How implement Rollback feature ?

Question

I want to create a C# application in which copy some files in two diffrent folders(already contains older version files) and also run sql scripts. During whole process if any exception generate i need to rollback all the changes.

For sql scripts, transation can be used but how implement files copying process with rollback?

Answer 1

Would it fit your use case to copy the files to a temporary directory and then move the whole directory into place? If so, rollback is as simple as deleting the temporary directory.

Answer 2

You can make a copy from the old file before replacing it, and then if an exception happened restore from this copy.

Answer 3

You can take advantage of Transactional NTFS if possible. If not, then you can keep a list of the operations you did and do the reverse of it when a rollback is needed.

Answer 4

Or you can evolve as a software developer and use the Command Pattern and implement a BatchCommand. Commands make it very easy to add undo functionality and encapsulate it in an intelligent way. A BatchCommand can then call undo() on each Command within its list.

For a good primer to patterns, check out Head First Design Patterns

Answer 5

I would copy the new files appending a suffix and a random number, thus avoiding to clash with preexisting file names.

Sample... Old file="myfile.txt", New file="myfile.txt.new.285387".

Then, when the copy process is finished ok, I would... -Rename the old file as "myfile.txt.old.3464353". -Rename the new file as "myfile.txt" -Finally the old will be erased.