tombentley commented on a change in pull request #9878: URL: https://github.com/apache/kafka/pull/9878#discussion_r663752257
########## File path: clients/src/main/java/org/apache/kafka/common/internals/KafkaCompletableFuture.java ########## @@ -0,0 +1,79 @@ +/* + * 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.internals; + +import java.util.concurrent.CompletableFuture; +import java.util.concurrent.Executor; +import java.util.concurrent.TimeUnit; +import java.util.function.Supplier; + +/** + * This internal class exists because CompletableFuture exposes complete(), completeExceptionally() and + * other methods which would allow erroneous completion by user code of a KafkaFuture returned from a + * Kafka API to a client application. + * @param <T> The type of the future value. + */ +public class KafkaCompletableFuture<T> extends CompletableFuture<T> { Review comment: The KIP describes it like this: > Adding toCompletionStage() is sufficient because CompletionStage itself exposes toCompletableFuture(), so anyone who needs an actual CompletableFuture (e.g. for interoperating with 3rd party APIs that require one) can get one. However, CompletableFuture exposes methods for future completion which should not be called by users (only the Admin client should be completing the returned futures), so calling these will be prevented. It is expected that users wanting to block on the completion of the KafkaFuture would use kafkaFuture.get(), rather than calling kafkaFuture.toCompletionStage().toCompletableFuture().get(), so the need to access the CompleteableFuture should be rare. Essentially we want to allow access to a `CompletableFuture` to allow interop with 3rd part APIs which might require it (e.g. for using the blocking `get` methods) , but not allow user code to complete those futures. The `CompletableFuture` API unhelpfully adds _both_ the blocking `get` methods and the `complete` methods. ########## File path: clients/src/main/java/org/apache/kafka/common/internals/KafkaCompletableFuture.java ########## @@ -0,0 +1,79 @@ +/* + * 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.internals; + +import java.util.concurrent.CompletableFuture; +import java.util.concurrent.Executor; +import java.util.concurrent.TimeUnit; +import java.util.function.Supplier; + +/** + * This internal class exists because CompletableFuture exposes complete(), completeExceptionally() and + * other methods which would allow erroneous completion by user code of a KafkaFuture returned from a + * Kafka API to a client application. + * @param <T> The type of the future value. + */ +public class KafkaCompletableFuture<T> extends CompletableFuture<T> { + + boolean kafkaComplete(T value) { Review comment: The idea is that all Kafka code knows it's using a `KafkaCompletableFuture` and knows to complete it via the `kafka*()` methods. User code which erroneously tries to complete via `complete()` gets the exception thrown. -- 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
