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From: Junio C Hamano <junkio@cox.net>
To: Petr Baudis <pasky@ucw.cz>
Cc: Linus Torvalds <torvalds@osdl.org>, git@vger.kernel.org
Subject: Re: Merge with git-pasky II.
Date: Thu, 14 Apr 2005 16:12:34 -0700	[thread overview]
Message-ID: <7vmzs1osv1.fsf@assigned-by-dhcp.cox.net> (raw)
In-Reply-To: <20050414193507.GA22699@pasky.ji.cz> (Petr Baudis's message of "Thu, 14 Apr 2005 21:35:07 +0200")

>>>>> "PB" == Petr Baudis <pasky@ucw.cz> writes:

PB> What I would like your script to do is therefore just do the
PB> merge in a given already prepared (including built index)
PB> directory, with a passed base. The base should be determined
PB> by a separate tool (I already saw some patches); most future
PB> "science" will probably go to a clever selection of this
PB> base, anyway.

I think you are contradicting yourself for saying the above
after agreeing with me that the script should just work on trees
not commits.  My understanding is that the tools is just to
merge two related trees relative to another ancestor tree,
nothing more.  Especially, it should not care what is in the
working directory---that is SCM person's business.

I am just trying to follow my understanding of what Linus
wanted.  One of the guiding principle is to do as much things as
in dircache without ever checking things out or touching working
files unnecessarily.

PB> This will give the tool maximal flexibility.

I suspect it would force me to have a working directory
populated with files, just to do a merge.

PB> I'm all for an -o, and I don't mind ,, - I just don't want it uselessly
PB> long. I hope "git~merge~$$" was a joke... :-)

Which part do you object to?  PID part?  or tilde?  Would
git~merge do, perhaps?  It probably would not matter to you
because as an SCM you would always give an explicit --output
parameter to the script anyway.

PB> By the way, what about indentation with tabs? If you have a
PB> strong opinion about this, I don't insist - but if you
PB> really don't mind/care either way, it'd be great to use tabs
PB> as in the rest of the git code.

I do not have a strong opinion, but it is more trouble for me
only because I am lazy and am used to the indentation my Emacs
gives me.  I write code other than git, so changing Perl-mode
indentation setting globally for all .pl files is not an option
for me.  I'll see what I can do when I have time.

PB> Is there a fundamental reason why the directory cache
PB> contains the ancestor instead of the destination branch?

Because you are thinking as an SCM person where there are
distinction between tree-A and tree-B, two heads being merged.
There is no "destination branch" nor "source branch" in what I
am doing.  It is a merge of two equals derived from the same
ancestor.

PB> I think the script actually does not fundamentally depend on it. My main
PB> motivation is that the user can then trivially see what is he actually
PB> going to commit to his destination branch, which would be bought for
PB> free by that.

And again the user is *not* commiting to his "destination
branch".  At the level I am working at, the merge result should
be commited with two -p parameters to commit-tree --- tree-A and
tree-B, both being equal parents from the POV of git object
storage.

PB> And this is another thing I dislike a lot. I'd like merge-tree.pl to
PB> leave my directory cache alone, thank you very much. You know, I see
PB> what goes to the directory cache as actually part of the policy part.

Remember I am not touching *your* dircache.  It is a dircache in
the temporary merge area, specifically set up to help you review
the merge.  

Can't the SCM driver do things along this line, perhaps?

 - You have your working files and your dircache.  They may not
   match because you have uncommitted changes to your
   environment.  You want to merge with Linus head.  You know
   its SHA1 (call it COMMIT-Linus).  Your SCM knows which commit
   you started with (call it COMMIT-Current).

 - First you merge the tree associated with COMMIT-Current.  Use
   it and COMMIT-Linus to find the common ancestor to use.

 - Now use the tree SHA of COMMIT-Current, tree SHA1 of
   COMMIT-Linus, and tree SHA1 of the common ancestor commit to
   drive git-merge.perl (to be renamed ;-).  You will get a
   temporary directory.  Have your user examine what is in
   there, and fix the merge and have them tell you they are
   happy.

 - You go to that temporary directory, do write-tree and
   commit-tree with -p parameter of COMMIT-Linus and
   COMMIT-Current.  This will result in a new commit.  Call that
   COMMIT-Merge.

 - You, as an SCM, should know what your user have done in the
   working directory relative to COMMIT-Current.  Especially you
   should know the set of paths involved in that change.  Go in
   to the temporary area, checkout-cache those files if you have
   not done so.  Apply the changes you have there.  Optionally
   have the user examine the changes and have him confirm.  Lift
   those files into the user's working directory.

 - Do your bookkeeping like "echo COMMIT-Merge >.git/Head", to
   make the user's working files based on COMMIT-Merge, and run
   read-tree using the COMMIT-Merge in the user's working
   directory.  At this point, show-diff output should show what
   the changes your user have had made if he had started working
   based on COMMIT-Merge instead of starting from
   COMMIT-Current.

I think the above would result in what SCM person would call
"merge upstream/sidestream changes into my working directory".


  parent reply	other threads:[~2005-04-14 23:10 UTC|newest]

Thread overview: 148+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-04-14  0:29 Merge with git-pasky II Petr Baudis
2005-04-13 21:25 ` Christopher Li
2005-04-14  0:45   ` Petr Baudis
2005-04-13 22:00     ` Christopher Li
2005-04-14  3:51     ` Linus Torvalds
2005-04-14  1:23       ` Christopher Li
2005-04-14  5:03         ` Paul Jackson
2005-04-14  2:16           ` Christopher Li
2005-04-14  6:16             ` Paul Jackson
2005-04-14  7:05       ` Junio C Hamano
2005-04-14  8:06         ` Linus Torvalds
2005-04-14  8:39           ` Junio C Hamano
2005-04-14  9:10             ` Linus Torvalds
2005-04-14 11:14               ` Junio C Hamano
2005-04-14 12:16                 ` Petr Baudis
2005-04-14 18:12                   ` Junio C Hamano
2005-04-14 18:36                     ` Linus Torvalds
2005-04-14 19:59                       ` Junio C Hamano
2005-04-14 20:20                         ` Petr Baudis
2005-04-15  0:42                         ` Linus Torvalds
2005-04-15  2:33                           ` Barry Silverman
2005-04-15 10:02                           ` David Woodhouse
2005-04-15 15:32                             ` Linus Torvalds
2005-04-15 16:01                               ` David Woodhouse
2005-04-15 16:31                                 ` C. Scott Ananian
2005-04-15 17:11                                   ` Linus Torvalds
2005-04-16 15:33                                 ` Johannes Schindelin
2005-04-17 13:14                                   ` David Woodhouse
2005-04-15 19:20                               ` Paul Jackson
2005-04-16  1:44                               ` Simon Fowler
2005-04-16 12:19                                 ` David Lang
2005-04-16 15:55                                   ` Simon Fowler
2005-04-16 16:03                                     ` Petr Baudis
2005-04-16 16:26                                       ` Simon Fowler
2005-04-16 16:26                                       ` Linus Torvalds
2005-04-16 23:02                                         ` David Lang
2005-04-17 14:52                                         ` Ingo Molnar
2005-04-17 15:08                                           ` Brad Roberts
2005-04-17 15:18                                             ` Ingo Molnar
2005-04-17 15:28                                           ` Ingo Molnar
2005-04-17 17:34                                             ` Linus Torvalds
2005-04-17 22:12                                               ` Herbert Xu
2005-04-17 22:35                                                 ` Linus Torvalds
2005-04-17 23:29                                                   ` Herbert Xu
2005-04-17 23:34                                                     ` Petr Baudis
2005-04-17 23:53                                                       ` Kenneth Johansson
2005-04-18  0:49                                                       ` Herbert Xu
2005-04-18  0:55                                                         ` Petr Baudis
2005-04-17 23:50                                                     ` Linus Torvalds
2005-04-18  4:16                                               ` Sanjoy Mahajan
2005-04-18  7:42                                               ` Ingo Molnar
2005-04-16 20:29                               ` Sanjoy Mahajan
2005-04-16 20:41                                 ` Linus Torvalds
2005-04-15  2:21                       ` [Patch] ls-tree enhancements Junio C Hamano
2005-04-15 16:13                         ` Petr Baudis
2005-04-15 18:25                           ` Junio C Hamano
2005-04-15  9:14                       ` Merge with git-pasky II David Woodhouse
2005-04-15  9:36                         ` Ingo Molnar
2005-04-15 10:05                           ` David Woodhouse
2005-04-15 14:53                             ` Ingo Molnar
2005-04-15 15:09                               ` David Woodhouse
2005-04-15 12:03                         ` Johannes Schindelin
2005-04-15 10:22                           ` Theodore Ts'o
2005-04-15 14:53                         ` Linus Torvalds
2005-04-15 15:29                           ` David Woodhouse
2005-04-15 15:51                             ` Linus Torvalds
2005-04-15 15:54                           ` Paul Jackson
2005-04-15 16:30                             ` C. Scott Ananian
2005-04-15 18:29                               ` Paul Jackson
2005-04-14 18:51                     ` Christopher Li
2005-04-14 19:35                     ` Petr Baudis
2005-04-14 20:01                       ` Live Merging from remote repositories Barry Silverman
2005-04-14 23:22                         ` Junio C Hamano
2005-04-15  1:07                           ` Question about git process model Barry Silverman
2005-04-14 20:23                       ` Re: Merge with git-pasky II Erik van Konijnenburg
2005-04-14 20:24                         ` Petr Baudis
2005-04-14 23:12                       ` Junio C Hamano [this message]
2005-04-14 20:24                         ` Christopher Li
2005-04-14 23:31                         ` Petr Baudis
2005-04-14 20:30                           ` Christopher Li
2005-04-14 20:37                             ` Christopher Li
2005-04-14 20:50                               ` Christopher Li
2005-04-15  0:58                           ` Junio C Hamano
2005-04-14 22:30                             ` Christopher Li
2005-04-15  7:43                               ` Junio C Hamano
2005-04-15  6:28                                 ` Christopher Li
2005-04-15 11:11                                   ` Junio C Hamano
     [not found]                                     ` <7vaco0i3t9.fsf_-_@assigned-by-dhcp.cox.net>
2005-04-15 18:44                                       ` write-tree is pasky-0.4 Linus Torvalds
2005-04-15 18:56                                         ` Petr Baudis
2005-04-15 20:13                                           ` Linus Torvalds
2005-04-15 22:36                                             ` Petr Baudis
2005-04-16  0:22                                               ` Linus Torvalds
2005-04-16  1:13                                                 ` Daniel Barkalow
2005-04-16  2:18                                                   ` Linus Torvalds
2005-04-16  2:49                                                     ` Daniel Barkalow
2005-04-16  3:13                                                       ` Linus Torvalds
2005-04-16  3:56                                                         ` Daniel Barkalow
2005-04-16  6:59                                                         ` Paul Jackson
2005-04-16 15:34                                                 ` Re: Re: " Petr Baudis
2005-04-15 20:10                                         ` Junio C Hamano
2005-04-15 20:58                                           ` C. Scott Ananian
2005-04-15 21:22                                             ` Petr Baudis
2005-04-15 23:16                                             ` Junio C Hamano
2005-04-15 21:48                                           ` [PATCH 1/2] merge-trees script for Linus git Junio C Hamano
2005-04-15 21:54                                             ` [PATCH 2/2] " Junio C Hamano
2005-04-15 23:33                                             ` [PATCH 3/2] " Junio C Hamano
2005-04-16  1:02                                               ` Linus Torvalds
2005-04-16  4:10                                                 ` Junio C Hamano
2005-04-16  5:02                                                   ` Linus Torvalds
2005-04-16  6:26                                                     ` Linus Torvalds
2005-04-16  8:12                                                     ` Junio C Hamano
2005-04-16  9:27                                                       ` [PATCH] Byteorder fix for read-tree, new -m semantics version Junio C Hamano
2005-04-16 10:35                                                       ` [PATCH 1/2] Add --stage to show-files for new stage dircache Junio C Hamano
2005-04-16 10:42                                                         ` [PATCH 2/2] " Junio C Hamano
2005-04-16 14:03                                                       ` Issues with higher-order stages in dircache Junio C Hamano
2005-04-17  5:11                                                         ` Junio C Hamano
2005-04-17  5:31                                                           ` Linus Torvalds
2005-04-17  6:01                                                             ` Junio C Hamano
2005-04-17 10:00                                                         ` Summary of "read-tree -m O A B" mechanism Junio C Hamano
2005-04-16 15:28                                                       ` [PATCH 3/2] merge-trees script for Linus git Linus Torvalds
2005-04-16 16:36                                                         ` Linus Torvalds
2005-04-16 17:14                                                           ` Junio C Hamano
2005-04-15 19:54                             ` Re: Merge with git-pasky II Petr Baudis
2005-04-15 10:22                           ` Junio C Hamano
2005-04-15 20:40                             ` Petr Baudis
2005-04-15 22:41                               ` Junio C Hamano
2005-04-15 19:57           ` Junio C Hamano
2005-04-15 20:45             ` Linus Torvalds
2005-04-14  0:30 ` Petr Baudis
2005-04-14 22:11 ` git merge Petr Baudis
     [not found] <000d01c541ed$32241fd0$6400a8c0@gandalf>
2005-04-15 20:31 ` Merge with git-pasky II Linus Torvalds
2005-04-15 23:00   ` Barry Silverman
2005-04-16  0:32     ` Linus Torvalds
  -- strict thread matches above, loose matches on Subject: below --
2005-04-26 18:55 Bram Cohen
2005-04-26 19:58 ` Linus Torvalds
2005-04-26 20:30   ` Tom Lord
2005-04-26 20:31   ` Bram Cohen
2005-04-26 20:39     ` Tom Lord
2005-04-26 20:58     ` Linus Torvalds
2005-04-26 21:25       ` Linus Torvalds
2005-04-26 21:28       ` Bram Cohen
2005-04-26 21:36         ` Fabian Franz
2005-04-26 22:30           ` Linus Torvalds
2005-04-26 22:25         ` Linus Torvalds
2005-04-28  0:42           ` Petr Baudis
2005-04-26 21:26     ` Diego Calleja
2005-04-26 20:31   ` Daniel Barkalow
2005-04-26 20:44     ` Tom Lord

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