异步编程设计模式

Question

我正在研究CF.NET的一个小技术框架,我的问题是,我应该如何编写异步部分？在MSDN上阅读很多内容但对我来说并不清楚.

所以,这是代码:

public class A
{
    public IAsyncResult BeginExecute(AsyncCallback callback)
    {
        // What should I put here ?
    }

    public void EndExecute()
    {
        // What should I put here ?
    }

    public void Execute()
    {
        Thread.Sleep(1000 * 10);
    }
}

如果有人可以帮助我......

谢谢 !

Answer 1

您可以使用委托:

public class A
{
    public void Execute()
    {
        Thread.Sleep(1000 * 3);
    }
}

class Program
{
    static void Main()
    {
        var a = new A();
        Action del = (() => a.Execute());
        var result = del.BeginInvoke(state =>
        {
            ((Action)state.AsyncState).EndInvoke(state);
            Console.WriteLine("finished");
        }, del);
        Console.ReadLine();
    }
}

更新:

根据评论部分的要求,这是一个示例实现:

public class A
{
    private Action _delegate;
    private AutoResetEvent _asyncActiveEvent;

    public IAsyncResult BeginExecute(AsyncCallback callback, object state)
    {
        _delegate = () => Execute();
        if (_asyncActiveEvent == null)
        {
            bool flag = false;
            try
            {
                Monitor.Enter(this, ref flag);
                if (_asyncActiveEvent == null)
                {
                    _asyncActiveEvent = new AutoResetEvent(true);
                }
            }
            finally
            {
                if (flag)
                {
                    Monitor.Exit(this);
                }
            }
        }
        _asyncActiveEvent.WaitOne();
        return _delegate.BeginInvoke(callback, state);
    }

    public void EndExecute(IAsyncResult result)
    {
        try
        {
            _delegate.EndInvoke(result);
        }
        finally
        {
            _delegate = null;
            _asyncActiveEvent.Set();
        }
    }

    private void Execute()
    {
        Thread.Sleep(1000 * 3);
    }
}

class Program
{
    static void Main()
    {
        A a = new A();
        a.BeginExecute(state =>
        {
            Console.WriteLine("finished");
            ((A)state.AsyncState).EndExecute(state);
        }, a);
        Console.ReadLine();
    }
}