From: Geert Bosch <bosch@adacore.com>
Date: Wed, 28 Nov 2007 04:07:29 GMT
Subject: Re: Rollback of git commands
Message-ID: <3AAC5548-A9AC-4236-B1F7-5CFDE11B52C4@adacore.com>
In-Reply-To: <9e4733910711271749q1b96bfe9i60e43619c89234b9@mail.gmail.com>

On Nov 27, 2007, at 20:49, Jon Smirl wrote:
> Rollback is too strong of name for this. Checkpoints would be better.
> The idea is to record the total system state at convenient moments and
> then allow moving back to the checkpointed state. The object store
> supports this, but the rest of the state in .git/* isn't being
> recorded.

I have always wondered why refs and tags are not
in the regular object store. In a way, there
should be just one root pointer (SHA1) pointing
to a tree with refs, etc.

As for the problem of "lots of loose objects", each
command could write a single pack file. By directly
writing deltas instead of complete new tree objects,
storage requirements should be modest. Also, just
writing a single new pack file is very efficient
for I/O purposes.

To prevent too many pack files, a merge policy
could allow a new pack to include (and thus obsolete)
a number of similarly sized or smaller packs.
After the new file has been successfully written, the
old files are no longer necessary and can be
moved to a "trashes" area to be expired.

   -Geert