/// <summary>
/// Reads a sub-range from the specified <paramref name="blob"/> into <see cref="_buffer"/>.
/// </summary>
/// <returns>
/// Total bytes read, may be smaller than requested, but only if there were
/// not enough bytes in the blob.
/// </returns>
private static async Task <int> ReadSubRangeAsync(
CloudAppendBlob blob,
byte[] buffer,
long start,
int bufferStart,
long maxBytes,
CancellationToken cancel)
{
while (true)
{
try
{
return(await blob.DownloadRangeToByteArrayAsync(
buffer,
bufferStart,
start,
maxBytes,
new AccessCondition(),
new BlobRequestOptions(),
new OperationContext(),
cancel));
}
catch (StorageException e) when(e.Message.StartsWith("Incorrect number of bytes received."))
{
// Due to a miscommunication between the Azure servers for Append Blob and the
// .NET client library, some responses are garbled due to a race condition out
// of our control. We retry straight away, as the problem is rarely present
// too many times in a row.
//
// See also: https://github.com/Azure/azure-storage-net/issues/366
}
}
}
public int Read(out byte[] buffer, int offset, int count)
{
var bytes = new byte[count];
var task = blob.DownloadRangeToByteArrayAsync(bytes, 0, offset, count);
buffer = bytes;
return(task.Result);
}
