private DownloadConnection SpawnConnection(StreamVolume stream)
{
var connection = new DownloadConnection(Request, new DownloadRange(stream.Range.Start), stream, 0);
connection.Completed += delegate(object sender, CompletedEventArgs args)
{
connection.Stream.Close();
OnProgressChanged();
};
connection.ProgressChanged += delegate(object sender, EventArgs args)
{
OnProgressChanged();
};
connection.ResponseReceived += delegate(object sender, ResponseReceivedEventArgs args)
{
if (args.Response.SupportsRange)
{
connection.Range = connection.Range.ShrinkLength(stream.Range.Length);
}
};
lock (_connections)
{
_connections.Add(connection);
}
return(connection);
}
public StreamVolume GetFreeVolume(long start, long maximumLength)
{
if (start >= TotalSize)
{
throw new ArgumentException("Start position is greater or equal to the total length.", nameof(start));
}
if (maximumLength == -1)
{
maximumLength = TotalSize - start;
}
var volumes = Volumes.ToList();
StreamVolume overlap;
do
{
overlap = volumes.FirstOrDefault(volume => volume.Range.Contains(start));
if (overlap != null)
{
start = overlap.Range.End + 1;
}
} while (overlap != null);
var end = Math.Min(start + maximumLength, TotalSize) - 1;
do
{
overlap = volumes.FirstOrDefault(volume => volume.Range.Contains(end));
if (overlap != null)
{
end = overlap.Range.Start - 1;
}
} while (overlap != null);
if (end >= start)
{
var volume = new StreamVolume(Stream, new StreamVolumeRange(start, end));
lock (_volumes)
{
_volumes.Add(volume);
}
return(volume);
}
return(null);
}
public async Task Start(CancellationToken token)
{
var partSize = 1024 * 1024 * 3;
var nConnections = 3;
var splitPartition = new StreamVolume(Partition.Stream, StreamVolumeRange.Empty);
var initialConnection = SpawnConnection(splitPartition);
var taskSource = new TaskCompletionSource <DownloadResponse>();
initialConnection.ResponseReceived += (sender, args) =>
{
if (OnResponseReceived(args.Response))
{
args.Abort = true;
taskSource.SetCanceled();
return;
}
if (args.Response.SupportsRange)
{
Partition.TotalSize = args.Response.FileSize;
Partition.Stream.SetLength(Partition.TotalSize);
var newRange = Partition.GetFreeVolume(0, partSize);
splitPartition.Range = newRange.Range;
initialConnection.Range = newRange.Range;
}
taskSource.SetResult(args.Response);
};
var initialTask = initialConnection.Start(token);
var response = await taskSource.Task;
if (!response.SupportsRange)
{
await Task.WhenAll(initialTask);
if (initialTask.IsCanceled)
{
// Canceled
}
return;
}
var connections = new List <Tuple <DownloadConnection, Task> >
{
new Tuple <DownloadConnection, Task>(initialConnection, initialTask)
};
StreamVolume range;
do
{
range = Partition.GetFreeVolume(0, partSize);
if (range != null)
{
while (connections.Count(t => t.Item1.Status == DownloadConnectionStatus.Downloading) >=
nConnections)
{
await
Task.WhenAny(
connections.Where(t => t.Item1.Status == DownloadConnectionStatus.Downloading)
.Select(t => t.Item2)
.ToArray());
}
var connection = SpawnConnection(range);
var task = connection.Start(token);
connections.Add(new Tuple <DownloadConnection, Task>(connection, task));
}
} while (!token.IsCancellationRequested && (range != null));
await Task.WhenAll(connections.Select(t => t.Item2).ToArray());
}