How to throttle upload speed using progress handler

RateThrottleProgress.cs

/* 
 * RateThrottleProgress.cs
 * Copyright (C) 2018 Kefei Lu
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * 
 *
 *
 * Usage with Azure Storage SDK:
 * 
 *     await blob.UploadFromFileAsync(
 *         @"some_file.dat", 
 *         null, null, null, 
 *         new RateThrottleProgress(300 * 1024), // throttle at 300kb/s
 *         CancellationToken.None);
 *     See my StackOverflow answer here: https://stackoverflow.com/a/48922875/695964
*/

class RateThrottleProgress : IProgress<StorageProgress>
{
    private readonly DateTime start = DateTime.Now;
    private readonly long maxbps;
    private long baseDelay, delay;

    public RateThrottleProgress(long maxbps)
    {
        this.maxbps = maxbps;
        baseDelay = 10;
        delay = baseDelay;
    }

    public void Report(StorageProgress value)
    {
        double duration = (DateTime.Now - start).TotalSeconds;
        double bps = value.BytesTransferred / duration;
        if (bps > maxbps) delay *= 2;
        else delay = Math.Max(baseDelay, delay/2);
        Console.WriteLine($"current estimated upload speed: {bps / 1024.0} KB/s. delay: {delay} ms");
        Thread.Sleep(TimeSpan.FromMilliseconds(delay));
    }
}