philipnee commented on code in PR #12862: URL: https://github.com/apache/kafka/pull/12862#discussion_r1042900099
########## clients/src/main/java/org/apache/kafka/clients/consumer/internals/CoordinatorRequestManager.java: ########## @@ -0,0 +1,303 @@ +/* + * 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.List; +import java.util.Objects; + +/** + * 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 long requestTimeoutMs; + 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.requestTimeoutMs = config.getInt(ConsumerConfig.REQUEST_TIMEOUT_MS_CONFIG); + 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 long requestTimeoutMs, + 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.requestTimeoutMs = requestTimeoutMs; + 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( + this.time.timer(requestTimeoutMs), + new FindCoordinatorRequest.Builder(data), + new FindCoordinatorRequestHandler()); + } + + /** + * 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 handleSuccessFindCoordinatorResponse( + 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 FindCoordinatorResponseData.Coordinator response, + final long currentTimeMS) { + Errors error = Errors.forCode(response.errorCode()); + log.debug("FindCoordinator request failed due to {}", error.toString()); + coordinatorRequestState.updateLastFailedAttempt(currentTimeMS); + markCoordinatorUnknown("coordinator unavailable", currentTimeMS); + if (!(error.exception() instanceof RetriableException)) { + log.info("FindCoordinator request hit fatal exception", error.exception()); + // Remember the exception if fatal so we can ensure + // it gets thrown by the main thread + errorHandler.handle(error.exception()); + return; + } + + if (error == Errors.GROUP_AUTHORIZATION_FAILED) { + errorHandler.handle(GroupAuthorizationException.forGroupId(this.groupId)); + return; + } + + log.debug("Group coordinator lookup failed: {}", response.errorMessage()); + errorHandler.handle(error.exception()); + + log.debug("Coordinator discovery failed, refreshing metadata", error.exception()); + } + + public void onResponse(final FindCoordinatorResponse response, Throwable t) { + long currentTimeMs = time.milliseconds(); + // handle Runtime exception + if (t != null) { + log.error("FindCoordinator request failed due to {}", t.getMessage()); + markCoordinatorUnknown("coordinator unavailable", currentTimeMs); + return; + } + + List<FindCoordinatorResponseData.Coordinator> coordinators = response.getCoordinatorByKey(this.groupId); + if (coordinators.size() != 1) { + coordinatorRequestState.updateLastFailedAttempt(currentTimeMs); + String msg = String.format("Group coordinator lookup failed: Response should contain exactly one " + + "coordinator, it has %d", coordinators.size()); + log.error(msg); + errorHandler.handle(new IllegalStateException(msg)); + return; + } + + FindCoordinatorResponseData.Coordinator node = coordinators.get(0); + if (node.errorCode() != Errors.NONE.code()) { + coordinatorRequestState.updateLastFailedAttempt(currentTimeMs); + handleFailedCoordinatorResponse(node, currentTimeMs); + return; + } + handleSuccessFindCoordinatorResponse(node, currentTimeMs); + } + + public Node coordinator() { + return this.coordinator; + } + + // Visible for testing + static class CoordinatorRequestState { + final static int RECONNECT_BACKOFF_EXP_BASE = 2; + final static double RECONNECT_BACKOFF_JITTER = 0.2; + private final ExponentialBackoff exponentialBackoff; + private long lastSentMs = -1; + private long lastReceivedMs = -1; + private int numAttempts = 0; + private long backoffMs = 0; + + public CoordinatorRequestState(ConsumerConfig config) { + this.exponentialBackoff = new ExponentialBackoff( + config.getLong(ConsumerConfig.RECONNECT_BACKOFF_MS_CONFIG), + RECONNECT_BACKOFF_EXP_BASE, + config.getLong(ConsumerConfig.RECONNECT_BACKOFF_MAX_MS_CONFIG), + RECONNECT_BACKOFF_JITTER); + } + + // Visible for testing + CoordinatorRequestState(final int reconnectBackoffMs, + final int reconnectBackoffExpBase, + final int reconnectBackoffMaxMs, + final int jitter) { + this.exponentialBackoff = new ExponentialBackoff( + reconnectBackoffMs, + reconnectBackoffExpBase, + reconnectBackoffMaxMs, + jitter); + } + + public void reset() { + this.lastSentMs = -1; + this.lastReceivedMs = -1; + this.numAttempts = 0; + this.backoffMs = exponentialBackoff.backoff(0); + } + + public boolean canSendRequest(final long currentTimeMs) { + if (this.lastSentMs == -1) { + // no request has been sent + return true; + } + + // TODO: I think there's a case when we want to resend the FindCoordinator when we haven't received + // anything yet. + if (this.lastReceivedMs == -1 || + this.lastReceivedMs < this.lastSentMs) { + // there is an inflight request + return false; + } + + return requestBackoffExpired(currentTimeMs); + } + + public void updateLastSend(final long currentTimeMs) { + // Here we update the timer everytime we try to send a request. Also increment number of attempts. + this.lastSentMs = currentTimeMs; + } + + public void updateLastFailedAttempt(final long currentTimeMs) { + this.lastReceivedMs = currentTimeMs; + this.backoffMs = exponentialBackoff.backoff(numAttempts); + this.numAttempts++; + } + + private boolean requestBackoffExpired(final long currentTimeMs) { + return (currentTimeMs - this.lastReceivedMs) >= this.backoffMs; Review Comment: Sounds good, but I think currentTimeMs should always >= lastReceivedMs. Trying to think of a case there... -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: jira-unsubscr...@kafka.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
