workflow question

workflow question

[Patrick Doyle]

I'm still trying to figure out how to adapt my workflow to git or git
to my workflow, and I've come up with yet another question or two...

I tend to work detached from our central SVN server, and I'm attracted
to the fact that I can work on my laptop, commit changes as I go
along, and later synchronize them back to the server.

On my current project, I am sole developer (at present) and the
central SVN server serves primarly as an off-site backup and
historical archive.

Enough of the setup, here are the questions...

1) I would like to make a (git) branch on which I can commit
hourly/daily/periodically as I add in a new feature (so that I can
roll back to the "Gee, I thought it was behaving yesterday -- what
does that code look like?" commit when I need to), but I don't want to
send all of the "commit as of 12:32 on Thursday" commits back to the
SVN server when I'm done.  Do I want to use a "squash" merge to merge
my changes back to the master branch before I synchronize with the
subversion server?  Or do I use the "--no-commit" option to merge?  Or
do I try something else?  The first/last time I tried this, I ended up
with a fast-forward merge back into master, which included all of my
stupid little commit messages.  I would rather one commit message that
read "Added XYZ feature".

2) When I don't fork a branch, and I don't commit until I've completed
the particular feature I'm working on, I can get a fairly good idea of
where I am and what I was doing last (which might be 5-7 days ago,
given high priority interrupts on other projects, summer vacations,
etc...) just by running a "git status".  I see that there are 7 new
files, and 2 modified files.  I know that, when I fork my branch, I
can use "git diff master" to see what's different between my branch
and the master, but then I get the diff of all of the changes as well,
which is too much information.  "git diff --name-only" and "git diff
--summary" are closer, but I can't tell what's been added vs. what's
been changed.  Any suggestions?

As an aside, is there an undocumented option to "git status" to
produce a less verbose report of what's been changed and what's not
checked in?  Perhaps a single line per file with a one or two letter
indication of the status of the file followed by the name?  If not,
would there be any violent objections to my submitting a patch to add
such a feature?

That's enough for now.  Thanks for reading this far :-)

--wpd

Re: workflow question

[Alex Riesen]

On 7/24/07, Patrick Doyle <wpdster@gmail.com> wrote:
> 2) When I don't fork a branch,

this is a confusing sentence: "fork" does not happen as
an explicit operation (if at all). You just commit somewhere
and depending on how you look at the history you either
see or not see a "fork".

> ... and I don't commit until I've completed
> the particular feature I'm working on, I can get a fairly good idea of
> where I am and what I was doing last (which might be 5-7 days ago,
> given high priority interrupts on other projects, summer vacations,
> etc...) just by running a "git status".  I see that there are 7 new
> files, and 2 modified files.  I know that, when I fork my branch, I
> can use "git diff master" to see what's different between my branch
> and the master, but then I get the diff of all of the changes as well,
> which is too much information.  "git diff --name-only" and "git diff
> --summary" are closer, but I can't tell what's been added vs. what's
> been changed.  Any suggestions?

"git log -p ..master", or even simpler "gitk ..master"

> As an aside, is there an undocumented option to "git status" to
> produce a less verbose report of what's been changed and what's not
> checked in?  Perhaps a single line per file with a one or two letter
> indication of the status of the file followed by the name?  If not,
> would there be any violent objections to my submitting a patch to add
> such a feature?

my_status() {
  git diff --cached --name-status -r -M -C HEAD -- "$@" && \
  git diff --name-status -r -M -C -- "$@"
}

Use as: my_status [pathname-limiter].
Does not show untracked files, though.

Re: workflow question

[Patrick Doyle]

On 7/24/07, Alex Riesen <raa.lkml@gmail.com> wrote:
> On 7/24/07, Patrick Doyle <wpdster@gmail.com> wrote:
> > 2) When I don't fork a branch,
>
> this is a confusing sentence: "fork" does not happen as
> an explicit operation (if at all). You just commit somewhere
> and depending on how you look at the history you either
> see or not see a "fork".
ok, I probably should have said, "When I don't create a branch, and
when I have not yet committed any changes for the particular
feature..."

>
> > ... and I don't commit until I've completed
> > the particular feature I'm working on, I can get a fairly good idea of
> > where I am and what I was doing last (which might be 5-7 days ago,
> > given high priority interrupts on other projects, summer vacations,
> > etc...) just by running a "git status".  I see that there are 7 new
> > files, and 2 modified files.  I know that, when I fork my branch, I
> > can use "git diff master" to see what's different between my branch
> > and the master, but then I get the diff of all of the changes as well,
> > which is too much information.  "git diff --name-only" and "git diff
> > --summary" are closer, but I can't tell what's been added vs. what's
> > been changed.  Any suggestions?
>
> "git log -p ..master", or even simpler "gitk ..master"
I was hoping for something less verbose than a diff or a patch file --
something that just listed what has changed -- I'll have to
investigate whether your "my_status()" macro provides the information
for which I was looking -- thanks for the pointer.

And, as for gitk, there is something about the combination of the
screen on my laptop, my Linux installation (FC6), my X server
configuration, and/or me that makes the fonts totally unreadable.  I
keep meaning to follow up on that, but I'm stuck in a
chicken-and-the-egg situation.  I don't see the utility of gitk
because I can't read the display that it produces.  I don't look for
the time to fix the display that it produces because, thus far, I
don't see the utility of gitk.  Sigh...


> my_status() {
>   git diff --cached --name-status -r -M -C HEAD -- "$@" && \
>   git diff --name-status -r -M -C -- "$@"
> }
>
> Use as: my_status [pathname-limiter].
> Does not show untracked files, though.
>
Ahhh... I was looking around git-status instead of git-diff.  That
makes sense now that you mention it.  Someday I may have the intuitive
understanding of git that would point me in that direction myself, but
I ain't there yet :-)

Thanks.

--wpd

Re: workflow question

[Julian Phillips]

On Tue, 24 Jul 2007, Patrick Doyle wrote:

>> >  ... and I don't commit until I've completed
>> >  the particular feature I'm working on, I can get a fairly good idea of
>> >  where I am and what I was doing last (which might be 5-7 days ago,
>> >  given high priority interrupts on other projects, summer vacations,
>> >  etc...) just by running a "git status".  I see that there are 7 new
>> >  files, and 2 modified files.  I know that, when I fork my branch, I
>> >  can use "git diff master" to see what's different between my branch
>> >  and the master, but then I get the diff of all of the changes as well,
>> >  which is too much information.  "git diff --name-only" and "git diff
>> >  --summary" are closer, but I can't tell what's been added vs. what's
>> >  been changed.  Any suggestions?
>>
>>  "git log -p ..master", or even simpler "gitk ..master"
> I was hoping for something less verbose than a diff or a patch file --
> something that just listed what has changed -- I'll have to
> investigate whether your "my_status()" macro provides the information
> for which I was looking -- thanks for the pointer.

"git log --stat ..master" perhaps?

-- 
Julian

  ---
The future isn't what it used to be.  (It never was.)

Re: workflow question

[Alex Riesen]

Julian Phillips, Tue, Jul 24, 2007 18:35:15 +0200:
> On Tue, 24 Jul 2007, Patrick Doyle wrote:
> 
> >>>  ... and I don't commit until I've completed
> >>>  the particular feature I'm working on, I can get a fairly good idea of
> >>>  where I am and what I was doing last (which might be 5-7 days ago,
> >>>  given high priority interrupts on other projects, summer vacations,
> >>>  etc...) just by running a "git status".  I see that there are 7 new
> >>>  files, and 2 modified files.  I know that, when I fork my branch, I
> >>>  can use "git diff master" to see what's different between my branch
> >>>  and the master, but then I get the diff of all of the changes as well,
> >>>  which is too much information.  "git diff --name-only" and "git diff
> >>>  --summary" are closer, but I can't tell what's been added vs. what's
> >>>  been changed.  Any suggestions?
> >>
> >> "git log -p ..master", or even simpler "gitk ..master"
> >I was hoping for something less verbose than a diff or a patch file --
> >something that just listed what has changed -- I'll have to
> >investigate whether your "my_status()" macro provides the information
> >for which I was looking -- thanks for the pointer.
> 
> "git log --stat ..master" perhaps?
> 

yep. Or just use the same options as with diff:

    $ git log -r --name-status -M -C ..master

Re: workflow question

[Alex Riesen]

Patrick Doyle, Tue, Jul 24, 2007 18:30:12 +0200:
> And, as for gitk, there is something about the combination of the
> screen on my laptop, my Linux installation (FC6), my X server
> configuration, and/or me that makes the fonts totally unreadable.  I
> keep meaning to follow up on that, but I'm stuck in a
> chicken-and-the-egg situation.  I don't see the utility of gitk
> because I can't read the display that it produces.  I don't look for
> the time to fix the display that it produces because, thus far, I
> don't see the utility of gitk.  Sigh...

That's a real pity, because it is very powerful.

Try removing ~/.gitk, or look into it and try changing the font.
Here is mine, for reference:

set mainfont {Helvetica 11}
set textfont {Courier 11}
set uifont {Helvetica 9 bold}
set tabstop 8
set findmergefiles 0
set maxgraphpct 50
set maxwidth 16
set cmitmode patch
set wrapcomment none
set showneartags 1
set showlocalchanges 1
set bgcolor white
set fgcolor black
set colors {green red blue magenta darkgrey brown orange}
set diffcolors {red "#00a000" blue}
set selectbgcolor gray85
set geometry(main) 1005x850+1417+41
set geometry(topwidth) 1001
set geometry(topheight) 458
set geometry(pwsash0) "684 2"
set geometry(pwsash1) "878 2"
set geometry(botwidth) 725
set geometry(botheight) 372
set permviews {}

Re: workflow question

[J. Bruce Fields]

On Tue, Jul 24, 2007 at 10:57:02PM +0200, Alex Riesen wrote:
> Patrick Doyle, Tue, Jul 24, 2007 18:30:12 +0200:
> > And, as for gitk, there is something about the combination of the
> > screen on my laptop, my Linux installation (FC6), my X server
> > configuration, and/or me that makes the fonts totally unreadable.  I
> > keep meaning to follow up on that, but I'm stuck in a
> > chicken-and-the-egg situation.  I don't see the utility of gitk
> > because I can't read the display that it produces.  I don't look for
> > the time to fix the display that it produces because, thus far, I
> > don't see the utility of gitk.  Sigh...
> 
> That's a real pity, because it is very powerful.
> 
> Try removing ~/.gitk, or look into it and try changing the font.

(Also, as a quick fix, note that ctrl-- and ctrl-= will adjust the font
size down or up (respectively).)

--b.

Re: workflow question

[Linus Torvalds]

On Tue, 24 Jul 2007, J. Bruce Fields wrote:
> 
> (Also, as a quick fix, note that ctrl-- and ctrl-= will adjust the font
> size down or up (respectively).)

Side note: this can be *really* confusing on non-US keyboards.

The "=" makes sense on a US keyboard, because it's really "ctrl-+" without 
the added need to press "shift".

On many non-US keyboards, there is no such arrangement of +/= on the 
keyboard.

So on a Finnish keyboard, for example, the sequence to make the fonts 
smaller is "ctrl--", but the sequence to make them larger is 
"contr-shift-0". Which makes *no* sense what-so-ever, but the "=" sign is 
"shift-0".

Oh, well. On a Finnish keyboard, "ctrl-+" would make tons of sense. I 
always try it, and am frustrated when it doesn't work.

			Linus

Workflow question

[Russ Brown]

Hi,

I've been trying to think of a git workflow that we could use to replace
our current svn/svk setup without simply using git in exactly the same
way that we use svn/svk.

Basically, we develop, maintain and enhance a website. On the central
repo is trunk which represents live, and any number of project branches.
Developers don't use local branches: they check out the project branches
they're working on and commit to those. Developers merge from trunk to
project branch from time to time to keep them current, and when a
project rolls out the branch is merged to trunk.

In addition to the obvious advantages that git would give us (such as
properly tracking that code author as opposed to the person who did the
merge), I'm wanting to gain the following benefits:

 * The repository is very large (multiple gigabytes) and mirroring using
svk obviously takes a lot of time and space, so I'm keen to bring that
down, most likely by the developer not needing to mirror branches he
doesn't care about, or by being able to throw away branches he's done with.
 * The repository is full of revisions that fail review (or break
things) and are fixed by subsequent revisions. We'd much rather be able
to have the developer fix his revisions before they get committed
'upstream' (whatever that ends up meaning).

I asked earlier about the email-based model that git itself uses, and
while it appears to work very well for a widely-dispersed open-source
project, I think it will be too cumbersome and slow for a fast-paced
internal development team who make a number of live releases every day.

So, I've been thinking and have come up with this, which I'd appreciate
comments about:

 1. On a server we stick a git repository which contains the master
branch, which represents what trunk did (i.e. the live platform). This
branch contains the full history for the live platform.
 2. On the same server we clone that repo to create a second repository
which is the developer area. In this we track master from the live repo,
and also create project branches.
 3. Developers clone this developer repo, but I'd like them to be able
to decide which branches they actually want to clone from that
repository rather than simply cloning them all. Is this possible?
 4. Developers create a local branch of the project they
are working on and commit to that.
 5. Once they think they're done, they publish their branch to the
development repo and request for comments.
 6. If all is not well, the developer creates a new local branch and
moves good revisions from his previous one to the new one, modifying
things as he goes, and republishes his new branch.
 7. If all is well, their works gets merged or rebased onto the main
project branch, and once that's ready it gets pushed to the master and
rolled to live. The developer's individual branches get deleted from the
dev repo since they're no longer required.
 8. From time to time the master branch gets merged to the project
branches. Developer's local branches can be rebased against the project
branch as they please.

Firstly, is all of this possible, and if so would it be considered a
good way of going about it?

Any comments appreciated.

-- 

Russ

Re: Workflow question

[Andreas Ericsson]

Russ Brown wrote:
> Hi,
> 
> I've been trying to think of a git workflow that we could use to replace
> our current svn/svk setup without simply using git in exactly the same
> way that we use svn/svk.
> 
> Basically, we develop, maintain and enhance a website. On the central
> repo is trunk which represents live, and any number of project branches.
> Developers don't use local branches: they check out the project branches
> they're working on and commit to those. Developers merge from trunk to
> project branch from time to time to keep them current, and when a
> project rolls out the branch is merged to trunk.
> 
> In addition to the obvious advantages that git would give us (such as
> properly tracking that code author as opposed to the person who did the
> merge), I'm wanting to gain the following benefits:
> 
>  * The repository is very large (multiple gigabytes) and mirroring using
> svk obviously takes a lot of time and space, so I'm keen to bring that
> down, most likely by the developer not needing to mirror branches he
> doesn't care about, or by being able to throw away branches he's done with.
>  * The repository is full of revisions that fail review (or break
> things) and are fixed by subsequent revisions. We'd much rather be able
> to have the developer fix his revisions before they get committed
> 'upstream' (whatever that ends up meaning).
> 
> I asked earlier about the email-based model that git itself uses, and
> while it appears to work very well for a widely-dispersed open-source
> project, I think it will be too cumbersome and slow for a fast-paced
> internal development team who make a number of live releases every day.
> 

We came to the same conclusion at our workplace. Email works great, but
it's faster and better to just walk over to your colleague and ask what
he/she thinks about something.

> So, I've been thinking and have come up with this, which I'd appreciate
> comments about:
> 
>  1. On a server we stick a git repository which contains the master
> branch, which represents what trunk did (i.e. the live platform). This
> branch contains the full history for the live platform.

A must-have for any more-than-two-developers setup, so so far so good ;-)

>  2. On the same server we clone that repo to create a second repository
> which is the developer area. In this we track master from the live repo,
> and also create project branches.

This isn't necessary. Branches in git are very nearly zero-cost, so having
them in the same repo as the master branch won't hurt a bit. You can add
an update-hook on the mothership repo to restrict access to the master
branch if you like, but creating two separate repos will likely give
more headache than it's worth.

>  3. Developers clone this developer repo, but I'd like them to be able
> to decide which branches they actually want to clone from that
> repository rather than simply cloning them all. Is this possible?

Yes, although I'd actually recommend you to clone the full repo anyway.
Since the various branches are likely to share quite a lot of history
the added overhead of a few extra branches will most likely be negligible.
git makes even very large codebases appear small and unobtrusive. The
linux kernel history since 2.6.12 contains 554853 objects and compresses
down to 178MiB.

I think KDE is the largest repo imported to git so far. I've forgotten
the exact numbers, but everyone was very impressed, and quite surprised,
at the vast difference between SVN and git storage requirements.


>  4. Developers create a local branch of the project they
> are working on and commit to that.
>  5. Once they think they're done, they publish their branch to the
> development repo and request for comments.

Using topic-branches is a much better strategy, usually, since that
allows each feature to be evaluated and improved on on its own, rather
than having to merge *all* of a particular developers changes just to
get desirable feature X. Note that cherry-pick provides ways of doing
that anyways, but in a much less elegant way, and your integrator/
release engineer will likely tear his hair out on a daily basis without
topic branches.

>  6. If all is not well, the developer creates a new local branch and
> moves good revisions from his previous one to the new one, modifying
> things as he goes, and republishes his new branch.
>  7. If all is well, their works gets merged or rebased onto the main
> project branch, and once that's ready it gets pushed to the master and
> rolled to live. The developer's individual branches get deleted from the
> dev repo since they're no longer required.

Topic branches would work the same, basically, except they can be pushed up
for review a lot faster.

If all the pushing gets cumbersome, it also makes it easy to send the patches
out as emails for discussion. It's usually easier to let git handle the
actual code transmissions, but discussing patches in emails works quite
well if it's intended for a wider audience.

>  8. From time to time the master branch gets merged to the project
> branches. Developer's local branches can be rebased against the project
> branch as they please.
> 

criss-cross merging can turn kinda nasty though, as you may have a hard time
finding *the* common point when you run into that rogue merge with conflict
markers everywhere (it happens for everyone sooner or later).

I'd suggest you rebase the developer/topic branches onto master with regular
intervals instead.

-- 
Andreas Ericsson                   andreas.ericsson@op5.se
OP5 AB                             www.op5.se
Tel: +46 8-230225                  Fax: +46 8-230231

Re: Workflow question

[Jeff King]

On Tue, Sep 25, 2007 at 09:09:00PM +0200, Andreas Ericsson wrote:

> We came to the same conclusion at our workplace. Email works great, but
> it's faster and better to just walk over to your colleague and ask what
> he/she thinks about something.

One of the projects I am working on does things this way, but I have to
admit that I miss the email code-review process. There are often small
fixups (stylistic, minor nits, "I would have done it this way...", etc)
that are worth pointing out at the time, but are more painful to go back
and correct much later.

And documenting those discussions can really help other developers
besides the author and reviewer.

-Peff

Re: Workflow question

[Wincent Colaiuta]

El 25/9/2007, a las 21:34, Jeff King escribió:

> On Tue, Sep 25, 2007 at 09:09:00PM +0200, Andreas Ericsson wrote:
>
>> We came to the same conclusion at our workplace. Email works  
>> great, but
>> it's faster and better to just walk over to your colleague and ask  
>> what
>> he/she thinks about something.
>
> One of the projects I am working on does things this way, but I  
> have to
> admit that I miss the email code-review process. There are often small
> fixups (stylistic, minor nits, "I would have done it this way...",  
> etc)
> that are worth pointing out at the time, but are more painful to go  
> back
> and correct much later.
>
> And documenting those discussions can really help other developers
> besides the author and reviewer.

Google has a pretty interesting internal code review system:

<http://video.google.com/videoplay?docid=-8502904076440714866>

Cheers,
Wincent

Re: Workflow question

[Jeff King]

On Tue, Sep 25, 2007 at 09:50:34PM +0200, Wincent Colaiuta wrote:

> Google has a pretty interesting internal code review system:
> 
> <http://video.google.com/videoplay?docid=-8502904076440714866>

Interesting pointer, thanks. Though I did get a little concerned when I
saw that it is based on Perforce. ;)

-Peff

Re: Workflow question

[Wincent Colaiuta]

El 25/9/2007, a las 22:20, Jeff King escribió:

> On Tue, Sep 25, 2007 at 09:50:34PM +0200, Wincent Colaiuta wrote:
>
>> Google has a pretty interesting internal code review system:
>>
>> <http://video.google.com/videoplay?docid=-8502904076440714866>
>
> Interesting pointer, thanks. Though I did get a little concerned  
> when I
> saw that it is based on Perforce. ;)

Yes (poor Google employees!), and not only that, I'm not aware of any  
public access to the code. But still, there are some interesting  
ideas about the review process in there.

W

Re: Workflow question

[Russ Brown]

Andreas Ericsson wrote:
> Russ Brown wrote:
>> Hi,
>>
>> I've been trying to think of a git workflow that we could use to replace
>> our current svn/svk setup without simply using git in exactly the same
>> way that we use svn/svk.
>>
>> Basically, we develop, maintain and enhance a website. On the central
>> repo is trunk which represents live, and any number of project branches.
>> Developers don't use local branches: they check out the project branches
>> they're working on and commit to those. Developers merge from trunk to
>> project branch from time to time to keep them current, and when a
>> project rolls out the branch is merged to trunk.
>>
>> In addition to the obvious advantages that git would give us (such as
>> properly tracking that code author as opposed to the person who did the
>> merge), I'm wanting to gain the following benefits:
>>
>>  * The repository is very large (multiple gigabytes) and mirroring using
>> svk obviously takes a lot of time and space, so I'm keen to bring that
>> down, most likely by the developer not needing to mirror branches he
>> doesn't care about, or by being able to throw away branches he's done
>> with.
>>  * The repository is full of revisions that fail review (or break
>> things) and are fixed by subsequent revisions. We'd much rather be able
>> to have the developer fix his revisions before they get committed
>> 'upstream' (whatever that ends up meaning).
>>
>> I asked earlier about the email-based model that git itself uses, and
>> while it appears to work very well for a widely-dispersed open-source
>> project, I think it will be too cumbersome and slow for a fast-paced
>> internal development team who make a number of live releases every day.
>>
> 
> We came to the same conclusion at our workplace. Email works great, but
> it's faster and better to just walk over to your colleague and ask what
> he/she thinks about something.
> 

Very true, with the minor exception that at my place there are
developers working at different sites, so the walk-over method will only
work for specific subsets of the team. :)

>> So, I've been thinking and have come up with this, which I'd appreciate
>> comments about:
>>
>>  1. On a server we stick a git repository which contains the master
>> branch, which represents what trunk did (i.e. the live platform). This
>> branch contains the full history for the live platform.
> 
> A must-have for any more-than-two-developers setup, so so far so good ;-)
> 
>>  2. On the same server we clone that repo to create a second repository
>> which is the developer area. In this we track master from the live repo,
>> and also create project branches.
> 
> This isn't necessary. Branches in git are very nearly zero-cost, so having
> them in the same repo as the master branch won't hurt a bit. You can add
> an update-hook on the mothership repo to restrict access to the master
> branch if you like, but creating two separate repos will likely give
> more headache than it's worth.
> 

Ah, right. I'm just trying to remember why it was I came up with that
idea in the first place, but I'm struggling a bit. :)

>>  3. Developers clone this developer repo, but I'd like them to be able
>> to decide which branches they actually want to clone from that
>> repository rather than simply cloning them all. Is this possible?
> 
> Yes, although I'd actually recommend you to clone the full repo anyway.
> Since the various branches are likely to share quite a lot of history
> the added overhead of a few extra branches will most likely be negligible.
> git makes even very large codebases appear small and unobtrusive. The
> linux kernel history since 2.6.12 contains 554853 objects and compresses
> down to 178MiB.
> 

Makes sense. Thing is, with git-svn (which I've been using for a while
now) it's possible to 'bring in' an upstream branch at will by adding it
to your config file, and on next git-svn fetch revisions that affect
that branch are automatically fetched. I figured it would just be a
little more efficient, though I appreciate it involves more 'fiddling'
by the client users.

Here's a question: is the creation and deletion of a branch also version
controlled as it is in Subversion? In other words, if I create a branch,
develop on it and delete it without merging it anywhere, will the
revisions hang around and get pulled down by future people cloning the
repository, or do they get thrown away?

> I think KDE is the largest repo imported to git so far. I've forgotten
> the exact numbers, but everyone was very impressed, and quite surprised,
> at the vast difference between SVN and git storage requirements.
> 
> 
>>  4. Developers create a local branch of the project they
>> are working on and commit to that.
>>  5. Once they think they're done, they publish their branch to the
>> development repo and request for comments.
> 
> Using topic-branches is a much better strategy, usually, since that
> allows each feature to be evaluated and improved on on its own, rather
> than having to merge *all* of a particular developers changes just to
> get desirable feature X. Note that cherry-pick provides ways of doing
> that anyways, but in a much less elegant way, and your integrator/
> release engineer will likely tear his hair out on a daily basis without
> topic branches.
> 

I've seen the term 'topic-branch' used here quite a bit but it's
unfamiliar to me. It is basically synonymous with what we call a
'project branch'? i.e. Management decide that feature X is required so
we create a branch to develop it on which all developers on the project
commit to.

Note that in step 4 above I mean the developer takes a local branch of
the topic branch. For example, we start projectX/main, and create branch
projectX on the shared repo. Developer 'jeff' works on the project and
so creates local branch projectX/jeff and begins work. In step 5 they
push this local branch to the shared repo so everyone can see it
(alternative to the 'walk-over' method or emailing). Note that all
changes jeff making in projectX/jeff are specific to the project branch,
so he can rebase against other changes that get committed to that
project branch.

If colleagues don't like his changes he can create projectXjeff2 and try
again.

Jeff can also have other local branches to keep separate changes he is
making on the other projects he is involved in.

That's how I'd thought of it happening...

>>  6. If all is not well, the developer creates a new local branch and
>> moves good revisions from his previous one to the new one, modifying
>> things as he goes, and republishes his new branch.
>>  7. If all is well, their works gets merged or rebased onto the main
>> project branch, and once that's ready it gets pushed to the master and
>> rolled to live. The developer's individual branches get deleted from the
>> dev repo since they're no longer required.
> 
> Topic branches would work the same, basically, except they can be pushed up
> for review a lot faster.
> 
> If all the pushing gets cumbersome, it also makes it easy to send the
> patches
> out as emails for discussion. It's usually easier to let git handle the
> actual code transmissions, but discussing patches in emails works quite
> well if it's intended for a wider audience.
> 

Yes, I am going to experiment with this a little too to see just how
much work it would involve for the developers (if it's too much they
won't do it) :)

>>  8. From time to time the master branch gets merged to the project
>> branches. Developer's local branches can be rebased against the project
>> branch as they please.
>>
> 
> criss-cross merging can turn kinda nasty though, as you may have a hard
> time
> finding *the* common point when you run into that rogue merge with conflict
> markers everywhere (it happens for everyone sooner or later).
> 
> I'd suggest you rebase the developer/topic branches onto master with
> regular
> intervals instead.
> 

Having been using git-svn for a while I really like the clean history
result that rebase gives, however my understanding was that you should
never rebase any published branch as it could screw up clones of that
branch. In fact, this is what has me the most confused: how to rebase a
project branch that is on a shared repository against master when
everyone will have it cloned? Or is this something that I clearly don't
understand properly?

(Thanks for your answers BTW Andreas)

-- 

Russ

Re: Workflow question

[Jeff King]

On Tue, Sep 25, 2007 at 02:42:11PM -0500, Russ Brown wrote:

> > This isn't necessary. Branches in git are very nearly zero-cost, so having
> > them in the same repo as the master branch won't hurt a bit. You can add
> > an update-hook on the mothership repo to restrict access to the master
> > branch if you like, but creating two separate repos will likely give
> > more headache than it's worth.
> > 
> 
> Ah, right. I'm just trying to remember why it was I came up with that
> idea in the first place, but I'm struggling a bit. :)

It's not entirely true that branches are zero-cost. They cost nothing to
make, but fetching a branch that has commits that you don't want is
going to cost something. And since git-clone doesn't have good support
for "fetch only this subset of the branches" you end up getting them
all.

That being said, you will be amazed how _little_ that cost is unless
one of the branches doesn't delta well (e.g., if one branch introduces 100M
of unrelated images, then getting that branch is going to cost). But
it's almost certainly worth seeing what your workload is like.

> Here's a question: is the creation and deletion of a branch also version
> controlled as it is in Subversion? In other words, if I create a branch,
> develop on it and delete it without merging it anywhere, will the
> revisions hang around and get pulled down by future people cloning the
> repository, or do they get thrown away?

Branch creation isn't version controlled, but your frame of reference is
obviously svn branches, not git branches. A git repo is just a
collection of refs, and each ref is a pointer to some commit (which
points to a tree and to further commits). Branches are just refs in a
given namespace (where the namespace refs/heads/ indicates "it's ok to
make further commits on top of these").

So if you create a branch in your private repo, it is a totally private
thing; the central repo has no notion of it. When you push that branch
to the central repo, you are creating a new ref at the central location
that points to some commits you made. People who clone it will clone
that ref and your commits. If you delete the branch locally, again it
has no effect on the master repo. If you delete the branch from the
central repo, then nobody will fetch those commits anymore (since
nothing will be pointing to them).

> I've seen the term 'topic-branch' used here quite a bit but it's
> unfamiliar to me. It is basically synonymous with what we call a
> 'project branch'? i.e. Management decide that feature X is required so
> we create a branch to develop it on which all developers on the project
> commit to.

Yes, that's exactly right. You have a "branch" for working on a "topic".

> Note that in step 4 above I mean the developer takes a local branch of
> the topic branch. For example, we start projectX/main, and create branch
> projectX on the shared repo. Developer 'jeff' works on the project and
> so creates local branch projectX/jeff and begins work. In step 5 they

You are actually talking about per-developer, per-topic branches. Which
is fine, too. It sounds like these projects are big (many participants
over an extended period), so you may want to do things hierarchically:

  1. project X starts, so you make a branch projectX and assign Bob to
     be the integrator (or if you prefer, nobody is the integrator).
  2. Jeff starts to work on project X, feature Y. He makes a branch
     projectX/featureY, based on projectX. He may publish this to the
     shared repo if he wants to communicate his progress.
  3. When featureY is "ready", he tells Bob to pull it into the main
     projectX branch (or if no integrator, he does it himself).

Any developer can see the progress of any "topic" by looking at its
branch. But only things which have advanced to the main "projectX"
branch are used as the basis for other topics. If you want, you can
replace featureY with "jeff" to indicate "this is the work Jeff is doing
on projectX", but then you will run into issues when Jeff is working on
two different topics of projectY.

> Having been using git-svn for a while I really like the clean history
> result that rebase gives, however my understanding was that you should
> never rebase any published branch as it could screw up clones of that
> branch. In fact, this is what has me the most confused: how to rebase a
> project branch that is on a shared repository against master when
> everyone will have it cloned? Or is this something that I clearly don't
> understand properly?

You generally don't want to rebase that branch. If there are other
branches based on some work, then it will become more difficult to merge
those branches into the rebased work. IOW, rebase works well only at the
"outermost" level of development. So if branch "featureY" is branched from
"projectX" which is branched from "main", then it is reasonable to
rebase featureY against projectX. But rebasing projectX against master
will make integrating "featureY" more difficult. So you should either:
  - just do regular merges of projectX into main (and hopefully, if
    projectX is an aggregate of features, it won't have _that_ many
    merges, so the history should still be quite readable)
  - wait until all such "featureY" branches are merged into projectX,
    announce a freeze of branching from projectX, and then rebase it
    forward.

-Peff

Re: Workflow question

[Russ Brown]

Jeff King wrote:
> On Tue, Sep 25, 2007 at 02:42:11PM -0500, Russ Brown wrote:
> 
>>> This isn't necessary. Branches in git are very nearly zero-cost, so having
>>> them in the same repo as the master branch won't hurt a bit. You can add
>>> an update-hook on the mothership repo to restrict access to the master
>>> branch if you like, but creating two separate repos will likely give
>>> more headache than it's worth.
>>>
>> Ah, right. I'm just trying to remember why it was I came up with that
>> idea in the first place, but I'm struggling a bit. :)
> 
> It's not entirely true that branches are zero-cost. They cost nothing to
> make, but fetching a branch that has commits that you don't want is
> going to cost something. And since git-clone doesn't have good support
> for "fetch only this subset of the branches" you end up getting them
> all.
> 
> That being said, you will be amazed how _little_ that cost is unless
> one of the branches doesn't delta well (e.g., if one branch introduces 100M
> of unrelated images, then getting that branch is going to cost). But
> it's almost certainly worth seeing what your workload is like.
> 

That's pretty much what I thought. Given that we'll probably only port
across a few (active) branches if we do decide to convert, I figure we
might as well start off by cloning them all and see how it goes.

>> Here's a question: is the creation and deletion of a branch also version
>> controlled as it is in Subversion? In other words, if I create a branch,
>> develop on it and delete it without merging it anywhere, will the
>> revisions hang around and get pulled down by future people cloning the
>> repository, or do they get thrown away?
> 
> Branch creation isn't version controlled, but your frame of reference is
> obviously svn branches, not git branches. A git repo is just a
> collection of refs, and each ref is a pointer to some commit (which
> points to a tree and to further commits). Branches are just refs in a
> given namespace (where the namespace refs/heads/ indicates "it's ok to
> make further commits on top of these").
> 

I keep reading things similar to this and bit by bit I'm starting to get
it. :) I suppose this is one case in which it's definitely a
disadvantage to have a good understanding of svn before coming to git...

<yoda>You must unlearn what you have learned</yoda>

> So if you create a branch in your private repo, it is a totally private
> thing; the central repo has no notion of it. When you push that branch
> to the central repo, you are creating a new ref at the central location
> that points to some commits you made. People who clone it will clone
> that ref and your commits. If you delete the branch locally, again it
> has no effect on the master repo. If you delete the branch from the
> central repo, then nobody will fetch those commits anymore (since
> nothing will be pointing to them).
> 

If you delete a branch that has commits on it that aren't referenced by
any other branches, will those commits be removed by something like git
pack or git gc?

>> I've seen the term 'topic-branch' used here quite a bit but it's
>> unfamiliar to me. It is basically synonymous with what we call a
>> 'project branch'? i.e. Management decide that feature X is required so
>> we create a branch to develop it on which all developers on the project
>> commit to.
> 
> Yes, that's exactly right. You have a "branch" for working on a "topic".
> 
>> Note that in step 4 above I mean the developer takes a local branch of
>> the topic branch. For example, we start projectX/main, and create branch
>> projectX on the shared repo. Developer 'jeff' works on the project and
>> so creates local branch projectX/jeff and begins work. In step 5 they
> 
> You are actually talking about per-developer, per-topic branches. Which
> is fine, too. It sounds like these projects are big (many participants
> over an extended period), so you may want to do things hierarchically:
> 
>   1. project X starts, so you make a branch projectX and assign Bob to
>      be the integrator (or if you prefer, nobody is the integrator).
>   2. Jeff starts to work on project X, feature Y. He makes a branch
>      projectX/featureY, based on projectX. He may publish this to the
>      shared repo if he wants to communicate his progress.
>   3. When featureY is "ready", he tells Bob to pull it into the main
>      projectX branch (or if no integrator, he does it himself).
> 
> Any developer can see the progress of any "topic" by looking at its
> branch. But only things which have advanced to the main "projectX"
> branch are used as the basis for other topics. If you want, you can
> replace featureY with "jeff" to indicate "this is the work Jeff is doing
> on projectX", but then you will run into issues when Jeff is working on
> two different topics of projectY.
> 

Yes, that's kinda like what I was thinking. The distinction between a
developer working on a named branch or a feature branch I suppose is one
to think about.

I suppose what has me the most confused is how a developer works with a
remote branch: I've come to understand that a developer should never
check out and work on a remote branch, and always create a local one and
work on that. If he does that using the above hierarchy, there then
becomes main->projectX->featureY->jeff_local_branch_of_featureY. Or is
is possible for a developer to work directory on a remote branch?

>> Having been using git-svn for a while I really like the clean history
>> result that rebase gives, however my understanding was that you should
>> never rebase any published branch as it could screw up clones of that
>> branch. In fact, this is what has me the most confused: how to rebase a
>> project branch that is on a shared repository against master when
>> everyone will have it cloned? Or is this something that I clearly don't
>> understand properly?
> 
> You generally don't want to rebase that branch. If there are other
> branches based on some work, then it will become more difficult to merge
> those branches into the rebased work. IOW, rebase works well only at the
> "outermost" level of development. So if branch "featureY" is branched from
> "projectX" which is branched from "main", then it is reasonable to
> rebase featureY against projectX. But rebasing projectX against master
> will make integrating "featureY" more difficult. So you should either:
>   - just do regular merges of projectX into main (and hopefully, if
>     projectX is an aggregate of features, it won't have _that_ many
>     merges, so the history should still be quite readable)
>   - wait until all such "featureY" branches are merged into projectX,
>     announce a freeze of branching from projectX, and then rebase it
>     forward.
> 
> -Peff

Ah,I see... The light is beginning to come on somewhat here, though it's
dimmed somewhat by the remote/local branch confusion I mention above,
which tends to imply that rebase is only really useful in local branches
since it is always the outer-most branch (assuming that my understanding
on that is correct, which it may well not be).

I actually quite like the idea of the freezing before re-basing in the
sub-branches. However, to answer the question of which merge strategy
would work best for us I think I need to actually set this up and have a
play with it to see how it all pans out using the various options available.

Thanks for your help!

-- 

Russ

Re: Workflow question

[Junio C Hamano]

Russ Brown <pickscrape@gmail.com> writes:

> I keep reading things similar to this and bit by bit I'm starting to get
> it. :) I suppose this is one case in which it's definitely a
> disadvantage to have a good understanding of svn before coming to git...
>
> <yoda>You must unlearn what you have learned</yoda>

You do not have to unlearn; if Jeff truly unlearned he wouldn't
have spotted you were trapped in SVN mentality.  You just need
to learn there could be other ways ;-).

> If you delete a branch that has commits on it that aren't referenced by
> any other branches, will those commits be removed by something like git
> pack or git gc?

Yes, eventually.

> I suppose what has me the most confused is how a developer works with a
> remote branch: I've come to understand that a developer should never
> check out and work on a remote branch, and always create a local one and
> work on that. If he does that using the above hierarchy, there then
> becomes main->projectX->featureY->jeff_local_branch_of_featureY. Or is
> is possible for a developer to work directory on a remote branch?

The statement in the last sentence does not make any sense.
Remote is called remote because it is remote and supposed to be
out of reach ;-)

More seriously, remotes are used as reference points so if you
"work directly on them", you cannot use them as reference points
any more; you defeat the sole purpose of existence of remotes.

You can work _without_ using remote tracking branches, but that
is mostly for merge based workflow.  It appears that you are
leaning towards rebase-heavy workflow, so I do not think it is
applicable to your project.

Re: Workflow question

[Russ Brown]

Junio C Hamano wrote:
> Russ Brown <pickscrape@gmail.com> writes:
> 
>> I keep reading things similar to this and bit by bit I'm starting to get
>> it. :) I suppose this is one case in which it's definitely a
>> disadvantage to have a good understanding of svn before coming to git...
>>
>> <yoda>You must unlearn what you have learned</yoda>
> 
> You do not have to unlearn; if Jeff truly unlearned he wouldn't
> have spotted you were trapped in SVN mentality.  You just need
> to learn there could be other ways ;-).
> 

I suppose what I really mean is you need to stop assuming what you've
already learned. :)

>> If you delete a branch that has commits on it that aren't referenced by
>> any other branches, will those commits be removed by something like git
>> pack or git gc?
> 
> Yes, eventually.
> 
>> I suppose what has me the most confused is how a developer works with a
>> remote branch: I've come to understand that a developer should never
>> check out and work on a remote branch, and always create a local one and
>> work on that. If he does that using the above hierarchy, there then
>> becomes main->projectX->featureY->jeff_local_branch_of_featureY. Or is
>> is possible for a developer to work directory on a remote branch?
> 
> The statement in the last sentence does not make any sense.
> Remote is called remote because it is remote and supposed to be
> out of reach ;-)
> 

Ah. I think I was a little confused by the fact that git does let you
checkout remote branches, through I see that it does warn you about it
when you do it.

> More seriously, remotes are used as reference points so if you
> "work directly on them", you cannot use them as reference points
> any more; you defeat the sole purpose of existence of remotes.
> 
> You can work _without_ using remote tracking branches, but that
> is mostly for merge based workflow.  It appears that you are
> leaning towards rebase-heavy workflow, so I do not think it is
> applicable to your project.

Right, I think we're going to be aiming for that, though as I say I'm
going to be experimenting a bit to see how things work when using both
approaches.

Thanks.

-- 

Russ

Re: Workflow question

[Jeff King]

On Tue, Sep 25, 2007 at 03:56:56PM -0500, Russ Brown wrote:

> I keep reading things similar to this and bit by bit I'm starting to get
> it. :) I suppose this is one case in which it's definitely a
> disadvantage to have a good understanding of svn before coming to git...
> 
> <yoda>You must unlearn what you have learned</yoda>

I prefer to think of it like a war movie, where I keep having
nightmarish flashbacks to CVS.

But yes, from the outside git _looks_ a lot like other SCMs you may have
used, and so it's tempting to keep their mental models. But that can
easily end up being confusing, as you have found. Personally, I think it
pays to learn a little about what's going on under the hood, and then
all of the commands Just Make Sense.

There are several explanations floating around; this is a pretty concise
one:

  http://eagain.net/articles/git-for-computer-scientists/

> If you delete a branch that has commits on it that aren't referenced by
> any other branches, will those commits be removed by something like git
> pack or git gc?

The 'git-prune' command will do this, though it is not run as part of
git-gc unless you specify --prune.

> I suppose what has me the most confused is how a developer works with a
> remote branch: I've come to understand that a developer should never
> check out and work on a remote branch, and always create a local one and
> work on that. If he does that using the above hierarchy, there then
> becomes main->projectX->featureY->jeff_local_branch_of_featureY. Or is
> is possible for a developer to work directory on a remote branch?

As Junio noted, you can't, because they're remote. What you have in your
local repository is a remote _tracking branch_, which is a local ref
that tracks your idea of what the remote's branches are. And git will
feel free to overwrite the contents of that tracking branch whenever you
do a fetch or pull. So if you make commits on it, they are subject to
being overwritten (and we note this property of the refs by putting them
in the refs/remotes hierarchy, rather than refs/heads).

So in the case of our developer Jeff, his local repository will have a
"projectX/featureY" branch that he works on. And he will also have a
remote tracking branch "origin/projectX/featureY" which indicates where
his local repo thinks the remote repo points. And the remote repo will
have a "projectX/featureY" branch, of course.

> Ah,I see... The light is beginning to come on somewhat here, though it's
> dimmed somewhat by the remote/local branch confusion I mention above,
> which tends to imply that rebase is only really useful in local branches
> since it is always the outer-most branch (assuming that my understanding
> on that is correct, which it may well not be).

Yes, although the important distinction is not so much "this is a local
branch" but rather "this is a _published_ branch" which implies that
other people are looking at (and possibly basing work on) it.

> I actually quite like the idea of the freezing before re-basing in the
> sub-branches. However, to answer the question of which merge strategy
> would work best for us I think I need to actually set this up and have a
> play with it to see how it all pans out using the various options available.

Yes, it is easy to get into academic discussions of setups, but in
practice you need to find a workflow that is smooth for your team.

On one web-based project I work on, we have a setup like this (which is
very centralized):

  - a central repo resides on a development server with two branches,
    "master" and "production"
  - each developer clones the repo with a working tree
  - some developers develop directly on 'master' if they have small
    changes, or only work on one thing at a time; other developers use
    topic branches to work on simultaneous changes
  - any developer can push to master; it is expected that your code is
    in a reasonable state, since it will now be consumed by other
    developers. Anything that has made it into master is considered
    published and should not be rebased. It is up to developers whether
    they want to rebase their work before publishing or to simply merge.
  - some developers communicate directly with each other: "hey, check
    out branch 'foo' in my repo" or "what do you think of this patch?"
  - The live site has a repo cloned from the central repo, pointing at
    "production".
  - there is a test site with a repo cloned from the master.
    Occasionally the master branch is pulled and tested. If it passes,
    it is pushed to the "production" branch. In addition, small
    immediate fixes can go onto "production", tested, and then pushed to
    the central repo's "production"

So this is not necessarily using the distributed nature of that much,
but it allows those developers who aren't very comfortable with SCMs to
stick to a "pull, hack, push" workflow. And those who want to can do
more interesting things if it helps them.

-Peff

Re: Workflow question

[Karl Hasselström]

On 2007-09-25 20:47:34 -0400, Jeff King wrote:

> Personally, I think it pays to learn a little about what's going on
> under the hood, and then all of the commands Just Make Sense.
>
> There are several explanations floating around; this is a pretty
> concise one:
>
>   http://eagain.net/articles/git-for-computer-scientists/

I agree. Once you understand that history in git is just a DAG of
commits, and that "branches" are just named pointers into this DAG to
help the user remember where to attach new commits, everything starts
to Just Make Sense.

(And FWIW, that article was quite good as I recall.)

-- 
Karl Hasselström, kha@treskal.com
      www.treskal.com/kalle

Re: Workflow question

[Russ Brown]

Jeff King wrote:
> On Tue, Sep 25, 2007 at 03:56:56PM -0500, Russ Brown wrote:
> 
>> I keep reading things similar to this and bit by bit I'm starting to get
>> it. :) I suppose this is one case in which it's definitely a
>> disadvantage to have a good understanding of svn before coming to git...
>>
>> <yoda>You must unlearn what you have learned</yoda>
> 
> I prefer to think of it like a war movie, where I keep having
> nightmarish flashbacks to CVS.
> 
> But yes, from the outside git _looks_ a lot like other SCMs you may have
> used, and so it's tempting to keep their mental models. But that can
> easily end up being confusing, as you have found. Personally, I think it
> pays to learn a little about what's going on under the hood, and then
> all of the commands Just Make Sense.
> 
> There are several explanations floating around; this is a pretty concise
> one:
> 
>   http://eagain.net/articles/git-for-computer-scientists/
> 

Yes, this is very helpful indeed: thank you for that. /me bookmarks. I
hadn't actually realised that rebase creates new commits and replaces
your old ones: I'd thought they just got 'moved' (dunno how I thought it
worked though!)

>> If you delete a branch that has commits on it that aren't referenced by
>> any other branches, will those commits be removed by something like git
>> pack or git gc?
> 
> The 'git-prune' command will do this, though it is not run as part of
> git-gc unless you specify --prune.
> 

Another thing makes sense now (helped by the link above also).

>> I suppose what has me the most confused is how a developer works with a
>> remote branch: I've come to understand that a developer should never
>> check out and work on a remote branch, and always create a local one and
>> work on that. If he does that using the above hierarchy, there then
>> becomes main->projectX->featureY->jeff_local_branch_of_featureY. Or is
>> is possible for a developer to work directory on a remote branch?
> 
> As Junio noted, you can't, because they're remote. What you have in your
> local repository is a remote _tracking branch_, which is a local ref
> that tracks your idea of what the remote's branches are. And git will
> feel free to overwrite the contents of that tracking branch whenever you
> do a fetch or pull. So if you make commits on it, they are subject to
> being overwritten (and we note this property of the refs by putting them
> in the refs/remotes hierarchy, rather than refs/heads).
> 
> So in the case of our developer Jeff, his local repository will have a
> "projectX/featureY" branch that he works on. And he will also have a
> remote tracking branch "origin/projectX/featureY" which indicates where
> his local repo thinks the remote repo points. And the remote repo will
> have a "projectX/featureY" branch, of course.
> 

I'm just wondering at this point why git lets you checkout remote
tracking branches if it's something you really shouldn't do. Unless it's
something you want to be able to do in edge cases to fix screwups maybe?

>> Ah,I see... The light is beginning to come on somewhat here, though it's
>> dimmed somewhat by the remote/local branch confusion I mention above,
>> which tends to imply that rebase is only really useful in local branches
>> since it is always the outer-most branch (assuming that my understanding
>> on that is correct, which it may well not be).
> 
> Yes, although the important distinction is not so much "this is a local
> branch" but rather "this is a _published_ branch" which implies that
> other people are looking at (and possibly basing work on) it.
> 
>> I actually quite like the idea of the freezing before re-basing in the
>> sub-branches. However, to answer the question of which merge strategy
>> would work best for us I think I need to actually set this up and have a
>> play with it to see how it all pans out using the various options available.
> 
> Yes, it is easy to get into academic discussions of setups, but in
> practice you need to find a workflow that is smooth for your team.
> 
> On one web-based project I work on, we have a setup like this (which is
> very centralized):
> 
>   - a central repo resides on a development server with two branches,
>     "master" and "production"
>   - each developer clones the repo with a working tree
>   - some developers develop directly on 'master' if they have small
>     changes, or only work on one thing at a time; other developers use
>     topic branches to work on simultaneous changes
>   - any developer can push to master; it is expected that your code is
>     in a reasonable state, since it will now be consumed by other
>     developers. Anything that has made it into master is considered
>     published and should not be rebased. It is up to developers whether
>     they want to rebase their work before publishing or to simply merge.
>   - some developers communicate directly with each other: "hey, check
>     out branch 'foo' in my repo" or "what do you think of this patch?"
>   - The live site has a repo cloned from the central repo, pointing at
>     "production".
>   - there is a test site with a repo cloned from the master.
>     Occasionally the master branch is pulled and tested. If it passes,
>     it is pushed to the "production" branch. In addition, small
>     immediate fixes can go onto "production", tested, and then pushed to
>     the central repo's "production"
> 
> So this is not necessarily using the distributed nature of that much,
> but it allows those developers who aren't very comfortable with SCMs to
> stick to a "pull, hack, push" workflow. And those who want to can do
> more interesting things if it helps them.
> 

Thanks for this, it's very useful to read examples of workflows in
actual use. In fact, I was thinking the other day that it would be good
to have a site that acts as a directory of many different workflows,
including descriptions of how they work, how you actually go about
setting it up and using it day to day (i.e. lists of commands for each
role/task) and the pros/cons that it provides. I reckon that would help
newbies out quite a bit (if only for the examples). I've seen a few
individual examples of workflow but nothing like a comprehensive set of
them.

> -Peff

Thanks!

-- 

Russ

Re: Workflow question

[Junio C Hamano]

Russ Brown <pickscrape@gmail.com> writes:

> I'm just wondering at this point why git lets you checkout remote
> tracking branches if it's something you really shouldn't do. Unless it's
> something you want to be able to do in edge cases to fix screwups maybe?

You actually never checkout "remote tracking branches".

You can be in two states, either you are on a branch (meaning,
if you create a commit, the new commit will have the current tip
commit of that branch as its first parent and will become the
new tip commit of that branch), or you aren't on _any_ branch.

The latter state is often affectionately called "detached HEAD"
state.

This is primarily useful for sightseeing.  Sometimes people
would want to check out a commit that is not a tip of any
branch.  The most typical one is "I want to have a checkout of
version 2.6.17", and people call that (loosely) as "checking out
a tag".  In the same way, you can "checkout a remote tracking
branch" (but if you want to be anal in terminology, you never
"check out a tag" nor "check out a remote branch"---you are
detaching your HEAD at the named commit (which could be the one
pointed at by the tag, or the one at the tip of your remote
tracking branch).

Detached HEAD state allows you to make further commits and
merges.  Because git allows you to create a new branch from the
current commit (i.e. whatever HEAD points at, be it on any
branch or detached) without losing local changes in the index
nor the work tree, this is often handy for doing quick fixups and
experiments --- you first start on detached HEAD and if it turns
out not to be so "quick" fixup, at that point you can create a
real branch so that you can continue working on it without
losing track.

> Thanks for this, it's very useful to read examples of workflows in
> actual use. In fact, I was thinking the other day that it would be good
> to have a site that acts as a directory of many different workflows,
> including descriptions of how they work, how you actually go about
> setting it up and using it day to day (i.e. lists of commands for each
> role/task) and the pros/cons that it provides. I reckon that would help
> newbies out quite a bit (if only for the examples). I've seen a few
> individual examples of workflow but nothing like a comprehensive set of
> them.

"Everyday" might be a good starting point for catalogs of
workflows for people playing various roles.

Re: Workflow question

[Jeff King]

On Tue, Sep 25, 2007 at 09:55:38PM -0500, Russ Brown wrote:

> Yes, this is very helpful indeed: thank you for that. /me bookmarks. I
> hadn't actually realised that rebase creates new commits and replaces
> your old ones: I'd thought they just got 'moved' (dunno how I thought it
> worked though!)

It's a necessity, since the commits are named by hash, and the hash
encompasses _all_ of the history. So the same change at a different
location in history will be a different commit.

And that is why rebases can make merging harder. Git can very quickly
compare two commits by hash and say "these are the same commit", or look
at them and say "one side has these changes, the other side has these
other changes, and here is where they meet." Rebasing ruins that, since
the same changes occur in two places with different names.

> I'm just wondering at this point why git lets you checkout remote
> tracking branches if it's something you really shouldn't do. Unless it's
> something you want to be able to do in edge cases to fix screwups maybe?

Junio explained in much more detail, but I use it largely for read-only
access ("oh, let me speed-test my branch against the upstream 'master'";
git-checkout master; test test test; git-checkout mybranch).

> Thanks for this, it's very useful to read examples of workflows in
> actual use. In fact, I was thinking the other day that it would be good
> to have a site that acts as a directory of many different workflows,
> including descriptions of how they work, how you actually go about
> setting it up and using it day to day (i.e. lists of commands for each
> role/task) and the pros/cons that it provides. I reckon that would help
> newbies out quite a bit (if only for the examples). I've seen a few
> individual examples of workflow but nothing like a comprehensive set of
> them.

I agree. That sort of information is sprinkled throughout the mailing
list, but it might be nice on a wiki. I have thought of it as a sort of
"git cookbook" where you say "here is a recipe for accomplishing X". The
user manual comes close to this for smaller tasks.

-Peff

Re: Workflow question

[Andreas Ericsson]

Russ Brown wrote:
> Andreas Ericsson wrote:
>> Russ Brown wrote:
>>> Hi,
>>>
>>> I've been trying to think of a git workflow that we could use to replace
>>> our current svn/svk setup without simply using git in exactly the same
>>> way that we use svn/svk.
>>>
>>> Basically, we develop, maintain and enhance a website. On the central
>>> repo is trunk which represents live, and any number of project branches.
>>> Developers don't use local branches: they check out the project branches
>>> they're working on and commit to those. Developers merge from trunk to
>>> project branch from time to time to keep them current, and when a
>>> project rolls out the branch is merged to trunk.
>>>
>>> In addition to the obvious advantages that git would give us (such as
>>> properly tracking that code author as opposed to the person who did the
>>> merge), I'm wanting to gain the following benefits:
>>>
>>>  * The repository is very large (multiple gigabytes) and mirroring using
>>> svk obviously takes a lot of time and space, so I'm keen to bring that
>>> down, most likely by the developer not needing to mirror branches he
>>> doesn't care about, or by being able to throw away branches he's done
>>> with.
>>>  * The repository is full of revisions that fail review (or break
>>> things) and are fixed by subsequent revisions. We'd much rather be able
>>> to have the developer fix his revisions before they get committed
>>> 'upstream' (whatever that ends up meaning).
>>>
>>> I asked earlier about the email-based model that git itself uses, and
>>> while it appears to work very well for a widely-dispersed open-source
>>> project, I think it will be too cumbersome and slow for a fast-paced
>>> internal development team who make a number of live releases every day.
>>>
>> We came to the same conclusion at our workplace. Email works great, but
>> it's faster and better to just walk over to your colleague and ask what
>> he/she thinks about something.
>>
> 
> Very true, with the minor exception that at my place there are
> developers working at different sites, so the walk-over method will only
> work for specific subsets of the team. :)
> 

So do what Peff suggested and use emails for code-review and git-pull/push
for shoveling the code around. He's got some valid points. Where I work,
there's mostly three or at most four developers at any one team, so paired
programming or walking over works quite well. Otherwise we'd likely use the
patch-emails-for-review thing.


> Here's a question: is the creation and deletion of a branch also version
> controlled as it is in Subversion? In other words, if I create a branch,
> develop on it and delete it without merging it anywhere, will the
> revisions hang around and get pulled down by future people cloning the
> repository, or do they get thrown away?
> 

They don't get thrown away unless you garbage-collect them, using git-gc,
but they won't get propagated unless they can't be reached from a 'ref'
or a ref's log. The refs that can be propagated between repos are tags
and branches. There are others too, but they are less user-visible and
oftentimes more for housekeeping than anything else.

>>
>>>  4. Developers create a local branch of the project they
>>> are working on and commit to that.
>>>  5. Once they think they're done, they publish their branch to the
>>> development repo and request for comments.
>> Using topic-branches is a much better strategy, usually, since that
>> allows each feature to be evaluated and improved on on its own, rather
>> than having to merge *all* of a particular developers changes just to
>> get desirable feature X. Note that cherry-pick provides ways of doing
>> that anyways, but in a much less elegant way, and your integrator/
>> release engineer will likely tear his hair out on a daily basis without
>> topic branches.
>>
> 
> I've seen the term 'topic-branch' used here quite a bit but it's
> unfamiliar to me. It is basically synonymous with what we call a
> 'project branch'? i.e. Management decide that feature X is required so
> we create a branch to develop it on which all developers on the project
> commit to.
> 

Pretty much, yes. 'feature branch' and 'topic branch' are interchangeable.

> Note that in step 4 above I mean the developer takes a local branch of
> the topic branch. For example, we start projectX/main, and create branch
> projectX on the shared repo. Developer 'jeff' works on the project and
> so creates local branch projectX/jeff and begins work. In step 5 they
> push this local branch to the shared repo so everyone can see it
> (alternative to the 'walk-over' method or emailing). Note that all
> changes jeff making in projectX/jeff are specific to the project branch,
> so he can rebase against other changes that get committed to that
> project branch.
> 
> If colleagues don't like his changes he can create projectXjeff2 and try
> again.
> 
> Jeff can also have other local branches to keep separate changes he is
> making on the other projects he is involved in.
> 
> That's how I'd thought of it happening...
> 

Ye, that sounds about right.

>>>  6. If all is not well, the developer creates a new local branch and
>>> moves good revisions from his previous one to the new one, modifying
>>> things as he goes, and republishes his new branch.
>>>  7. If all is well, their works gets merged or rebased onto the main
>>> project branch, and once that's ready it gets pushed to the master and
>>> rolled to live. The developer's individual branches get deleted from the
>>> dev repo since they're no longer required.
>> Topic branches would work the same, basically, except they can be pushed up
>> for review a lot faster.
>>
>> If all the pushing gets cumbersome, it also makes it easy to send the
>> patches
>> out as emails for discussion. It's usually easier to let git handle the
>> actual code transmissions, but discussing patches in emails works quite
>> well if it's intended for a wider audience.
>>
> 
> Yes, I am going to experiment with this a little too to see just how
> much work it would involve for the developers (if it's too much they
> won't do it) :)
> 

It's a slightly steeper starting cost, but the maintenance costs go way
down, so the developers can spend more of their time doing fun and new
stuff rather than figuring out how to get their already-ancient fixes
merged to the master-branch.

>>>  8. From time to time the master branch gets merged to the project
>>> branches. Developer's local branches can be rebased against the project
>>> branch as they please.
>>>
>> criss-cross merging can turn kinda nasty though, as you may have a hard
>> time
>> finding *the* common point when you run into that rogue merge with conflict
>> markers everywhere (it happens for everyone sooner or later).
>>
>> I'd suggest you rebase the developer/topic branches onto master with
>> regular
>> intervals instead.
>>
> 
> Having been using git-svn for a while I really like the clean history
> result that rebase gives, however my understanding was that you should
> never rebase any published branch as it could screw up clones of that
> branch. In fact, this is what has me the most confused: how to rebase a
> project branch that is on a shared repository against master when
> everyone will have it cloned? Or is this something that I clearly don't
> understand properly?
> 

Well, afaiu you want every developer to have his own topic-branch, in
which case they can simply rebase those topic-branches onto master,
which will make sure they always know they're conflict-free with the
latest bugfixes and whatnot.

They don't really have to push their changes upstream until they're
ready for review.

> (Thanks for your answers BTW Andreas)
> 

np. Happy to help :)

-- 
Andreas Ericsson                   andreas.ericsson@op5.se
OP5 AB                             www.op5.se
Tel: +46 8-230225                  Fax: +46 8-230231