CompletableFuture with Timeouts

CompletableFutureTest.java

package test;

import java.time.Duration;
import java.time.Instant;
import java.time.temporal.ChronoUnit;
import java.util.Random;
import java.util.concurrent.*;
import java.util.function.Function;


public class CompletableFutureTest {


    static public void main(String[] args) throws Exception {
        Random random = new Random(Instant.now().getNano());
        CompletableFuture<Integer> number =CompletableFuture.supplyAsync(() -> {
            return task(random.nextInt(3000),2);
        });


        final CompletableFuture<Integer> responseFuture = within(number, Duration.ofSeconds(1));
        CompletableFuture<Void> last = responseFuture
                .thenAccept(System.out::print)
                .exceptionally(throwable -> {
                    System.out.println("Unrecoverable error " + throwable);
                    return null;
                });

        last.thenRun(()-> System.exit(0));



    }

    public static <T> CompletableFuture<T> within(CompletableFuture<T> future, Duration duration) {
        final CompletableFuture<T> timeout = failAfter(duration);
        return future.applyToEither(timeout, Function.identity());
    }

    public static <T> CompletableFuture<T> failAfter(Duration duration) {
        final CompletableFuture<T> promise = new CompletableFuture<>();
        scheduler.schedule(() -> {
            final TimeoutException ex = new TimeoutException("Timeout after " + duration);
            return promise.completeExceptionally(ex);
        }, duration.toMillis(), TimeUnit.MILLISECONDS);
        return promise;
    }


    private static final ScheduledExecutorService scheduler =
            Executors.newScheduledThreadPool(1);


    static Integer task(long sleep, int number) {
        try {
            Thread.sleep(sleep);
            System.out.println(Thread.currentThread().getName() + "with number " + number);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return number;
    }
}

Thanks for this, it helped me out quite a bit.

I think you should mention the source code uses snippets from: https://www.nurkiewicz.com/2014/12/asynchronous-timeouts-with.html