C#, Catch and retry, CatchAndHandling, Aspect, AOP

catch_and_retry.cs

using System;

class Program
{
    static void Main(string[] args)
    {

        CatchAndRetry<ApplicationException>(2, 3000, n =>
        {
            Console.WriteLine($"AAA{n}");
            if (n > 1)
                throw new ApplicationException("Fail!");

            Console.WriteLine($"Success{n}");
        });

        CatchAndRetry<ApplicationException>(new int[] { 1000, 2000, 3000 }, n =>
        {
            Console.WriteLine($"AAA{n}");
            if(n < 2)
            throw new ApplicationException("Fail!");

            Console.WriteLine($"Success{n}");
        });

        Console.WriteLine("Press any key to continue.");
        Console.ReadKey();
    }

    static void CatchAndRetry<TException>(int retryCount, int retryDuration, Action<int> act)
        where TException : Exception
    {
        for (; ; )
        {
            try
            {
                act.Invoke(retryCount);
                break;
            }
            catch (TException)
            {
                if (retryCount-- > 0) // decide to retry or not.
                {
                    // waiting short time and then re-exec.
                    System.Threading.SpinWait.SpinUntil(() => false, retryDuration);
                    continue; // retry
                }
                throw; // fail & leave
            }
        }
    }

    static void CatchAndRetry<TException>(int[] retryDuration, Action<int> act)
        where TException : Exception
    {
        int idx = 0;
        for (; ; )
        {
            try
            {
                act.Invoke(idx);
                break;
            }
            catch (TException)
            {
                if (retryDuration.Length > idx) // decide to retry or not.
                {
                    // waiting short time and then re-exec.
                    System.Threading.SpinWait.SpinUntil(() => false, retryDuration[idx++]);
                    continue; // retry
                }
                throw; // fail & leave
            }
        }
    }
}

CatchHandling.cs

Task HandleQuery() => CatchHandling(async () =>
{
  var qryArgs = new TodoQryAgs
    {
      Msg = f_testFail ? "測試邏輯失敗" : "今天天氣真好",
      Amt = 999
    };

  dataList = await bizApi.QryDataListAsync(qryArgs);
});

Task HandleAdd() => CatchHandling(async () =>
{
  var newTodo = await bizApi.AddFormDataAsync(newTodoDesc);

  // Success
  dataList.Add(newTodo);
  newTodoDesc = string.Empty;
});

//----------------------------------------------------------------------
//# AOP with Decorator
async Task CatchHandling(Func<Task> action)
{
  try
  {
    f_loading = true;
    errMsg = string.Empty;
    await action();
  }
  catch (ApiException ex)
  {
    if (ex.StatusCode == HttpStatusCode.BadRequest)
    {
      var msg = await ex.GetContentAsAsync<ErrMsg>();
      errMsg = $"ApiException: {msg.Severity}-{msg.Message}";
    }
    else
    {
      errMsg = $"ApiException: {ex.Message}";
    }
  }
  catch (Exception ex)
  {
    errMsg = "EXCEPTION: " + ex.Message;
  }
  finally
  {
    f_loading = false;
  }
}

CatchHandling.sample.razor

@page "/FooPage"
@attribute [Authorize]
@inject IDialogServiceEx dlgSvc
@inject ILogger<_SSO1010> logger
@inject FooBiz bizSvc

<MudContainer>
  <FooForm ...>
</MudContainer>

@code {
  //## State
  List<FooItemInfo> dataList = new();
  bool f_loading = false;

  protected override Task OnInitializedAsync() => CatchHandling(async () =>
  {
      dataList = await Task.Run(() => bizSvc.QryDataList());
  });

  Task HandleAdd(FooItemInfo item) => CatchHandling(async () =>
  {
    //# 資料演算
    (item, string message) = await Task.Run(() => bizSvc.AddFormData(item));
    if (message != "SUCCESS")
    {
      dlgSvc.ShowAlert(message);
      return;
    }

    // UI
    dataList.Add(item);
    dataList = dataList.OrderBy(c => c.OrderBy).ToList();
  });

  Task HandleUpdate(FooItemInfo item) => CatchHandling(async () =>
  {
    //# 資料演算
    (item, string message) = await Task.Run(() => bizSvc.UpdFormData(item));
    if (message != "SUCCESS")
    {
      await dlgSvc.ConfirmAsync(message, "更新失敗請重新確認！");
      await refDataGrid.SetEditingItemAsync(item);
      return;
    }

    // UI
    dataList = dataList.OrderBy(c => c.OrderBy).ToList();
  });

  Task HandleRemove(FooItemInfo item) => CatchHandling(async () =>
  {
    //# 再確定一次
    bool isConfirm = await dlgSvc.ConfirmAsync($"再確定一次要刪除這筆資料？");
    if (!isConfirm) return;

    //# 資料演算
    await Task.Run(() => bizSvc.DelFormData(item));

    //# 成功後同步UI資料 & 刷新畫面
    dataList.Remove(item);
    dlgSvc.ShowAlert("刪除完成。", type: Severity.Success);
  });

  //# AOP with Decorator ------------------------------------------------
  async Task CatchHandling(Func<Task> action)
  {
    try
    {
      f_loading = true;
      await InvokeAsync(StateHasChanged);
      await action();
    }
    catch (Exception ex)
    {
      logger.LogError(ex, "出現例外！" + ex.Message);
      dlgSvc.ShowAlert(ex.Message, "出現例外！");
    }
    finally
    {
      f_loading = false;
      await InvokeAsync(StateHasChanged);
    }
  }
}