Re: git peer-to-peer project: info needed

From: Luke Kenneth Casson Leighton <luke.leighton@gmail.com>
Date: Aug 29, 2010, 22:57 UTC
Message-ID: <AANLkTi=vcXX8n3NzGF51c=wPhgqushpwM4R7hR=O6QuU@mail.gmail.com>
In-Reply-To: <20100829220654.GH1890@burratino>

On Sun, Aug 29, 2010 at 11:06 PM, Jonathan Nieder <jrnieder@gmail.com> wrote:

Show 11 quoted lines

> Hi Luke,
>
> Luke Kenneth Casson Leighton wrote:
>
>> i need some guidance on what i should be doing, to add peer-to-peer
>> networking to "git fetch".  i can take care of the peer-to-peer
>> networking side: the bit i'm unsure about is what sequence of events
>> are required to happen.
>
> Not sure if this is the best answer or not, but you might enjoy
> looking at the git-remote-helpers(7) feature

       git-remote-helpers - Helper programs to interact with remote
       repositories

okaay, i see where you're going with that one.  thanks.

> and git-remote-testgit.py
> example.

 have to find that.

> Also, in case it is useful: the old scripted "git fetch" is available
> as contrib/examples/git-fetch.sh.

 ahh.  ah _ha_.  yes.  excellent.

 btw, gitpython interestingly has a 4-line method for working out the
list of commits required to be obtained in order for the local copy to
catch up:

        repo_refs = self.git.rev_list(ref, '--').strip().splitlines()
        other_repo_refs = other_repo.git.rev_list(other_ref,
'--').strip().splitlines()
        diff_refs = list(set(other_repo_refs) - set(repo_refs))
        return map(lambda ref: Commit.find_all(other_repo, ref,
max_count=1)[0], diff_refs)

it's going to be a leeetle more tricky than that, over a p2p network, unless i cheat, and place the other_repo's rev-list into a meta-file which is also distributed over the p2p network.... yuk to that, on the basis that long-living repos that's going to be a biiig file (would that actually be the case? what's the largest "git rev-list --all" that anyone's ever seen? yikes - on git itself it's 860k!) hmmm.. git rev {commit1}...{commit2} might give me what i need (and be equivalent to the above 4 python lines but it can be done by the remote end - that's still potentially a damn big amount of info. well, i'm sure i'll cope :)

i just want to get something working, damnit. there simply aren't enough free software client-server-paradigm-independent development tools around, and that's a situation that's causing me some concern.

l.