Question

假设我在列表中有三个产品。为了启用某个动作，所有三个动作都需要属于某种类型。为了找出产品的类型，我需要拨打服务电话并等待回复。

我想做的是等待所有三个回复（如果出现问题可能会超时），并且在收集完所有信息后，决定是否启用可能的操作。

我曾经通过一些计数器或重置事件来解决这个问题，以便跟踪已完成的事件，但我想看看我是否可以使用Rx以更清洁的方式进行。

由于我对Rx不太熟悉，我正在寻找一些提示/指针。我明白我可以用

Observable.FromEventPattern

我正在等待的事件。我订阅并等待响应并处理它。我不清楚如何组合多个事件。

Answer 1

您正在寻找的组合器是CombineLatest

说你有这样的课程：

public class Foo
{
    public delegate void FooEventHandler(object sender, EventArgs args);

    public event FooEventHandler FirstEvent = delegate {};    
    public event FooEventHandler SecondEvent = delegate {};    
    public event FooEventHandler ThirdEvent = delegate {};    

    public void DoIt()
    {
        FireOne();
        FireTwo();
        FireThree();
    }

    public void FireOne()
    {
        Console.WriteLine("Firing event 1...");
        Thread.Sleep(1000);
        FirstEvent(this, new EventArgs());
    }
    public void FireTwo()
    {
        Console.WriteLine("Firing event 2...");
        Thread.Sleep(1000);
        SecondEvent(this, new EventArgs());
    }
    public void FireThree()
    {
        Console.WriteLine("Firing event 3...");
        Thread.Sleep(1000);
        ThirdEvent(this, new EventArgs());
    }
}

首先，您要将这些事件“转换”为Observable：

var foo = new Foo();
var firstWatcher = Observable.FromEventPattern(foo, "FirstEvent");
var secondWatcher = Observable.FromEventPattern(foo, "SecondEvent");
var thirdWatcher = Observable.FromEventPattern(foo, "ThirdEvent");

现在你想要“只有当所有这些已经被解雇时才开火”选择器，即CombineLatest：

var allDone = Observable.CombineLatest(firstWatcher, secondWatcher, thirdWatcher);

并测试出来：

using(allDone.Subscribe(_ => Console.WriteLine("Boop! You sunk my battleship!")))
{
    foo.DoIt();
}

替代“测试工具”：

var foo = new Foo();
var firstWatcher = Observable.FromEventPattern(foo, "FirstEvent");
var secondWatcher = Observable.FromEventPattern(foo, "SecondEvent");
var thirdWatcher = Observable.FromEventPattern(foo, "ThirdEvent");

var allDone = Observable.CombineLatest(firstWatcher, secondWatcher, thirdWatcher);

// keep a handle on the subscription            
IDisposable subscription = null;

// to prevent premature exiting...
var blocker = new ManualResetEvent(false);

// explicit subscribe
subscription = allDone.Subscribe(
    whoCares => 
    {
        Console.WriteLine("BOOM! We're done!");
        // always clean up after yourself
        if(subscription != null)
        {
            subscription.Dispose();
        }
        // it's ok, we can quit now
        blocker.Set();
    });

foo.DoIt();

// Wait until it's clear to go ahead...
blocker.WaitOne();

使用RX同步多个事件

1 个答案: