Reading from a Flux<Integer> in chunks

Question

Is it possible do read from a webflux flux in chunks? ( other than using delayElements )

For example after I write

Flux.range(1, 10).doOnNext(System.out::println).take(5).subscribe();

is there any way to continue to read the next 5 integers?

If not, is there an alternative for the consumer to decide when to request the next piece of data?

Edit:

To clarify, I would like to read the first 5 values, then pause, then read the next 5 values without recreating the emitter flux.

Answer 1

then you need a full-fledged asynchronous subscriber object, not just a chain of methods.

// use maven dependency 'org.df4j:df4j-core:8.3'
import org.df4j.core.dataflow.Actor;
import org.df4j.core.port.InpFlow;
import org.junit.Assert;
import org.junit.Test;
import reactor.core.publisher.Flux;

public class FluxSubscriberTest {

    @Test
    public  void test10() {
        FluxSubscriber subscriber = new FluxSubscriber();
        Flux.range(1, 10).subscribe(subscriber.inp);
        subscriber.start();
        boolean ok = subscriber.blockingAwait(5000);
        Assert.assertTrue(ok);
    }

    static class FluxSubscriber extends Actor {
        InpFlow<Integer> inp = new InpFlow<>(this, 5);
        int count = 0;

        @Override
        protected void runAction() throws Throwable {
            if (inp.isCompleted()) {
                System.out.println("input stream completed");
                complete();
                return;
            }
            Integer value = inp.remove();
            System.out.println("value="+value);
            if (++count==5) {
                count = 0;
                System.out.println("pause:");
                delay(1000);
            }
        }
    }
}

In fact, it reads 5 items first, and then one by one after each call to inp.remove() . If this is not exactly what you want, then you can extend class InpFlow to modify the policy when it invokes Subscription.request() .

Source codes are avalable at https://github.com/akaigoro/df4j (yes I am the author).