presto-main/src/main/java/io/prestosql/server/remotetask/RequestErrorTracker.java/RequestErrorTracker/acquireRequestPermit
class RequestErrorTracker:    public ListenableFuture<?> acquireRequestPermit()
    {
        long delayNanos = backoff.getBackoffDelayNanos();

        if (delayNanos == 0) {
            return Futures.immediateFuture(null);
        }

        ListenableFutureTask<Object> futureTask = ListenableFutureTask.create(() -> null);
        scheduledExecutor.schedule(futureTask, delayNanos, NANOSECONDS);
        return futureTask;
    }