public async Task <Errorable <IStreamedBlob> > PersistBlob(PersistingBlob blob)
{
SqlCommand insert, update;
insert = new SqlCommand(@"INSERT INTO [dbo].[Blob] ([blobid], [contents]) VALUES (@pk, @chunk)");
insert.Parameters.Add("@pk", System.Data.SqlDbType.Binary, 21);
insert.Parameters.Add("@chunk", System.Data.SqlDbType.Binary);
update = new SqlCommand(@"UPDATE [dbo].[Blob] SET [contents].WRITE(@chunk, NULL, NULL) WHERE [blobid] = @pk");
update.Parameters.Add("@pk", System.Data.SqlDbType.Binary, 21);
update.Parameters.Add("@chunk", System.Data.SqlDbType.Binary);
// Create a random dummy ID for uploading:
// FIXME: we need guaranteed uniqueness!
byte[] dummyID = new byte[21];
using (var rng = System.Security.Cryptography.RandomNumberGenerator.Create())
rng.GetBytes(dummyID);
dummyID[20] = 0xFF;
// Create a BlobWriter to INSERT and UPDATE to the database in chunks:
var bw = new BlobWriter(db, insert, update, dummyID);
// Create a SHA1 calculating wrapper around the input stream:
var sha1Reader = new SHA1StreamReader(blob.Stream);
// Asynchronously upload the blob:
await bw.UploadAsync(sha1Reader);
// Get the hash and use that as the BlobID:
byte[] blobHash = sha1Reader.GetHash();
// Now update the Blob record with the new BlobID:
await db.ExecuteNonQueryAsync(new BlobIDUpdate(dummyID, blobHash));
// Return the StreamedBlob instance that can read from the uploaded blob record:
return(new StreamedBlob(this, new BlobID(blobHash), bw.Length));
}
