Github user tillrohrmann commented on a diff in the pull request:
https://github.com/apache/flink/pull/2629#discussion_r88680106
--- Diff:
flink-streaming-java/src/main/java/org/apache/flink/streaming/api/functions/async/AsyncFunction.java
---
@@ -0,0 +1,85 @@
+/*
+ * 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.api.common.functions.Function;
+import org.apache.flink.streaming.api.operators.async.AsyncCollector;
+
+import java.io.Serializable;
+
+/**
+ * A function to trigger Async I/O operation.
+ * <p>
+ * For each #asyncInvoke, an async io operation can be triggered, and once
it has been done,
+ * the result can be collected by calling {@link AsyncCollector#collect}.
For each async
+ * operations, their contexts are buffered in the operator immediately
after invoking
+ * #asyncInvoke, leading to no blocking for each stream input as long as
internal buffer is not full.
+ * <p>
+ * {@link AsyncCollector} can be passed into callbacks or futures provided
by async client to
+ * fetch result data. Any error can also be propagate to the operator by
{@link AsyncCollector#collect(Throwable)}.
+ *
+ * <p>
+ * Typical usage for callback:
+ * <pre>{@code
+ * public class HBaseAsyncFunc implements AsyncFunction<String, String> {
+ * @Override
+ * public void asyncInvoke(String row, AsyncCollector<String> collector)
throws Exception {
+ * HBaseCallback cb = new HBaseCallback(collector);
+ * Get get = new Get(Bytes.toBytes(row));
+ * hbase.asyncGet(get, cb);
+ * }
+ * }
+ * }
+ * </pre>
+ *
+ * <p>
+ * Typical usage for {@link
com.google.common.util.concurrent.ListenableFuture}
+ * <pre>{@code
+ * public class HBaseAsyncFunc implements AsyncFunction<String, String> {
+ * @Override
+ * public void asyncInvoke(String row, final AsyncCollector<String>
collector) throws Exception {
+ * Get get = new Get(Bytes.toBytes(row));
+ * ListenableFuture<Result> future = hbase.asyncGet(get);
+ * Futures.addCallback(future, new FutureCallback<Result>() {
+ * public void onSuccess(Result result) {
+ * List<String> ret = process(result);
+ * collector.collect(ret);
+ * }
+ * public void onFailure(Throwable thrown) {
+ * collector.collect(thrown);
+ * }
+ * });
+ * }
+ * }
+ * }
+ * </pre>
+ *
+ * @param <IN> The type of the input elements.
+ * @param <OUT> The type of the returned elements.
+ */
+public interface AsyncFunction<IN, OUT> extends Function, Serializable {
--- End diff --
`PublicEvolving`
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at infrastruct...@apache.org or file a JIRA ticket
with INFRA.
---
