Github user bjlovegithub commented on a diff in the pull request: https://github.com/apache/flink/pull/2629#discussion_r92314677 --- Diff: flink-streaming-java/src/main/java/org/apache/flink/streaming/api/functions/async/RichAsyncFunction.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.flink.streaming.api.functions.async; + +import org.apache.flink.annotation.PublicEvolving; +import org.apache.flink.api.common.functions.AbstractRichFunction; +import org.apache.flink.api.common.functions.IterationRuntimeContext; +import org.apache.flink.api.common.functions.RichFunction; +import org.apache.flink.api.common.functions.RuntimeContext; +import org.apache.flink.streaming.api.functions.async.collector.AsyncCollector; + +/** + * Rich variant of the {@link AsyncFunction}. As a {@link RichFunction}, it gives access to the + * {@link org.apache.flink.api.common.functions.RuntimeContext} and provides setup and teardown methods: + * {@link RichFunction#open(org.apache.flink.configuration.Configuration)} and + * {@link RichFunction#close()}. + * + * <p> + * {@link RichAsyncFunction#getRuntimeContext()} and {@link RichAsyncFunction#getRuntimeContext()} are + * not supported because the key may get changed while accessing states in the working thread. + * + * @param <IN> The type of the input elements. + * @param <OUT> The type of the returned elements. + */ + +@PublicEvolving +public abstract class RichAsyncFunction<IN, OUT> extends AbstractRichFunction + implements AsyncFunction<IN, OUT> { + + @Override + public abstract void asyncInvoke(IN input, AsyncCollector<OUT> collector) throws Exception; + + @Override + public RuntimeContext getRuntimeContext() { --- End diff -- Hi @mproch, In our use case in the production env, we provide some metrics in the `AsyncWaitOperator`, like the number of elements in the `AsyncCollectorBuffer` etc. Maybe the `AsyncWaitOperator` provides those basic statistics metrics. The `RichAsyncFunction` is useful for its `open()` and `close()` methods, where the async clients can be initialized and freed. I think there are two options: 1. Remove `RichAsyncFunction`, since `AsyncWaitOperator` currently only supports non-keyed stream. 2. Keep `RichAsyncFunction` but it is different to use `RichAsyncFunction.getRuntimeContext()`...
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