我們經常有這樣的需求：如果一個方法的執行，超過了一個設定時間（timeout）就需要立即返回不再繼續，這裡我利用 C# 非同步委託的 AsyncWaitHandle 來儘量簡便的實現這一需求。

具體實現如下。注意，這裡需要被呼叫的方法遵守 delegate TR TimeOutDelegate(T param); 形式的方法簽名，如有其他需要，可以自行定製也很方便。

[csharp]
namespace TimeOutHelper
{
#region using directives

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Threading;

#endregion using directives

internal class Program
{
public delegate TR TimeOutDelegate<in T, out TR>(T param);

private static void Main()
{
Dictionary<Guid, string> result;
Console.WriteLine(TimeoutFunction.Execute(Test, "Hello, World!", out result, TimeSpan.FromSeconds(3)));
Console.WriteLine("Hello, World!");
Console.ReadKey();
}

public static Dictionary<Guid, string> Test(string sourceString)
{
var result = sourceString.ToDictionary(
character => Guid.NewGuid(),
character => character.ToString(CultureInfo.InvariantCulture));
Thread.Sleep(4000);
return result;
}

public static class TimeoutFunction
{
/// <summary>
/// Execute a method with timeout check
/// </summary>
/// <typeparam name="T">Target method parameter type</typeparam>
/// <typeparam name="TR">The result type of execution</typeparam>
/// <param name="timeoutMethod">Target method</param>
/// <param name="param">Target method parameter</param>
/// <param name="result">The result of execution</param>
/// <param name="timeout">Set timeout length</param>
/// <returns>Is timeout</returns>
public static Boolean Execute<T, TR>(
TimeOutDelegate<T, TR> timeoutMethod, T param, out TR result, TimeSpan timeout)
{
var asyncResult = timeoutMethod.BeginInvoke(param, null, null);
if (!asyncResult.AsyncWaitHandle.WaitOne(timeout, false))
{
result = default(TR);
return true;
}
result = timeoutMethod.EndInvoke(asyncResult);
return false;
}
}
}
}
[/csharp]