在事件被编组到主线程之后,我想抛出一个新的异常,将原始异常集作为内部异常.我的问题是：这个新例外的类型应该是什么？对于这种情况是否存在特定的System.somethingException,我应该为这种特定情况设计我自己的Exception类,还是抛出标准的System.Exception并认为合适的消息是合适的？
C#-psuedo代码：
class MyThread
{
public TerminationState Termination { get; private set; }
public Exception UncaughtException { get; private set; }
public delegate void ThreadTerminatedDelegate(MyThread thread);
public event ThreadTerminatedDelegate ThreadTerminated;
private void run()
{
try
{
doSomeWork();
}
catch(Exception e)
{
UncaughtException = e;
Termination = TerminationState.AbortOnException;
ThreadTerminated(this);
return;
}
Termination = TerminationState.normalTermination;
ThreadTerminated(this);
}
}
class MainThread
{
private MyThread myThread = new MyThread();
private void run()
{
myThread.ThreadTerminated += handleTermination;
myThread.Start();
}
private void handleTermination(MyThread thread)
{
if (Invokerequired)
{
MyThread.ThreadTerminatedDelegate cb = new MyThread.ThreadTerminatedDelegate(handleTermination);
BeginInvoke(cb,new object[] { thread });
}
else
{
if (thread.Termination == TerminationState.AbortOnException)
{
if (isFatal(thread.UncaughtException))
throw new Exception("",thread.UncaughtException); //what to do here?
else
fixTheProblem();
}
else
{
//normal wrapping up
}
}
}
}
解决方法
Task.Factory.StartNew(
() =>
{
// Do some work that may throw.
// This code runs on the Threadpool.
// Any exceptions will be propagated
// to continuation tasks and awaiters
// for observation.
throw new StackOverflowException(); // :)
}
).ContinueWith(
(a) =>
{
// Handle your exception here.
// This code runs on the thread
// that started the worker task.
if (a.Exception != null)
{
foreach (var ex in a.Exception.InnerExceptions)
{
// Try to handle or throw.
}
}
},CancellationToken.None,TaskContinuationoptions.None,TaskScheduler.FromCurrentSynchronizationContext()
);
另一个有用的链接是MSDN’s Asyncronous Programming Patterns.它标识了在应用程序中实现异步操作的3种主要方法.您当前的实现听起来与文章所称的EAP(基于事件的异步模式)非常相似.
我个人更喜欢TAP(基于任务的异步模式),它依赖于.NET 4.0 TPL(任务并行库).由于其语法简单和广泛的功能,它值得掌握.
来自MSDN：
>异步编程模型(APM)模式(也称为IAsyncResult模式),其中异步操作需要Begin和End方法(例如,BeginWrite和EndWrite用于异步写入操作).这种模式不再推荐用于新开发.有关更多信息,请参阅异步编程模型(APM).
>基于事件的异步模式(EAP),它需要具有Async后缀的方法,并且还需要一个或多个事件,事件处理程序委托类型和EventArg派生类型. EAP是在.NET Framework 2.0中引入的.它不再被推荐用于新开发.有关更多信息,请参阅基于事件的异步模式(EAP).
>基于任务的异步模式(TAP),它使用单个方法来表示异步操作的启动和完成. TAP是在.NET Framework 4中引入的,是.NET Framework中异步编程的推荐方法.有关更多信息,请参阅基于任务的异步模式(TAP).
此外,不要忘记值得信赖的BackgroundWorker课程.这个课程对我来说很长一段时间,尽管它已经被TAP略微弃用,它仍然可以完成工作并且非常容易理解和使用.
// Create a new background worker.
var bgw = new BackgroundWorker();
// Assign a delegate to perform the background work.
bgw.DoWork += (s,e) =>
{
// Runs in background thread. Unhandled exceptions
// will cause the thread to terminate immediately.
throw new StackOverflowException();
};
// Assign a delegate to perform any cleanup/error handling/UI updating.
bgw.RunWorkerCompleted += (s,e) =>
{
// Runs in UI thread. Any unhandled exception that
// occur in the background thread will be accessible
// in the event arguments Error property.
if (e.Error != null)
{
// Handle or rethrow.
}
};
// Start the background worker asynchronously.
bgw.RunWorkerAsync();
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