private List <DownloadRange> DetermineToDoRanges(long fileSize, List <DownloadRange> alreadyDoneRanges)
{
var result = new List <DownloadRange>();
var initialRange = new DownloadRange(0, fileSize);
result.Add(initialRange);
if (alreadyDoneRanges != null && alreadyDoneRanges.Count > 0)
{
foreach (var range in alreadyDoneRanges)
{
var newResult = new List <DownloadRange>(result);
foreach (var resultRange in result)
{
if (this.downloadRangeHelper.RangesCollide(range, resultRange))
{
newResult.Remove(resultRange);
var difference = this.downloadRangeHelper.RangeDifference(resultRange, range);
newResult.AddRange(difference);
}
}
result = newResult;
}
}
return(result);
}
public List <DownloadRange> RangeDifference(DownloadRange fullRange, DownloadRange range)
{
var result = new List <DownloadRange>();
// no intersection
if (!RangesCollide(fullRange, range))
{
result.Add(fullRange);
return(result);
}
// fullRange is part of range --> difference is empty
if (fullRange.Start >= range.Start && fullRange.End <= range.End)
{
return(result);
}
if (fullRange.Start < range.Start)
{
result.Add(new DownloadRange(fullRange.Start, range.Start - fullRange.Start));
}
if (fullRange.End > range.End)
{
result.Add(new DownloadRange(range.End + 1, fullRange.End - range.End));
}
return(result);
}
public bool Equals(DownloadRange r)
{
if ((Object)r == null)
{
return(false);
}
return((this.Start == r.Start) && (this.Length == r.Length));
}
public override bool Equals(Object obj)
{
if (obj == null)
{
return(false);
}
DownloadRange r = obj as DownloadRange;
return(Equals(r));
}
private void StartDownload(DownloadRange range)
{
var download = this.downloadBuilder.Build(this.url, this.bufferSize, range.Start, range.Length);
download.DataReceived += downloadDataReceived;
download.DownloadCancelled += downloadCancelled;
download.DownloadCompleted += downloadCompleted;
download.Start();
lock (this.monitor)
{
this.downloads.Add(download, range);
}
}
private void downloadDataReceived(DownloadDataReceivedEventArgs args)
{
var offset = args.Offset;
var count = args.Count;
var data = args.Data;
lock (this.monitor)
{
var justDownloadedRange = new DownloadRange(offset, count);
var todoRange = this.ToDoRanges.Single(r => downloadRangeHelper.RangesCollide(r, justDownloadedRange));
this.ToDoRanges.Remove(todoRange);
var differences = downloadRangeHelper.RangeDifference(todoRange, justDownloadedRange);
this.ToDoRanges.AddRange(differences);
var alreadyDoneRange = this.AlreadyDownloadedRanges.FirstOrDefault(r => r.End + 1 == justDownloadedRange.Start);
if (alreadyDoneRange == null)
{
alreadyDoneRange = justDownloadedRange;
this.AlreadyDownloadedRanges.Add(alreadyDoneRange);
}
else
{
alreadyDoneRange.Length += justDownloadedRange.Length;
}
var neighborRange = this.AlreadyDownloadedRanges.FirstOrDefault(r => r.Start == alreadyDoneRange.End + 1);
if (neighborRange != null)
{
this.AlreadyDownloadedRanges.Remove(alreadyDoneRange);
this.AlreadyDownloadedRanges.Remove(neighborRange);
var combinedRange = new DownloadRange(alreadyDoneRange.Start, alreadyDoneRange.Length + neighborRange.Length);
this.AlreadyDownloadedRanges.Add(combinedRange);
}
}
this.OnDataReceived(new DownloadDataReceivedEventArgs(this, data, offset, count));
}
private void StartDownloadOfNextRange()
{
DownloadRange nextRange = null;
lock (this.monitor)
{
nextRange = this.ToDoRanges.FirstOrDefault(r => !this.downloads.Values.Any(r2 => downloadRangeHelper.RangesCollide(r, r2)));
}
if (nextRange != null)
{
StartDownload(nextRange);
}
if (!this.downloads.Any())
{
lock (this.monitor)
{
this.state = DownloadState.Finished;
}
this.OnDownloadCompleted(new DownloadEventArgs(this));
}
}
public bool RangesCollide(DownloadRange range1, DownloadRange range2)
{
return(range1.Start <= range2.End && range2.Start <= range1.End);
}
