Improve update procedure

[JustArchi]

Checklist

• I read and understood ASF's Contributing guidelines
• I also read Setting-up and FAQ, I don't need help, this is an enhancement idea
• This is not a duplicate of an existing issue
• My idea doesn't duplicate existing ASF functionality described on the wiki
• I believe that my idea falls into ASF's scope and should be offered as part of ASF built-in functionality
• My idea doesn't violate the Steam Subscriber Agreement
• My idea doesn't violate the Steam Online Conduct
• This is not ASF-ui suggestion

Enhancement purpose

Current update procedure is vastly inefficient on top of being actually risky in terms of files corruption - we move everything out of the picture to _old directory, then we extract new files in current place. This is just horrible, we need to load whole archive into memory to even ensure it's possible, on top of the fact that if user kills the process during update, everything breaks.

Solution

Extract files to _new directory or similar. Kill it among _old during restart to keep it clean. If user kills process during extraction, no harm done, we'll try again next time. We still risk corruption during short window between moving current files to _old and _new to current, but this is much less likely considering it's mostly just metadata changes without moving data physically on the disk.

Why currently available solutions are not sufficient?

Current update procedure was written when Archi barely knew how to code, it works, but if you asked me if I'm proud of it, you wouldn't get the answer you expected.

Can you help us with this enhancement idea?

Yes, I can code the solution myself and send a pull request

Additional info

No response