How to move a directory in C# .NET in a single atomic operation

Question

I need to be able to move an entire directory in a single atomic operation, guaranteeing that nothing else on the system will be able to subvert the operation by creating new files after I start, having a lock on a file, etc.

Presumably, I would use System.IO.Directory.Move() if the directories were on the same volume (if Directory.GetDirectoryRoot() is the same), otherwise I'd have to create a new target directory on the other volume and recursively copy/move all the directories and files underneath.

Nothing I've read shows how to gain an exclusive lock to an entire directory leaf in .NET so this can be done safely. Is there a recommended/supported way to do this?

Answer 1

I'd say what you really need is a transactional file system... which NTFS ain't, and while there have been MS plans for such, it was cut from Longhorn before it became Vista (and from Cairo before that).

You could try to gain exclusive locks on every file in the directory before the move, and do the moving with explicit file reading/writing, but recursively? I'm not so sure that's a good idea... and besides, that won't protect against new files being added.

What are you really trying to do? Why are you worried about concurrent activity?

Answer 2

Could you work around this by renaming the "root" directory temporarily (creating a directory with the same name immediately thereafter so that anyone accessing that directory doesn't encounter an error), then work on the files in the renamed directory?

Answer 3

Vista does support transactions in NTFS volumes:

http://msdn.microsoft.com/en-us/magazine/cc163388.aspx