/// <summary>
/// Safely receive the header.
/// </summary>
/// <param name="blob">blob</param>
/// <param name="headerDefinition">header definition</param>
/// <param name="exception">exception that occured</param>
/// <returns>the header, otherwise null if it could not be fetched</returns>
private StreamBlobHeader SafeGetHeader(WrappedPageBlob blob, HeaderDefinitionMetadata headerDefinition, out Exception exception)
{
StreamBlobHeader header = null;
exception = null;
try
{
if (headerDefinition == null || headerDefinition.HeaderSizeInBytes == 0)
{
throw new InvalidHeaderDataException(
$"Attempted to download a header, but the size specified is zero. This aggregate with id [{blob.Name}] may be corrupt.");
}
var downloadedData = blob.DownloadBytes(headerDefinition.HeaderStartLocationOffsetBytes,
headerDefinition.HeaderStartLocationOffsetBytes + headerDefinition.HeaderSizeInBytes);
using (var ms = new MemoryStream(downloadedData, false))
{
header = _serializer.Deserialize <StreamBlobHeader>(ms.ToArray());
}
}
catch (Exception ex)
{
exception = ex;
}
return(header);
}
/// <summary>
/// Creates a commit from the provided definition
/// </summary>
/// <param name="streamId"></param>
/// <param name="commitDefinition"></param>
/// <returns></returns>
private ICommit CreateCommitFromDefinition(WrappedPageBlob blob, PageBlobCommitDefinition commitDefinition)
{
var startIndex = commitDefinition.StartPage * BlobPageSize;
var endIndex = startIndex + commitDefinition.DataSizeBytes;
var downloadedData = blob.DownloadBytes(startIndex, endIndex, true);
using (var ms = new MemoryStream(downloadedData, false))
{
AzureBlobCommit azureBlobCommit;
try
{
azureBlobCommit = _serializer.Deserialize <AzureBlobCommit>(ms);
}
catch (Exception ex)
{
var message = $"Blob with uri [{((CloudPageBlob) blob).Uri}] is corrupt.";
Logger.Fatal(message);
throw new InvalidDataException(message, ex);
}
return(CreateCommitFromAzureBlobCommit(azureBlobCommit));
}
}
