Support @HystrixCommand for rx.Single and rx.Completable similar to rx.Observable

[piotrturski]

@HystrixCommand doesn't work as expected for methods that return rx.Single or rx.Completable. it would be nice to have them handled in a same way as rx.Observable

[mattrjacobs]

I think this could get addressed at the hystrix-core or hystrix-javanica layer. I'm happy to review PRs for either, if anyone is interested in this.

[piotrturski]

i'm willing to try if someone can point me to classes that do that for Observable, so i can understand the architecture

[mattrjacobs]

In Javanica, the support is here: https://github.com/Netflix/Hystrix/blob/master/hystrix-contrib/hystrix-javanica/src/main/java/com/netflix/hystrix/contrib/javanica/command/GenericObservableCommand.java.

In hystrix-core, the class is here: https://github.com/Netflix/Hystrix/blob/master/hystrix-core/src/main/java/com/netflix/hystrix/HystrixObservableCommand.java.

If you're interested in working on the extension to hystrix-core, please let me know, so I can help with design considerations. Thanks!

[piotrturski]

of course i'm open to suggestions. after a quick look at the code, i was thinking about adding .toSingle() and .toCompletable() somewhere in HystrixCommandAspect or create new ExecutionTypes. it would be perfect to just add some post-processing to existing observableCommand, but yet i don't see any quick way of doing it

[dmgcodevil]

@piotrturski If it's still relevant, I believe that first of all hystrix-core should be extended to support Completable , Single and etc. Currently it's not possible to implement it using HystrixObservableCommand because HystrixObservableCommand#construct returns Observable, but Completable and Observable are different types. However, possible workaround is to add a logic to transform incompatible rx types once command action executed and before passing a result to a caller. I have made some changes and pushed to my branch. Checkout out my changes by the following commit.

[pmendelski]

Hi, I stuck on the same problem - HystrixCommand with rx.Single. @dmgcodevil did you think about making a PR from your branch?

[dmgcodevil]

@mendlik basically I can, however I'm not sure whether this implementation makes sense from reactive programming perspective, could you review my commit ?

[pmendelski]

@dmgcodevil thanks for staying on this issue. I read your code and it looks ok to me. IMHO it's ready to become a PR.

I also agree with your comment #1403 (comment) . It would be nice to make hystrix-core extendible for all kinds of reactive streams. But in the meantime your PR will make hystrix support for RxJava close to complete. Thanks.

[dmgcodevil]

@mattrjacobs This issue can be close since PR is closed