Hangleton commented on code in PR #13240: URL: https://github.com/apache/kafka/pull/13240#discussion_r1129407685
########## clients/src/main/java/org/apache/kafka/common/TopicResolver.java: ########## @@ -0,0 +1,92 @@ +/* + * 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.common; + +import org.apache.kafka.common.errors.InvalidTopicException; + +import java.util.Collections; +import java.util.HashMap; +import java.util.Map; +import java.util.Optional; + +/** + * Encapsulates the resolution of a topic name from its ID, or its ID from its name, using a local + * bidirectional mapping. This resolver assumes there is a bijection between topic IDs and topic names. + * <p></p> + * Note that this class intends to be used for the (reverse) lookup of topic IDs/names, but + * not to characterize the set of topics which are known by a client. Use the + * {@link org.apache.kafka.clients.MetadataCache} for that purpose. + */ +//@Immutable, @ThreadSafe +public class TopicResolver { + private final Map<String, Uuid> topicIds; + private final Map<Uuid, String> topicNames; + + /** + * A resolver which universe of topic ids and names is captured from the input map. The reverse association + * between a topic ID and a topic name is computed by this method. If there are more than one topic name + * resolving to the same topic ID, an {@link InvalidTopicException} is thrown. + */ + public static TopicResolver fromTopicIds(Map<String, Uuid> topicIds) { + Map<Uuid, String> topicNames = new HashMap<>(topicIds.size()); + + for (Map.Entry<String, Uuid> e: topicIds.entrySet()) { + String conflicting = topicNames.putIfAbsent(e.getValue(), e.getKey()); + if (conflicting != null) { + throw new InvalidTopicException( + "Topic " + e.getKey() + " shares the same ID " + e.getValue() + " as topic " + conflicting); + } + } + + return new TopicResolver(topicIds, topicNames); + } + + /** + * A resolver which acts as a wrapper around the input mapping of topic ids from/to topic names. + * No validation is performed about the consistency of the mapping. This method is to be preferred + * when the copy of the input maps needs to be avoided. + */ + public static TopicResolver wrap(Map<String, Uuid> topicIds, Map<Uuid, String> topicNames) { + return new TopicResolver(topicIds, topicNames); + } + + /** + * A resolver with no existing mapping between any topic name and id. + */ + public static TopicResolver emptyResolver() { + return fromTopicIds(Collections.emptyMap()); + } + + private TopicResolver(Map<String, Uuid> topicIds, Map<Uuid, String> topicNames) { + this.topicIds = Collections.unmodifiableMap(topicIds); + this.topicNames = Collections.unmodifiableMap(topicNames); + } + + /** + * Returns the ID of the topic with the given name, if that association exists. + */ + public Optional<Uuid> getTopicId(String name) { Review Comment: Yes, there is a code smell here. -- 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
