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[PATCH v2] submodule: Allow tracking of the newest revision of a branch in a submodule

From
FFFabian Franz <git@fabian-franz.de>
Date
Dec 11, 2008, 13:16 UTC
Message-ID
<1229001361-9301-1-git-send-email-git@fabian-franz.de>

Submodules currently only allow tracking a specific revision and each update in a submodule leads to a new commit in the master repository. However some users may want to always track the newest revision of a specific (named) tag or branch or HEAD. For example the user might want to track a staging branch in all submodules.

To allow this the "--track|-t <branch>" parameter was added to git-submodule.sh, which is added to .gitmodules config file as well as "track" parameter. This creates a new local branch on checkout, which is tracking the remote branch in case the local branch does not yet exist.

Technically the gitlink code was changed to always compare successful (so no changes) in case the sha1 is null. In that case no new commit is created when there are changes in the submodule.

The submodule code is adding the file with 0000* on "add".

Signed-off-by: Fabian Franz <git@fabian-franz.de>
---
On Tue, Dec 9, 2008 at 01:57, Fabian Franz <git@xxxxxxxxxxxxxxx> wrote:
>> Technically the gitlink code was changed to read .git/HEAD.gitlink
>> if it exists instead of the normal HEAD. If you add 0000* as sha1
>> sum to .git/HEAD.gitlink the submodule code will always fetch HEAD.
>This feels like the porcelain "fooling" the plumbing. How about
>something like this instead:
>This should make the plumbing happy no matter which commit is actually
>checked out in the submodule (not actually tested...). 
Yeah, that works, thank you very much.
>Then, cmd_update() can check if the requested sha1 is all '0' and
>fetch+checkout latest HEAD (or some branch) without playing games with
>.git/HEAD.gitlink.
Okay. I do agree that this solution is much nicer.
>Finally, cmd_add() needs to update the index in the
>containing repository with the magic '0*' sha1 if '--track' is
>specifed. This can be achieved by replacing 'git add $path' with 'echo
>$mode $sha1\t$path | git update-index --index-info'.
>What do you think?
I added that solution and it does work. However I see problems on remove (thought there is no submodule remove so far):
Neither a new git add nor a git rm nor a git-update-index --remove do work afterwards.
This can just be done by doing the above command with some non-null sha1.
Show 5 quoted lines
>> @@ -327,10 +335,14 @@ cmd_update()
>>                        say "Maybe you want to use 'update --init'?"
>>                        continue
>>                fi
>> +               track=$(git config -f .gitmodules submodule."$name".track)
>I'm pretty certain that we don't want to use info from .gitmodules in
>cmd_update(). Instead, cmd_init() probably should move the info from
>.gitmodules into .git/config and cmd_update() should check the latter.
Okay, I did this, however now I need a flag for init to be able to specify -f or a initalways command shortcut, so I can do in script:

git checkout staging # changes track = staging in .gitmodules git submodule init -f git submodule update # changes all branches to staging

Should I add this in a different patch?
Talking about script: Is there a possibility for a checkout hook?
Does something like that exist? Or do I need to add this myself, too?
So my workflow really is:

git checkout master # done long before [...] git checkout staging # => in submodules/client/ # Checked out submodules/client/ staging. # => in submodules/client/component1/ # Checked out submodules/client/component/1 staging.

So I would like to have this recursively and I think a post checkout hook would be nice for that to achieve.
>Btw: cmd_status() probably also needs some modifications to handle
>this special case.
I added the special case.
Here is the new patch.
What do you think?
Or do we need a track and untrack command for the rm of a submodule to work properly?
Best Wishes,
Fabian
 Documentation/git-submodule.txt |   10 +++++++++-
 git-submodule.sh                |   38 ++++++++++++++++++++++++++++++++++++--
 read-cache.c                    |    5 +++++
 3 files changed, 50 insertions(+), 3 deletions(-)
diff --git a/Documentation/git-submodule.txt b/Documentation/git-submodule.txt
index babaa9b..9c29678 100644
--- a/Documentation/git-submodule.txt
+++ b/Documentation/git-submodule.txt
@@ -9,7 +9,7 @@ git-submodule - Initialize, update or inspect submodules
 SYNOPSIS
 --------
 [verse]
-'git submodule' [--quiet] add [-b branch] [--] <repository> <path>
+'git submodule' [--quiet] add [-b branch] [-t|--track <branch>] [--] <repository> <path>
 'git submodule' [--quiet] status [--cached] [--] [<path>...]
 'git submodule' [--quiet] init [--] [<path>...]
 'git submodule' [--quiet] update [--init] [--] [<path>...]
@@ -118,6 +118,10 @@ update::
 If the submodule is not yet initialized, and you just want to use the
 setting as stored in .gitmodules, you can automatically initialize the
 submodule with the --init option.
++
+If you used --track or set the "track" option in .gitmodules this will
+automatically pull the newest updates from remote instead of tracking a
+specific revision.
 
 summary::
 	Show commit summary between the given commit (defaults to HEAD) and
@@ -159,6 +163,10 @@ OPTIONS
 --branch::
 	Branch of repository to add as submodule.
 
+-t::
+--track::
+	Branch/Tag/HEAD of repository to track in a submodule.
+
 --cached::
 	This option is only valid for status and summary commands.  These
 	commands typically use the commit found in the submodule HEAD, but
diff --git a/git-submodule.sh b/git-submodule.sh
index 2f47e06..f25e744 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -5,7 +5,7 @@
 # Copyright (c) 2007 Lars Hjemli
 
 USAGE="[--quiet] [--cached] \
-[add <repo> [-b branch] <path>]|[status|init|update [-i|--init]|summary [-n|--summary-limit <n>] [<commit>]] \
+[add <repo> [-b branch] [--track|-t <branch>] <path>]|[status|init|update [-i|--init]|summary [-n|--summary-limit <n>] [<commit>]] \
 [--] [<path>...]|[foreach <command>]|[sync [--] [<path>...]]"
 OPTIONS_SPEC=
 . git-sh-setup
@@ -16,6 +16,7 @@ command=
 branch=
 quiet=
 cached=
+track=
 
 #
 # print stuff on stdout unless -q was specified
@@ -130,6 +131,11 @@ cmd_add()
 		-q|--quiet)
 			quiet=1
 			;;
+		-t|--track)
+			case "$2" in '') usage ;; esac
+			track=$2
+			shift
+			;;
 		--)
 			shift
 			break
@@ -197,12 +203,14 @@ cmd_add()
 		(unset GIT_DIR; cd "$path" && git checkout -f -q ${branch:+-b "$branch" "origin/$branch"}) ||
 		die "Unable to checkout submodule '$path'"
 	fi
+	[ -n "$track" ] && echo "160000 0000000000000000000000000000000000000000\t$path" | git update-index --index-info
 
 	git add "$path" ||
 	die "Failed to add submodule '$path'"
 
 	git config -f .gitmodules submodule."$path".path "$path" &&
 	git config -f .gitmodules submodule."$path".url "$repo" &&
+	git config -f .gitmodules submodule."$path".track "$track" &&
 	git add .gitmodules ||
 	die "Failed to register submodule '$path'"
 }
@@ -277,6 +285,10 @@ cmd_init()
 		git config submodule."$name".url "$url" ||
 		die "Failed to register url for submodule path '$path'"
 
+		track=$(git config -f .gitmodules submodule."$name".track)
+		git config submodule."$name".track "$track" ||
+		die "Failed to register track for submodule path '$path'"
+
 		say "Submodule '$name' ($url) registered for path '$path'"
 	done
 }
@@ -327,10 +339,12 @@ cmd_update()
 			say "Maybe you want to use 'update --init'?"
 			continue
 		fi
+		track=$(git config submodule."$name".track)
 
 		if ! test -d "$path"/.git -o -f "$path"/.git
 		then
 			module_clone "$path" "$url" || exit
+
 			subsha1=
 		else
 			subsha1=$(unset GIT_DIR; cd "$path" &&
@@ -345,11 +359,28 @@ cmd_update()
 			then
 				force="-f"
 			fi
+			pull=
+			if [ "$sha1" = "0000000000000000000000000000000000000000" ]
+			then
+				[ -z "$track" ] && track="HEAD"
+				# if the local branch does not yet exist, create it
+				( unset GIT_DIR; cd "$path"; git-show-ref --heads --tags -q "$track" || git branch --track "$track" "origin/$track" )
+				sha1="$track"
+				pull=1
+			fi
+
 			(unset GIT_DIR; cd "$path" && git-fetch &&
 				git-checkout $force -q "$sha1") ||
 			die "Unable to checkout '$sha1' in submodule path '$path'"
 
 			say "Submodule path '$path': checked out '$sha1'"
+
+			if [ "$pull" = "1" ]
+			then
+				# Now pull new updates from origin
+				( unset GIT_DIR; cd "$path"; git-pull )
+			fi
+
 		fi
 	done
 }
@@ -596,7 +627,10 @@ cmd_status()
 		set_name_rev "$path" "$sha1"
 		if git diff-files --quiet -- "$path"
 		then
-			say " $sha1 $path$revname"
+			track=$(git config submodule."$name".track)
+			tracking=
+			[ -n "$track" ] && tracking=" (tracking $track)"
+			say " $sha1 $path$revname$tracking"
 		else
 			if test -z "$cached"
 			then
diff --git a/read-cache.c b/read-cache.c
index 8579663..0c14b68 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -137,6 +137,11 @@ static int ce_compare_gitlink(struct cache_entry *ce)
 	 */
 	if (resolve_gitlink_ref(ce->name, "HEAD", sha1) < 0)
 		return 0;
+
+	// To be able to track newest revision
+	if (is_null_sha1(ce->sha1))
+		return 0;
+
 	return hashcmp(sha1, ce->sha1);
 }
 

-- 
1.6.1.rc2.1.g4859.dirty
Next: Johannes Sixt
Message 1 of 3 in “submodule: Allow tracking of the newest revision of a branch in a submodule”
  1. submodule: Allow tracking of the newest revision of a branch in a submoduleFabian Franz, Dec 11, 2008
  2. Johannes SixtDec 11, 2008
  3. Junio C HamanoDec 11, 2008

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