Re: [RFD] making separate-remote layout easier to use

From: Junio C Hamano <junkio@cox.net>
Date: Nov 26, 2006, 05:11 UTC
Message-ID: <7vk61iyeq4.fsf@assigned-by-dhcp.cox.net>
In-Reply-To: <20061126042311.GB30001@spearce.org>

Shawn Pearce <spearce@spearce.org> writes:

Show 17 quoted lines

> So now we're at a point of:
>
>  * how do we get this branch information from the remote?
>  * how does the remote store this branch information?
>
> I'm leaning towards the repo config for the latter, with say:
>
> 	[branch "pu"]
> 		rewinds = true
> 		description = This branch contains some proposed updates to git.\n\
> 	It rewinds often, as different updates are proposed or merged into 'next'.
>
> but looking at that think its rather horrible looking.  :-)
>
> However for the former it may be useful if the client can download
> the repo config from the remote repository, such as to fetch
> the branch description data.

For the former, I was hoping that we could do a new action against remote repository that is "get remote information". Just like we have "ls-remote" as a protocol neutral front-end to get what git native protocol would give "peek-remote", git native protocol would have get-repository-info action to transfer this information, and http and dumb transports do a file download from a known file, just like they download files prepared with update-server-info. Most likely, that get-repository-info is just a glorified single file transfer and nothing more.

As an implementation detail, I think it is one possibility to store this information in the config of the repository being cloned from. We should be able to use repo-config to parse that file in config-like syntax to extract what we would want, so we do not have to come up with a new syntax nor a new parser, which is a big plus.

	Side note: repo-config, especially the updating side of
	it, is one of the programs I find the most brittle in
	the whole system, and it always makes me hesitate when
	somebody proposes to use config file in any important
	way read-write for this reason.  But this "reading out
	per-branch information from the file" is read-only so I
	would not worry too much about it.

Strictly speaking, however, the config file is a wrong place to store it. For one thing it has core.sharedrepository and receive.denynonfastforwards that are true configuration to control the behaviour of git _at_ _the_ _repository_ the configuration is at. The new "branch property" are primarily to help the other end, and the "filtering rewinding ones" we want at the clone/fetch side wants that information only and not interested in the true configuration information at that repository.

So my preference is:

 * store it in a fixed filename under $GIT_DIR/$something, in a
   format that is similar to the true config file.

 * Dumb transports would just do a file transfer, and we add a
   new command (like "upload-pack", "upload-archive") for git
   native transport to read that file.  We might want to have a
   protocol neutral wrapper (just like "ls-remote").

 * Cloners and fetchers would do the file transfer and use
   repo-config to read from that transferred file to find out
   which are rewinding branches.