private static BlobIdentifier ComputeIdentifierBasedOnBlocks(IEnumerable <BlobBlockHash> blocks)
{
var rollingId = new VsoHash.RollingBlobIdentifier();
// ReSharper disable once GenericEnumeratorNotDisposed
IEnumerator <BlobBlockHash> enumerator = blocks.GetEnumerator();
bool isLast = !enumerator.MoveNext();
if (isLast)
{
throw new InvalidDataException("Blob must have at least one block.");
}
BlobBlockHash current = enumerator.Current;
isLast = !enumerator.MoveNext();
while (!isLast)
{
rollingId.Update(current);
current = enumerator.Current;
isLast = !enumerator.MoveNext();
}
return(rollingId.Finalize(current));
}
private byte[]? TryHashAllBytesWithNoCopy(ReadOnlySpan <byte> source)
{
int startIndex = 0;
byte[]? finalizedBytes = null;
// If we know the size of the input upfront, we can hash all the data
// without copying them into a temporary buffer.
if (source.Length == _expectedInputLength && _currentOffset == 0)
{
// The span still maybe bigger than 2Mb buffer the hash algorithm uses to compute hash blocks.
// Need to split the input source into the 2Mb pieces.
int remaining = source.Length;
int blockSize = GlobalObjectPools.TwoMbByteArrayPool.ArraySize;
while (remaining > 0)
{
int bytesToCopy = Math.Min(blockSize, source.Length - startIndex);
var currentBatch = source.Slice(startIndex, bytesToCopy);
startIndex += bytesToCopy;
remaining -= bytesToCopy;
var blockHash = HashBlock(currentBatch);
if (remaining == 0)
{
// Finalizing the hash. We're done.
finalizedBytes = _rollingId.Finalize(blockHash).Bytes;
}
else
{
// Not done yet.
_rollingId.Update(blockHash);
}
}
}
return(finalizedBytes);
}
/// <inheritdoc />
protected override void HashCore(byte[] array, int ibStart, int cbSize)
{
Contract.AssertDebug(_buffer != null);
while (cbSize > 0)
{
if (_currentOffset == _buffer.Length)
{
var blockHash = HashBlock(_buffer, _buffer.Length);
_rollingId.Update(blockHash);
_currentOffset = 0;
}
int bytesToCopy = Math.Min(cbSize, _buffer.Length - _currentOffset);
Buffer.BlockCopy(array, ibStart, _buffer, _currentOffset, bytesToCopy);
_currentOffset += bytesToCopy;
ibStart += bytesToCopy;
cbSize -= bytesToCopy;
}
}
/// <inheritdoc />
protected override byte[] HashFinal()
{
var rollingId = new VsoHash.RollingBlobIdentifier();
// Flush out buffer
if (_currentOffset != 0)
{
_blockHashes.Add(VsoHash.HashBlock(_buffer, _currentOffset));
}
// if there are no blocks add an empty block
if (_blockHashes.Count == 0)
{
_blockHashes.Add(VsoHash.HashBlock(new byte[] { }, 0));
}
for (int i = 0; i < _blockHashes.Count - 1; i++)
{
rollingId.Update(_blockHashes[i]);
}
return(rollingId.Finalize(_blockHashes[_blockHashes.Count - 1]).Bytes);
}
