merlimat commented on code in PR #25559: URL: https://github.com/apache/pulsar/pull/25559#discussion_r3139756010
########## pulsar-broker/src/main/java/org/apache/pulsar/broker/service/scalable/ScalableTopicService.java: ########## @@ -0,0 +1,218 @@ +/* + * 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.pulsar.broker.service.scalable; + +import java.util.Map; +import java.util.concurrent.CompletableFuture; +import java.util.concurrent.ConcurrentHashMap; +import lombok.extern.slf4j.Slf4j; +import org.apache.pulsar.broker.resources.ScalableTopicMetadata; +import org.apache.pulsar.broker.resources.ScalableTopicResources; +import org.apache.pulsar.broker.service.BrokerService; +import org.apache.pulsar.common.naming.TopicDomain; +import org.apache.pulsar.common.naming.TopicName; +import org.apache.pulsar.common.scalable.SegmentInfo; +import org.apache.pulsar.common.scalable.SegmentTopicName; +import org.apache.pulsar.metadata.api.coordination.CoordinationService; +import org.apache.pulsar.metadata.api.coordination.LeaderElection; +import org.apache.pulsar.metadata.api.coordination.LeaderElectionState; + +/** + * Central service managing all scalable topics on this broker. + * + * <p>Lifecycle is tied to {@link BrokerService}. This service handles: + * <ul> + * <li>Creating and deleting scalable topics</li> + * <li>Managing {@link ScalableTopicController} instances for topics this broker coordinates</li> + * <li>Admin operations: split/merge</li> + * </ul> + */ +@Slf4j +public class ScalableTopicService { + + private final BrokerService brokerService; + private final ScalableTopicResources resources; + private final CoordinationService coordinationService; + + /** Active controllers for topics this broker coordinates. */ + private final ConcurrentHashMap<String, ScalableTopicController> controllers = new ConcurrentHashMap<>(); + + public ScalableTopicService(BrokerService brokerService, + ScalableTopicResources resources, + CoordinationService coordinationService) { + this.brokerService = brokerService; + this.resources = resources; + this.coordinationService = coordinationService; + } + + // --- Lifecycle --- + + public void start() { + log.info("ScalableTopicService started"); + } + + public void close() { + log.info("Closing ScalableTopicService, releasing {} controllers", controllers.size()); + controllers.values().forEach(controller -> { + try { + controller.close().join(); + } catch (Exception e) { + log.warn("Error closing controller for topic {}", controller.getTopicName(), e); + } + }); + controllers.clear(); + } + + // --- Controller management --- + + /** + * Get or create a controller for a scalable topic. The controller will attempt + * leader election; only the leader actively coordinates consumers. + */ + public CompletableFuture<ScalableTopicController> getOrCreateController(TopicName topic) { + String key = topic.toString(); + ScalableTopicController existing = controllers.get(key); + if (existing != null) { + return CompletableFuture.completedFuture(existing); + } + + String lockPath = resources.controllerLockPath(topic); + LeaderElection<String> election = coordinationService.getLeaderElection( + String.class, lockPath, state -> onLeaderStateChange(topic, state)); + + ScalableTopicController controller = new ScalableTopicController( + topic, resources, brokerService, election); + controllers.put(key, controller); + + return controller.initialize() + .thenApply(__ -> controller) + .exceptionally(ex -> { + controllers.remove(key); + throw new RuntimeException("Failed to initialize controller for " + topic, ex); + }); + } + + /** + * Release the controller for a topic (e.g., on topic unload). + */ + public CompletableFuture<Void> releaseController(TopicName topic) { + ScalableTopicController controller = controllers.remove(topic.toString()); + if (controller != null) { + return controller.close(); + } + return CompletableFuture.completedFuture(null); + } + + // --- Admin operations --- + + /** + * Create a new scalable topic with the given number of initial segments. + */ + public CompletableFuture<Void> createScalableTopic(TopicName topic, int numInitialSegments) { + return createScalableTopic(topic, numInitialSegments, Map.of()); + } + + public CompletableFuture<Void> createScalableTopic(TopicName topic, int numInitialSegments, + Map<String, String> properties) { + if (topic.getDomain() != TopicDomain.topic) { + return CompletableFuture.failedFuture( + new IllegalArgumentException("Expected topic domain, got: " + topic.getDomain())); + } + if (numInitialSegments < 1) { + return CompletableFuture.failedFuture( + new IllegalArgumentException("numInitialSegments must be >= 1")); + } + + ScalableTopicMetadata metadata = ScalableTopicController.createInitialMetadata( + numInitialSegments, properties); + + return resources.createScalableTopicAsync(topic, metadata) + .thenCompose(__ -> { + // Create underlying persistent topics for each initial segment + CompletableFuture<?>[] segmentFutures = metadata.getSegments().values().stream() + .map(segment -> createUnderlyingSegmentTopic(topic, segment)) + .toArray(CompletableFuture[]::new); + return CompletableFuture.allOf(segmentFutures); + }); + } + + /** + * Delete a scalable topic and all its segment topics. + */ + public CompletableFuture<Void> deleteScalableTopic(TopicName topic) { + return releaseController(topic) + .thenCompose(__ -> resources.getScalableTopicMetadataAsync(topic)) + .thenCompose(optMd -> { + if (optMd.isEmpty()) { + return CompletableFuture.completedFuture(null); + } + ScalableTopicMetadata metadata = optMd.get(); + // Delete all underlying segment topics + CompletableFuture<?>[] deleteFutures = metadata.getSegments().values().stream() + .map(segment -> deleteUnderlyingSegmentTopic(topic, segment)) + .toArray(CompletableFuture[]::new); + return CompletableFuture.allOf(deleteFutures); + }) + .thenCompose(__ -> resources.deleteScalableTopicAsync(topic)); + } + + // --- Internal helpers --- + + private void onLeaderStateChange(TopicName topic, LeaderElectionState state) { + log.info("Leader state change for scalable topic {}: {}", topic, state); + if (state == LeaderElectionState.NoLeader) { + // Try to re-elect + ScalableTopicController controller = controllers.get(topic.toString()); + if (controller != null) { + controller.initialize().exceptionally(ex -> { + log.warn("Failed to re-elect for topic {}", topic, ex); + return null; + }); + } Review Comment: There is still the possibility for bad-version when there are 2 clients trying to become leader at same time. Ultimately it's a conditional write (create-if-not-exists) and only 1 will succeed. -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
