Spring webclient - increase timeout duration after each retry

Question

I am looking for a way to increase the duration of the timeout after successive retries on webclient calls.

For example, I want the first request to timeout after 50ms, the first retry will then timeout after 500ms, and a second and final retry to have a timeout duration of 5000ms.

I am not sure how to go about doing this. I am only aware of how to set the timeout value to a fixed duration for all retries.

ex.

public Flux<Employee> findAll() 
{
    return webClient.get()
        .uri("/employees")
        .retrieve()
        .bodyToFlux(Employee.class)
        .timeout(Duration.ofMillis(50))
        .retry(2);
}

Answer 1

You can abstract out your backoff & timeout logic into a separate utility function, then simply call transform() on your publisher.

In your case, it looks like you're after basic backoff functionality - take an initial timeout value, then multiply it by a factor until we reach a maximum. We can implement this like so:

public <T> Flux<T> retryWithBackoffTimeout(Flux<T> flux, Duration timeout, Duration maxTimeout, int factor) {
    return mono.timeout(timeout)
            .onErrorResume(e -> timeout.multipliedBy(factor).compareTo(maxTimeout) < 1,
                    e -> retryWithBackoffTimeout(mono, timeout.multipliedBy(factor), maxTimeout, factor));
}

...but this can of course be any kind of timeout logic you like.

With that utility function in place, your findAll() method becomes:

public Flux<Employee> findAll()
{
    return webClient.get()
            .uri("/employees")
            .retrieve()
            .bodyToFlux(Employee.class)
            .transform(m -> retryWithBackoffTimeout(m, Duration.ofMillis(50), Duration.ofMillis(500), 10));
}