Add randomExpression to backoff annotation

[Deviad]

No description provided.

[pivotal-cla]

@Deviad Please sign the Contributor License Agreement!

Click here to manually synchronize the status of this Pull Request.

See the FAQ for frequently asked questions.

[pivotal-cla]

@Deviad Thank you for signing the Contributor License Agreement!

[garyrussell]

Thanks for the contribution. It looks ok to me, but I am curious as to why this needs to be an expression; it seems to me this would be set by the developer and not need to be evaluated during initialization; just interested in the use case.

[Deviad]

    @Retryable(include = {Exception.class}, backoff = @Backoff(
            delayExpression = "#{new Long(${property.delay})}",
            multiplierExpression = "#{new Long(${property.multiplier})}",
            maxDelayExpression = "#{new Long(${property.maxDelay})}",
            randomExpression = "#{new Boolean(${property.random})}",
    ))
    public FancyDTO somethingFancy(final String foobar) {
    }

Instead of creating a feature flag to activate/deactivate it, and use @ConditionalOnProperty, which would cause code duplication (as I would need to copy paste an entire class), I can simply activate/deactivate it with a property set accordingly for each environment (and avoid code duplication) where I want to test it and make a note of the outcome.
E.g.: you wanna push the changes initially to stage but leave prod unchanged.

This is available already here:
https://reflectoring.io/retry-with-springboot-resilience4j/

I managed to reproduce that with SPEL so that props are fetched from properties files.

[garyrussell]

Thanks; I understand what it does, and how it does it; my question is why someone would want to do it?

i.e. why would you want it different in dev Vs. prod?

[Deviad]

Cos we can can monitor the effects of the change as I said (in terms of throughput, back-pressure, etc.) and push it forward if it satisfies our needs (for a particular endpoint).