Cancellation on ExcelFile.Load

GemBox.Spreadsheet
1

The application I’m working on is async and supports cancellation for async operations. The ExcelFile.Load method can be long running, but is not async and doesn’t support cancellation. Is there a recommended approach for handling cancellation if required?

If there isn’t a supported technique for dealing with cancellation, will I run into trouble if I do the following:

  • Create a “wrapper stream” class called CancellationAwareStream that inherits from System.IO.Stream. This CancellationAwareStream will accept a Stream for the .xlsx file and a CancellationToken in its constructor.
  • Close the .xlsx stream from within the CancellationAwareStream if the cancellation token is cancelled.
  • Pass the CancellationAwareStream in to the ExcelSheet.Load method

The implementation surrounding ExcelFile.Load would look something like this:

public Task LoadExcelAsync(string filePath, CancellationToken cancellationToken)
{
    return Task.Run(() =>
    {
        // Open the file stream
        using (var fileStream = File.OpenRead(filePath))
        // Wrap it with the cancellation-aware stream.
        using (var wrapperStream = new CancellationAwareStream(fileStream, cancellationToken))
        {
            // load using the cancellation aware stream.
            var excelFile = ExcelFile.Load(wrapperStream);

            // Process the excelFile as needed...
        }
    }, cancellationToken);
}
2

Hi,

Unfortunately, I’m not sure how that will work. How exactly will CancellationAwareStream cancel the synchronous work of the underlined stream?

Nevertheless, please check the “Progress Reporting and Cancellation” example:

Last, regarding the async methods, as shown in the above example, the asynchronous execution is currently event-based.
However, starting this year, we have removed support for .NET Framework 3.5. Now, the minimum supported version is 4.6.2, making it easier to incorporate the asynchronous execution with a task-based approach in the future.

Regards,
Mario

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