Re: worktrees vs. alternates

From: Konstantin Ryabitsev <konstantin@linuxfoundation.org>
Date: May 16, 2018, 18:12 UTC
Message-ID: <a933cb3a-6c04-d963-aeda-b5850ca8994c@linuxfoundation.org>
In-Reply-To: <87h8n7bhro.fsf@evledraar.gmail.com>

On 05/16/18 14:02, Ævar Arnfjörð Bjarmason wrote:

Show 11 quoted lines

> 
> On Wed, May 16 2018, Konstantin Ryabitsev wrote:
> 
>> Maybe git-repack can be told to only borrow parent objects if they are
>> in packs. Anything not in packs should be hardlinked into the child
>> repo. That's my wishful think for the day. :)
> 
> Can you elaborate on how this would help?
> 
> We're just going to create loose objects on interactive "git commit",
> presumably you're not adding someone's working copy as the alternate.

The loose objects I'm thinking of are those that are generated when we do "git repack -Ad" -- this takes all unreachable objects and loosens them (see man git-repack for more info). Normally, these would be pruned after a certain period, but we're deliberately keeping them around forever just in case another repo relies on them via alternates. I want those repos to "claim" these loose objects via hardlinks, such that we can run git-prune on the mother repo instead of dragging all the unreachable objects on forever just in case.

> Otherwise if it's just being pushed to all those pushes are going to be
> in packs, and the packs may contain e.g. pushes for the "pu" branch or
> whatever, which are objects that'll go away.

There are lots of cases where unreachable objects in one repo would never become unreachable in another -- for example, if the author had stopped updating it.

Hope this helps.

Best,

-- 
Konstantin Ryabitsev
Director, IT Infrastructure Security
The Linux Foundation