4

我正在使用 GUIDE 在 Matlab 中编写一个小型应用程序。此应用程序调用 .Net 库。该库连接到串行设备。使用 a BackgroundWorker，库会轮询端口以获取新数据，并IncomingData在收到新数据包时引发事件。（我知道这一点是因为我使用反编译器来查看库的内容。）

问题是我使用的 SDK 没有正确实现该RunWorkerCompleted方法。e.Errors在访问属性之前，它不会检查是否通过属性发生异常e.Result。这会导致引发TargetInvocationException。此异常未处理并导致 Matlab 崩溃并在 Windows 事件日志中出现以下事件。内部异常没有序列化到事件日志中，所以我不知道究竟是什么导致了失败。

Application: MATLAB.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.Reflection.TargetInvocationException
Stack:
   at System.ComponentModel.AsyncCompletedEventArgs.RaiseExceptionIfNecessary()
   at System.ComponentModel.RunWorkerCompletedEventArgs.get_Result()
   at TargetInvocationIssueMVCE.BlackBox._backgroundWorker_RunWorkerCompleted(System.Object, System.ComponentModel.RunWorkerCompletedEventArgs)
   at System.ComponentModel.BackgroundWorker.OnRunWorkerCompleted(System.ComponentModel.RunWorkerCompletedEventArgs)
   at System.ComponentModel.BackgroundWorker.AsyncOperationCompleted(System.Object)
   at System.Threading.QueueUserWorkItemCallback.WaitCallback_Context(System.Object)
   at System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)
   at System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext,  System.Threading.ContextCallback, System.Object, Boolean)
   at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem()
   at System.Threading.ThreadPoolWorkQueue.Dispatch()
   at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback()

我能够通过以下 C# 类库复制我正在使用的库的行为。您可以将BlackBox下面的示例视为我无法更改的库。

using System;
using System.ComponentModel;

namespace TargetInvocationIssueMVCE
{
    public class BlackBox
    {
        private BackgroundWorker _backgroundWorker;

        public event EventHandler<EventArgs> IncomingData;

        public void Connect()
        {
            _backgroundWorker = new BackgroundWorker()
            {
                WorkerSupportsCancellation = true
            };

            _backgroundWorker.DoWork += _backgroundWorker_DoWork;
            _backgroundWorker.RunWorkerCompleted += _backgroundWorker_RunWorkerCompleted;
            _backgroundWorker.RunWorkerAsync();
        }

        private void _backgroundWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            // BlackBox should check e.Errors first, but doesn't, so throws a TargetInvocationException that I can't seem to catch, so it crashes Matlab.
            Console.Write(e.Result == null ? "Failure" : "Success");
        }

        private void _backgroundWorker_DoWork(object sender, DoWorkEventArgs e)
        {
            throw new InvalidOperationException("I could be any exception.");

            // the real worker is supposed to raise IncomingData here.
        }
    }
}

我在像这样的 Matlab GUIDE GUI 中调用这个库。

% --- Executes just before Figure1 is made visible.
function Figure1_OpeningFcn(hObject, eventdata, handles, varargin)
% This function has no output args, see OutputFcn.
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
% varargin   command line arguments to Figure1 (see VARARGIN)

% load the library

NET.addAssembly('C:\path\to\TargetInvocationIssueMVCE.dll');
blackbox = TargetInvocationIssueMVCE.BlackBox();
handles.blackbox = blackbox;

addlistener(blackbox, 'IncomingData', @OnIncomingData);

% Choose default command line output for Figure1
handles.output = hObject;

% Update handles structure
guidata(hObject, handles);

% ... some other irrelevant callbacks

% --- button click callback starts .Net BackgroundWorker process
function btnConnect_Callback(hObject, eventdata, handles)
try
    handles.blackbox.Connect();
    set(hObject, 'String', 'Disconnect');

catch ex
    warning(ex.message);
    set(hObject, 'Value', 1);
end

% --- Callback to process incoming data packets
function OnIncomingData(source, arg)
    % It doesn't matter what I put here, the exception is raised before
    % I ever get a packet event and Matlab crashes.

    msgbox('Received Packet');

在.Net 中，如果我真的需要，我可以在我的方法中设置一个catch，static void Main()这样我就可以检查内部异常。

try
{
    Application.Run(new Form1());
}
catch (TargetInvocationException exception)
{
    System.Windows.Forms.MessageBox.Show(exception.InnerException.ToString());
}

我在 Matlab 中通过创建一个脚本来运行该图进行了相同的尝试，但它仍然没有发现问题。它似乎以某种方式绕过了下面的问题。如果我只是双击Figure1运行它，Matlab 仍然会因我得到的相同事件日志而崩溃。

try
    Figure1
catch ex
    warning(ex.message)
end

所以，我真的不知道从这里去哪里。我知道这是一个 XY 问题。我真的不需要能够捕捉到这个异常，但我确实需要能够检查内部异常，而且我不知道还能做些什么来查看它。

我刚刚发现了这个有趣的花絮。

各种回调在基本工作区的上下文中执行，而不是在设置回调函数的例程的上下文中。您只能“捕获”您直接调用的语句的异常，而不是通过回调自动执行的函数的异常。

如果这是真的，它将解释为什么我在从脚本创建图形时无法捕获异常。我搞砸了吗？这是否意味着我无法捕捉到这个异常？

4

0 回答 0