philipnee commented on code in PR #12862: URL: https://github.com/apache/kafka/pull/12862#discussion_r1043793970
########## clients/src/main/java/org/apache/kafka/clients/consumer/internals/CoordinatorRequestManager.java: ########## @@ -0,0 +1,289 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +package org.apache.kafka.clients.consumer.internals; + +import org.apache.kafka.clients.ClientResponse; +import org.apache.kafka.clients.consumer.ConsumerConfig; +import org.apache.kafka.common.Node; +import org.apache.kafka.common.errors.GroupAuthorizationException; +import org.apache.kafka.common.errors.RetriableException; +import org.apache.kafka.common.message.FindCoordinatorRequestData; +import org.apache.kafka.common.message.FindCoordinatorResponseData; +import org.apache.kafka.common.protocol.Errors; +import org.apache.kafka.common.requests.FindCoordinatorRequest; +import org.apache.kafka.common.requests.FindCoordinatorResponse; +import org.apache.kafka.common.utils.ExponentialBackoff; +import org.apache.kafka.common.utils.LogContext; +import org.apache.kafka.common.utils.Time; +import org.slf4j.Logger; + +import java.util.ArrayList; +import java.util.Collections; +import java.util.Objects; +import java.util.Optional; + +/** + * Handles the timing of the next FindCoordinatorRequest based on the {@link CoordinatorRequestState}. It checks for: + * 1. If there's an existing coordinator. + * 2. If there is an inflight request + * 3. If the backoff timer has expired + * + * The {@link org.apache.kafka.clients.consumer.internals.NetworkClientDelegate.PollResult} contains either a wait + * timer, or a singleton list of + * {@link org.apache.kafka.clients.consumer.internals.NetworkClientDelegate.UnsentRequest}. + * + * The FindCoordinatorResponse will be handled by the {@link FindCoordinatorRequestHandler} callback, which + * subsequently invokes {@code onResponse} to handle the exceptions and responses. Note that, the coordinator node + * will be marked {@code null} upon receiving a failure. + */ +public class CoordinatorRequestManager implements RequestManager { + + private final Logger log; + private final Time time; + private final ErrorEventHandler errorHandler; + private final long rebalanceTimeoutMs; + private final String groupId; + + private final CoordinatorRequestState coordinatorRequestState; + private long timeMarkedUnknownMs = -1L; // starting logging a warning only after unable to connect for a while + private Node coordinator; + + + public CoordinatorRequestManager(final Time time, + final LogContext logContext, + final ConsumerConfig config, + final ErrorEventHandler errorHandler, + final String groupId, + final long rebalanceTimeoutMs) { + Objects.requireNonNull(groupId); + this.time = time; + this.log = logContext.logger(this.getClass()); + this.errorHandler = errorHandler; + this.groupId = groupId; + this.rebalanceTimeoutMs = rebalanceTimeoutMs; + this.coordinatorRequestState = new CoordinatorRequestState(config); + } + + // Visible for testing + CoordinatorRequestManager(final Time time, + final LogContext logContext, + final ErrorEventHandler errorHandler, + final String groupId, + final long rebalanceTimeoutMs, + final CoordinatorRequestState coordinatorRequestState) { + Objects.requireNonNull(groupId); + this.time = time; + this.log = logContext.logger(this.getClass()); + this.errorHandler = errorHandler; + this.groupId = groupId; + this.rebalanceTimeoutMs = rebalanceTimeoutMs; + this.coordinatorRequestState = coordinatorRequestState; + } + + @Override + public NetworkClientDelegate.PollResult poll(final long currentTimeMs) { + if (this.coordinator != null) { + return new NetworkClientDelegate.PollResult(Long.MAX_VALUE, Collections.emptyList()); + } + + if (coordinatorRequestState.canSendRequest(currentTimeMs)) { + NetworkClientDelegate.UnsentRequest request = makeFindCoordinatorRequest(currentTimeMs); + return new NetworkClientDelegate.PollResult(0, Collections.singletonList(request)); + } + + return new NetworkClientDelegate.PollResult( + coordinatorRequestState.remainingBackoffMs(currentTimeMs), + new ArrayList<>()); + } + + private NetworkClientDelegate.UnsentRequest makeFindCoordinatorRequest(final long currentTimeMs) { + coordinatorRequestState.updateLastSend(currentTimeMs); + FindCoordinatorRequestData data = new FindCoordinatorRequestData() + .setKeyType(FindCoordinatorRequest.CoordinatorType.GROUP.id()) + .setKey(this.groupId); + return NetworkClientDelegate.UnsentRequest.makeUnsentRequest( + new FindCoordinatorRequest.Builder(data), + new FindCoordinatorRequestHandler(), + null); + } + + /** + * Mark the current coordinator null and return the old coordinator. Return an empty Optional + * if the current coordinator is unknown. + * @param cause why the coordinator is marked unknown + * @return Optional coordinator node that can be null. + */ + protected void markCoordinatorUnknown(final String cause, final long currentTimeMs) { + if (this.coordinator != null) { + log.info("Group coordinator {} is unavailable or invalid due to cause: {}. " + + "Rediscovery will be attempted.", this.coordinator, cause); + this.coordinator = null; + timeMarkedUnknownMs = currentTimeMs; + } else { + long durationOfOngoingDisconnect = Math.max(0, currentTimeMs - timeMarkedUnknownMs); + if (durationOfOngoingDisconnect > this.rebalanceTimeoutMs) + log.debug("Consumer has been disconnected from the group coordinator for {}ms", + durationOfOngoingDisconnect); + } + } + + private void onSuccessfulResponse( + final FindCoordinatorResponseData.Coordinator coordinator, + final long currentTimeMS) { + // use MAX_VALUE - node.id as the coordinator id to allow separate connections + // for the coordinator in the underlying network client layer + int coordinatorConnectionId = Integer.MAX_VALUE - coordinator.nodeId(); + + this.coordinator = new Node( + coordinatorConnectionId, + coordinator.host(), + coordinator.port()); + log.info("Discovered group coordinator {}", coordinator); + coordinatorRequestState.reset(); + return; + } + + private void handleFailedCoordinatorResponse( + final Exception exception, + final long currentTimeMs) { + coordinatorRequestState.updateLastFailedAttempt(currentTimeMs); + markCoordinatorUnknown("coordinator unavailable", currentTimeMs); + + if (exception == Errors.GROUP_AUTHORIZATION_FAILED.exception()) { + log.debug("FindCoordinator request failed due to authorization error {}", exception.getMessage()); + errorHandler.handle(GroupAuthorizationException.forGroupId(this.groupId)); + return; + } + + if (exception instanceof RetriableException) { + log.debug("FindCoordinator request failed due to retriable exception", exception); + return; + } + + log.warn("FindCoordinator request failed due to fatal exception", exception); + errorHandler.handle(exception); + } + + public void onResponse(final FindCoordinatorResponse response, final long currentTimeMs, final Throwable t) { + // handle Runtime exception + if (t != null) { + log.error("FindCoordinator request failed due to {}", t.getMessage()); + return; + } + + Optional<FindCoordinatorResponseData.Coordinator> coordinator = response.getCoordinatorByKey(this.groupId); + if (!coordinator.isPresent()) { + String msg = String.format("Coordinator not found for groupId: %s", this.groupId); + handleFailedCoordinatorResponse(new IllegalStateException(msg), currentTimeMs); + return; + } + + FindCoordinatorResponseData.Coordinator node = coordinator.get(); + if (node.errorCode() != Errors.NONE.code()) { + handleFailedCoordinatorResponse(Errors.forCode(node.errorCode()).exception(), currentTimeMs); + return; + } + onSuccessfulResponse(node, currentTimeMs); + } + + public Node coordinator() { + return this.coordinator; + } + + // Visible for testing Review Comment: Thanks, that make sense. -- This is an automated message from the Apache Git Service. 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