对一段时间内未发生不同事件的事件的响应式订阅

本文关键字：事件 响应 一段时间 | 更新日期: 2023-09-27 17:58:30

我正试图弄清楚如何为一个事件创建一个Reactive订阅，而不是在特定的时间窗口内创建一个不同的事件。

为了说明，这里有一个用例：

由两个事件触发的繁忙指示器。忙和不忙。它们可以近距离发射，但指示灯不应经常闪烁。

当NotBusy激发时，应该没有指示器。当Busy启动并且NotBusy在5秒内没有启动时，它应该显示出来。

有没有一种方法可以在不添加外部状态的情况下完全在Reactive中做到这一点？

对一段时间内未发生不同事件的事件的响应式订阅

啊，我忍不住了——你多久会反驳一次源材料的作者（参见Benjol对问题的评论）：）

这是我的尝试（LINQPad就绪）：

输出如下：

At 1/1/0001 12:00:00 AM +00:00, Busy Signal Indicator is now:OFF
Sending BUSY at 1/1/0001 12:00:00 AM +00:00
Sending NOTBUSY at 1/1/0001 12:00:02 AM +00:00
Sending BUSY at 1/1/0001 12:00:03 AM +00:00
Sending BUSY at 1/1/0001 12:00:06 AM +00:00
At 1/1/0001 12:00:08 AM +00:00, Busy Signal Indicator is now:ON
Sending NOTBUSY at 1/1/0001 12:00:09 AM +00:00
At 1/1/0001 12:00:09 AM +00:00, Busy Signal Indicator is now:OFF

以下是我们活动的基本定义：

enum EventType 
{ 
    Busy, 
    NotBusy 
}
class StreamEvent 
{ 
     public EventType Type {get; set;} 
     public StreamEvent(EventType type) { Type = type;}
}

这是查询+测试代码：

void Main()
{
    // our simulated event stream
    var fakeSource = new System.Reactive.Subjects.Subject<StreamEvent>();
    // Let's use a scheduler we actually don't have to wait for
    var theTardis = new System.Reactive.Concurrency.HistoricalScheduler();
    var busySignal = fakeSource
        // Batch up events:
        .Window(
            // Starting batching on a busy signal
            fakeSource.Where(e => e.Type == EventType.Busy),
            // Stop batching on a not busy signal
            (open) => fakeSource.Where(e => e.Type == EventType.NotBusy)
                // but throw a timeout if we exceed 5 seconds per window
                .Timeout(TimeSpan.FromSeconds(5), theTardis))       
        // Unpack the windows
        .Switch()
        // Catch any timeout exception and inject a NULL into the stream        
        .Catch(fakeSource.StartWith((StreamEvent)null))
        // Bool-ify on "did a timeout happen?"
        .Select(e => e == null)
        // Start in an "unbusy" state
        .StartWith(false)
        // And only tell us about transitions
        .DistinctUntilChanged();    
    using(busySignal.Subscribe(signal => 
        Console.WriteLine("At {0}, Busy Signal Indicator is now:{1}",
            theTardis.Now,
            signal ? "ON" : "OFF")))
    {
        // should not generate a busy signal
        Console.WriteLine("Sending BUSY at {0}", theTardis.Now);
        fakeSource.OnNext(new StreamEvent(EventType.Busy));
        theTardis.AdvanceBy(TimeSpan.FromSeconds(2));
        Console.WriteLine("Sending NOTBUSY at {0}", theTardis.Now);
        fakeSource.OnNext(new StreamEvent(EventType.NotBusy));
        theTardis.AdvanceBy(TimeSpan.FromSeconds(1));
        Console.WriteLine();
        // should generate a busy signal
        Console.WriteLine("Sending BUSY at {0}", theTardis.Now);
        fakeSource.OnNext(new StreamEvent(EventType.Busy));
        theTardis.AdvanceBy(TimeSpan.FromSeconds(3));
        Console.WriteLine("Sending BUSY at {0}", theTardis.Now);
        fakeSource.OnNext(new StreamEvent(EventType.Busy));
        theTardis.AdvanceBy(TimeSpan.FromSeconds(3));
        // and this should clear it
        Console.WriteLine("Sending NOTBUSY at {0}", theTardis.Now);
        fakeSource.OnNext(new StreamEvent(EventType.NotBusy));      
        theTardis.AdvanceBy(TimeSpan.FromSeconds(1));
        Console.WriteLine();    
    }
}
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