private EncryptionBuffer GetBufferAndAddToTxState(long pageNumber, CryptoTransactionState state, int size)
{
var ptr = _encryptionBuffersPool.Get(size, out var thread);
var buffer = new EncryptionBuffer
{
Size = size,
Pointer = ptr,
AllocatingThread = thread
};
state.LoadedBuffers[pageNumber] = buffer;
return(buffer);
}
private void ReturnBuffer(EncryptionBuffer buffer)
{
if (buffer.OriginalSize != null && buffer.OriginalSize != 0)
{
// First page of a separated section, returned with its original size.
_encryptionBuffersPool.Return(buffer.Pointer, (int)buffer.OriginalSize, buffer.AllocatingThread);
_encryptionBuffersPool.Return(buffer.Hash, EncryptionBuffer.HashSizeInt, buffer.AllocatingThread);
}
else
{
// Normal buffers
_encryptionBuffersPool.Return(buffer.Pointer, buffer.Size, buffer.AllocatingThread);
_encryptionBuffersPool.Return(buffer.Hash, EncryptionBuffer.HashSizeInt, buffer.AllocatingThread);
}
}
public override void BreakLargeAllocationToSeparatePages(IPagerLevelTransactionState tx, long pageNumber)
{
if (tx == null)
{
throw new NotSupportedException("Cannot use crypto pager without a transaction");
}
var state = GetTransactionState(tx);
if (state.LoadedBuffers.TryGetValue(pageNumber, out var encBuffer) == false)
{
throw new InvalidOperationException("Tried to break buffer that wasn't allocated in this tx");
}
for (int i = 1; i < encBuffer.Size / Constants.Storage.PageSize; i++)
{
var buffer = new EncryptionBuffer
{
Pointer = encBuffer.Pointer + i * Constants.Storage.PageSize,
Size = Constants.Storage.PageSize,
OriginalSize = 0,
};
buffer.Hash = _encryptionBuffersPool.Get(EncryptionBuffer.HashSizeInt, out var thread);
buffer.AllocatingThread = thread;
// here we _intentionally_ copy the old hash from the large page, so when we commit
// the tx, the pager will realize that we need to write this page
Memory.Copy(buffer.Hash, encBuffer.Hash, EncryptionBuffer.HashSizeInt);
state.LoadedBuffers[pageNumber + i] = buffer;
}
encBuffer.OriginalSize = encBuffer.Size;
encBuffer.Size = Constants.Storage.PageSize;
// here we _intentionally_ don't modify the hash of the page, even though its size was
// changed, because we need the pager to recognize that it was modified on tx commit
// encBuffer.Hash = remains the same
}