Just a quick example with reactor

reactor.kt

Flux.error<String>(RuntimeException())
    .retryWhen { error ->
        error.doOnNext { println(it) }
            .zipWith(Flux.range(1, 4))
            .map { tuple -> if (tuple.t2 < 4) tuple.t2 else throw Exceptions.propagate(tuple.t1) }
            .flatMap { Mono.delay(Duration.ofMillis(it.toLong() * 1000)) }
            .doOnNext { println("Retrying... ${LocalTime.now()}") }
    }
    .doOnError { println("Finished with ERROR!") }
    .subscribe()