId = Optional.ofNullable(request.groupInstanceId());
+ String newMemberId = group.generateMemberId(context.clientId(), groupInstanceId);
+
+ if (groupInstanceId.isPresent()) {
Review Comment:
What happens if the group instance id is an empty string?
##########
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/GroupMetadataManager.java:
##########
@@ -874,4 +1045,1265 @@ public void replay(
consumerGroup.updateMember(newMember);
}
}
+
+ // Below stores all methods to handle generic group APIs.
+
+ /**
+ * Handle a JoinGroupRequest.
+ *
+ * @param context The request context.
+ * @param request The actual JoinGroup request.
+ *
+ * @return The result that contains records to append if the join group phase completes.
+ */
+ public CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoin(
+ RequestContext context,
+ JoinGroupRequestData request,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ CoordinatorResult<CompletableFuture<Errors>, Record> result = EMPTY_RESULT;
+ String groupId = request.groupId();
+ String memberId = request.memberId();
+ int sessionTimeoutMs = request.sessionTimeoutMs();
+
+ if (sessionTimeoutMs < groupMinSessionTimeoutMs ||
+ sessionTimeoutMs > groupMaxSessionTimeoutMs
+ ) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.INVALID_SESSION_TIMEOUT.code())
+ );
+ } else {
+ boolean isUnknownMember = memberId.equals(UNKNOWN_MEMBER_ID);
+ // Group is created if it does not exist and the member id is UNKNOWN. if member
+ // is specified but group does not exist, request is rejected with GROUP_ID_NOT_FOUND
+ GenericGroup group;
+ try {
+ group = (GenericGroup) getOrMaybeCreateGroup(groupId, GENERIC, isUnknownMember);
+ } catch (Throwable t) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.forException(t).code())
+ );
+ return EMPTY_RESULT;
+ }
+
+ String joinReason = request.reason();
+ if (joinReason == null || joinReason.isEmpty()) {
+ joinReason = "not provided";
+ }
+
+ if (!acceptJoiningMember(group, memberId)) {
+ group.remove(memberId);
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.GROUP_MAX_SIZE_REACHED.code())
+ );
+
+ } else if (isUnknownMember) {
+ result = genericGroupJoinNewMember(
+ context,
+ request,
+ group,
+ joinReason,
+ responseFuture
+ );
+ } else {
+ result = genericGroupJoinExistingMember(
+ context,
+ request,
+ group,
+ joinReason,
+ responseFuture
+ );
+ }
+
+ // Attempt to complete join group phase. We do not complete
+ // the join group phase if this is the initial rebalance.
+ if (group.isInState(PREPARING_REBALANCE) &&
+ group.hasAllMembersJoined() &&
+ group.generationId() != 0
+ ) {
+ completeGenericGroupJoin(group);
+ }
+ }
+
+ return result;
+ }
+
+ /**
+ * Handle a new member generic group join.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinNewMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ List<Protocol> protocols = new ArrayList<>();
+ request.protocols().forEach(protocol -> protocols.add(new Protocol(protocol.name(), protocol.metadata())));
+ if (group.isInState(DEAD)) {
+ // if the group is marked as dead, it means some other thread has just removed the group
+ // from the coordinator metadata; it is likely that the group has migrated to some other
+ // coordinator OR the group is in a transient unstable phase. Let the member retry
+ // finding the correct coordinator and rejoin.
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.COORDINATOR_NOT_AVAILABLE.code())
+ );
+ } else if (!group.supportsProtocols(request.protocolType(), GenericGroupMember.plainProtocolSet(protocols))) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.INCONSISTENT_GROUP_PROTOCOL.code())
+ );
+ } else {
+ Optional<String> groupInstanceId = Optional.ofNullable(request.groupInstanceId());
+ String newMemberId = group.generateMemberId(context.clientId(), groupInstanceId);
+
+ if (groupInstanceId.isPresent()) {
+ return genericGroupJoinNewStaticMember(
+ context,
+ request,
+ group,
+ newMemberId,
+ joinReason,
+ responseFuture
+ );
+ } else {
+ return genericGroupJoinNewDynamicMember(
+ context,
+ request,
+ group,
+ newMemberId,
+ joinReason,
+ responseFuture
+ );
+ }
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Handle new static member join. If there was an existing member id for the group instance id,
+ * replace that member. Otherwise, add the member and rebalance.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param newMemberId The newly generated member id.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinNewStaticMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String newMemberId,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ String groupInstanceId = request.groupInstanceId();
+ String existingMemberId = group.staticMemberId(groupInstanceId);
+ if (existingMemberId != null) {
+ log.info("Static member with groupInstanceId={} and unknown member id joins " +
+ "group {} in {} state. Replacing previously mapped member {} with this groupInstanceId.",
+ groupInstanceId, group.groupId(), group.currentState(), existingMemberId);
+
+ return updateStaticMemberAndRebalance(
+ context,
+ request,
+ group,
+ existingMemberId,
+ newMemberId,
+ joinReason,
+ responseFuture
+ );
+
+ } else {
+ log.info("Static member with groupInstanceId={} and unknown member id joins " +
+ "group {} in {} state. Created a new member id {} for this member and added to the group.",
+ groupInstanceId, group.groupId(), group.currentState(), newMemberId);
+
+ return addMemberAndRebalance(context, request, group, newMemberId, joinReason, responseFuture);
+ }
+ }
+
+ /**
+ * Handle a new dynamic member join. If the member id field is required, the group metadata manager
+ * will add the new member id to the pending members and respond with MEMBER_ID_REQUIRED along with
+ * the new member id for the client to join with.
+ *
+ * Otherwise, add the new member to the group and rebalance.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param newMemberId The newly generated member id.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinNewDynamicMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String newMemberId,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ boolean requireKnownMemberId = context.apiVersion() >= 4
+ && (request.groupInstanceId() == null || request.groupInstanceId().isEmpty());
+
+ if (requireKnownMemberId) {
+ // If member id required, register the member in the pending member list and send
+ // back a response to call for another join group request with allocated member id.
+ log.info("Dynamic member with unknown member id joins group {} in {} state. " +
+ "Created a new member id {} and requesting the member to rejoin with this id.",
+ group.groupId(), group.currentState(), newMemberId);
+
+ group.addPendingMember(newMemberId);
+ String heartbeatKey = heartbeatKey(group.groupId(), newMemberId);
+
+ timer.schedule(
+ heartbeatKey,
+ request.sessionTimeoutMs(),
+ TimeUnit.MILLISECONDS,
+ () -> expireGenericGroupMemberHeartbeat(group, newMemberId)
+ );
+
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(newMemberId)
+ .setErrorCode(Errors.MEMBER_ID_REQUIRED.code())
+ );
+
+ } else {
+ log.info("Dynamic member with unknown member id joins group {} in state {}. " +
+ "Created a new member id {} and added the member to the group.",
+ group.groupId(), group.currentState(), newMemberId);
+
+ return addMemberAndRebalance(context, request, group, newMemberId, joinReason, responseFuture);
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Handle a join group request for an existing member.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinExistingMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ List<Protocol> protocols = request.protocols().stream()
+ .map(protocol -> new Protocol(protocol.name(), protocol.metadata())).collect(Collectors.toList());
Review Comment:
I have seen this code in a few place. It would be great to avoid it if possible.
##########
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/GroupMetadataManager.java:
##########
@@ -874,4 +1045,1265 @@ public void replay(
consumerGroup.updateMember(newMember);
}
}
+
+ // Below stores all methods to handle generic group APIs.
+
+ /**
+ * Handle a JoinGroupRequest.
+ *
+ * @param context The request context.
+ * @param request The actual JoinGroup request.
+ *
+ * @return The result that contains records to append if the join group phase completes.
+ */
+ public CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoin(
+ RequestContext context,
+ JoinGroupRequestData request,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ CoordinatorResult<CompletableFuture<Errors>, Record> result = EMPTY_RESULT;
+ String groupId = request.groupId();
+ String memberId = request.memberId();
+ int sessionTimeoutMs = request.sessionTimeoutMs();
+
+ if (sessionTimeoutMs < groupMinSessionTimeoutMs ||
+ sessionTimeoutMs > groupMaxSessionTimeoutMs
+ ) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.INVALID_SESSION_TIMEOUT.code())
+ );
+ } else {
+ boolean isUnknownMember = memberId.equals(UNKNOWN_MEMBER_ID);
+ // Group is created if it does not exist and the member id is UNKNOWN. if member
+ // is specified but group does not exist, request is rejected with GROUP_ID_NOT_FOUND
+ GenericGroup group;
+ try {
+ group = (GenericGroup) getOrMaybeCreateGroup(groupId, GENERIC, isUnknownMember);
+ } catch (Throwable t) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.forException(t).code())
+ );
+ return EMPTY_RESULT;
+ }
+
+ String joinReason = request.reason();
+ if (joinReason == null || joinReason.isEmpty()) {
+ joinReason = "not provided";
+ }
+
+ if (!acceptJoiningMember(group, memberId)) {
+ group.remove(memberId);
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.GROUP_MAX_SIZE_REACHED.code())
+ );
+
+ } else if (isUnknownMember) {
+ result = genericGroupJoinNewMember(
+ context,
+ request,
+ group,
+ joinReason,
+ responseFuture
+ );
+ } else {
+ result = genericGroupJoinExistingMember(
+ context,
+ request,
+ group,
+ joinReason,
+ responseFuture
+ );
+ }
+
+ // Attempt to complete join group phase. We do not complete
+ // the join group phase if this is the initial rebalance.
+ if (group.isInState(PREPARING_REBALANCE) &&
+ group.hasAllMembersJoined() &&
+ group.generationId() != 0
+ ) {
+ completeGenericGroupJoin(group);
+ }
+ }
+
+ return result;
+ }
+
+ /**
+ * Handle a new member generic group join.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinNewMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ List<Protocol> protocols = new ArrayList<>();
+ request.protocols().forEach(protocol -> protocols.add(new Protocol(protocol.name(), protocol.metadata())));
+ if (group.isInState(DEAD)) {
+ // if the group is marked as dead, it means some other thread has just removed the group
+ // from the coordinator metadata; it is likely that the group has migrated to some other
+ // coordinator OR the group is in a transient unstable phase. Let the member retry
+ // finding the correct coordinator and rejoin.
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.COORDINATOR_NOT_AVAILABLE.code())
+ );
+ } else if (!group.supportsProtocols(request.protocolType(), GenericGroupMember.plainProtocolSet(protocols))) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.INCONSISTENT_GROUP_PROTOCOL.code())
+ );
+ } else {
+ Optional<String> groupInstanceId = Optional.ofNullable(request.groupInstanceId());
+ String newMemberId = group.generateMemberId(context.clientId(), groupInstanceId);
+
+ if (groupInstanceId.isPresent()) {
+ return genericGroupJoinNewStaticMember(
+ context,
+ request,
+ group,
+ newMemberId,
+ joinReason,
+ responseFuture
+ );
+ } else {
+ return genericGroupJoinNewDynamicMember(
+ context,
+ request,
+ group,
+ newMemberId,
+ joinReason,
+ responseFuture
+ );
+ }
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Handle new static member join. If there was an existing member id for the group instance id,
+ * replace that member. Otherwise, add the member and rebalance.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param newMemberId The newly generated member id.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinNewStaticMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String newMemberId,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ String groupInstanceId = request.groupInstanceId();
+ String existingMemberId = group.staticMemberId(groupInstanceId);
+ if (existingMemberId != null) {
+ log.info("Static member with groupInstanceId={} and unknown member id joins " +
+ "group {} in {} state. Replacing previously mapped member {} with this groupInstanceId.",
+ groupInstanceId, group.groupId(), group.currentState(), existingMemberId);
+
+ return updateStaticMemberAndRebalance(
+ context,
+ request,
+ group,
+ existingMemberId,
+ newMemberId,
+ joinReason,
+ responseFuture
+ );
+
+ } else {
+ log.info("Static member with groupInstanceId={} and unknown member id joins " +
+ "group {} in {} state. Created a new member id {} for this member and added to the group.",
+ groupInstanceId, group.groupId(), group.currentState(), newMemberId);
+
+ return addMemberAndRebalance(context, request, group, newMemberId, joinReason, responseFuture);
+ }
+ }
+
+ /**
+ * Handle a new dynamic member join. If the member id field is required, the group metadata manager
+ * will add the new member id to the pending members and respond with MEMBER_ID_REQUIRED along with
+ * the new member id for the client to join with.
+ *
+ * Otherwise, add the new member to the group and rebalance.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param newMemberId The newly generated member id.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinNewDynamicMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String newMemberId,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ boolean requireKnownMemberId = context.apiVersion() >= 4
+ && (request.groupInstanceId() == null || request.groupInstanceId().isEmpty());
+
+ if (requireKnownMemberId) {
+ // If member id required, register the member in the pending member list and send
+ // back a response to call for another join group request with allocated member id.
+ log.info("Dynamic member with unknown member id joins group {} in {} state. " +
+ "Created a new member id {} and requesting the member to rejoin with this id.",
+ group.groupId(), group.currentState(), newMemberId);
+
+ group.addPendingMember(newMemberId);
+ String heartbeatKey = heartbeatKey(group.groupId(), newMemberId);
+
+ timer.schedule(
+ heartbeatKey,
+ request.sessionTimeoutMs(),
+ TimeUnit.MILLISECONDS,
+ () -> expireGenericGroupMemberHeartbeat(group, newMemberId)
+ );
+
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(newMemberId)
+ .setErrorCode(Errors.MEMBER_ID_REQUIRED.code())
+ );
+
+ } else {
+ log.info("Dynamic member with unknown member id joins group {} in state {}. " +
+ "Created a new member id {} and added the member to the group.",
+ group.groupId(), group.currentState(), newMemberId);
+
+ return addMemberAndRebalance(context, request, group, newMemberId, joinReason, responseFuture);
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Handle a join group request for an existing member.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinExistingMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ List<Protocol> protocols = request.protocols().stream()
+ .map(protocol -> new Protocol(protocol.name(), protocol.metadata())).collect(Collectors.toList());
+
+ String memberId = request.memberId();
+ String groupInstanceId = request.groupInstanceId();
+
+ if (group.isInState(DEAD)) {
+ // If the group is marked as dead, it means the group was recently removed the group
+ // from the coordinator metadata; it is likely that the group has migrated to some other
+ // coordinator OR the group is in a transient unstable phase. Let the member retry
+ // finding the correct coordinator and rejoin.
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.COORDINATOR_NOT_AVAILABLE.code())
+ );
+ } else if (!group.supportsProtocols(
+ request.protocolType(),
+ GenericGroupMember.plainProtocolSet(protocols))
+ ) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.INCONSISTENT_GROUP_PROTOCOL.code())
+ );
+ } else if (group.isPendingMember(memberId)) {
+ // A rejoining pending member will be accepted. Note that pending member cannot be a static member.
+ if (groupInstanceId != null) {
+ throw new IllegalStateException("Received unexpected JoinGroup with groupInstanceId=" +
+ groupInstanceId + " for pending member with memberId=" + memberId);
+ }
+
+ log.debug("Pending dynamic member with id {} joins group {} in {} state. Adding to the group now.",
+ memberId, group.groupId(), group.currentState());
+
+ return addMemberAndRebalance(
+ context,
+ request,
+ group,
+ memberId,
+ joinReason,
+ responseFuture
+ );
+ } else {
+ Optional<Errors> memberError = validateExistingMember(
+ group,
+ memberId,
+ groupInstanceId,
+ "join-group"
+ );
+
+ if (memberError.isPresent()) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(memberError.get().code())
+ );
+ } else {
+ GenericGroupMember member = group.member(memberId);
+ if (group.isInState(PREPARING_REBALANCE)) {
+ return updateMemberAndRebalance(
+ request,
+ group,
+ member,
+ "Member " + member.memberId() + " is joining group during " +
+ group.stateAsString() + "; client reason: " + joinReason,
+ responseFuture
+ );
+ } else if (group.isInState(COMPLETING_REBALANCE)) {
+ if (member.matches(protocols)) {
+ // Member is joining with the same metadata (which could be because it failed to
+ // receive the initial JoinGroup response), so just return current group information
+ // for the current generation.
+ List<JoinGroupResponseData.JoinGroupResponseMember> members = Collections.emptyList();
+ if (group.isLeader(memberId)) {
+ members = group.currentGenericGroupMembers();
+ }
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMembers(members)
+ .setMemberId(memberId)
+ .setGenerationId(group.generationId())
+ .setProtocolName(group.protocolName().orElse(null))
+ .setProtocolType(group.protocolType().orElse(null))
+ .setLeader(group.leaderOrNull())
+ .setSkipAssignment(false)
+ .setErrorCode(Errors.NONE.code())
+ );
+ } else {
+ // Member has changed metadata, so force a rebalance
+ return updateMemberAndRebalance(
+ request,
+ group,
+ member,
+ "Updating metadata for member " + memberId + " during " +
+ group.stateAsString() + "; client reason: " + joinReason,
+ responseFuture
+ );
+ }
+ } else if (group.isInState(STABLE)) {
+ if (group.isLeader(memberId)) {
+ // Force a rebalance if the leader sends JoinGroup;
+ // This allows the leader to trigger rebalances for changes affecting assignment
+ // which do not affect the member metadata (such as topic metadata changes for the consumer)
+ return updateMemberAndRebalance(
+ request,
+ group,
+ member,
+ "Leader " + memberId + " re-joining group during " +
+ group.stateAsString() + "; client reason: " + joinReason,
+ responseFuture
+ );
+ } else if (!member.matches(protocols)) {
+ return updateMemberAndRebalance(
+ request,
+ group,
+ member,
+ "Updating metadata for member " + memberId + " during " +
+ group.stateAsString() + "; client reason: " + joinReason,
+ responseFuture
+ );
+ } else {
+ // For followers with no actual change to their metadata, just return group information
+ // for the current generation which will allow them to issue SyncGroup.
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMembers(Collections.emptyList())
+ .setMemberId(memberId)
+ .setGenerationId(group.generationId())
+ .setProtocolName(group.protocolName().orElse(null))
+ .setProtocolType(group.protocolType().orElse(null))
+ .setLeader(group.leaderOrNull())
+ .setSkipAssignment(false)
+ .setErrorCode(Errors.NONE.code())
+ );
+ }
+ } else {
+ // Group reached unexpected (Empty) state. Let the joining member reset their generation and rejoin.
+ log.warn("Attempt to add rejoining member {} of group {} in unexpected group state {}",
+ memberId, group.groupId(), group.stateAsString());
+
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.UNKNOWN_MEMBER_ID.code())
+ );
+ }
+ }
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Complete the join group phase. Remove all dynamic members that have not rejoined
+ * during this stage and proceed with the next generation for this group. The generation id
+ * is incremented and the group transitions to CompletingRebalance state if there is at least
+ * one member.
+ *
+ * If the group is in Empty state, append a new group metadata record to the log. Otherwise,
+ * complete all members' join group response futures and wait for sync requests from members.
+ *
+ * @param group The group that is completing the join group phase.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> completeGenericGroupJoin(
+ GenericGroup group
+ ) {
+ timer.cancel(joinKey(group.groupId()));
+ String groupId = group.groupId();
+
+ Map<String, GenericGroupMember> notYetRejoinedDynamicMembers =
+ group.notYetRejoinedMembers().entrySet().stream()
+ .filter(entry -> !entry.getValue().isStaticMember())
+ .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
+
+ if (!notYetRejoinedDynamicMembers.isEmpty()) {
+ notYetRejoinedDynamicMembers.values().forEach(failedMember -> {
+ group.remove(failedMember.memberId());
+ timer.cancel(heartbeatKey(group.groupId(), failedMember.memberId()));
+ });
+
+ log.info("Group {} removed dynamic members who haven't joined: {}",
+ groupId, notYetRejoinedDynamicMembers.keySet());
+ }
+
+ if (group.isInState(DEAD)) {
+ log.info("Group {} is dead, skipping rebalance stage.", groupId);
+ } else if (!group.maybeElectNewJoinedLeader() && !group.allMembers().isEmpty()) {
+ // If all members are not rejoining, we will postpone the completion
+ // of rebalance preparing stage, and send out another delayed operation
+ // until session timeout removes all the non-responsive members.
+ log.error("Group {} could not complete rebalance because no members rejoined.", groupId);
+
+ return tryCompleteJoinElseSchedule(group);
+ } else {
+ group.initNextGeneration();
+ if (group.isInState(EMPTY)) {
+ log.info("Group {} with generation {} is now empty ({}-{})",
+ groupId, group.generationId(), topicPartition.topic(), topicPartition.partition());
+
+ CompletableFuture<Errors> appendFuture = new CompletableFuture<>();
+ appendFuture.whenComplete((error, t) -> {
+ if (t != null || error != Errors.NONE) {
+ // We failed to write the empty group metadata. If the broker fails before another rebalance,
+ // the previous generation written to the log will become active again (and most likely timeout).
+ // This should be safe since there are no active members in an empty generation, so we just warn.
+ String message = t != null ? t.getMessage() : error.message();
+ log.warn("Failed to write empty metadata for group {}: {}", group.groupId(), message);
+ }
+ });
+
+ List<Record> records = Collections.singletonList(
+ RecordHelpers.newGroupMetadataRecord(group, metadataImage.features().metadataVersion())
+ );
+
+ return new CoordinatorResult<>(records, appendFuture);
+
+ } else {
+ log.info("Stabilized group {} generation {} ({}-{}) with {} members",
+ groupId, group.generationId(), topicPartition.topic(),
+ topicPartition.partition(), group.size());
+
+ // Complete the awaiting join group response future for all the members after rebalancing
+ group.allMembers().forEach(member -> {
+
+ List<JoinGroupResponseData.JoinGroupResponseMember> members = Collections.emptyList();
+ if (group.isLeader(member.memberId())) {
+ members = group.currentGenericGroupMembers();
+ }
+
+ JoinGroupResponseData response = new JoinGroupResponseData()
+ .setMembers(members)
+ .setMemberId(member.memberId())
+ .setGenerationId(group.generationId())
+ .setProtocolName(group.protocolName().orElse(null))
+ .setProtocolType(group.protocolType().orElse(null))
+ .setLeader(group.leaderOrNull())
+ .setSkipAssignment(false)
+ .setErrorCode(Errors.NONE.code());
+
+ group.completeJoinFuture(member, response);
+ rescheduleGenericGroupMemberHeartbeat(group, member);
+ member.setIsNew(false);
+
+ group.addPendingSyncMember(member.memberId());
+ });
+
+ schedulePendingSync(group);
+ }
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Wait for sync requests for the group.
+ *
+ * @param group The group.
+ */
+ private void schedulePendingSync(GenericGroup group) {
+ timer.schedule(syncKey(group.groupId()),
+ group.rebalanceTimeoutMs(),
+ TimeUnit.MILLISECONDS,
+ () -> expirePendingSync(group, group.generationId()));
+ }
+
+ /**
+ * Invoked when the heartbeat operation is expired from the timer. Possibly remove the member and
+ * try complete the join phase.
+ *
+ * @param group The group.
+ * @param memberId The member id.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> expireGenericGroupMemberHeartbeat(
+ GenericGroup group,
+ String memberId
+ ) {
+ if (group.isInState(DEAD)) {
+ log.info("Received notification of heartbeat expiration for member {} after group {} " +
+ "had already been unloaded or deleted.",
+ memberId, group.groupId());
+
+ } else if (group.isPendingMember(memberId)) {
+ log.info("Pending member {} in group {} has been removed after session timeout expiration.",
+ memberId, group.groupId());
+
+ return removePendingMemberAndUpdateGenericGroup(group, memberId);
+ } else if (!group.hasMemberId(memberId)) {
+ log.debug("Member {} has already been removed from the group.", memberId);
+ } else {
+ GenericGroupMember member = group.member(memberId);
+ if (!member.hasSatisfiedHeartbeat()) {
Review Comment:
Do we still need `hasSatisfiedHeartbeat` in the new model? If the timeout expires, it seems to me that it means that the member has failed to heartbeat in time; the timer would have been reset otherwise.
##########
group-coordinator/src/main/java/org/apache/kafka/coordinator/group/GroupMetadataManager.java:
##########
@@ -874,4 +1045,1265 @@ public void replay(
consumerGroup.updateMember(newMember);
}
}
+
+ // Below stores all methods to handle generic group APIs.
+
+ /**
+ * Handle a JoinGroupRequest.
+ *
+ * @param context The request context.
+ * @param request The actual JoinGroup request.
+ *
+ * @return The result that contains records to append if the join group phase completes.
+ */
+ public CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoin(
+ RequestContext context,
+ JoinGroupRequestData request,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ CoordinatorResult<CompletableFuture<Errors>, Record> result = EMPTY_RESULT;
+ String groupId = request.groupId();
+ String memberId = request.memberId();
+ int sessionTimeoutMs = request.sessionTimeoutMs();
+
+ if (sessionTimeoutMs < groupMinSessionTimeoutMs ||
+ sessionTimeoutMs > groupMaxSessionTimeoutMs
+ ) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.INVALID_SESSION_TIMEOUT.code())
+ );
+ } else {
+ boolean isUnknownMember = memberId.equals(UNKNOWN_MEMBER_ID);
+ // Group is created if it does not exist and the member id is UNKNOWN. if member
+ // is specified but group does not exist, request is rejected with GROUP_ID_NOT_FOUND
+ GenericGroup group;
+ try {
+ group = (GenericGroup) getOrMaybeCreateGroup(groupId, GENERIC, isUnknownMember);
+ } catch (Throwable t) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.forException(t).code())
+ );
+ return EMPTY_RESULT;
+ }
+
+ String joinReason = request.reason();
+ if (joinReason == null || joinReason.isEmpty()) {
+ joinReason = "not provided";
+ }
+
+ if (!acceptJoiningMember(group, memberId)) {
+ group.remove(memberId);
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.GROUP_MAX_SIZE_REACHED.code())
+ );
+
+ } else if (isUnknownMember) {
+ result = genericGroupJoinNewMember(
+ context,
+ request,
+ group,
+ joinReason,
+ responseFuture
+ );
+ } else {
+ result = genericGroupJoinExistingMember(
+ context,
+ request,
+ group,
+ joinReason,
+ responseFuture
+ );
+ }
+
+ // Attempt to complete join group phase. We do not complete
+ // the join group phase if this is the initial rebalance.
+ if (group.isInState(PREPARING_REBALANCE) &&
+ group.hasAllMembersJoined() &&
+ group.generationId() != 0
+ ) {
+ completeGenericGroupJoin(group);
+ }
+ }
+
+ return result;
+ }
+
+ /**
+ * Handle a new member generic group join.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinNewMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ List<Protocol> protocols = new ArrayList<>();
+ request.protocols().forEach(protocol -> protocols.add(new Protocol(protocol.name(), protocol.metadata())));
+ if (group.isInState(DEAD)) {
+ // if the group is marked as dead, it means some other thread has just removed the group
+ // from the coordinator metadata; it is likely that the group has migrated to some other
+ // coordinator OR the group is in a transient unstable phase. Let the member retry
+ // finding the correct coordinator and rejoin.
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.COORDINATOR_NOT_AVAILABLE.code())
+ );
+ } else if (!group.supportsProtocols(request.protocolType(), GenericGroupMember.plainProtocolSet(protocols))) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.INCONSISTENT_GROUP_PROTOCOL.code())
+ );
+ } else {
+ Optional<String> groupInstanceId = Optional.ofNullable(request.groupInstanceId());
+ String newMemberId = group.generateMemberId(context.clientId(), groupInstanceId);
+
+ if (groupInstanceId.isPresent()) {
+ return genericGroupJoinNewStaticMember(
+ context,
+ request,
+ group,
+ newMemberId,
+ joinReason,
+ responseFuture
+ );
+ } else {
+ return genericGroupJoinNewDynamicMember(
+ context,
+ request,
+ group,
+ newMemberId,
+ joinReason,
+ responseFuture
+ );
+ }
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Handle new static member join. If there was an existing member id for the group instance id,
+ * replace that member. Otherwise, add the member and rebalance.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param newMemberId The newly generated member id.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinNewStaticMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String newMemberId,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ String groupInstanceId = request.groupInstanceId();
+ String existingMemberId = group.staticMemberId(groupInstanceId);
+ if (existingMemberId != null) {
+ log.info("Static member with groupInstanceId={} and unknown member id joins " +
+ "group {} in {} state. Replacing previously mapped member {} with this groupInstanceId.",
+ groupInstanceId, group.groupId(), group.currentState(), existingMemberId);
+
+ return updateStaticMemberAndRebalance(
+ context,
+ request,
+ group,
+ existingMemberId,
+ newMemberId,
+ joinReason,
+ responseFuture
+ );
+
+ } else {
+ log.info("Static member with groupInstanceId={} and unknown member id joins " +
+ "group {} in {} state. Created a new member id {} for this member and added to the group.",
+ groupInstanceId, group.groupId(), group.currentState(), newMemberId);
+
+ return addMemberAndRebalance(context, request, group, newMemberId, joinReason, responseFuture);
+ }
+ }
+
+ /**
+ * Handle a new dynamic member join. If the member id field is required, the group metadata manager
+ * will add the new member id to the pending members and respond with MEMBER_ID_REQUIRED along with
+ * the new member id for the client to join with.
+ *
+ * Otherwise, add the new member to the group and rebalance.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param newMemberId The newly generated member id.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinNewDynamicMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String newMemberId,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ boolean requireKnownMemberId = context.apiVersion() >= 4
+ && (request.groupInstanceId() == null || request.groupInstanceId().isEmpty());
+
+ if (requireKnownMemberId) {
+ // If member id required, register the member in the pending member list and send
+ // back a response to call for another join group request with allocated member id.
+ log.info("Dynamic member with unknown member id joins group {} in {} state. " +
+ "Created a new member id {} and requesting the member to rejoin with this id.",
+ group.groupId(), group.currentState(), newMemberId);
+
+ group.addPendingMember(newMemberId);
+ String heartbeatKey = heartbeatKey(group.groupId(), newMemberId);
+
+ timer.schedule(
+ heartbeatKey,
+ request.sessionTimeoutMs(),
+ TimeUnit.MILLISECONDS,
+ () -> expireGenericGroupMemberHeartbeat(group, newMemberId)
+ );
+
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(newMemberId)
+ .setErrorCode(Errors.MEMBER_ID_REQUIRED.code())
+ );
+
+ } else {
+ log.info("Dynamic member with unknown member id joins group {} in state {}. " +
+ "Created a new member id {} and added the member to the group.",
+ group.groupId(), group.currentState(), newMemberId);
+
+ return addMemberAndRebalance(context, request, group, newMemberId, joinReason, responseFuture);
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Handle a join group request for an existing member.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> genericGroupJoinExistingMember(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ List<Protocol> protocols = request.protocols().stream()
+ .map(protocol -> new Protocol(protocol.name(), protocol.metadata())).collect(Collectors.toList());
+
+ String memberId = request.memberId();
+ String groupInstanceId = request.groupInstanceId();
+
+ if (group.isInState(DEAD)) {
+ // If the group is marked as dead, it means the group was recently removed the group
+ // from the coordinator metadata; it is likely that the group has migrated to some other
+ // coordinator OR the group is in a transient unstable phase. Let the member retry
+ // finding the correct coordinator and rejoin.
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.COORDINATOR_NOT_AVAILABLE.code())
+ );
+ } else if (!group.supportsProtocols(
+ request.protocolType(),
+ GenericGroupMember.plainProtocolSet(protocols))
+ ) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.INCONSISTENT_GROUP_PROTOCOL.code())
+ );
+ } else if (group.isPendingMember(memberId)) {
+ // A rejoining pending member will be accepted. Note that pending member cannot be a static member.
+ if (groupInstanceId != null) {
+ throw new IllegalStateException("Received unexpected JoinGroup with groupInstanceId=" +
+ groupInstanceId + " for pending member with memberId=" + memberId);
+ }
+
+ log.debug("Pending dynamic member with id {} joins group {} in {} state. Adding to the group now.",
+ memberId, group.groupId(), group.currentState());
+
+ return addMemberAndRebalance(
+ context,
+ request,
+ group,
+ memberId,
+ joinReason,
+ responseFuture
+ );
+ } else {
+ Optional<Errors> memberError = validateExistingMember(
+ group,
+ memberId,
+ groupInstanceId,
+ "join-group"
+ );
+
+ if (memberError.isPresent()) {
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(memberError.get().code())
+ );
+ } else {
+ GenericGroupMember member = group.member(memberId);
+ if (group.isInState(PREPARING_REBALANCE)) {
+ return updateMemberAndRebalance(
+ request,
+ group,
+ member,
+ "Member " + member.memberId() + " is joining group during " +
+ group.stateAsString() + "; client reason: " + joinReason,
+ responseFuture
+ );
+ } else if (group.isInState(COMPLETING_REBALANCE)) {
+ if (member.matches(protocols)) {
+ // Member is joining with the same metadata (which could be because it failed to
+ // receive the initial JoinGroup response), so just return current group information
+ // for the current generation.
+ List<JoinGroupResponseData.JoinGroupResponseMember> members = Collections.emptyList();
+ if (group.isLeader(memberId)) {
+ members = group.currentGenericGroupMembers();
+ }
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMembers(members)
+ .setMemberId(memberId)
+ .setGenerationId(group.generationId())
+ .setProtocolName(group.protocolName().orElse(null))
+ .setProtocolType(group.protocolType().orElse(null))
+ .setLeader(group.leaderOrNull())
+ .setSkipAssignment(false)
+ .setErrorCode(Errors.NONE.code())
+ );
+ } else {
+ // Member has changed metadata, so force a rebalance
+ return updateMemberAndRebalance(
+ request,
+ group,
+ member,
+ "Updating metadata for member " + memberId + " during " +
+ group.stateAsString() + "; client reason: " + joinReason,
+ responseFuture
+ );
+ }
+ } else if (group.isInState(STABLE)) {
+ if (group.isLeader(memberId)) {
+ // Force a rebalance if the leader sends JoinGroup;
+ // This allows the leader to trigger rebalances for changes affecting assignment
+ // which do not affect the member metadata (such as topic metadata changes for the consumer)
+ return updateMemberAndRebalance(
+ request,
+ group,
+ member,
+ "Leader " + memberId + " re-joining group during " +
+ group.stateAsString() + "; client reason: " + joinReason,
+ responseFuture
+ );
+ } else if (!member.matches(protocols)) {
+ return updateMemberAndRebalance(
+ request,
+ group,
+ member,
+ "Updating metadata for member " + memberId + " during " +
+ group.stateAsString() + "; client reason: " + joinReason,
+ responseFuture
+ );
+ } else {
+ // For followers with no actual change to their metadata, just return group information
+ // for the current generation which will allow them to issue SyncGroup.
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMembers(Collections.emptyList())
+ .setMemberId(memberId)
+ .setGenerationId(group.generationId())
+ .setProtocolName(group.protocolName().orElse(null))
+ .setProtocolType(group.protocolType().orElse(null))
+ .setLeader(group.leaderOrNull())
+ .setSkipAssignment(false)
+ .setErrorCode(Errors.NONE.code())
+ );
+ }
+ } else {
+ // Group reached unexpected (Empty) state. Let the joining member reset their generation and rejoin.
+ log.warn("Attempt to add rejoining member {} of group {} in unexpected group state {}",
+ memberId, group.groupId(), group.stateAsString());
+
+ responseFuture.complete(new JoinGroupResponseData()
+ .setMemberId(memberId)
+ .setErrorCode(Errors.UNKNOWN_MEMBER_ID.code())
+ );
+ }
+ }
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Complete the join group phase. Remove all dynamic members that have not rejoined
+ * during this stage and proceed with the next generation for this group. The generation id
+ * is incremented and the group transitions to CompletingRebalance state if there is at least
+ * one member.
+ *
+ * If the group is in Empty state, append a new group metadata record to the log. Otherwise,
+ * complete all members' join group response futures and wait for sync requests from members.
+ *
+ * @param group The group that is completing the join group phase.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> completeGenericGroupJoin(
+ GenericGroup group
+ ) {
+ timer.cancel(joinKey(group.groupId()));
+ String groupId = group.groupId();
+
+ Map<String, GenericGroupMember> notYetRejoinedDynamicMembers =
+ group.notYetRejoinedMembers().entrySet().stream()
+ .filter(entry -> !entry.getValue().isStaticMember())
+ .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
+
+ if (!notYetRejoinedDynamicMembers.isEmpty()) {
+ notYetRejoinedDynamicMembers.values().forEach(failedMember -> {
+ group.remove(failedMember.memberId());
+ timer.cancel(heartbeatKey(group.groupId(), failedMember.memberId()));
+ });
+
+ log.info("Group {} removed dynamic members who haven't joined: {}",
+ groupId, notYetRejoinedDynamicMembers.keySet());
+ }
+
+ if (group.isInState(DEAD)) {
+ log.info("Group {} is dead, skipping rebalance stage.", groupId);
+ } else if (!group.maybeElectNewJoinedLeader() && !group.allMembers().isEmpty()) {
+ // If all members are not rejoining, we will postpone the completion
+ // of rebalance preparing stage, and send out another delayed operation
+ // until session timeout removes all the non-responsive members.
+ log.error("Group {} could not complete rebalance because no members rejoined.", groupId);
+
+ return tryCompleteJoinElseSchedule(group);
+ } else {
+ group.initNextGeneration();
+ if (group.isInState(EMPTY)) {
+ log.info("Group {} with generation {} is now empty ({}-{})",
+ groupId, group.generationId(), topicPartition.topic(), topicPartition.partition());
+
+ CompletableFuture<Errors> appendFuture = new CompletableFuture<>();
+ appendFuture.whenComplete((error, t) -> {
+ if (t != null || error != Errors.NONE) {
+ // We failed to write the empty group metadata. If the broker fails before another rebalance,
+ // the previous generation written to the log will become active again (and most likely timeout).
+ // This should be safe since there are no active members in an empty generation, so we just warn.
+ String message = t != null ? t.getMessage() : error.message();
+ log.warn("Failed to write empty metadata for group {}: {}", group.groupId(), message);
+ }
+ });
+
+ List<Record> records = Collections.singletonList(
+ RecordHelpers.newGroupMetadataRecord(group, metadataImage.features().metadataVersion())
+ );
+
+ return new CoordinatorResult<>(records, appendFuture);
+
+ } else {
+ log.info("Stabilized group {} generation {} ({}-{}) with {} members",
+ groupId, group.generationId(), topicPartition.topic(),
+ topicPartition.partition(), group.size());
+
+ // Complete the awaiting join group response future for all the members after rebalancing
+ group.allMembers().forEach(member -> {
+
+ List<JoinGroupResponseData.JoinGroupResponseMember> members = Collections.emptyList();
+ if (group.isLeader(member.memberId())) {
+ members = group.currentGenericGroupMembers();
+ }
+
+ JoinGroupResponseData response = new JoinGroupResponseData()
+ .setMembers(members)
+ .setMemberId(member.memberId())
+ .setGenerationId(group.generationId())
+ .setProtocolName(group.protocolName().orElse(null))
+ .setProtocolType(group.protocolType().orElse(null))
+ .setLeader(group.leaderOrNull())
+ .setSkipAssignment(false)
+ .setErrorCode(Errors.NONE.code());
+
+ group.completeJoinFuture(member, response);
+ rescheduleGenericGroupMemberHeartbeat(group, member);
+ member.setIsNew(false);
+
+ group.addPendingSyncMember(member.memberId());
+ });
+
+ schedulePendingSync(group);
+ }
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Wait for sync requests for the group.
+ *
+ * @param group The group.
+ */
+ private void schedulePendingSync(GenericGroup group) {
+ timer.schedule(syncKey(group.groupId()),
+ group.rebalanceTimeoutMs(),
+ TimeUnit.MILLISECONDS,
+ () -> expirePendingSync(group, group.generationId()));
+ }
+
+ /**
+ * Invoked when the heartbeat operation is expired from the timer. Possibly remove the member and
+ * try complete the join phase.
+ *
+ * @param group The group.
+ * @param memberId The member id.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> expireGenericGroupMemberHeartbeat(
+ GenericGroup group,
+ String memberId
+ ) {
+ if (group.isInState(DEAD)) {
+ log.info("Received notification of heartbeat expiration for member {} after group {} " +
+ "had already been unloaded or deleted.",
+ memberId, group.groupId());
+
+ } else if (group.isPendingMember(memberId)) {
+ log.info("Pending member {} in group {} has been removed after session timeout expiration.",
+ memberId, group.groupId());
+
+ return removePendingMemberAndUpdateGenericGroup(group, memberId);
+ } else if (!group.hasMemberId(memberId)) {
+ log.debug("Member {} has already been removed from the group.", memberId);
+ } else {
+ GenericGroupMember member = group.member(memberId);
+ if (!member.hasSatisfiedHeartbeat()) {
+ log.info("Member {} in group {} has failed, removing it from the group.",
+ member.memberId(), group.groupId());
+
+ return removeMemberAndUpdateGenericGroup(
+ group,
+ member,
+ "removing member " + member.memberId() + " on heartbeat expiration."
+ );
+ }
+ }
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Invoked when the heartbeat key is expired from the timer. Possibly remove the member
+ * from the group and try to complete the join phase.
+ *
+ * @param group The group.
+ * @param member The member.
+ * @param reason The reason for removing the member.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> removeMemberAndUpdateGenericGroup(
+ GenericGroup group,
+ GenericGroupMember member,
+ String reason
+ ) {
+ // New members may timeout with a pending JoinGroup while the group is still rebalancing, so we have
+ // to invoke the response future before removing the member. We return UNKNOWN_MEMBER_ID so
+ // that the consumer will retry the JoinGroup request if it is still active.
+ group.completeJoinFuture(member, new JoinGroupResponseData()
+ .setMemberId(UNKNOWN_MEMBER_ID)
+ .setErrorCode(Errors.UNKNOWN_MEMBER_ID.code())
+ );
+ group.remove(member.memberId());
+
+ if (group.isInState(STABLE) || group.isInState(COMPLETING_REBALANCE)) {
+ return maybePrepareRebalance(group, reason);
+ } else if (group.isInState(PREPARING_REBALANCE) && group.hasAllMembersJoined()) {
+ return completeGenericGroupJoin(group);
+ } // Do nothing if state is DEAD or EMPTY.
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Remove a pending member from the group and possibly complete the join phase.
+ *
+ * @param group The group.
+ * @param memberId The member id.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> removePendingMemberAndUpdateGenericGroup(
+ GenericGroup group,
+ String memberId
+ ) {
+ group.remove(memberId);
+
+ if (group.isInState(PREPARING_REBALANCE) && group.hasAllMembersJoined()) {
+ return completeGenericGroupJoin(group);
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Update an existing member and rebalance.
+ *
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param member The member.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> updateMemberAndRebalance(
+ JoinGroupRequestData request,
+ GenericGroup group,
+ GenericGroupMember member,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ List<Protocol> protocols = request.protocols().stream()
+ .map(protocol -> new Protocol(protocol.name(), protocol.metadata()))
+ .collect(Collectors.toList());
+
+ group.updateMember(member, protocols, request.rebalanceTimeoutMs(), request.sessionTimeoutMs(), responseFuture);
+ return maybePrepareRebalance(group, joinReason);
+ }
+
+ /**
+ * We are validating two things:
+ * 1. If `groupInstanceId` is present, then it exists and is mapped to `memberId`
+ * 2. The `memberId` exists in the group
+ *
+ * @param group The generic group.
+ * @param memberId The member id.
+ * @param groupInstanceId The group instance id.
+ * @param operation The API operation.
+ *
+ * @return the error.
+ */
+ private Optional<Errors> validateExistingMember(
+ GenericGroup group,
+ String memberId,
+ String groupInstanceId,
+ String operation
+ ) {
+ if (groupInstanceId == null) {
+ if (!group.hasMemberId(memberId)) {
+ return Optional.of(Errors.UNKNOWN_MEMBER_ID);
+ } else {
+ return Optional.empty();
+ }
+ }
+
+ String existingMemberId = group.staticMemberId(groupInstanceId);
+ if (existingMemberId == null) {
+ return Optional.of(Errors.UNKNOWN_MEMBER_ID);
+ }
+
+ if (!existingMemberId.equals(memberId)) {
+ log.info("Request memberId={} for static member with groupInstanceId={} " +
+ "is fenced by existing memberId={} during operation {}",
+ memberId, groupInstanceId, existingMemberId, operation);
+
+ return Optional.of(Errors.FENCED_INSTANCE_ID);
+ }
+
+ return Optional.empty();
+ }
+
+ /**
+ * Add a member and rebalance.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group to add the member.
+ * @param memberId The member id.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> addMemberAndRebalance(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String memberId,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ List<Protocol> protocols = new ArrayList<>();
+ request.protocols().forEach(protocol -> protocols.add(new Protocol(protocol.name(), protocol.metadata())));
+ Optional<String> groupInstanceId = Optional.ofNullable(request.groupInstanceId());
+ GenericGroupMember member = new GenericGroupMember(
+ memberId,
+ groupInstanceId,
+ context.clientId(),
+ context.clientAddress().toString(),
+ request.rebalanceTimeoutMs(),
+ request.sessionTimeoutMs(),
+ request.protocolType(),
+ protocols
+ );
+
+ member.setIsNew(true);
+
+ // Update the newMemberAdded flag to indicate that the initial rebalance can be further delayed
+ if (group.isInState(PREPARING_REBALANCE) && group.generationId() == 0) {
+ group.setNewMemberAdded(true);
+ }
+
+ group.add(member, responseFuture);
+
+ // The session timeout does not affect new members since they do not have their memberId and
+ // cannot send heartbeats. Furthermore, we cannot detect disconnects because sockets are muted
+ // while the JoinGroup request is parked. If the client does disconnect (e.g. because of a request
+ // timeout during a long rebalance), they may simply retry which will lead to a lot of defunct
+ // members in the rebalance. To prevent this going on indefinitely, we time out JoinGroup requests
+ // for new members. If the new member is still there, we expect it to retry.
+ rescheduleGenericGroupMemberHeartbeat(group, member, newMemberJoinTimeoutMs);
+
+ return maybePrepareRebalance(group, "Adding new member " + memberId + " with group instance id " +
+ request.groupInstanceId() + "; client reason: " + joinReason);
+ }
+
+ /**
+ * Prepare a rebalance if the group is in a valid state.
+ *
+ * @param group The group to rebalance.
+ * @param reason The reason for the rebalance.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> maybePrepareRebalance(
+ GenericGroup group,
+ String reason
+ ) {
+ if (group.canRebalance()) {
+ return prepareRebalance(group, reason);
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Prepare a rebalance.
+ *
+ * @param group The group to rebalance.
+ * @param reason The reason for the rebalance.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ CoordinatorResult<CompletableFuture<Errors>, Record> prepareRebalance(
+ GenericGroup group,
+ String reason
+ ) {
+ // If any members are awaiting sync, cancel their request and have them rejoin.
+ if (group.isInState(COMPLETING_REBALANCE)) {
+ resetAndPropagateAssignmentWithError(group, Errors.REBALANCE_IN_PROGRESS);
+ }
+
+ // If a sync expiration is pending, cancel it.
+ removeSyncExpiration(group);
+
+ boolean isInitialRebalance = group.generationId() == 0;
+ if (isInitialRebalance) {
+ // The group is new. Provide more time for the members to join.
+ int delayMs = initialRebalanceDelayMs;
+ int remainingMs = Math.max(group.rebalanceTimeoutMs() - initialRebalanceDelayMs, 0);
+ group.setInitialRebalanceTimeoutMs(remainingMs);
+ group.setInitialRebalanceDelayMs(delayMs);
+
+ timer.schedule(
+ joinKey(group.groupId()),
+ delayMs,
+ TimeUnit.MILLISECONDS,
+ () -> tryCompleteInitialRebalanceElseSchedule(group)
+ );
+ }
+
+
+ group.transitionTo(PREPARING_REBALANCE);
+
+ log.info("Preparing to rebalance group {} in state {} with old generation {} ({}-{}) (reason: {})",
+ group.groupId(), group.currentState(), group.generationId(),
+ topicPartition.topic(), topicPartition.partition(), reason);
+
+ return isInitialRebalance ? EMPTY_RESULT : tryCompleteJoinElseSchedule(group);
+ }
+
+ /**
+ * Try to complete the join phase. Otherwise, schedule a new join operation.
+ *
+ * @param group The group.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> tryCompleteJoinElseSchedule(
+ GenericGroup group
+ ) {
+ String joinKey = joinKey(group.groupId());
+ if (group.hasAllMembersJoined()) {
+ // All members have joined. Proceed to sync phase.
+ return completeGenericGroupJoin(group);
+ } else {
+ timer.schedule(
+ joinKey,
+ group.rebalanceTimeoutMs(),
+ TimeUnit.MILLISECONDS,
+ () -> completeGenericGroupJoin(group)
+ );
+ return EMPTY_RESULT;
+ }
+ }
+
+ /**
+ * Try to complete the join phase of the initial rebalance.
+ * Otherwise, extend the rebalance.
+ *
+ * @param group The group under initial rebalance.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> tryCompleteInitialRebalanceElseSchedule(
+ GenericGroup group
+ ) {
+ int remainingMs = group.initialRebalanceTimeoutMs();
+ int delayMs = group.initialRebalanceDelayMs();
+ if (group.newMemberAdded() && remainingMs != 0) {
+ // A new member was added. Extend the delay.
+ group.setNewMemberAdded(false);
+ int newDelayMs = Math.min(initialRebalanceDelayMs, remainingMs);
+ int newRemainingMs = Math.max(remainingMs - delayMs, 0);
+
+ group.setInitialRebalanceTimeoutMs(newRemainingMs);
+ group.setInitialRebalanceDelayMs(newDelayMs);
+
+ timer.schedule(
+ joinKey(group.groupId()),
+ newDelayMs,
+ TimeUnit.MILLISECONDS,
+ () -> tryCompleteInitialRebalanceElseSchedule(group)
+ );
+ } else {
+ // No more time remaining. Complete the join phase.
+ group.setInitialRebalanceTimeoutMs(0);
+ group.setInitialRebalanceDelayMs(0);
+ return completeGenericGroupJoin(group);
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Reset assignment for all members and propagate the error to all members in the group.
+ *
+ * @param group The group.
+ * @param error The error to propagate.
+ */
+ private void resetAndPropagateAssignmentWithError(GenericGroup group, Errors error) {
+ if (!group.isInState(COMPLETING_REBALANCE)) {
+ throw new IllegalStateException("Group " + group.groupId() + " must be in " + COMPLETING_REBALANCE.name() +
+ " state but is in " + group.currentState() + ".");
+ }
+
+ group.allMembers().forEach(member -> member.setAssignment(GenericGroupMember.EMPTY_ASSIGNMENT));
+ propagateAssignment(group, error);
+ }
+
+ /**
+ * Propagate assignment and error to all members.
+ *
+ * @param group The group.
+ * @param error The error to propagate.
+ */
+ private void propagateAssignment(GenericGroup group, Errors error) {
+ Optional<String> protocolName = Optional.empty();
+ Optional<String> protocolType = Optional.empty();
+ if (error == Errors.NONE) {
+ protocolName = group.protocolName();
+ protocolType = group.protocolType();
+ }
+
+ for (GenericGroupMember member : group.allMembers()) {
+ if ((member.assignment() == null || member.assignment().length == 0) && error == Errors.NONE) {
+ log.warn("Sending empty assignment to member {} of {} for " + "generation {} with no errors",
+ member.memberId(), group.groupId(), group.generationId());
+ }
+
+ if (group.completeSyncFuture(member,
+ new SyncGroupResponseData()
+ .setProtocolName(protocolName.orElse(null))
+ .setProtocolType(protocolType.orElse(null))
+ .setAssignment(member.assignment())
+ .setErrorCode(error.code()))) {
+
+ // Reset the session timeout for members after propagating the member's assignment.
+ // This is because if any member's session expired while we were still awaiting either
+ // the leader sync group or the append future, its expiration will be ignored and no
+ // future heartbeat expectations will not be scheduled.
+ rescheduleGenericGroupMemberHeartbeat(group, member);
+ }
+ }
+ }
+
+ /**
+ * Complete and schedule next heartbeat.
+ *
+ * @param group The group.
+ * @param member The member.
+ */
+ private void rescheduleGenericGroupMemberHeartbeat(
+ GenericGroup group,
+ GenericGroupMember member
+ ) {
+ rescheduleGenericGroupMemberHeartbeat(group, member, member.sessionTimeoutMs());
+ }
+
+ /**
+ * Reschedule the heartbeat key from the timer and schedule
+ * a new heartbeat.
+ *
+ * @param group The group.
+ * @param member The member.
+ * @param timeoutMs The timeout for the new heartbeat.
+ */
+ private void rescheduleGenericGroupMemberHeartbeat(
+ GenericGroup group,
+ GenericGroupMember member,
+ long timeoutMs
+ ) {
+ String heartbeatKey = heartbeatKey(group.groupId(), member.memberId());
+
+ // Reschedule the next heartbeat expiration deadline
+ timer.schedule(heartbeatKey,
+ timeoutMs,
+ TimeUnit.MILLISECONDS,
+ () -> expireGenericGroupMemberHeartbeat(group, member.memberId()));
+ }
+
+ /**
+ * Remove the sync key from the timer and clear all pending sync members from the group.
+ * Invoked when a new rebalance is triggered.
+ *
+ * @param group The group.
+ */
+ private void removeSyncExpiration(GenericGroup group) {
+ group.clearPendingSyncMembers();
+ timer.cancel(syncKey(group.groupId()));
+ }
+
+ /**
+ * Expire pending sync.
+ *
+ * @param group The group.
+ * @param generationId The generation when the pending sync was originally scheduled.
+ *
+ * @return The coordinator result that will be appended to the log.
+ * */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> expirePendingSync(
+ GenericGroup group,
+ int generationId
+ ) {
+ if (generationId != group.generationId()) {
+ log.error("Received unexpected notification of sync expiration for {} with an old " +
+ "generation {} while the group has {}.", group.groupId(), generationId, group.generationId());
+ } else {
+ if (group.isInState(DEAD) || group.isInState(EMPTY) || group.isInState(PREPARING_REBALANCE)) {
+ log.error("Received unexpected notification of sync expiration after group {} already " +
+ "transitioned to {} state.", group.groupId(), group.stateAsString());
+ } else if (group.isInState(COMPLETING_REBALANCE) || group.isInState(STABLE)) {
+ if (!group.hasReceivedSyncFromAllMembers()) {
+ Set<String> pendingSyncMembers = group.allPendingSyncMembers();
+ pendingSyncMembers.forEach(memberId -> {
+ group.remove(memberId);
+ timer.cancel(heartbeatKey(group.groupId(), memberId));
+ });
+
+ log.debug("Group {} removed members who haven't sent their sync requests: {}",
+ group.groupId(), pendingSyncMembers);
+
+ return prepareRebalance(group, "Removing " + pendingSyncMembers + " on pending sync request expiration");
+ }
+ }
+ }
+
+ return EMPTY_RESULT;
+ }
+
+ /**
+ * Checks whether the group can accept a joining member.
+ *
+ * @param group The group.
+ * @param memberId The member.
+ *
+ * @return whether the group can accept a joining member.
+ */
+ private boolean acceptJoiningMember(GenericGroup group, String memberId) {
+ if (group.isInState(EMPTY) || group.isInState(DEAD)) {
+ // Always accept the request when the group is empty or dead
+ return true;
+
+ } else if (group.isInState(PREPARING_REBALANCE)) {
+ // An existing member is accepted if it is already awaiting. New members are accepted
+ // up to the max group size. Note that the number of awaiting members is used here
+ // for two reasons:
+ // 1) the group size is not reliable as it could already be above the max group size
+ // if the max group size was reduced.
+ // 2) using the number of awaiting members allows to kick out the last rejoining
+ // members of the group.
+ return (group.hasMemberId(memberId) && group.member(memberId).isAwaitingJoin()) ||
+ group.numAwaitingJoinResponse() < groupMaxSize;
+
+ } else if (group.isInState(COMPLETING_REBALANCE) || group.isInState(STABLE)) {
+ // An existing member is accepted. New members are accepted up to the max group size.
+ // Note that the group size is used here. When the group transitions to CompletingRebalance,
+ // members who haven't rejoined are removed.
+ return group.hasMemberId(memberId) || group.size() < groupMaxSize;
+ } else {
+ throw new IllegalStateException("Cannot handle state " + group.stateAsString());
+ }
+ }
+
+ /**
+ * Update a static member and rebalance.
+ *
+ * @param context The request context.
+ * @param request The join group request.
+ * @param group The group of the static member.
+ * @param oldMemberId The existing static member id.
+ * @param newMemberId The new joining static member id.
+ * @param joinReason The client reason for the join request.
+ * @param responseFuture The response future to complete.
+ *
+ * @return The coordinator result that will be appended to the log.
+ */
+ private CoordinatorResult<CompletableFuture<Errors>, Record> updateStaticMemberAndRebalance(
+ RequestContext context,
+ JoinGroupRequestData request,
+ GenericGroup group,
+ String oldMemberId,
+ String newMemberId,
+ String joinReason,
+ CompletableFuture<JoinGroupResponseData> responseFuture
+ ) {
+ String currentLeader = group.leaderOrNull();
+ GenericGroupMember member = group.replaceStaticMember(request.groupInstanceId(), oldMemberId, newMemberId);
+
+ // Heartbeat of old member id will expire without effect since the group no longer contains that member id.
+ // New heartbeat shall be scheduled with new member id.
+ rescheduleGenericGroupMemberHeartbeat(group, member);
+
+ List<Protocol> protocols = new ArrayList<>(request.protocols().size());
+ request.protocols().forEach(protocol -> protocols.add(new Protocol(protocol.name(), protocol.metadata())));
+
+ int oldRebalanceTimeoutMs = member.rebalanceTimeoutMs();
+ int oldSessionTimeoutMs = member.sessionTimeoutMs();
+ List<Protocol> oldProtocols = member.supportedProtocols();
+
+ group.updateMember(
+ member,
+ protocols,
+ request.rebalanceTimeoutMs(),
+ request.sessionTimeoutMs(),
+ responseFuture
+ );
+
+ if (group.isInState(STABLE)) {
+ // Check if group's selected protocol of next generation will change, if not, simply store group to persist
+ // the updated static member, if yes, rebalance should be triggered to keep the group's assignment
+ // and selected protocol consistent
+ String groupInstanceId = request.groupInstanceId();
+ String selectedProtocolForNextGeneration = group.selectProtocol();
+ if (group.protocolName().orElse("").equals(selectedProtocolForNextGeneration)) {
+ log.info("Static member which joins during Stable stage and doesn't affect " +
+ "the selected protocol will not trigger a rebalance.");
+
+ CompletableFuture<Errors> appendFuture = new CompletableFuture<>();
Review Comment:
Shouldn't we use `CompletableFuture<Void>` and complete the future exceptionally with the exception corresponding to the error?
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