java - RxJava - 通过另一个控制一个 Observable

Question

已更新

我正在寻找一种方法来控制一个可被另一个观察到的流量。例如，让我们有 2 个单调递增(重要) 整数观测值:

source  : 1----2-2---2--3--3--4----4--5---6----8---9---10--------11------
control : -1----3----------------5-----------6-------9-----------12------

我需要生成一个新的可观察对象，其元素与源完全匹配，但它们的时间由控制可观察对象以下列方式控制:源值应始终小于或等于控制值。这意味着只有大于最近发布的控件的所有源值应该等到它们被控件“释放”

source         : 1----2-2---2--3--3--4----4--5---6----8---9---10--------11------
control        : -1----3----------------5-----------6-------9-----------12------
expected result: -1----2-2--2--3--3-----4-4--5------6-------8-9---------10-11---

请看下面的代码示例:

private static <T, C> Observable<T> combine(Observable<T> source, Observable<C> control, BiFunction<T, C, Boolean> predicate) {
    // ???
}

@Test
public void testControl() throws InterruptedException {
    Subject<Integer> control = PublishSubject.create();
    Observable<Integer> source = Observable.fromArray(1, 2, 2, 2, 3, 3, 4, 4, 5, 6, 8, 10, 11);
    Observable<Integer> combined = combine(source, control, (s, c) -> s <= c);
    control.subscribe(val -> System.out.println("Control: " + val));
    combined.observeOn(Schedulers.io()).subscribe(val -> System.out.println("Value: " + val));

    control.onNext(3); // should release 1,2,2,2,3,3
    Thread.sleep(1000);
    control.onNext(6); // should release 4,4,5,6
    Thread.sleep(1000);
    control.onNext(11); // should release 8,10,11
    Thread.sleep(1000);
}

Answer 1

由于我没有找到任何优雅的解决方案，所以我最终自己实现了它。如果有人能提出更优雅的解决方案，我会很高兴(在这种情况下，我将不接受这个答案并接受更好的答案)。以下是我的解决方案:

private static <T, C> Observable<T> combine(Observable<T> source, Observable<C> control, BiFunction<T, C, Boolean> predicate) {
    return Observable.create(emitter -> {
        Queue<T> buffer = new ArrayDeque<>();
        AtomicReference<C> lastControl = new AtomicReference<>();
        CompletableSubject sourceCompletable = CompletableSubject.create();
        CompletableSubject controlCompletable = CompletableSubject.create();
        Disposable disposable = new CompositeDisposable(
                control.subscribe(
                        val -> {
                            lastControl.set(val);
                            synchronized (buffer) {
                                while (!buffer.isEmpty() && predicate.apply(buffer.peek(), val)) {
                                    emitter.onNext(buffer.poll());
                                }
                            }
                        },
                        emitter::onError,
                        controlCompletable::onComplete),
                source.subscribe(
                        val -> {
                            C lastControlVal = lastControl.get();
                            synchronized (buffer) {
                                if (lastControlVal != null && predicate.apply(val, lastControlVal)) {
                                    emitter.onNext(val);
                                } else {
                                    buffer.add(val);
                                }
                            }
                        },
                        emitter::onError,
                        sourceCompletable::onComplete),
                controlCompletable.andThen(sourceCompletable).subscribe(emitter::onComplete));
        emitter.setDisposable(disposable);
    });
}