Progress monitoring with GetRawFile()

[ningma97]

Hi, I am trying to use this nice client to download a large data file (>2GB) and would like to monitor the progress and download speed.

Is there any build-in API for doing so? Otherwise I guess I will need to read the stream returned by GetRawFile(), something like

using (var response = await client.GetRawFile("data.mp4"))
{
    using (fileStream = new FileStream("data.mp4", FileMode.Create, FileAccess.Write, FileShare.None, 8192, true))
    {
        var totalRead = 0L;
        var totalReads = 0L;
        var buffer = new byte[8192];
        var isMoreToRead = true;

        do
        {
            var read = await response.Stream.ReadAsync(buffer, 0, buffer.Length);
            if (read == 0)
            {
                isMoreToRead = false;
            }
            else
            {
                await fileStream.WriteAsync(buffer, 0, read);

                totalRead += read;
                totalReads += 1;

                if (totalReads % 2000 == 0)
                {
                    Console.WriteLine(string.Format("total bytes downloaded so far: {0:n0}", totalRead));
                }
            }
        }
        while (isMoreToRead);
    }
}

Your help is much appreciated.

[skazantsev]

Hi Ning Ma,

Unfortunately, there's no built-in API to monitor download progress and there's no plan to add it to the lib. You either need to read a stream yourself the way you proposed or pass your own instance of HttpClient with ProgressMessageHandler that supports reporting the progress (see https://github.com/dotnet/corefx/issues/6849). But I'm not sure if ProgressMessageHandler is a part of ASP.NET Core though.

Anyway, thank you for asking this question and posting a code snippet. This can be helpful to other users.

[ngbrown]

I submitted pull request #52 specifically to support progress monitoring. It also lowers memory consumption since the entire file isn't read into memory.

I separately use a wrapper stream that then reports to an IProgress<double> interface. See this gist for an example.

[skazantsev]

A version 2.5.0 with merged #52 is available in NuGet.