Re: [PATCHv4 07/10] pack-objects: Allow --max-pack-size to be used together with --stdout

From: Junio C Hamano <gitster@pobox.com>
Date: May 24, 2011, 00:09 UTC
Message-ID: <7vlixxrmbr.fsf@alter.siamese.dyndns.org>
In-Reply-To: <1306111923-16859-8-git-send-email-johan@herland.net>

Johan Herland <johan@herland.net> writes:

Show 8 quoted lines

> Currently we refuse combining --max-pack-size with --stdout since there's
> no way to make multiple packs when the pack is written to stdout. However,
> we want to be able to limit the maximum size of the pack created by
> --stdout (and abort pack-objects if we are unable to meet that limit).
>
> Therefore, when used together with --stdout, we reinterpret --max-pack-size
> to indicate the maximum pack size which - if exceeded - will cause
> pack-objects to abort with an error message.

I have to say that I am not very fond of this approach.

Imagine that in the future we may want to allow 32-bit receivers to say "I want you to transfer data but I cannot handle very large packs locally, so please send the packs in less-than-1GB chunks to make it easier for me to store them in separate packfiles" (obviously this involves a new protocol extension). The underlying machinery the sending side would use would naturally want to say

	git pack-objects --max-pack-size=1GB --stdout

and you would see the data for the first pack, followed by the data for the second pack, etc. on the standard output. Such a receiver might also want to say "You are not allowed to send more than 3GB at once to me" to the sending side. What should the "pack-objects" command line look like?

I think you should keep the two concepts separate. max-pack-size should stay the limit of each packfile "git pack-objects" is allowed to produce, and there should be another option to specify the total pack data to be produced, perhaps named --max-total-pack-size or something.

That would make your earlier "count" thing --max-total-commit-count; it is perfectly fine that we do not plan to have the --max-commit-count option that is per packfile.

Some people may kvetch about "inconsistency", but I think this is a justifiable inconsistency, as "You should refrain from putting more than this number of commits in a single pack" is a limit that does not have any practical use, while "You should refrain from sending more than this number of commits in total" does.