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名师互学网 > IT > 面试经验 > 面试问答

抛出UnobservedTaskException,但是由TaskScheduler.UnobservedTaskException处理程序和延续OnlyOnFaulted处理程序处理。

面试问答 更新时间: 发布时间: IT归档 最新发布 模块sitemap 名妆网 法律咨询 聚返吧 英语巴士网 伯小乐 网商动力

抛出UnobservedTaskException,但是由TaskScheduler.UnobservedTaskException处理程序和延续OnlyOnFaulted处理程序处理。

该解决方案基于使用Task Parallel
Library时如何处理所有未处理的异常?

class Program{    static void Main(string[] args)    {        Program p = new Program();        p.tplTestOne();    }    public void tplTestOne()    {        //-------------------------------------------------        MyClassHere.onUnobservedTaskException += (object sender, EventException e) =>        { Console.WriteLine(e.Exception.Message); //its fired OK        };        TaskScheduler.UnobservedTaskException += (object sender, UnobservedTaskExceptionEventArgs e) =>        { Console.WriteLine(e.Exception.Message); // its not fired, buggy        };        //-------------------------------------------------        CancellationTokenSource source = new CancellationTokenSource();        Task tz = MyClassHere.CreateHandledTask( new TaskScheduled(0, () => {     if (!source.IsCancellationRequested)     {         Console.WriteLine("A-main-task-started");     }     Thread.Sleep(5000);     if (source.IsCancellationRequested)     {         Console.WriteLine("CancelingMainTask");     } }) , new TaskScheduled(3000, () => { Console.WriteLine("okTaskCalled"); })  , null //new TaskScheduled(0, () => { Console.WriteLine("cancelTaskCalled"); }) , TaskCreationOptions.AttachedToParent , source.Token , new TaskScheduled(2000, () => {     if (!source.IsCancellationRequested)     {         Console.WriteLine("B-timeout");     } }) , new TaskScheduled(1000, () => {     if (!source.IsCancellationRequested)     {         Console.WriteLine("C-timeout");     }     source.Cancel(); })        );        if(tz != null)        { tz.ContinueWith(t => { Console.WriteLine("END"); });        }        Task tsk_1 = MyClassHere.createHandledTask(() =>        { double x = 1; x = (x + 1) / x;        }, false);        Task tsk_2 = MyClassHere.createHandledTask(() =>        { double y = 0; throw new Exception("forced_divisionbyzerodontthrowanymore_test"); // here -> System.Exception was unhandled by user pre        }, true);        Task tsk_3 = MyClassHere.createHandledTask(() =>        { double z = 1; z = (z + 1) / z;        }, true);        Task tsk_4 = MyClassHere.createHandledTask(() =>        { double k = 1; k = (k + 1) / k;        }, true);        Console.ReadLine();    }}public class EventException : EventArgs{    public Exception Exception;    public Task task;    public EventException(Exception err, Task tsk)    {        Exception = err;        task = tsk;    }}public class TaskScheduled{    public int waitTime;    public Action action;    public DateTime datestamp;    public bool isCalled = false;    public TaskScheduled(int _waitTime, Action _action)    {        this.waitTime = _waitTime;        this.action = _action;    }}public static class MyClassHere{    public delegate void UnobservedTaskException(object sender, EventException e);    public static event UnobservedTaskException onUnobservedTaskException;    //-------------------------------------------------    public static void waitForTsk(Task t)    {        try        { t.Wait();        }        catch (AggregateException ae)        { ae.Handle((err) => {     throw err; });        }    }    //-------------------------------------------------    public static void RaiseUnobsrvEvtForEachIfHappens(this Task task)    {        task.ContinueWith(t =>        { var aggException = t.Exception.Flatten(); foreach (var exception in aggException.InnerExceptions) {     onUnobservedTaskException(task, new EventException(exception, task)); }        },        TaskContinuationOptions.OnlyOnFaulted); // not valid for multi task continuations    }    //-------------------------------------------------    public static Task CreateHandledTask(Action action)    {        return CreateHandledTask(action, false);    }    public static Task CreateHandledTask(Action action, bool attachToParent)    {        Task tsk = null;        tsk = CreateHandledTask(action, attachToParent, CancellationToken.None);        return tsk;    }    public static Task CreateHandledTask(Action action, bool attachToParent, CancellationToken cancellationToken)    {        Task tsk = null;        TaskCreationOptions atp = TaskCreationOptions.None;        if (attachToParent) { atp = TaskCreationOptions.AttachedToParent; }        tsk = CreateHandledTask(action, atp, cancellationToken);        return tsk;    } public static Task CreateHandledTask(Action action, TaskCreationOptions tco, CancellationToken cancellationToken)    {        Task tsk = null;        tsk = Task.Factory.StartNew(action, cancellationToken, tco, TaskScheduler.Default);        tsk.RaiseUnobsrvEvtForEachIfHappens();        return tsk;    }    public static Task CreateHandledTask(TaskScheduled mainTask,        TaskScheduled onSuccessTask,          TaskScheduled onCancelationTask,        TaskCreationOptions tco,         CancellationToken cancellationToken,         params TaskScheduled[] timeouts)    {        Task tsk = null;        ManualResetEvent me = new ManualResetEvent(false);        if (timeouts == null || timeouts.Length < 1 || timeouts[0] == null)        { tsk = CreateHandledTask(mainTask.action, tco, cancellationToken); me.Set();        }        else        { bool isCancelation = false; bool isSuccess = true; Task NonBlockCtxTask = CreateHandledTask(() => {     tsk = CreateHandledTask(mainTask.action, tco, cancellationToken);     me.Set();     int qtdt = timeouts.Count(st => st.action != null);     CountdownEvent cde_pas = new CountdownEvent(3);     CountdownEvent cde_pat = new CountdownEvent(qtdt);     Parallel.ForEach<TaskScheduled>(timeouts, (ts) =>     {         try         {  bool itsonTime = tsk.Wait(ts.waitTime, cancellationToken);  cde_pat.Signal();  if (!itsOnTime)  {      isSuccess = false;      Task tact = CreateHandledTask(ts.action, TaskCreationOptions.None, cancellationToken);  }         }         catch (OperationCanceledException oce)         {  isSuccess = false;  cde_pat.Signal(cde_pat.CurrentCount);  isCancelation = true;         }     });     try     {         isSuccess &= cde_pat.Wait(System.Threading.Timeout.Infinite, cancellationToken) && !isCancelation;     }     catch (OperationCanceledException oce)     {         isCancelation = true;         isSuccess = false;     }     finally     {         cde_pas.Signal();     }     try     {         if (isCancelation && onCancelationTask != null)         {  Thread.Sleep(onCancelationTask.waitTime);  Task tcn = CreateHandledTask(onCancelationTask.action);         }     }     catch { }     finally {         cde_pas.Signal();     }     try     {         if (isSuccess && onSuccessTask != null)         {  Thread.Sleep(onSuccessTask.waitTime);  Task tcn = CreateHandledTask(onSuccessTask.action);         }     }     catch { }     finally     {         cde_pas.Signal();     }     cde_pas.Wait(System.Threading.Timeout.Infinite); }, TaskCreationOptions.None, cancellationToken);}        me.WaitOne();        return tsk;    }    //-------------------------------------------------}


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