From: Jonathan Tan <jonathantanmy@google.com>
To: peff@peff.net
Cc: jonathantanmy@google.com, git@vger.kernel.org
Subject: Re: Git in Outreachy December 2019?
Date: Mon, 23 Sep 2019 13:38:54 -0700 [thread overview]
Message-ID: <20190923203854.171170-1-jonathantanmy@google.com> (raw)
In-Reply-To: <20190923191509.GC21344@sigill.intra.peff.net>
> I think this is an OK level of detail. I'm not sure quite sure about the
> goal of the project, though. In particular:
>
> - I'm not clear what we'd hope to gain. I.e., what richer information
> would we want to pass back and forth between index-pack and the
> other processes? It might also be more efficient, but I'm not sure
> it's measurably so (we save a single process, and we save some pipe
> traffic, but the sideband demuxer would probably end up passing it
> over a self-pipe anyway).
I didn't have any concrete ideas so I didn't include those, but some
unrefined ideas:
- index-pack has the CLI option to specify a message to be written into
the .promisor file, but in my patch to write fetched refs to
.promisor [1], I ended up making fetch-pack.c write the information
because I didn't know how many refs were going to be written (and I
didn't want to bump into CLI argument length limits). If we had this
feature, I might have been able to pass a callback to index-pack that
writes the list of refs once we have the fd into .promisor,
eliminating some code duplication (but I haven't verified this).
- In your reply [2] to the above [1], you mentioned the possibility of
keeping a list of cutoff points. One way of doing this, as I state in
[3], is my original suggestion back in 2017 of one such
repository-wide list. If we do this, it would be better for
fetch-pack to handle this instead of index-pack, and it seems more
efficient to me to have index-pack be able to pass objects to
fetch-pack as they are inflated instead of fetch-pack rereading the
compressed forms on disk (but again, I haven't verified this).
[1] https://public-inbox.org/git/20190826214737.164132-1-jonathantanmy@google.com/
[2] https://public-inbox.org/git/20190905070153.GE21450@sigill.intra.peff.net/
[3] https://public-inbox.org/git/20190905183926.137490-1-jonathantanmy@google.com/
There are also the debuggability improvements of not having to deal with
2 processes.
> - index-pack is prone to dying on bad input, and we wouldn't want it
> to take down the outer fetch-pack or receive-pack, which are what
> produce useful messages to the user. That's something that could be
> fixed as part of the libification, but I suspect the control flow
> might be a little tricky.
Good point.
> - we don't always call index-pack, but sometimes call unpack-objects.
> I suppose we could continue to call an external unpack-objects in
> that path, but that eliminates the utility of having richer
> communication if we sometimes have to take the "dumb" path. A while
> ago I took a stab at teaching index-pack to unpack. It works, but
> there are a few ugly bits, as discussed in:
>
> https://github.com/peff/git/commit/7df82454a855281e9c147f3023225f8a6f72e303
>
> Maybe that would be worth making part of the project?
I'm reluctant to do so because I don't want to increase the scope too
much - although if my project has relatively narrow scope for an
Outreachy project, we can do so. As for eliminating the utility of
having richer communication, I don't think so, because in the situations
where we require richer communication (right now, situations to do with
partial clone), we specifically run index-pack anyway.
next prev parent reply other threads:[~2019-09-23 20:39 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-27 5:17 Git in Outreachy December 2019? Jeff King
2019-08-31 7:58 ` Christian Couder
2019-08-31 19:44 ` Olga Telezhnaya
2019-09-04 19:41 ` Jeff King
2019-09-05 7:24 ` Christian Couder
2019-09-05 19:39 ` Emily Shaffer
2019-09-06 11:55 ` Carlo Arenas
2019-09-07 6:39 ` Jeff King
2019-09-07 10:13 ` Carlo Arenas
2019-09-07 6:36 ` Jeff King
2019-09-08 14:56 ` Pratyush Yadav
2019-09-09 17:00 ` Jeff King
2019-09-23 18:07 ` SZEDER Gábor
2019-09-26 9:47 ` SZEDER Gábor
2019-09-26 19:32 ` Johannes Schindelin
2019-09-26 21:54 ` SZEDER Gábor
2019-09-26 11:42 ` Johannes Schindelin
2019-09-13 20:03 ` Jonathan Tan
2019-09-13 20:51 ` Jeff King
2019-09-16 18:42 ` Emily Shaffer
2019-09-16 21:33 ` Eric Wong
2019-09-16 21:44 ` SZEDER Gábor
2019-09-16 23:13 ` Jonathan Nieder
2019-09-17 0:59 ` Jeff King
2019-09-17 11:23 ` Johannes Schindelin
2019-09-17 12:02 ` SZEDER Gábor
2019-09-23 12:47 ` Johannes Schindelin
2019-09-23 16:58 ` SZEDER Gábor
2019-09-26 11:04 ` Johannes Schindelin
2019-09-26 13:28 ` SZEDER Gábor
2019-09-26 19:39 ` Johannes Schindelin
2019-09-26 21:44 ` SZEDER Gábor
2019-09-27 22:18 ` Jeff King
2019-10-09 17:25 ` SZEDER Gábor
2019-10-11 6:34 ` Jeff King
2019-09-23 18:19 ` Jeff King
2019-09-24 14:30 ` Johannes Schindelin
2019-09-17 15:10 ` Christian Couder
2019-09-23 12:50 ` Johannes Schindelin
2019-09-23 19:30 ` Jeff King
2019-09-23 18:07 ` Jeff King
2019-09-24 14:25 ` Johannes Schindelin
2019-09-24 15:33 ` Jeff King
2019-09-28 3:56 ` Junio C Hamano
2019-09-24 0:55 ` Eric Wong
2019-09-26 12:45 ` Johannes Schindelin
2019-09-30 8:55 ` Eric Wong
2019-09-28 4:01 ` Junio C Hamano
2019-09-20 17:04 ` Jonathan Tan
2019-09-21 1:47 ` Emily Shaffer
2019-09-23 14:23 ` Christian Couder
2019-09-23 19:40 ` Jeff King
2019-09-23 22:29 ` Philip Oakley
2019-10-22 21:16 ` Emily Shaffer
2019-09-23 11:49 ` Christian Couder
2019-09-23 17:58 ` Jonathan Tan
2019-09-23 19:27 ` Jeff King
2019-09-23 20:48 ` Jonathan Tan
2019-09-23 19:15 ` Jeff King
2019-09-23 20:38 ` Jonathan Tan [this message]
2019-09-23 21:28 ` Jeff King
2019-09-24 17:07 ` Jonathan Tan
2019-09-26 7:09 ` Jeff King
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