Re: Default remote branch for local branch

5 messages, 3 authors, 2016-06-15 · open the first message on its own page

Re: Default remote branch for local branch

From: Junio C Hamano <hidden>
Date: 2016-06-15 22:42:23

Josef Weidendorfer [off-list ref] writes:
On Saturday 01 April 2006 06:18, Pavel Roskin wrote:
quoted
On Fri, 2006-03-31 at 19:05 -0800, Junio C Hamano wrote:
quoted
Maybe you would want something like this.

In $GIT_DIR/config:

	[pull]
	origin = linus for master
        origin = irq-pio of libata for ata-irq-pio
        origin = pata-drivers of libata for ata-pata
Let me try to understand this: the general idea is that

  pull.origin = [<refspec> of] <remote> for <branch>

specifies the default action of git-pull if we are on <branch>, ie.
a "git pull" then runs "git pull <remote> [<refspec>]".
Not quite.

It will be (if this were a serious proposal -- I am not
absolutely convinced this is a good idea) more like "git fetch
<remote>" followed by "git-merge HEAD the-refspec-named-there".
The implementation of the above would involve changes to
git-fetch, because it needs to give ".not-for-merge" mark to
different line in FETCH_HEAD depending on [<refspec> of] part.
So the example above, if .git/remotes/linus would contain two
refspecs, and you are on the branch of the 2nd refspec, it would
do the wrong thing: merge the 1st refspec with current branch.
Sorry I fail to visualize this part.
quoted
Secondly, I think the relationship should be between a local development
branch and a local tracking branch.
Agree.
It is also useful to specify this relation if the upstream is purely a
local branch, e.g. when branching off a local branch, and you want to
pull in changes from the local upstream.

This works automatically if git-pull only does upstream fetching if
there is a remote branch associated. The default action of git-fetch
similar could be "fetch the upstream branch, if that tracks a remote
branch", using the same configuration.
Interesting.  

You would need sanity checker for $GIT_DIR/remotes/* files if
you do this to make sure no local tracking branch is by mistake
configured to track two remote branches, which is a good change,
but then:

	git-pull, without parameter, would:

        (1) check if this branch has any local branch it usually
            merges from; if not, do whatever we traditionally
            did (or barf).

        (2) if there is a local branch it merges from, check if
            it is a tracking branch for a remote, by looking at
            remotes/* files.  It would be nice if we could
            detect tracking branches fed from external svn/cvs
            repositories via svn/cvs-import this way at this
            time.  If not, skip the next step and go directly to
            (4).

        (3) run git-fetch (or svn/cvs-import) to update the
            tracking branch;

        (4) merge from that other local branch.
Junio's proposal has the advantage that you do not have to search in all
files in .git/remotes (and even .git/branches) for the remote branch that
maps to a given local branch.
But that is not the big issue.
A bigger thing is that I am trying to avoid _requiring_ tracking
branches.  If you are not micromanaging your subsystem
maintainers, you should not have to care where they were the
last time you pulled from them.  You should be able to just
pull, examine what the merge brings in, and decide it is worth
merging.  If it isn't, do a "reset", tell them "not good, please
rework and let me know when you are ready," and forget about it.

If we are going require tracking branches, we could do a bit
more with them, like remembering where the tip was when we
fetched the last time (or the time before that...) and diff with
that, but the tracking branch heads are not set up to do things
like that right now -- they are single pointers.
quoted
Perhaps you are missing a remotes editor command?
Perhaps.  Also perhaps a remotes/ sanity checker.
Something like this:

	$ git branch --describe ata-pata
        Typically merges from pata-drivers branch of
        	git://.../jgarzik/libata-dev.git
	which is tracked with local refs/remotes/libata/pata-drivers.

	$ git branch --decribe refs/remotes/libata/pata-drivers
	Tracking branch for pata-drivers branch of
               	git://.../jgarzik/libata-dev.git

	$ git checkout origin
        warning: you are checking out a tracking branch for "master" branch of
	warning:	git://.../torvalds/linux-2.6.git
	warning: commit/pull/merge commands are disabled.
	hint: you can still create a new branch from here.

Re: Default remote branch for local branch

From: Josef Weidendorfer <hidden>
Date: 2016-06-15 22:42:23

On Sunday 02 April 2006 23:40, you wrote:
quoted
Let me try to understand this: the general idea is that

  pull.origin = [<refspec> of] <remote> for <branch>

specifies the default action of git-pull if we are on <branch>, ie.
a "git pull" then runs "git pull <remote> [<refspec>]".
Not quite.

It will be (if this were a serious proposal -- I am not
absolutely convinced this is a good idea) more like "git fetch
<remote>" followed by "git-merge HEAD the-refspec-named-there".
So it is not really a <refspec>, but a <localbranch> which has to
appear in the .git/remotes file on the right side of a refspec on
a Pull line.
Then, I think it is redundant to specify the <remote>, as
this can be detected by looking at the .git/remotes files and
searching for <localbranch>.
quoted
So the example above, if .git/remotes/linus would contain two
refspecs, and you are on the branch of the 2nd refspec, it would
do the wrong thing: merge the 1st refspec with current branch.
Sorry I fail to visualize this part.
All I wanted to remark is, that, with

 URL: <remote-URL>
 Pull: refs/head/master:refs/head/remote1
 Pull: refs/head/other:refs/head/remote2

the config

 pull.origin = <remote> for refs/head/my-devel-for-remote2

which does not use the [<refspec> of] part, always is bogus:
We get remote1 merged into my-devel-for-remote2 on a git-pull,
which is not what we want.
quoted
It is also useful to specify this relation if the upstream is purely a
local branch, e.g. when branching off a local branch, and you want to
pull in changes from the local upstream.
Interesting.

You would need sanity checker for $GIT_DIR/remotes/* files if
you do this to make sure no local tracking branch is by mistake
configured to track two remote branches,
Why should this always be a mistake? If you have two developers
doing topic branches for you, you could use this type of config
to make "git-pull" fetching both remotes, and creating an
octopus merge.

And for your "next", you could use this to make "git-pull" merge
both from the stable branch and all topics.
which is a good change, 
The sanity checker probably should be put into a branch attribute
editor which allows to add the config discussed here. And it
should only print a warning when you are trying to add multiple
upstreams.
but then:

	git-pull, without parameter, would:

        (1) check if this branch has any local branch it usually
            merges from; if not, do whatever we traditionally
            did (or barf).
Yes. This is simply looking up the config.
We could automatically add such a config when branching off to
specify the upstream of a branch.
And git-clone should set this, too, and: We get rid of the current
"origin" hardcoded special handling.

Optionally, branching <new> off from <old> could add <new> as
topic branch of <old>: Thus, if you are on <old> and do git-pull,
you get <new> merged in.
        (2) if there is a local branch it merges from, check if
            it is a tracking branch for a remote, by looking at
            remotes/* files.  It would be nice if we could
            detect tracking branches fed from external svn/cvs
            repositories via svn/cvs-import this way at this
            time.
Good idea. I suppose this needs an entry in .git/remotes like

 URL: ...
 Type: SVN 
            If not, skip the next step and go directly to 
            (4).

        (3) run git-fetch (or svn/cvs-import) to update the
            tracking branch;
If (1) found multiple branches, do (2)/(3) for every branch.
        (4) merge from that other local branch.
Or for multiple, do an octopus.

A bigger thing is that I am trying to avoid _requiring_ tracking
branches.
I don't think you force anything when you add functionality to git-pull
for the config discussed here. Nobody *has* to use this config - it's
a porcelain thingie.

Cogito could use this, too. AFAIK, it has the same origin/master hardcoded
tracking behavior.
If you are not micromanaging your subsystem 
maintainers, you should not have to care where they were the
last time you pulled from them.  You should be able to just
pull, examine what the merge brings in, and decide it is worth
merging.  If it isn't, do a "reset", tell them "not good, please
rework and let me know when you are ready," and forget about it.

If we are going require tracking branches,
I do not understand. Why should we require this?
we could do a bit 
more with them, like remembering where the tip was when we
fetched the last time (or the time before that...) and diff with
that, but the tracking branch heads are not set up to do things
like that right now -- they are single pointers.
quoted
quoted
Perhaps you are missing a remotes editor command?
Perhaps.  Also perhaps a remotes/ sanity checker.
Something like this:
...
Doing this as part of git-branch sounds good.

Josef

Re: Default remote branch for local branch

From: Andreas Ericsson <hidden>
Date: 2016-06-15 22:42:23

Josef Weidendorfer wrote:
Optionally, branching <new> off from <old> could add <new> as
topic branch of <old>: Thus, if you are on <old> and do git-pull,
you get <new> merged in.
This is clearly insane. If I'm on <old> and want to sync with my 
upstream source that would be impossible without explicitly telling it 
*not* to merge with <new>. Iow, this change would (possibly) simplify 
for the one repo maintainer, but make things harder for the 30-odd 
developers.

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

Re: Default remote branch for local branch

From: Josef Weidendorfer <hidden>
Date: 2016-06-15 22:42:23

On Monday 03 April 2006 09:56, Andreas Ericsson wrote:
Josef Weidendorfer wrote:
quoted
Optionally, branching <new> off from <old> could add <new> as
topic branch of <old>: Thus, if you are on <old> and do git-pull,
you get <new> merged in.
This is clearly insane. If I'm on <old> and want to sync with my 
upstream source that would be impossible without explicitly telling it 
*not* to merge with <new>. Iow, this change would (possibly) simplify 
for the one repo maintainer, but make things harder for the 30-odd 
developers.
Yes.
Therefore I put "optionally" above. But you are right, mixing up
"merge upstream" and "merge downstream" into one config option is insane.

Some idea independent but related:
I still think it is a better UI of a porcelain to try to note metainfo
automatically, ie. storing somewhere that we branched one off another.
What about adding "branch.topic" config option for this?
"git-branch -t newtopic"/"git-checkout -b newtopic -t"
would create a new topic branch, which is remembered in "branch.topic",
and "git-pull -t" merges these topic branches?
To specify that a remote branch is a topic branch of a given local
branch (to be pulled into with "git-pull -t"), we could add
"git-branch --add-topic <refspec>|<remoteURL>".

Josef

Re: Default remote branch for local branch

From: Andreas Ericsson <hidden>
Date: 2016-06-15 22:42:23

Josef Weidendorfer wrote:
On Monday 03 April 2006 09:56, Andreas Ericsson wrote:
quoted
Josef Weidendorfer wrote:
quoted
Optionally, branching <new> off from <old> could add <new> as
topic branch of <old>: Thus, if you are on <old> and do git-pull,
you get <new> merged in.
This is clearly insane. If I'm on <old> and want to sync with my 
upstream source that would be impossible without explicitly telling it 
*not* to merge with <new>. Iow, this change would (possibly) simplify 
for the one repo maintainer, but make things harder for the 30-odd 
developers.

Yes.
Therefore I put "optionally" above. But you are right, mixing up
"merge upstream" and "merge downstream" into one config option is insane.

Some idea independent but related:
I still think it is a better UI of a porcelain to try to note metainfo
automatically, ie. storing somewhere that we branched one off another.
What about adding "branch.topic" config option for this?
"git-branch -t newtopic"/"git-checkout -b newtopic -t"
would create a new topic branch, which is remembered in "branch.topic",
and "git-pull -t" merges these topic branches?
To specify that a remote branch is a topic branch of a given local
branch (to be pulled into with "git-pull -t"), we could add
"git-branch --add-topic <refspec>|<remoteURL>".
Sorry, but I still don't see the use of it. Usually, some topics mature 
faster than others, meaning I'd still have to do the old "git pull . 
this and that", leaving "the-other-one" to soak a bit longer. What 
you're suggesting would make the odd case easier while adding nothing 
for the normal flow.

For archeological purposes it might make some sense to record what the 
branch was named that you forked from, but to me it's more interesting 
to see which state the code was in when the code forked, and this is 
discernable by the merge-base command.

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