org.apache.flink.runtime.io.NullableAsyncDataInput Maven / Gradle / Ivy
/*
* 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 extends AvailabilityListener {
/**
* Poll the next element. This method should be non blocking.
*
* @return {@code null} will be returned if there is no data to return or
* if {@link #isFinished()} returns true. Otherwise return {@code element}.
*/
@Nullable
T pollNextNullable() throws Exception;
}