Rxjava2 delay

delay操作符的作用是延时执行

 Observable.just(1, 2, 3).delay(2, TimeUnit.SECONDS).subscribe(new Observer<Integer>() {
            @Override
            public void onSubscribe(@NotNull Disposable d) {
                System.out.println("onSubscribe");
            }

            @Override
            public void onNext(@NotNull Integer integer) {
                System.out.println("onNext " + integer);
            }

            @Override
            public void onError(@NotNull Throwable e) {
                System.out.println("onError " + e.getMessage());
            }

            @Override
            public void onComplete() {
                System.out.println("onSubscribe");
            }
        });

看看源码

  public final Observable<T> delay(long delay, TimeUnit unit) {
        return delay(delay, unit, Schedulers.computation(), false);
    }
    
   public final Observable<T> delay(long delay, TimeUnit unit, Scheduler scheduler, boolean delayError) {
       ...
        return RxJavaPlugins.onAssembly(new ObservableDelay<T>(this, delay, unit, scheduler, delayError));
    }

ObservableDelay 创建一个Scheduler.Worker实例，用来执行延时任务。

public final class ObservableDelay<T> extends AbstractObservableWithUpstream<T, T> {
    final long delay;
    final TimeUnit unit;
    final Scheduler scheduler;
    final boolean delayError;

    public ObservableDelay(ObservableSource<T> source, long delay, TimeUnit unit, Scheduler scheduler, boolean delayError) {
        super(source);
        this.delay = delay;
        this.unit = unit;
        this.scheduler = scheduler;
        this.delayError = delayError;
    }

    @Override
    @SuppressWarnings("unchecked")
    public void subscribeActual(Observer<? super T> t) {
        Observer<T> observer;
        if (delayError) {
            observer = (Observer<T>)t;
        } else {
            observer = new SerializedObserver<T>(t);
        }

        Scheduler.Worker w = scheduler.createWorker();

        source.subscribe(new DelayObserver<T>(observer, delay, unit, w, delayError));
    }
...

}

每次上游发送数据，都会执行延时任务，delay表示从当前时间延时。

 public void onNext(final T t) {
      w.schedule(new OnNext(t), delay, unit);
  }