在 ASP.Net Webforms 上捕获线程异常

Question

我有私有方法，它尝试生成 pdf 文件，然后使用此 pdf 发送电子邮件。如果一切正常，则此方法将表单上的文本更改为 "Pdf were generated successfully"。

我的方法：

private void RegenerateSubmissionPdf(int submissionId)
{
    var submissionPath = PublisherConfigurationManager.SubmissionPath + submissionId;

    var tasks = new List<Task>
    {
        HttpContext.Current.GeneratePdfTask(submissionPath, submissionId, PublisherConst.SubmissionPdfName,
            _objSubmission.SaveSubmissionPdf)
    };

    tasks.SendEmailTasks(u => SendRegenerateSubmissionPdfEmail(submissionId, u));
}

和 returns Task 的方法：

public static Task GeneratePdfTask(this HttpContext context, string path, int submissionId, string pdfName, Action<int, byte[]> postAction = null)
{
    var local = context;
    return Task.Factory.StartNew(() =>
    {
        HttpContext.Current = local;
        SessionHelper.Set(SessionKey.IsPdfRendering, true);
        var pdfFile = new PdfGenerator().Generate(path, pdfName, submissionId);
        if (postAction != null && pdfFile != null)
        {
            postAction(submissionId, pdfFile);
        }

    });
}

在最后一种方法中，有时我会遇到异常（可能路径错误，某些图像丢失或其他原因）。我找到了 this solution，但不知道如何将其应用到我的案例中。

Answer 1

你试过这个吗：

private void RegenerateSubmissionPdf(int submissionId)
{
    var submissionPath = PublisherConfigurationManager.SubmissionPath + submissionId;

    var tasks = new List<Task>
    {
        HttpContext.Current.GeneratePdfTask(submissionPath, submissionId, PublisherConst.SubmissionPdfName,
            _objSubmission.SaveSubmissionPdf)
    };
    tasks.ForEach(t => t.ContinueWith(ExceptionHandler, TaskContinuationOptions.OnlyOnFaulted));
    tasks.SendEmailTasks(u => SendRegenerateSubmissionPdfEmail(submissionId, u));
}

private void ExceptionHandler(Task task)
{
    // Handle exception
}

在您创建并启动列表中的任务后，您为每个任务分配一个延续，以防抛出异常。但是根据您的代码，我看不到需要任务列表的必要性。您可以简单地使用任务对象并将其分配给延续。

Answer 2

据我了解，SendEmailTasks是一种扩展方法，但您可以只使用一个任务，如下所示：

private void RegenerateSubmissionPdf(int submissionId)
{
    var submissionPath = PublisherConfigurationManager.SubmissionPath + submissionId;

    var task = HttpContext.Current.GeneratePdfTask(submissionPath, submissionId, PublisherConst.SubmissionPdfName,
            _objSubmission.SaveSubmissionPdf);
    task.ContinueWith(t =>  
      SendRegenerateSubmissionPdfEmail(submissionId, task),  
      TaskContinuationOptions.OnlyOnRanToCompletion);
    task.ContinueWith(t =>  
      HandleException(task.Exception),  
      TaskContinuationOptions.OnlyOnFaulted);
    await task;
}

这个方法如果没有异常就继续执行，如果有异常就处理。并考虑使用 Stephen Cleary 的 await constructure or Run method instead of StartNew (great article about this）。

在 ASP.Net Webforms 上捕获线程异常

Catch thread exception on ASP.Net Webforms

c#

pdf

asp.net

multithreading

exception-handling