Redpoint.ProgressMonitor 2023.162.418

Redpoint.ProgressMonitor

This library provides APIs for monitoring and reporting the progress of arbitrary operations in console applications.

Read on for the following examples:

• Example for a generic stream
• Example for a HTTP download

Example for a generic stream

You can monitor an operation that uses a stream like so:

// Inject these services.
IProgressFactory _progressFactory;
IMonitorFactory _monitorFactory;

using (var stream = new FileStream(...))
{
    // Start monitoring.
    var cts = new CancellationTokenSource();
    var progress = _progressFactory.CreateProgressForStream(stream);
    var monitorTask = Task.Run(async () =>
    {
        var consoleWidth = 0;
        try
        {
            consoleWidth = Console.BufferWidth;
        }
        catch
        {
            // Not connected to a console, e.g. output is
            // redirected.
        }

        var monitor = _monitorFactory.CreateByteBasedMonitor();
        await monitor.MonitorAsync(
            progress,
            null,
            (message, count) =>
            {
                if (consoleWidth != 0)
                {
                    // Emit the progress information in such a
                    // way that we overwrite the previous info
                    // reported to the console.
                    Console.Write($"\r{message}".PadRight(consoleWidth));
                }
                else
                {
                    // Emit onto a new line every 5 seconds. This
                    // callback is invoked every 100ms.
                    if (count % 50 == 0)
                    {
                        Console.WriteLine(message);
                    }
                }
            },
            cts.Token);
    });

    // e.g. hash the stream.
    byte[] hashBytes;
    using (var hasher = SHA256.Create())
    {
        hashBytes = await hasher.ComputeHashAsync(stream);
    }

    // Stop monitoring.
    cts.Cancel();
    try
    {
        await monitorTask;
    }
    catch (OperationCanceledException) { }

    // Emit a newline after our progress message.
    if (consoleWidth != 0)
    {
        Console.WriteLine();
    }
}

Example for a HTTP download

If you're reporting progress on a HTTP stream, there's a few extra things to keep in mind:

• You need to pass HttpCompletionOption.ResponseHeadersRead as the completion option, or HttpClient will buffer the entire response by default.
• You need to wrap the stream you read from in PositionAwareStream, which is a class provided by this library. Since the underlying HTTP stream does not support Position or Length, this wrapping stream tracks the position as the stream is read from and allows the length to be passed in as a constructor parameter (which you should set based on the Content-Length header).

Below is a concise example of how to show the progress of downloading a file:

using (var client = new HttpClient())
{
    using (var target = new FileStream(targetPath, FileMode.Create, FileAccess.Write, FileShare.None))
    {
        var response = await client.GetAsync(downloadUrl, HttpCompletionOption.ResponseHeadersRead);
        using (var stream = new PositionAwareStream(
            await response.Content.ReadAsStreamAsync(),
            response.Content.Headers.ContentLength!.Value))
        {
            var cts = new CancellationTokenSource();
            var progress = _progressFactory.CreateProgressForStream(stream);
            var monitorTask = Task.Run(async () =>
            {
                var consoleWidth = 0;
                try
                {
                    consoleWidth = Console.BufferWidth;
                }
                catch { }

                var monitor = _monitorFactory.CreateByteBasedMonitor();
                await monitor.MonitorAsync(
                    progress,
                    null,
                    (message, count) =>
                    {
                        if (consoleWidth != 0)
                        {
                            Console.Write($"\r{message}".PadRight(consoleWidth));
                        }
                        else if (count % 50 == 0)
                        {
                            Console.WriteLine(message);
                        }
                    },
                    cts.Token);
            });

            await stream.CopyToAsync(target);

            cts.Cancel();
            try
            {
                await monitorTask;
            }
            catch (OperationCanceledException) { }
        }
    }
}