configuring cherry-pick to always use -x?

configuring cherry-pick to always use -x?

[Adam Monsen]

Is there a configuration option to make cherry-pick always include the
source commit hash in the new commit log message?

e.g., make "git cherry-pick" always behave like "git cherry-pick -x"?

My most frequent use case for cherry picking is between publicly visible
branches.

I have the following configuration option set:

  alias.cpx=cherry-pick -x

but I rarely remember to use it.

Re: configuring cherry-pick to always use -x?

[Jay Soffian]

On Mon, Feb 14, 2011 at 12:19 PM, Adam Monsen <haircut@gmail.com> wrote:
> Is there a configuration option to make cherry-pick always include the
> source commit hash in the new commit log message?
>
> e.g., make "git cherry-pick" always behave like "git cherry-pick -x"?

Nope, but one would be appreciated. :-)

> My most frequent use case for cherry picking is between publicly visible
> branches.
>
> I have the following configuration option set:
>
>  alias.cpx=cherry-pick -x
>
> but I rarely remember to use it.

It's worse than that. I like to keep the message generated after a
cherry-pick conflict, but the original commit authorship. I have this,
which I call recommit:

<snip>
#!/bin/sh
# Used after a cherry-pick conflicts to commit with the original
# authorship (commit -c) but keep the newly generated commit message
#
self=$(cd "$(dirname "$0")" && pwd -P)/$(basename "$0")
. "$(git --exec-path)/git-sh-setup"
require_work_tree
cd_to_toplevel
test -f .git/MERGE_MSG || die "No .git/MERGE_MSG"

if test "$GIT_EDITOR" = "$self"
then
  cat .git/MERGE_MSG > .GIT/COMMIT_EDITMSG
  exit 0
fi

if sha1=$(sed -ne \
  's/^(cherry picked from commit \([a-f0-9]\{40\}\))$/\1/p' .git/MERGE_MSG)
then
  export GIT_EDITOR="$self"
  git commit -c $sha1
fi
</snip>

I've had it on my TODO list for a while now to:

1. add a config option to enable -x by default

2. improve the cherry-pick conflict UX. I was thinking of out
CHERRY_HEAD on conflict and then adding a cherry-pick --continue
option which acts like rebase --continue. CHERRY_HEAD is what was
being picked at the time of conflict and can be used by the bash
completion script for proper prompting, as well as obviously the
--continue option.

j.

Re: configuring cherry-pick to always use -x?

[Junio C Hamano]

On Mon, Feb 14, 2011 at 9:19 AM, Adam Monsen <haircut@gmail.com> wrote:
> Is there a configuration option to make cherry-pick always include the
> source commit hash in the new commit log message?

Not currently, but before we go any further, could you please justify
in what workflow it would make sense to use -x most of the time?

We used to add the "cherry-picked from" by default in the very early
days, and stopped doing so for a reason, and also deliberately stayed
away from adding such a configuration to actively discourage the use
of -x without making the user thinking twice.

Re: configuring cherry-pick to always use -x?

[Junio C Hamano]

On Mon, Feb 14, 2011 at 10:09 AM, Jay Soffian <jaysoffian@gmail.com> wrote:
> I've had it on my TODO list for a while now to:
> ...
> 2. improve the cherry-pick conflict UX. I was thinking of out
> CHERRY_HEAD on conflict and then adding a cherry-pick --continue
> option which acts like rebase --continue. CHERRY_HEAD is what was
> being picked at the time of conflict and can be used by the bash
> completion script for proper prompting, as well as obviously the
> --continue option.

Yes, we have so far only "use commit -c $that_one", which is an
obvious and low hanging fruit for improvement.
Thanks.

Re: configuring cherry-pick to always use -x?

[Adam Monsen]

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Junio C Hamano wrote:
> could you please justify in what workflow it would make sense to use
> -x most of the time?

Sure. Summary: two long-lived publicly visible branches.

Details:
Mifos is what I'm usually working on lately. We have branches "master"
and "f-release" both present in our public git repository called "head"
(hosted at sf.net). master is the bleeding edge of development,
f-release is a release maintenance branch recently created off the tip
of master. I expect both to live on forever (even though commits to
f-release will eventually cease).

Right after f-release was cut, we merged f-release to master every day
or so to make sure bugfixes for f-release were also propagated to future
releases. After a while, merging resulted in too many conflicts and we
started cherry picking instead.

This process is described generally at
http://mifosforge.jira.com/wiki/display/MIFOS/Release+Branch+Merging+Policy
.

If the source commit is present in the log message of the new (cherry
picked) commit, it's easy to (1) find the source commit (gitweb creates
a hyperlink, for instance) and (2) know that, when viewing the log of
master, a particular commit is also present on another branch. Right now
I just keep reminding folks to use -x.

For (2), I generally assume that branch is a release branch, but come to
think of it, it would be nice to know what branch a commit was cherry
picked from. For example: "(cherry picked from BRANCHNAME commit
c6e08938e352f3ec99a29a67dd192945d2bcf00d)" would be better than the
current message generated by -x.

See also:
http://mifosforge.jira.com/wiki/display/MIFOS/Mifos+Version+Control+Guide


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Re: configuring cherry-pick to always use -x?

[Jay Soffian]

On Mon, Feb 14, 2011 at 4:05 PM, Junio C Hamano <gitster@pobox.com> wrote:
> Not currently, but before we go any further, could you please justify
> in what workflow it would make sense to use -x most of the time?

In one of my repos, most of the time my cherry-picks are between two
public branches. Perhaps a better enhancement would be something like:

  branch.<name>.annotate_cherry_pick = {true, false}

which could be set to true for source branches that you wish to
default to -x. Or, maybe it makes sense in cases where the source
branch is a remote-tracking branch:

   cherry_pick.annotate = {local, remote}

I'm not sure how good a remote-tracking branch is as an indicator of
'public branch', though, so I think explicitly configuring it
per-branch makes more sense. I hesitate there only because we don't
currently put remote-tracking branches in the branch section names.

j.

Re: configuring cherry-pick to always use -x?

[Michael J Gruber]

Adam Monsen venit, vidit, dixit 14.02.2011 22:50:
> Junio C Hamano wrote:
>> could you please justify in what workflow it would make sense to use
>> -x most of the time?
> 
> Sure. Summary: two long-lived publicly visible branches.
> 
> Details:
> Mifos is what I'm usually working on lately. We have branches "master"
> and "f-release" both present in our public git repository called "head"
> (hosted at sf.net). master is the bleeding edge of development,
> f-release is a release maintenance branch recently created off the tip
> of master. I expect both to live on forever (even though commits to
> f-release will eventually cease).
> 
> Right after f-release was cut, we merged f-release to master every day
> or so to make sure bugfixes for f-release were also propagated to future
> releases. After a while, merging resulted in too many conflicts and we
> started cherry picking instead.
> 
> This process is described generally at
> http://mifosforge.jira.com/wiki/display/MIFOS/Release+Branch+Merging+Policy

I don't quite understand how cherry picks could conflict less then
merges if the release branch contains fixes only. Also, I don't think
the advice to use "merge+revert" is a good one. All of this indicates a
suboptimal use of branches. My impression is that "f-release" actually
mixes release engineering and maintenance. Two possible remedies:

- Separate release engineering from maintenance and merge only the
latter to master

- If you do want them on the same branch "f-release", you probably know
beforehand which commits you don't want on master. You can fake-merge
these ("merge -Xours") to master and merge the others, which is somewhat
ugly but still better than cherry-picking everything. In some sense this
is "manual rerere" whose results are shared (pushed) easily.(*)

Michael

(*) If that is cryptic, I mean something like:

git checkout master
git merge f-release
#be happy if it succeeds, identify problematic commit X if not; decide
whether X belongs on master; if yes resolve, if not reset and:
git merge X^
git merge -Xours X
#back to start

Re: configuring cherry-pick to always use -x?

[Jonathan Nieder]

Michael J Gruber wrote:

> - If you do want them on the same branch "f-release", you probably know
> beforehand which commits you don't want on master. You can fake-merge
> these ("merge -Xours") to master and merge the others

For the record, I think that should be -sours.

I think it's just a typo but the difference is big --- -sours means
"supersede by pretending to merge but actually keeping our version",
while -Xours means "do a normal merge but be sloppy and favor our
change when encountering adjacent or overlapping changes".

I suppose -Xours should have been named -Xfavor-ours,
-Xsloppy-favoring-ours, or something similarly explicit.

> git checkout master
> git merge f-release
> #be happy if it succeeds, identify problematic commit X if not; decide
> whether X belongs on master; if yes resolve, if not reset and:
> git merge X^
> git merge -Xours X
> #back to start

Thanks for a nice example.
Jonathan

Re: configuring cherry-pick to always use -x?

[Michael J Gruber]

Jonathan Nieder venit, vidit, dixit 15.02.2011 10:18:
> Michael J Gruber wrote:
> 
>> - If you do want them on the same branch "f-release", you probably know
>> beforehand which commits you don't want on master. You can fake-merge
>> these ("merge -Xours") to master and merge the others
> 
> For the record, I think that should be -sours.
> 
> I think it's just a typo but the difference is big --- -sours means
> "supersede by pretending to merge but actually keeping our version",
> while -Xours means "do a normal merge but be sloppy and favor our
> change when encountering adjacent or overlapping changes".

Yes, sorry and thanks.

-Xours may still be useful to know for the OP, but for the complete
fake-merge you need -sours. In fact, "-sours" has an awfully good
mnemonic when used for fake-merging commits which you do not want to
cherry-pick :)

Michael

Re: configuring cherry-pick to always use -x?

[Ivan Kanis]

Hi Junio,

Junio C Hamano <gitster@pobox.com> wrote:

> On Mon, Feb 14, 2011 at 9:19 AM, Adam Monsen <haircut@gmail.com> wrote:
>> Is there a configuration option to make cherry-pick always include the
>> source commit hash in the new commit log message?
>
> Not currently, but before we go any further, could you please justify
> in what workflow it would make sense to use -x most of the time?
>
> We used to add the "cherry-picked from" by default in the very early
> days, and stopped doing so for a reason, and also deliberately stayed
> away from adding such a configuration to actively discourage the use
> of -x without making the user thinking twice.

Could you elaborate on the reason why -x is a bad idea?

Kind regards,
-- 
Ivan Kanis, Release Manager, Vision Objects,
Tel +33 2 28 01 84 44,  Fax +33 2 40 25 89 20
http://www.visionobjects.com

We meet no Stranger, but Ourself.
    -- Emily Dickinson 

Re: configuring cherry-pick to always use -x?

[Jay Soffian]

On Tue, Feb 15, 2011 at 3:58 AM, Michael J Gruber
<git@drmicha.warpmail.net> wrote:
> - If you do want them on the same branch "f-release", you probably know
> beforehand which commits you don't want on master. You can fake-merge
> these ("merge -Xours") to master and merge the others, which is somewhat
> ugly but still better than cherry-picking everything. In some sense this
> is "manual rerere" whose results are shared (pushed) easily.(*)

I personally prefer cherry-pick, as the fake merge clutters mainline's
history with the superseded commits.

It would be interesting to have a history simplification that given a
merge M of parents A and B, ignored commits $(merge-base A B)..B where
M is TREESAME to A. Hmm, that's effectively "git rev-list ." isn't it?

j.

release maintenance vs. release engineering (was: configuring cherry-pick to always use -x?)

[Adam Monsen]

Michael J Gruber wrote:
> I don't quite understand how cherry picks could conflict less then
> merges if the release branch contains fixes only.

The last time I experienced a painful merge from f-release to master, it
was because some files had been culled from master but left extant on
f-release. Not too hard to resolve, actually. But I really only needed
one change pulled into master, and when I cherry picked instead of
merging the whole branch, there were no conflicts, and master ended up
containing exactly what I wanted.

> My impression is that "f-release" actually
> mixes release engineering and maintenance. Two possible remedies:
> 
> - Separate release engineering from maintenance and merge only the
> latter to master

Ah, thank you! This is invaluable advice. I think I'll go with this
option since mixing release engineering and maintenance is exactly what
I'm doing. Hopefully it's worth the added complexity of having another
public branch.

I pushed an example to https://github.com/meonkeys/releaseBranchDemo
that I'll share with my developers.

"git merge -sours" will definitely be something useful to add to the
quiver too.