Re: [PATCH] logging branch deletion to help recovering from mistakes

From: Jonathan Nieder <jrnieder@gmail.com>
Date: Dec 7, 2010, 20:55 UTC
Message-ID: <20101207205526.GA25008@burratino>
In-Reply-To: <7vfwu9pbyj.fsf@alter.siamese.dyndns.org>

Junio C Hamano wrote:

> "git log -g HEAD"
> keeps track of what was at the tip of HEAD, be it pointing at a branch or
> pointing diretly at a commit in a detached state, no?

Yes.

1. Imagine I have an interesting branch and delete it:

	$ git branch interesting $(lots of hard work)
	$ git branch -D interesting

Oops. If I want to recover that branch, I may have a lot of digging to do in the HEAD reflog. It may not be there are all. Your patch mitigates that by allowing a simple "I didn't mean that" command.

	$ git branch --undelete interesting

2. Great.  Another way to lose a line of development, as Casey
mentioned, is to not give it a branch name in the first place:

	$ git checkout HEAD^0
	...
	$ git checkout something-else

Oops. Well, not so bad. If I want to recover my old work, I can simply use

	$ git checkout HEAD@{1}

3. Now suppose I was not paying attention and made the mistake
from (1) or (2) a week ago and didn't realize it.  Now I want to
get back that code.

If it was situation (1), I can remember the name of the branch and do

	$ git branch --undelete interesting

No problem [1]. If it was situation (2), I need to dig through the HEAD reflog. As Jeff explained, it is possible to script something up to help organize the search. I think Casey was suggesting doing that work at HEAD-reattachment time instead, so you could do

	$ git branch --undelete-detached-head=old-head

to recover the last line of development made without a branch; my response was that if this ends up frequently being useful then I suspect something is wrong with the workflow.

Hoping that is clearer, Jonathan

[1] as long as the branch name was not reused