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https://issues.apache.org/jira/browse/FLINK-4391?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15635053#comment-15635053
]
ASF GitHub Bot commented on FLINK-4391:
---------------------------------------
Github user bjlovegithub commented on a diff in the pull request:
https://github.com/apache/flink/pull/2629#discussion_r86482845
--- Diff:
flink-examples/flink-examples-streaming/src/main/java/org/apache/flink/streaming/examples/async/AsyncIOExample.java
---
@@ -0,0 +1,194 @@
+/*
+ * 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.examples.async;
+
+import org.apache.flink.api.common.functions.FlatMapFunction;
+import org.apache.flink.api.java.tuple.Tuple2;
+import org.apache.flink.configuration.Configuration;
+import org.apache.flink.runtime.state.filesystem.FsStateBackend;
+import org.apache.flink.streaming.api.CheckpointingMode;
+import org.apache.flink.streaming.api.TimeCharacteristic;
+import org.apache.flink.streaming.api.checkpoint.Checkpointed;
+import org.apache.flink.streaming.api.datastream.AsyncDataStream;
+import org.apache.flink.streaming.api.datastream.DataStream;
+import
org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
+import org.apache.flink.streaming.api.functions.async.AsyncFunction;
+import org.apache.flink.streaming.api.functions.async.RichAsyncFunction;
+import org.apache.flink.streaming.api.functions.source.SourceFunction;
+import org.apache.flink.streaming.api.operators.async.AsyncCollector;
+import org.apache.flink.util.Collector;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Random;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Example to illustrates how to use {@link
org.apache.flink.streaming.api.functions.async.AsyncFunction}
+ */
+public class AsyncIOExample {
+
+ /**
+ * A checkpointed source.
+ */
+ private static class SimpleSource implements SourceFunction<Integer>,
Checkpointed<Integer> {
+ private static final long serialVersionUID = 1L;
+
+ private volatile boolean isRunning = true;
+ private int counter = 0;
+ private int start = 0;
+
+ @Override
+ public void restoreState(Integer state) throws Exception {
+ this.start = state;
+ }
+
+ @Override
+ public Integer snapshotState(long checkpointId, long
checkpointTimestamp) throws Exception {
+ return start;
+ }
+
+ public SimpleSource(int maxNum) {
+ this.counter = maxNum;
+ }
+
+ @Override
+ public void run(SourceContext<Integer> ctx) throws Exception {
+ while (start < counter && isRunning) {
+ synchronized (ctx.getCheckpointLock()) {
+ ctx.collect(start);
+ ++start;
+ }
+ Thread.sleep(10);
+ }
+ }
+
+ @Override
+ public void cancel() {
+ isRunning = false;
+ }
+ }
+
+
+ public static void main(String[] args) throws Exception {
+
+ // obtain execution environment and set setBufferTimeout to 1
to enable
+ // continuous flushing of the output buffers (lowest latency)
+ StreamExecutionEnvironment env =
StreamExecutionEnvironment.getExecutionEnvironment()
+ .setBufferTimeout(1);
--- End diff --
It is optional here ;D. I will remove it later.
> Provide support for asynchronous operations over streams
> --------------------------------------------------------
>
> Key: FLINK-4391
> URL: https://issues.apache.org/jira/browse/FLINK-4391
> Project: Flink
> Issue Type: New Feature
> Components: DataStream API
> Reporter: Jamie Grier
> Assignee: david.wang
>
> Many Flink users need to do asynchronous processing driven by data from a
> DataStream. The classic example would be joining against an external
> database in order to enrich a stream with extra information.
> It would be nice to add general support for this type of operation in the
> Flink API. Ideally this could simply take the form of a new operator that
> manages async operations, keeps so many of them in flight, and then emits
> results to downstream operators as the async operations complete.
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