/// <summary>
/// Main entry point
/// </summary>
/// <param name="args">Arguments to be passed to the application</param>
public static void Main(string[] args)
{
try
{
Downloader.ProgressUpdateEvent += Print;
string retry;
do
{
Print("How many parallel downloads do you want to execute?");
int numOfParallelDownloads = int.Parse(Console.ReadLine());
DownloadResult result = Downloader.Download(ConfigurationManager.AppSettings["fileUrl"], ConfigurationManager.AppSettings["downloadLocation"], numOfParallelDownloads);
Print($"Download Summary:\n FileSize: {DisplayFormatHelper.FormatSize(result.Size)}\n Number of chunks: {numOfParallelDownloads}" +
$"\n Chunk size: {DisplayFormatHelper.FormatSize(result.ChunkSize)}\n Time taken : {DisplayFormatHelper.TimeSpanDisplayFormat(result.TimeTaken)} \n Downloaded File: {result.FilePath}");
Print("Try again? (Y/N)");
retry = Console.ReadLine();
}while (!string.IsNullOrWhiteSpace(retry) && retry.ToLower() == "y");
}
catch (FriendlyException ex)
{
Console.WriteLine(ex.Message);
}
Console.Read();
}
private static void UpdateProgress(long chunkSize, TimeSpan chunkTime, TimeSpan totalTime, long total, int parallelDownloads)
{
if (ProgressUpdateEvent == null)
{
return;
}
StringBuilder sb = new StringBuilder();
//Given the size of the chunk just downloaded and the chunks remaining, calculate the time remaining for the download to complete.
sb.Append($"{downloadedChunks * 100 / total}% - Speed {DisplayFormatHelper.FormatSize((long)(chunkSize / chunkTime.TotalSeconds))}ps");
if (total > downloadedChunks)
{
//Assuming all the downloads start at relatively the same time ((total - downloadedChunks) * chunkTime.Ticks) - chunkTime.Ticks))
sb.Append($" - Estimated time remaining {DisplayFormatHelper.TimeSpanDisplayFormat((long)((total - downloadedChunks) * chunkTime.Ticks) - chunkTime.Ticks)}");
}
ProgressUpdateEvent(sb.ToString());
}
public static DownloadResult Download(string fileUrl, string destinationFolderPath, int numberOfParallelDownloads)
{
downloadedChunks = 0;
Uri uri = new Uri(fileUrl);
//Input validation
if (!Directory.Exists(destinationFolderPath))
{
throw new FriendlyException($"Invalid value for destinationFolderPath. Directory {destinationFolderPath} does not exist.");
}
if (numberOfParallelDownloads <= 0)
{
throw new FriendlyException("Invalid value for numberOfParallelDownloads. Please enter a value greater than zero.");
}
//Calculate destination path
String destinationFilePath = Path.Combine(destinationFolderPath, uri.Segments.Last());
DownloadResult result = new DownloadResult()
{
FilePath = destinationFilePath
};
#region Get file size
WebRequest webRequest = HttpWebRequest.Create(fileUrl);
webRequest.Method = "HEAD";
long responseLength;
using (WebResponse webResponse = webRequest.GetResponse())
{
if (!webResponse.Headers.AllKeys.Contains("Content-Length"))
{
throw new FriendlyException("Unable to download file. Content-Length not present.");
}
responseLength = long.Parse(webResponse.Headers.Get("Content-Length"));
result.Size = responseLength;
}
#endregion
UpdateProgress($"File Size:{responseLength} bytes");
if (File.Exists(destinationFilePath))
{
File.Delete(destinationFilePath);
}
if (responseLength < numberOfParallelDownloads)
{
throw new FriendlyException($"The file is too small to be divided into chunks to have {numberOfParallelDownloads} parallel downloads. Please select a value less than {numberOfParallelDownloads}.");
}
UpdateProgress("Dividing in to chunks...");
ConcurrentDictionary <long, string> tempFilesDictionary = new ConcurrentDictionary <long, string>();
#region Calculate ranges
List <DataRange> readRanges = new List <DataRange>();
for (int chunk = 0; chunk < numberOfParallelDownloads - 1; chunk++)
{
DataRange range = new DataRange()
{
Start = chunk * (responseLength / numberOfParallelDownloads),
End = ((chunk + 1) * (responseLength / numberOfParallelDownloads)) - 1
};
readRanges.Add(range);
}
readRanges.Add(new DataRange()
{
Start = readRanges.Any() ? readRanges.Last().End + 1 : 0,
End = responseLength - 1
});
result.ChunkSize = readRanges[0].End - readRanges[0].Start;
#endregion
UpdateProgress($"Divided into {numberOfParallelDownloads} chunks of {readRanges[0].End - readRanges[0].Start} bytes each.");
DateTime startTime = DateTime.Now;
#region Parallel download
long total = readRanges.Count();
UpdateProgress("Starting downloads...");
Parallel.ForEach(readRanges, new ParallelOptions()
{
MaxDegreeOfParallelism = numberOfParallelDownloads
}, readRange =>
{
DateTime chunkStart = DateTime.Now;
HttpWebRequest httpWebRequest = HttpWebRequest.Create(fileUrl) as HttpWebRequest;
httpWebRequest.Method = "GET";
httpWebRequest.AddRange(readRange.Start, readRange.End);
using (HttpWebResponse httpWebResponse = httpWebRequest.GetResponse() as HttpWebResponse)
{
String tempFilePath = Path.GetTempFileName();
using (FileStream fileStream = new FileStream(tempFilePath, FileMode.Create, FileAccess.Write, FileShare.Write))
{
httpWebResponse.GetResponseStream().CopyTo(fileStream);
tempFilesDictionary.TryAdd(readRange.Start, tempFilePath);
}
}
downloadedChunks++;
UpdateProgress(readRange.End - readRange.Start, DateTime.Now - chunkStart, DateTime.Now - startTime, total, numberOfParallelDownloads);
});
#endregion
result.TimeTaken = DateTime.Now.Subtract(startTime);
UpdateProgress($"Total time for downloading : {DisplayFormatHelper.TimeSpanDisplayFormat(result.TimeTaken)}");
UpdateProgress("Merging chunks..");
#region Merge to single file
using (FileStream destinationStream = new FileStream(destinationFilePath, FileMode.Append))
{
foreach (KeyValuePair <long, string> tempFile in tempFilesDictionary.OrderBy(b => b.Key))
{
byte[] tempFileBytes = File.ReadAllBytes(tempFile.Value);
destinationStream.Write(tempFileBytes, 0, tempFileBytes.Length);
File.Delete(tempFile.Value);
}
#endregion
}
result.TimeTaken = DateTime.Now.Subtract(startTime);
UpdateProgress("Process complete!");
return(result);
}
