Cleaner error propagation in hystrix core v2

[mNantern]

I have exactly the same issue as in #1414 (fix works great btw, thx!) but for HystrixBadRequestException.

I tried to implement a HystrixCommandExecutionHook but all the methods are executed before decomposeException so I don't know how to make it work.

Any idea ?

Thank you !

[mattrjacobs]

I'm not sure I follow. HystrixRuntimeException is generated by the Hystrix execution mechanism. In that case, having the option to wrap with or without it is reasonable. HystrixBadRequestException is never added by Hystrix, only by user code. So if you don't want callers to get HystrixBadRequestException, then you should de line to use it in your code.

[mNantern]

My use case is pretty simple:

my HTTP clients are throwing functional exceptions that are catch in different places in my code. I don't want Hystrix to count some of the exception as server error (for example: bad parameters) and so I wrapped them in HystrixBadRequestException.
But now I'm forced to change all my catch to check for HystrixBadRequestException instead of my functional exceptions.

A possible workaround would be to check for the same interface (ExceptionNotWrappedByHystrix) in order to unwrap HystrixBadRequestException too.

What do you think ?

[mattrjacobs]

OK, got it, thanks for clarifying - that does make sense to me now. For next steps, I can imagine the following implementations:

• User can wrap business exception with HystrixBadRequestException and ExceptionNotWrappedByHystrix. Hystrix knows both should get unwrapped
• We invent a new exception type: HystrixUnwrappedBadRequestException that has the proper semantics w.r.t. circuit-breaking but is handled by not propagating this Hystrix-internal type
• We add configuration that decides whether to drop a HystrixBadRequestException or propagate it.

Any thoughts on which of these makes sense from your perspective?

[mNantern]

Clearly the first one. I really like the fact that you can just add to your exception an implements ExceptionNotWrappedByHystrix and that's it everything works as expected !

[mattrjacobs]

My schedule is jammed at the moment. Would you like to submit a PR with an implementation of this?

[mNantern]

Sure !

I will change the method decomposeException in AbstractCommand to return the original exception when it is wrapped with HystrixBadRequestException and ExceptionNotWrappedByHystrix.

I don't know Hystrix very well but does it sound good for you ?

[mukteshkrmishra]

My :+1 for above approach. HowyI would like to have a look on it once ✅