Added util class to determine whether Circuit Breaker permits calls

Given you have use case where there’s need to check Circuit Breaker state before call and consider it only if it’s able to operate on underlying service.

There’s a possibility to check state of Circuit Breaker first:

boolean canBeUsed = circuitBreaker.getState().allowPublish

All states represents this flag correctly except OPEN, which should be false, but currently is true.

Reference:

• https://github.com/resilience4j/resilience4j/blob/b1f05b0f0e66e7906714d12ddb0d78133735b346/resilience4j-circuitbreaker/src/main/java/io/github/resilience4j/circuitbreaker/CircuitBreaker.java#L411

Real life example: You have list of services behind Circuit Breaker being used in Round-Robin manner. You don’t want to distribute load over service instances that are not operative to not waste time to call Circuit Breaker and doing unnecessary Retry (state is known ahead).

[RobWin]

No, DISABLED means that the CircuitBreaker is disabled. That means the backend instance is not tracked anymore. But the backend instance could be available. All calls are permitted when the CircuitBreaker is disabled.

[RobWin]

Thanks