MessageBox.Show 捕获异常时偶尔不显示

Question

我正在用 C# 编写 Visual Studio 扩展，但在管理异常和显示错误消息时出现奇怪的行为。基本上，我只想向异常消息添加一些详细信息，以帮助我在出现问题时进行调查。

这一切都是从上下文菜单项上的命令开始的，我怀疑它可能与 async/await 机制背后的线程管理有关。但我不确定我猜对了，我找不到任何解决方案。帮助！

从我的菜单项回调开始：

internal sealed class My_RunAnalysis
{
    //...
    public static async Task InitializeAsync(AsyncPackage package)
    {
        // Switch to the main thread - the call to AddCommand in PS_RunAnalysis's constructor requires
        // the UI thread.
        await ThreadHelper.JoinableTaskFactory.SwitchToMainThreadAsync(package.DisposalToken);

        OleMenuCommandService commandService = await package.GetServiceAsync((typeof(IMenuCommandService))) as OleMenuCommandService;
        Instance = new My_RunAnalysis(package, commandService);
    }

    //...
    private async void ExecuteAsync(object sender, EventArgs e)
    {
        try
        {
            await My_ViewModel.RunAnalysisAsync();
        }
        catch (Exception exc)
        {
            await ThreadHelper.JoinableTaskFactory.SwitchToMainThreadAsync(package.DisposalToken);

            MessageBox.Show(exc.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Warning);
        }
    }
}

//...

class My_ViewModel
{
    async public static Task RunAnalysisAsync()
    {
        await My_Model.GetResultsListAsync();
    }
}

//...

class My_Model
    async public static Task GetResultsListAsync()
    {
        ResultsList = new My_ResultsList();

        var rawResultsList = await QueryServerAsync<RawResultsListResponse>("GET", My_Request.GetResults());

        //...
    }

    async public static Task<JsonResponse> QueryServerAsync<JsonResponse>(string method, 
        string request)
    {
        try
        {
            HttpResponseMessage response;

            switch (method)
            {
                case "GET":
                    response = await _httpClient.GetAsync(request);
                    break;
                case "POST":
                default:
                    StringContent httpContent = new StringContent("", Encoding.UTF8, "application/json");
                    response = await _httpClient.PostAsync(request, httpContent);
                    break;
            }

            if (!response.IsSuccessStatusCode) //<<<<<<CASE #1
            {
                throw new My_Exception(
                response.ReasonPhrase,
                "Exception while querying server for " + request);
            }

            string serializedJson = await response.Content.ReadAsStringAsync();
            // CASE #2>>>>>
            var jsonResponse = serializer.Deserialize<JsonResponse>(serializedJson); 

            return jsonResponse;
        }
        catch (Exception e)
        {
            throw new My_Exception(
                e.Message,
                "Exception while querying server for " + request);
        }
    }

奇怪的是：

当案例 #1 发生错误并且我创建了自定义异常（我的服务器响应但存在内部错误并且我有一个干净的错误代码）时，MessageBox 在 My_ViewModel::RunAnalysisAsync() 将立即正确显示。
当在案例 #2 中发生本机异常时（我的服务器响应格式错误 json 并且我从 serializer.Deserialize 收到异常），My_ViewModel::RunAnalysisAsync() 不会显示，IDE 将在重新启动前挂起大约 15 秒（并且仍然不会显示 MessageBox）。

知道出了什么问题吗？

谢谢！

EDIT:

Seeing that the template for my custom command initializes also with SwitchToMainThreadAsync, I have tried to do the same with the Execute method. I updated the code above but it still does not work: an exception thrown by serializer.Deserialize will still freeze the UI for 10 to 15s and the MessageBox will not show!

Also note that the debugger can step immediately on "await ThreadHelper.JoinableTaskFactory.SwitchToMainThreadAsync(package.DisposalToken);" and go on next step to MessageBox. I would tend to suppose it means that the switch to the main thread is immediate but there is still something wrong...

Any idea what's wrong? I really need to capture exceptions a reliable way...

Answer 1

使用await JoinableTaskFactory.SwitchToMainThreadAsync();切换到主线程JoinableTaskFactory是AsyncPackage的成员。如果还是不行试试

public static void ShowMessageBox(string title, string text)
        {
            Microsoft.VisualStudio.Shell.ThreadHelper.ThrowIfNotOnUIThread();

            IVsUIShell uiShell = Microsoft.VisualStudio.Shell.ServiceProvider.GlobalProvider.GetService(typeof(SVsUIShell)) as IVsUIShell;
            Guid clsid = Guid.Empty;
            int result;
            Microsoft.VisualStudio.ErrorHandler.ThrowOnFailure(uiShell.ShowMessageBox(
                       0,
                       ref clsid,
                       title,
                       text,
                       string.Empty,
                       0,
                       OLEMSGBUTTON.OLEMSGBUTTON_OK,
                       OLEMSGDEFBUTTON.OLEMSGDEFBUTTON_FIRST,
                       OLEMSGICON.OLEMSGICON_INFO,
                       0,        // false
                       out result));
        }

Answer 2

我找不到任何关于 MessageBox 在一个案例上工作而不在另一个案例上工作的解释。我最终使用 FileStream.WriteAsync 找到了一些日志解决方案。因此一切都保持异步，我不必再使用 MessageBox 了。

MessageBox.Show 捕获异常时偶尔不显示

MessageBox.Show sporadically don't show on catching exception

c#

visual-studio-extensions