How to convert Future to Uni?

Question

I have a Java API that returns a Future instance. I need to convert it to a Uni. From the mutiny documentation, I see it is possible to convert a CompletionStage to Uni, but I couldn't find how to convert a standard Future to Uni.

Q: How to convert java.util.concurrent.Future to Uni?

I understand that I can warp it's get() call to Uni, but it would be blocking, isn't it?

Davide D'Alto · Accepted Answer · 2021-05-07T12:30:25.160

4

The problem with Future is that it's a blocking API and, unlike CompletionStage, there is no way to chain a stream of operations.

However, Mutiny has a way to deal with blocking API:

Future future = ...;
Uni<Object> uni = Uni.createFrom()
    .item( () -> future.get() )
    .runSubscriptionOn( Infrastructure.getDefaultWorkerPool() );

UPDATE:

My answer will work for all blocking code but the correct answer is in the comments:

Uni.createFrom().future(future);

or

Uni.createFrom().future(() -> future))

edited May 07 '21 at 12:30

answered Apr 28 '21 at 22:34

Davide D'Alto

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Thank you. But how does it answer my question? – Sasha Shpota Apr 29 '21 at 06:39
Sorry... It was late and I was thinking about `CompletableFuture` and not `Future`. I will update the answer :) – Davide D'Alto Apr 29 '21 at 08:05
1

You can use `Uni.createFrom().future(future)` or `Uni.createFrom().future(() -> future))` – Clement May 05 '21 at 09:36
Related, if you have a vert.x Future: https://stackoverflow.com/questions/73631825/java-how-to-uni-createfrom-future-and-return-that-uni-from-the-enclosing-met – Nino Walker Feb 09 '23 at 16:48

How to convert Future to Uni?

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