frankvicky commented on code in PR #22511: URL: https://github.com/apache/kafka/pull/22511#discussion_r3381009919
########## server/src/main/java/org/apache/kafka/server/streams/InMemoryTopologyDescriptionPlugin.java: ########## @@ -0,0 +1,73 @@ +/* + * 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.server.streams; + +import org.apache.kafka.coordinator.group.api.streams.StreamsGroupTopologyDescription; +import org.apache.kafka.coordinator.group.api.streams.StreamsGroupTopologyDescriptionPlugin; + +import java.util.Map; +import java.util.concurrent.CompletableFuture; +import java.util.concurrent.ConcurrentHashMap; + +/** + * Reference {@link StreamsGroupTopologyDescriptionPlugin} that stores topology descriptions + * in an in-memory map. Intended for testing and as a starting point for real implementations; + * not suitable for production because its state is lost on broker restart and is not shared + * across brokers. + * + * <p>Stores at most one description per group, identified by its topology epoch. A + * {@code setTopology} call overwrites any previously stored description for that group; + * {@code getTopology} returns the stored description only when the requested topology epoch + * matches the stored epoch, and {@code null} otherwise. + */ +public class InMemoryTopologyDescriptionPlugin implements StreamsGroupTopologyDescriptionPlugin { + + private record Entry(int topologyEpoch, StreamsGroupTopologyDescription description) { } + + private final ConcurrentHashMap<String, Entry> store = new ConcurrentHashMap<>(); + + @Override + public void configure(Map<String, ?> configs) { + // No-op. + } + + @Override + public CompletableFuture<Void> setTopology(String groupId, int topologyEpoch, StreamsGroupTopologyDescription description) { + store.put(groupId, new Entry(topologyEpoch, description)); + return CompletableFuture.completedFuture(null); + } Review Comment: The wire schema declares groupId as a `non-nullable` string (no nullableVersions), and broker-side validation will land in KAFKA-20623 — there's no caller in this PR yet. The SPI's "must not throw synchronously" javadoc is guidance for production plugin authors whose backends can fail asynchronously. The in-memory reference is intentionally fail-fast — wrapping NPE in failedFuture would swallow a programmer error and be misleading when debugging. -- 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]
