如果延迟很大，如何在情感之间的Observable上运行函数？

Question

I have a PublishSubject which receive emits from UI:

myPublishSubject
        .map {
            ...
        }
        .doOnNext {
            // using emitted item
        }
        .timeout (...) // wait for the gap!
        .doOnNext {
            // running a function after a specific gap between two item
        }
        .subscribe()

I want to wait a specific amount of time after last emit (not onComplete, cause it continue emitting later) and run a function. It can be interpreted as a gap between item emotion.

I am looking for something like timeout but this method issue is it kills the Observable with error.

Answer 1

You have to be a bit creative with publish and switchMap for example:

PublishSubject<Integer> ps = PublishSubject.create();

ps.publish(o -> 
    o.mergeWith(
        o.switchMap(e -> 
             Observable.just(1).delay(200, TimeUnit.MILLISECONDS)
            .ignoreElements()
            .doOnCompleted(() -> System.out.println("Timeout action: " + e))
        )
    )
).subscribe(System.out::println);

ps.onNext(1);
ps.onNext(2);

Thread.sleep(100);

ps.onNext(3);

Thread.sleep(250);

ps.onNext(4);

Thread.sleep(250);

It works by sharing a source and routing into two ways, one is directly emitting while the other feeds a switchMap that when receives a new item, starts a delayed Observable and reacts to its completion (ignoring the original trigger element to avoid duplicate events due to mergeWith ). When there is a new signal during the grace period, switchMap will cancel the previous delay and start with the newer delay.