Support Cancelling Retries

[rgmz]

Describe the feature

Presently, the retryPolicy method specifies how often the circuit breaker should try before failing; however, in certain cases (e.g. expected failures) it is not desirable to continue retrying.

(If this feature exists, I couldn't find any mention of this in the documentation.)

Use cases

Something like a retryOrCancelPolicy would be desirable, where returning -1L would cease the circuit breaker from retrying:

CircuitBreaker.create("my-circuit-breaker", vertx)
    .retryOrCancelPolicy { retryCount: Int, cause: Throwable? ->
       if (cause is MyExpectedException) {
          -1L
       } else {
         retryCount * 1000L
       }
    }

I tend to use michaelbull/kotlin-retry for retrying, which has a pretty elegant way of handling retry policies.

For example:

val retryTimeouts: RetryPolicy<Throwable> = {
    if (reason is SQLDataException) ContinueRetrying else StopRetrying
}

suspend fun printExchangeBetween(a: Long, b: Long) {
  val customer1 = customers.nameFromId(a)
  val customer2 = customers.nameFromId(b)
  println("$customer1 exchanged with $customer2")
}

fun main() = runBlocking {
    retry(retryTimeouts + limitAttempts(5) + constantDelay(20)) {
        printExchangeBetween(1L, 2L)
    }
}

Contribution

I will try to realize this if I get the time; right now I'm holed up with my work laptop, which does not allow me to push externally... even posting this issue was a pain. :|

[vietj]

@rgmz that would be a great contribution