延长WaitHandle.WaitOne超时时间

Question

框架中是否有一种现有的类型，可以让我做一些类似下面的例子？基本上，我想要增加超时时间的能力。

MagicWaitHandle waitHandle;

Main()
{
 var fooBar = new FooBar();
 fooBar.OnEvent += HandleEvent;
 fooBar.Start(); // starts new thread

 waitHandle.WaitOne(new TimeSpan(0,1,0)); // suspend
}

HandleEvent(Foo f)
{
 if(f.SomeCondition) waitHandle.ExtendWaitPeriodBy(new TimeSpan(0,1,0)); // extend
 else if(f.OtherCondition) waitHandle.Set(); // signal
}

Answer 1

框架中没有任何东西能提供您所要求的内容。不过，您可以为WaitHandle编写一个装饰器，然后使用它。

下面的伪代码可以帮助您启动实现。

public class MagicWaitHandle : WaitHandle
{
    private readonly WaitHandle inner;
    public MagicWaitHandle(WaitHandle inner)
    {
        if (inner == null) throw new ArgumentNullException("inner");
        this.inner = inner;
        this.SafeWaitHandle = inner.SafeWaitHandle;
    }

    public override bool WaitOne(TimeSpan timeout)
    {
        if (!base.WaitOne(timeout) )
        {
            if (<needs Apply Extended Timeout>)
            {
                return base.WaitOne(extendedTimeSpan);
            }
        }
        return false;
    }

    public override bool WaitOne(TimeSpan timeout, bool exitContext)
    {
        if (!base.WaitOne(timeout, exitContext))
        { 
            if (<needs Apply Extended Timeout>)
            {
                return base.WaitOne(extendedTimeSpan, exitContext);
            }
        }
        return false;
    }

    public void ExtendWaitPeriodBy(TimeSpan timeSpan)
    {
        //...
    }
}

确保在实现时考虑线程安全。一旦您完成了MagicWaitHandle的实现，您就可以使用它作为

MagicWaitHandle magicHandle = new MagicWaitHandle(new ManualResetEvent(false));
...
magicHandle.WaitOne(timeout);

其他代码中的位置

magicHandle.ExtendWaitPeriodBy(extensionTimeout);