Issue with retry an mutiple chained Unis

[manofthepeace]

I am currently having an issue I am not able to solve when using retry with multiple chained unis.

I have something like this

uni1.chain(uni2::get).chain(uni3::get) //uni 2 and 3 are suppliers

I want to retry only uni 3 when it fails, but I want it to actually rerun the supplier since some data the supplier is using may have changed and needs to be rebuilt before going outside.

When trying

uni1.chain(uni2::get).chain(uni3::get).onFailure().call(onfailure::get).onFailure().retry().until(predicate);

it does partially work, but the whole chain is retried, which I am unsure why in a way since the onfailure is after a single uni, after the other emitted OK. So this does not work.

Then I tried something more like this;

uni1.chain(uni2::get)
.chain(
    ()->uni3.get().onFailure().call(onfailure::get).onFailure().retry().until(predicate)
);

using this way the supplier is called once but never on failure. The idea was to have uni3 as a supplier but be called before appending the onFailure.

I would like to know how can I retry a single step in a chained pipeline, while recalling the supplier/or method/ so I can do the http call with the updated data.

Thanks in advance.

[manofthepeace]

@jponge sorry for the ping, any ideas here how the retry could use the supplier? Only idea I have is quite cumbersome which would be to have the cancellation in a AtomicReference, and cancel in the failure then resubscribe, if that can even work.

[jponge]

The whole pipeline chain before a retry will be re-subscribed, that's by design I'm afraid

[manofthepeace]

I have tried using call() instead of chain() and the result is similar. I was a little under the impression that by using call it would not be the same pipeline per se.

Otherwise is there a way to "split" the pipeline in a way that part1 runs, then part2 runs and retries only that part if it fails?

I saw there is a stage api but It seems to be only for logical separation.

[jponge]

onFailure().call(...) is a good option if you want to have programatic control on the recovery strategy, because you can return a new Uni. But that Uni doesn't replace the early part of the pipeline, just what happens downstream.

[manofthepeace]

Would you be open to have the option for retry() to have the option to have or a Uni<>, as it does now, or a Supplier<Uni<>> This way if the onFailure is within a particular uni (inside the chain, not outside) , it could rerun the supplier do get the last data, if any.

[jponge]

Sure, feel-free to explore a solution 😃

[manofthepeace]

I forgot to follow up on this. Ultimately the solution was quite easy, once you know about it. Ultimately a uni, can already be a sort of supplier by using either
this Uni.createFrom().item(() -> x);or Uni.createFrom().deferred(...)

So in the end I could have, re-subscribtion, in a portion of the pipeline by using the syntax above.