[PATCH 1/2] Teach git-describe to display distances from tags.

[PATCH 1/2] Teach git-describe to display distances from tags.

[Shawn O. Pearce]

Junio C Hamano <junkio@cox.net>:
> However, I suspect that we could do better with Shawn's new
> fangled describe implementation that actually counts the
> distance between what is described and the tag.  We could add
> "number of commits since the tag" somewhere, to describe:
>
>   v2.6.20-rc5-256-g419dd83
>   v2.6.20-rc5-217-gde14569
>
> to say that the first one has 256 commits accumulated since the
> given tag "v2.6.20-rc5" and the second one has only 217
> commits, to get the sense of how busy the development activity
> is.
>
> Is it useful?  That is something I am not sure.

Yes, its very useful.  If you get two different describes at different
times from a non-rewinding branch and they both come up with the same
tag name, you can tell which is the 'newer' one by distance.  This is
rather common in practice, so its incredibly useful.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
---
 builtin-describe.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/builtin-describe.c b/builtin-describe.c
index e7b8f95..d8ff621 100644
--- a/builtin-describe.c
+++ b/builtin-describe.c
@@ -189,7 +189,8 @@ static void describe(const char *arg, int last_one)
 				sha1_to_hex(gave_up_on->object.sha1));
 		}
 	}
-	printf("%s-g%s\n", all_matches[0].name->path,
+	printf("%s-%i-g%s\n", all_matches[0].name->path,
+		   all_matches[0].depth,
 		   find_unique_abbrev(cmit->object.sha1, abbrev));
 
 	if (!last_one)
-- 
1.5.0.rc2.g18af

Re: [PATCH 1/2] Teach git-describe to display distances from tags.

[Junio C Hamano]

"Shawn O. Pearce" <spearce@spearce.org> writes:

> Yes, its very useful.  If you get two different describes at different
> times from a non-rewinding branch and they both come up with the same
> tag name, you can tell which is the 'newer' one by distance.  This is
> rather common in practice, so its incredibly useful.
>
> Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
> ---
>  builtin-describe.c |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/builtin-describe.c b/builtin-describe.c
> index e7b8f95..d8ff621 100644
> --- a/builtin-describe.c
> +++ b/builtin-describe.c
> @@ -189,7 +189,8 @@ static void describe(const char *arg, int last_one)
>  				sha1_to_hex(gave_up_on->object.sha1));
>  		}
>  	}
> -	printf("%s-g%s\n", all_matches[0].name->path,
> +	printf("%s-%i-g%s\n", all_matches[0].name->path,
> +		   all_matches[0].depth,
>  		   find_unique_abbrev(cmit->object.sha1, abbrev));
>  
>  	if (!last_one)

Two comments.

 - This is purely style, but we seem to prefer %d instead of %i
   elsewhere in the code (three existing offenders are
   builtin-describe.c, receive-pack.c and sha1_file which we may
   want to clean up for consistency).

 - How much damage are we talking about with this patch to
   People's existing scripts?  I expect they all extract the
   hash from last -g (because they cannot rely on particular
   convention in tagnames), but I am also worried if people are
   expecting everything that comes before the last -g is the
   whole tag.

Re: [PATCH 1/2] Teach git-describe to display distances from tags.

[Shawn O. Pearce]

Junio C Hamano <junkio@cox.net> wrote:
>  - This is purely style, but we seem to prefer %d instead of %i
>    elsewhere in the code (three existing offenders are
>    builtin-describe.c, receive-pack.c and sha1_file which we may
>    want to clean up for consistency).

I'll send a cleanup patch then for these locations.
 
>  - How much damage are we talking about with this patch to
>    People's existing scripts?  I expect they all extract the
>    hash from last -g (because they cannot rely on particular
>    convention in tagnames), but I am also worried if people are
>    expecting everything that comes before the last -g is the
>    whole tag.

No way to know for sure.  I almost put this as an option
(e.g. "--include-distance") but didn't want everyone to need to
update their existing git-describe callers to obtain this new data.
I would hope that people split on last -g to get at or remove the
commit SHA-1, but they probably are also assiming te tag name is
everything to the left.  Including the distance would certainly
violate that.

-- 
Shawn.

Re: [PATCH 1/2] Teach git-describe to display distances from tags.

[Junio C Hamano]

Junio C Hamano <junkio@cox.net> writes:

>> ---
>>  builtin-describe.c |    3 ++-
>>  1 files changed, 2 insertions(+), 1 deletions(-)
>>
>> diff --git a/builtin-describe.c b/builtin-describe.c
>> index e7b8f95..d8ff621 100644
>> --- a/builtin-describe.c
>> +++ b/builtin-describe.c
>> @@ -189,7 +189,8 @@ static void describe(const char *arg, int last_one)
>>  				sha1_to_hex(gave_up_on->object.sha1));
>>  		}
>>  	}
>> -	printf("%s-g%s\n", all_matches[0].name->path,
>> +	printf("%s-%i-g%s\n", all_matches[0].name->path,
>> +		   all_matches[0].depth,
>>  		   find_unique_abbrev(cmit->object.sha1, abbrev));
>>  
>>  	if (!last_one)
>
> Two comments.
>
>  - This is purely style, but we seem to prefer %d instead of %i
>    elsewhere in the code (three existing offenders are
>    builtin-describe.c, receive-pack.c and sha1_file which we may
>    want to clean up for consistency).
>
>  - How much damage are we talking about with this patch to
>    People's existing scripts?  I expect they all extract the
>    hash from last -g (because they cannot rely on particular
>    convention in tagnames), but I am also worried if people are
>    expecting everything that comes before the last -g is the
>    whole tag.

Actually there is a third one and a half.

  - We need to update the documentation to say what this new
    number means.

It's some number close to the number of revs since the named
tag, but not exactly.

    $ git describe --debug 65ebe634 2>&1 | head -4
    searching to describe 65ebe634
     annotated        251 v2.6.20-rc5
     annotated        427 v2.6.20-rc4
     annotated        594 v2.6.20-rc3
    $ git rev-list v2.6.20-rc5..65ebe634 | wc -l
    254
    $ git rev-list v2.6.20-rc4..65ebe634 | wc -l
    430

And it does not seem to be always "minus 3" either.

Re: [PATCH 1/2] Teach git-describe to display distances from tags.

[Shawn O. Pearce]

Junio C Hamano <junkio@cox.net> wrote:
>   - We need to update the documentation to say what this new
>     number means.

Indeed; I apologize for forgetting to do that.  At this point
I'll wind up resending the patch to address everything so toss
what you have.
 
> It's some number close to the number of revs since the named
> tag, but not exactly.
> 
>     $ git describe --debug 65ebe634 2>&1 | head -4
>     searching to describe 65ebe634
>      annotated        251 v2.6.20-rc5
>      annotated        427 v2.6.20-rc4
>      annotated        594 v2.6.20-rc3
>     $ git rev-list v2.6.20-rc5..65ebe634 | wc -l
>     254
>     $ git rev-list v2.6.20-rc4..65ebe634 | wc -l
>     430
> 
> And it does not seem to be always "minus 3" either.

What you skipped in the --debug output above was that we hit
our internal possible tag limit (10 by default) and aborted
walking the revision chain.  That's why we missed 3 revs in
our counting.  :)

We probably should make an option to enable the count, and
if the count is enabled then we'll have to pickup counting
where we left off and finish it out for the chosen tag so
the count is correct.

-- 
Shawn.

Re: [PATCH 1/2] Teach git-describe to display distances from tags.

[Nicolas Pitre]

On Thu, 25 Jan 2007, Shawn O. Pearce wrote:

> We probably should make an option to enable the count, and
> if the count is enabled then we'll have to pickup counting
> where we left off and finish it out for the chosen tag so
> the count is correct.
Please don't make it an option.  This is too useful to require an 
additional switch all the time.


Nicolas

Re: [PATCH 1/2] Teach git-describe to display distances from tags.

[Junio C Hamano]

Nicolas Pitre <nico@cam.org> writes:

> On Thu, 25 Jan 2007, Shawn O. Pearce wrote:
>
>> We probably should make an option to enable the count, and
>> if the count is enabled then we'll have to pickup counting
>> where we left off and finish it out for the chosen tag so
>> the count is correct.
>
> Please don't make it an option.  This is too useful to require an 
> additional switch all the time.

Hmph.  And an option --no-number to disable this is probably not
worth it, as it forces the existing scripts that wants the
tagname to be updated to pass that new option.  If the users
need to update their scripts anyway, they can sed/expr the
number out just as easily as passing the new option.

Another backward incompatibility to mention in the release
notes.  I guess it is not too big a deal but makes me feel
uneasy.

Re: [PATCH 1/2] Teach git-describe to display distances from tags.

[Francis Moreau]

On 1/26/07, Junio C Hamano <junkio@cox.net> wrote:
> Another backward incompatibility to mention in the release
> notes.  I guess it is not too big a deal but makes me feel
> uneasy.
>

Sorry if I missed any discussions about that point but why not calling
the coming release 2.0 instead of 1.5 if this one implies some
backward incompabilities and a lot of change in the UI ?

thanks
-- 
Francis

Re: [PATCH 1/2] Teach git-describe to display distances from tags.

[Junio C Hamano]

"Francis Moreau" <francis.moro@gmail.com> writes:

> On 1/26/07, Junio C Hamano <junkio@cox.net> wrote:
>> Another backward incompatibility to mention in the release
>> notes.  I guess it is not too big a deal but makes me feel
>> uneasy.
>>
>
> Sorry if I missed any discussions about that point but why not calling
> the coming release 2.0 instead of 1.5 if this one implies some
> backward incompabilities and a lot of change in the UI ?

Because with the usual numbering the next normal feature release
would have been called 1.4.5, we said we would bump to 1.5 some
time ago.

There is no fundamental change between 1.4.4 series and the
upcoming 1.5.0 -- only superficial ones.  I do not think it
deserves a bump in the major version; well, at least I did not
think it would, when we first started talking about "the new
release whose main theme was usability enhancements".

Re: [PATCH 1/2] Teach git-describe to display distances from tags.

[Francis Moreau]

On 1/26/07, Junio C Hamano <junkio@cox.net> wrote:
> There is no fundamental change between 1.4.4 series and the
> upcoming 1.5.0 -- only superficial ones.  I do not think it

But there are incompatibilities.

Another example, which may be a bad one since I unfortunately don't
have time to follow closely git's development: the internal of 'git
pull' has completely changed. If I clone a repo with git v1.4.x and I
pull in this repo with git v1.5.x, does it still works ?

thanks
-- 
Francis

Re: [PATCH 1/2] Teach git-describe to display distances from tags.

[Shawn O. Pearce]

Francis Moreau <francis.moro@gmail.com> wrote:
> But there are incompatibilities.

Nothing really *that* major.  Heck, that git-describe change is
probably one of the biggest, if not the biggest.
 
> Another example, which may be a bad one since I unfortunately don't
> have time to follow closely git's development: the internal of 'git
> pull' has completely changed. If I clone a repo with git v1.4.x and I
> pull in this repo with git v1.5.x, does it still works ?

Yes, of course.  Just like before too.

What's different is if you clone with 1.5.x, as we now default to the
seperate remotes layout.  This was an option in 1.4.x and earlier,
its now the only way its done in 1.5.x.

-- 
Shawn.

Re: [PATCH 1/2] Teach git-describe to display distances from tags.

[Andy Parkins]

On Friday 2007 January 26 00:13, Junio C Hamano wrote:

> Hmph.  And an option --no-number to disable this is probably not
> worth it, as it forces the existing scripts that wants the
> tagname to be updated to pass that new option.  If the users
> need to update their scripts anyway, they can sed/expr the
> number out just as easily as passing the new option.

Actually, the more useful switch would be "--tag-only"; then

x=$(git-describe HEAD | sed 's/-g*//')

In scripts could become

x=$(git-describe --tag-only HEAD)

Then, the suffix can be anything we want, and can change in the future without 
affecting these scripts.


Andy
-- 
Dr Andy Parkins, M Eng (hons), MIEE
andyparkins@gmail.com

Re: [PATCH 1/2] Teach git-describe to display distances from tags.

[Jakub Narebski]

[Cc: git@vger.kernel.org]

Shawn O. Pearce wrote:

> +       printf("%s-%i-g%s\n", all_matches[0].name->path,

I'd rather use "%s+%i-g%s\n" here...
-- 
Jakub Narebski
Warsaw, Poland
ShadeHawk on #git

[PATCH] If abbrev is set to zero in git-describe, don't add the unique suffix

[Andy Parkins]

When on a non-tag commit, git-describe normally outputs descriptions of
the form
  v1.0.0-g1234567890
Some scripts (for example the update hook script) might just want to
know the name of the nearest tag, so they then have to do
 x=$(git-describe HEAD | sed 's/-g*//')
This is costly, but more importantly is fragile as it is relying on the
output format of git-describe, which we would then have to maintain
forever.

This patch adds support for setting the --abbrev option to zero.  In
that case git-describe does as it always has, but outputs only the
nearest found tag instead of a completely unique name.  This means that
scripts would not have to parse the output format and won't need
changing if the git-describe suffix is ever changed.

Signed-off-by: Andy Parkins <andyparkins@gmail.com>
---
 builtin-describe.c |    9 ++++++---
 1 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/builtin-describe.c b/builtin-describe.c
index 4921eee..f3ac2d5 100644
--- a/builtin-describe.c
+++ b/builtin-describe.c
@@ -188,8 +188,11 @@ static void describe(const char *arg, int last_one)
 				sha1_to_hex(gave_up_on->object.sha1));
 		}
 	}
-	printf("%s-g%s\n", all_matches[0].name->path,
-		   find_unique_abbrev(cmit->object.sha1, abbrev));
+	if (abbrev == 0)
+		printf("%s\n", all_matches[0].name->path );
+	else
+		printf("%s-g%s\n", all_matches[0].name->path,
+			   find_unique_abbrev(cmit->object.sha1, abbrev));
 
 	if (!last_one)
 		clear_commit_marks(cmit, -1);
@@ -212,7 +215,7 @@ int cmd_describe(int argc, const char **argv, const char *prefix)
 			tags = 1;
 		else if (!strncmp(arg, "--abbrev=", 9)) {
 			abbrev = strtoul(arg + 9, NULL, 10);
-			if (abbrev < MINIMUM_ABBREV || 40 < abbrev)
+			if (abbrev != 0 && (abbrev < MINIMUM_ABBREV || 40 < abbrev))
 				abbrev = DEFAULT_ABBREV;
 		}
 		else if (!strncmp(arg, "--candidates=", 13)) {
-- 
1.5.0.rc2.gc3537-dirty

Re: [PATCH 1/2] Teach git-describe to display distances from tags.

[Matthias Lederhofer]

Jakub Narebski <jnareb@gmail.com> wrote:
> I'd rather use "%s+%i-g%s\n" here...
Ack, this makes it much easier to recognise what this number is.