adikou commented on code in PR #22271: URL: https://github.com/apache/kafka/pull/22271#discussion_r3506540252
########## clients/src/main/java/org/apache/kafka/clients/consumer/internals/InternalRebalanceListener.java: ########## @@ -0,0 +1,58 @@ +/* + * 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.common.TopicPartition; + +import java.util.Collection; + +/** + * Internal counterpart to the public rebalance listener interfaces. The consumer's runtime internals + * (subscription state, rebalance listener invoker, membership management) operates exclusively against + * this type rather than the user-facing {@link org.apache.kafka.clients.consumer.RebalanceListener}. + * + * <p>Keeping a single internal abstraction with the simple one-argument signatures means the invocation + * path can pass implementation-specific arguments and lifecycle hooks without leaking them into the public + * API. + */ +public abstract class InternalRebalanceListener { Review Comment: I agree with the fact that it's a callback is well-captured in a lambda. But I don't see the benefit of moving 3 different methods as 3 different functional parameters, because the same behaviour still needs to be applied to revoked/lost (reusing the same functional interface to return 3 different callbacks doesn't sit right even if the parameter signature is the same). When invoking the method, `onPartitionsAssigned.apply(partitions)` doesn't seem necessarily better than `internalRebalanceListener.onPartitionsAssigned(partitions)`. Consumer and BiConsumer work ok now but there's no TriConsumer. We'll have to switch to Function and custom arg classes and at this point we're back to where we started. If creating a new abstract class is a pain point, what if we use the new public interface but we just pass a null for the second parameter but it's going to be ignored/intercepted by the consumer-aware implementation. Keeps things consistent with the existent implementation without much hassle. -- 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]
