1u0 commented on a change in pull request #8467: [FLINK-12535][network] Make CheckpointBarrierHandler non-blocking URL: https://github.com/apache/flink/pull/8467#discussion_r288418129
########## File path: flink-runtime/src/main/java/org/apache/flink/runtime/io/NullableAsyncDataInput.java ########## @@ -0,0 +1,39 @@ +/* + * 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.flink.runtime.io; + +import org.apache.flink.annotation.Internal; + +import javax.annotation.Nullable; + +/** + * The variant of {@link AsyncDataInput} that for performance reasons returns {@code null} from + * {@link #pollNextNullable()} instead returning {@code Optional.empty()} from + * {@link AsyncDataInput#pollNext()}. + */ +@Internal +public interface NullableAsyncDataInput<T> extends AvailabilityListener { Review comment: You can introduce it in another PR, as it's not used here yet. Nit: `Nullable` in this name and in `pollNextNullable()` maybe interpreted that elements of data input can be `null`. So if a client code gets `null` from the method, it can mean either that there is no data (`null` as a marker, client needs to check the input later) or that the retrieved element is actually `null` and the client (implicitly) can continue reading. But your intended use is probably about the first case (use `null` as marker). ---------------------------------------------------------------- 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. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
