Re: [PATCH] git clone depth of 0 not possible.

From: Matthijs Kooijman <matthijs@stdin.nl>
Date: May 28, 2013, 09:18 UTC
Message-ID: <20130528091812.GG25742@login.drsnuggles.stderr.nl>
In-Reply-To: <7vvcb8f6aw.fsf@alter.siamese.dyndns.org>

Hi Junio,

I'm interested in getting a fetch tip commit only feature into git, I'll probably look into creating a patch for this.

Show 22 quoted lines

> >>> Sounds buggy.  Would anything break if we were to make --depth=1 mean
> >>> "1 deep, including the tip commit"?
> >>
> >> As long as we do not change the meaning of the "shallow" count going
> >> over the wire (i.e. the number we receive from the user will be
> >> fudged, so that user's "depth 1" that used to mean "the tip and one
> >> behind it" is expressed as "depth 2" at the end-user level, and we
> >> send over the wire the number that corresponded to the old "depth
> >> 1"), I do not think anything will break, and then --depth=0 may
> >> magically start meaning "only the tip; its immediate parents will
> >> not be transferred and recorded as the shallow boundary in the
> >> receiving repository".
> >
> > I'd rather we reserve 0 for unlimited fetch, something we haven't done
> > so far [1]. And because "unlimited clone" with --depth does not make
> > sense, --depth=0 should be rejected by git-clone.
> 
> I actually was thinking about changing --depth=1 to mean "the tip,
> with zero commits behind it" (and that was consistent with my
> description of "fudging"), but ended up saying "--depth=0" by
> mistake.  I too think "--depth=0" or "--depth<0" does not make
> sense, so we are in agreement.

Did you consider how to implement this? Looking at the code, it seems
the "deepen" parameter in the wire protocol now means:
 - 0: Do not change anything about the shallowness (i.e., fetch
   everything from the shallow root to the tip).
 - > 0: Create new shallow commits at depth commits below the tip (so
   depth == 1 means tip and one below).
 - INFINITE_DEPTH (0x7fffffff): Remove all shallowness and fetch
   complete history.

Given this, I'm not sure how one can express "fetch the tip and nothing below that", since depth == 0 already has a different meaning.

Of course, one could using depth == 1 in this case to receive two commits and then drop one, but this would seem a bit pointless to me (especially if the commit below the tip is very different from the tip leading to a lot of useless data transfer).

Or did I misunderstand something here?

Gr.

Matthijs