[jira] [Assigned] (CAMEL-24818) circuitBreaker: set CamelCircuitBreakerResponseRejected when the fallback runs because the breaker is open

["Claus Ibsen (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CAMEL-24818?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Claus Ibsen reassigned CAMEL-24818:
-----------------------------------

    Assignee: Claus Ibsen

> circuitBreaker: set CamelCircuitBreakerResponseRejected when the fallback runs because the breaker is open
> ----------------------------------------------------------------------------------------------------------
>
>                 Key: CAMEL-24818
>                 URL: https://issues.apache.org/jira/browse/CAMEL-24818
>             Project: Camel
>          Issue Type: Improvement
>          Components: camel-microprofile-fault-tolerance, eip
>            Reporter: Claus Ibsen
>            Assignee: Claus Ibsen
>            Priority: Minor
>
> When a circuitBreaker has an onFallback, the fallback path in ResilienceProcessor and FaultToleranceProcessor sets the same exchange properties for every cause: CamelCircuitBreakerResponseFromFallback=true and CamelCircuitBreakerResponseShortCircuited=true, plus CamelCircuitBreakerResponseTimedOut for a timeout. CamelCircuitBreakerResponseRejected is only set when there is *no* fallback.
> So inside an onFallback there is no way to tell whether the call was made and failed (breaker closed or half open) or whether the call was never attempted because the breaker is open (Resilience4j CallNotPermittedException, fault tolerance CircuitBreakerOpenException), other than inspecting the exception class. CamelCircuitBreakerState does not help either: it is read after the failure is recorded, so the call that trips the breaker reports OPEN although the call was made.
> Proposal:
> # In the fallback path of both processors set CamelCircuitBreakerResponseRejected=true when the throwable is CallNotPermittedException / BulkheadFullException (Resilience4j) or CircuitBreakerOpenException / BulkheadException (fault tolerance), false otherwise.
> # Keep CamelCircuitBreakerResponseShortCircuited as is for compatibility, but correct its description: it means the fallback handled the exchange, not that the breaker skipped the call.
> # Document the properties on the circuitBreaker EIP page.
> A fallback can then answer differently for one failed call versus a dead service, e.g. "breaker open, supplier not called" in the circuit-breaker example of camel-jbang-examples (CAMEL-24808).



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