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https://issues.apache.org/jira/browse/KAFKA-6900?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16490546#comment-16490546
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ASF GitHub Bot commented on KAFKA-6900:
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RichoDemus opened a new pull request #5080: KAFKA-6900: Add thenCompose to
KafkaFuture
URL: https://github.com/apache/kafka/pull/5080
Add KafkaFuture.thenCompose which behaves similarly to
KafkaFuture.thenAccept except that it flattens Futures. This means that it's
possible to do another async call inside thenCompose without getting a
KafkaFuture<KafkaFuture<T>>
It's implemented to have the same signature and behaviour as
CompletableFuture.thenCompose
Tested both by writing unit tests but I've also done manual testing
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> Add thenCompose to KafkaFuture
> ------------------------------
>
> Key: KAFKA-6900
> URL: https://issues.apache.org/jira/browse/KAFKA-6900
> Project: Kafka
> Issue Type: Improvement
> Components: clients
> Affects Versions: 1.1.0
> Reporter: Richard Tjerngren
> Priority: Minor
>
> KafkaFuture supports Future chaining via the thenApply method just like
> CompletableFuture, however, thenApply is not intended to be used for lambdas
> that in turn return a future:
>
> {code:java}
> KafkaFutureImpl<String> future = new KafkaFutureImpl<>();
> KafkaFuture<KafkaFuture<String>> nestedFuture = future.thenApply(result ->
> methodThatReturnsFuture(result));
> {code}
> Completable future has a method called thenCompose
> [javadoc|https://docs.oracle.com/javase/10/docs/api/java/util/concurrent/CompletionStage.html#thenCompose(java.util.function.Function)]
> The would be:
> {code:java}
> public KafkaFuture<R> thenCompose(Function<T, KafkaFuture<T> func);{code}
> So the above example would look like this:
> {code:java}
> KafkaFutureImpl<String> future = new KafkaFutureImpl<>();
> KafkaFuture<String> nestedFuture = future.thenCompose(result ->
> methodThatReturnsFuture(result));
> {code}
> This would enable developers to chain asynchronous calls in a more natural
> way and it also makes KafkaFuture behave more similar to Javas
> CompletableFuture and Javascripts Promise
>
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