/// <summary>
/// Wraps the downloadToStream logic to retry/recover the download operation
/// in the case that the last time the input stream has been written to exceeds a threshold.
/// </summary>
/// <param name="stream"></param>
/// <param name="blobOffset"></param>
/// <param name="length"></param>
/// <param name="accessCondition"></param>
/// <param name="options"></param>
/// <param name="operationContext"></param>
/// <param name="cancellationToken"></param>
/// <returns></returns>
private async Task downloadToStreamWrapper(UnmanagedMemoryStream stream, long blobOffset, long length, AccessCondition accessCondition, BlobRequestOptions options, OperationContext operationContext, CancellationToken cancellationToken)
{
long startingOffset = blobOffset;
LargeDownloadStream largeDownloadStream = null;
while (true)
{
try
{
largeDownloadStream = new LargeDownloadStream(stream, blobOffset);
CancellationTokenSource cts = CancellationTokenSource.CreateLinkedTokenSource(largeDownloadStream.CancellationToken, cancellationToken);
Task downloadTask = this.LargeDownloadToFileSettings.Blob.DownloadRangeToStreamAsync(largeDownloadStream, blobOffset, length, this.accessConditions, this.blobRequestOptions, this.operationContext, cts.Token);
await downloadTask;
largeDownloadStream.Close();
break;
}
catch (OperationCanceledException)
// only catch if the stream triggered the cancellation
when(!cancellationToken.IsCancellationRequested)
{
blobOffset = startingOffset + largeDownloadStream.Position;
largeDownloadStream.Close();
length -= (blobOffset - startingOffset);
Console.WriteLine($"cancellation for offset:{startingOffset}, now at position:{blobOffset}. With remaining length:{length}");
if (length == 0)
{
break;
}
}
}
stream.Dispose();
}
public LargeDownloadRange(Task downloadTask, LargeDownloadStream largeDownloadStream, long blobOffSet, long rangeLength)
{
this.DownloadTask = downloadTask;
this.LargeDownloadStream = largeDownloadStream;
this.BlobOffset = blobOffSet;
this.RangeLength = rangeLength;
}