Re: Git Notes idea.

["Govind Salinas" <govind@sophiasuchtig.com>]

On Wed, Dec 17, 2008 at 4:11 AM, Jeff King <peff@peff.net> wrote:
> On Wed, Dec 17, 2008 at 04:43:57AM +0100, Johannes Schindelin wrote:
>
>> > I agree, I haven't thought of any fix along these lines other than to
>> > make gc do the clean up.
>>
>> I have, and IIRC I briefly mentioned it back then.  Basically, you will
>> have to add a "git notes gc" or some such, which basically reads in the
>> whole notes, traverses all reachable commits, marking the corresponding
>> notes, and then writes out all marked notes (leaving the other notes
>> behind).
>
> I was thinking something similar, but I think it is even easier. Make
> the rule "if we still have the object, then we still have the note".
> That has three benefits:
>
>  - implementation is simple: for each note $n, delete it unless
>   has_sha1_file($n).
>
>  - it handles notes on non-commit objects
>
>  - it kills off notes when an object is _pruned_, not when it stops
>   being _reachable_. So if I delete a branch with a commit found
>   nowhere else, its notes will hang around until it is actually pruned.
>   If I pull it from lost+found, I still keep the notes.
>
> Note that all of this garbage collection of notes is really just
> removing them from the most current notes _tree_. If the notes structure
> is actually composed of commits, then old notes that are "deleted" will
> still be available historically.
>

This is my concern with keeping a history of the notes pseudo-branch. Let
us say that I do the following

1) on branch A commit a
2) add note a`
3) on branch B commit b
4) add note b`
5) on branch B commit c
6) add note c`
7) delete branch A
8) gc after a time such that a is pruned

Now either I will always have  anote a`