/// <summary>
/// Transfer data from the source stream to the destination stream. This method also performs the necessary
/// data transforms (throttling, hashing, encrypting, etc) as the data is streamed. This allows a the
/// source stream to only be read a single time while performing multiple operations on the data.
/// </summary>
/// <param name="sourceStream">The stream that the data is read from</param>
/// <param name="destinationStream">The stream that the data is written to</param>
/// <returns>(async) The result of the transfer</returns>
private async Task <TransferResult> TransferDataWithTransformsAsync(
Stream sourceStream,
Stream destinationStream)
{
SHA1Cng sha1 = null;
MD5Cng md5 = null;
try
{
// By default, we will compute the SHA1 and MD5 hashes of the file as it is streamed.
sha1 = new SHA1Cng();
md5 = new MD5Cng();
// Allocate the buffer that will be used to transfer the data. The source stream will be read one
// suffer-size as a time, then written to the destination.
byte[] buffer = new byte[TransferBufferSize];
long readTotal = 0;
long writtenTotal = 0;
while (true)
{
// If we are using a throttling manager, get the necessary number of tokens to
// transfer the data
if (this.throttlingManager != null)
{
int tokens = 0;
while (true)
{
// Get the number of tokens needed. We will require tokens equaling the number of
// bytes to be transferred. This is a non-blocking calling and will return between
// 0 and the number of requested tokens.
tokens += this.throttlingManager.GetTokens(TransferBufferSize - tokens);
if (tokens >= TransferBufferSize)
{
// We have enough tokens to transfer the buffer
break;
}
// We don't (yet) have enough tokens, so wait for a short duration and try again
await Task.Delay(10, this.cancellationToken).ConfigureAwait(false);
}
}
// Read data from the source adapter
int read = sourceStream.Read(buffer, 0, buffer.Length);
CounterManager.LogSyncJobCounter(
"SyncJob/BytesRead",
read);
// Increment the total number of bytes read from the source adapter
readTotal += read;
int bytesWritten;
if (read < buffer.Length)
{
// Compute the last part of the SHA1 and MD5 hashes (this finished the algorithm's work).
sha1.TransformFinalBlock(buffer, 0, read);
md5.TransformFinalBlock(buffer, 0, read);
if (this.encryptionManager != null)
{
bytesWritten = this.encryptionManager.TransformFinalBlock(buffer, 0, read);
}
else
{
destinationStream.Write(buffer, 0, read);
destinationStream.Flush();
bytesWritten = buffer.Length;
}
CounterManager.LogSyncJobCounter(
"SyncJob/BytesWritten",
read);
writtenTotal += bytesWritten;
// Increment the total number of bytes written to the desination adapter
this.bytesCompleted += read;
this.progressChanged(new CopyProgressInfo(this.bytesCompleted, this.updateInfo));
// Read the end of the stream
break;
}
// Pass the data through the required hashing algorithms.
sha1.TransformBlock(buffer, 0, read, buffer, 0);
md5.TransformBlock(buffer, 0, read, buffer, 0);
// Write the data to the destination adapter
if (this.encryptionManager != null)
{
bytesWritten = this.encryptionManager.TransformBlock(buffer, 0, read);
}
else
{
destinationStream.Write(buffer, 0, read);
bytesWritten = buffer.Length;
}
CounterManager.LogSyncJobCounter(
"SyncJob/BytesWritten",
read);
writtenTotal += bytesWritten;
// Increment the total number of bytes written to the desination adapter
this.bytesCompleted += read;
if (this.syncProgressUpdateStopwatch.ElapsedMilliseconds > 100)
{
this.progressChanged(new CopyProgressInfo(this.bytesCompleted, this.updateInfo));
// After reporting the number of bytes copied for this file, set back to 0 so that we are only
// reporting the number of bytes sync we last invoked the callback.
this.bytesCompleted = 0;
this.syncProgressUpdateStopwatch.Restart();
}
}
TransferResult result = new TransferResult
{
BytesRead = readTotal,
BytesWritten = writtenTotal
};
if (this.encryptionManager != null)
{
if (this.encryptionManager.Mode == EncryptionMode.Encrypt)
{
result.Sha1Hash = sha1.Hash;
result.Md5Hash = md5.Hash;
result.TransformedSha1Hash = this.encryptionManager.Sha1Hash;
result.TransformedMd5Hash = this.encryptionManager.Md5Hash;
}
else
{
result.TransformedSha1Hash = sha1.Hash;
result.TransformedMd5Hash = md5.Hash;
result.Sha1Hash = this.encryptionManager.Sha1Hash; // The SHA1 hash of the data written by the encryption manager
result.Md5Hash = this.encryptionManager.Md5Hash;
}
}
else
{
result.Sha1Hash = sha1.Hash;
result.Md5Hash = md5.Hash;
}
return(result);
}
finally
{
sha1?.Dispose();
md5?.Dispose();
}
}