How does receive-pack and pre-receive hook works ?

How does receive-pack and pre-receive hook works ?

[Mahesh Vaidya]

How does receive-pack and pre-receive hook works ?

I have added following in pre-recieve hook; all works fine. git
rev-list --pretty d6d147f432869037a7ac8bdca3a2d5bc0cdc1e9f
^a3fe19833480023b72350d6e56e939cbd0ba2c8b

I Would like know where does Git saves whatever I am pushing before
exit 0 of this hook; Specifically how does it understand about
'd6d147f432869037a7ac8bdca3a2d5bc0cdc1e9f' which is not part of
destination depot / repo.

Thx/ Mahesh.

Re: How does receive-pack and pre-receive hook works ?

[Shawn Pearce]

On Sat, Jun 26, 2010 at 7:24 PM, Mahesh Vaidya <forvaidya@gmail.com> wrote:
> How does receive-pack and pre-receive hook works ?
>
> I Would like know where does Git saves whatever I am pushing before
> exit 0 of this hook; Specifically how does it understand about
> 'd6d147f432869037a7ac8bdca3a2d5bc0cdc1e9f' which is not part of
> destination depot / repo.

The objects that were sent are actually added to the destination
repository, by creating one or more loose objects in the objects/
directory, or a single new pack file in the objects/pack/ directory if
more than 100 objects were sent.  These objects are in the repository,
but they aren't actually reachable from any ref, so they are subject
to garbage collection during a future `git gc`.  Once the objects are
safely stored, the hooks are invoked... which means the hooks can
access the objects, as they are already part of the repository.

If pre-receive or update exits with a non-zero status, the objects
stay around, but the references aren't updated.  By not updating the
references, the objects aren't reachable, and the objects will be
automatically removed during a future `git gc`.

-- 
Shawn.