[PATCH v2] rebase -i: avoid 'git reset' when possible

From

Johannes Schindelin <johannes.schindelin@gmx.de>

Date

Mar 3, 2009, 09:55 UTC

Message-ID

<alpine.DEB.1.00.0903031024420.6399@intel-tinevez-2-302>

In-Reply-To

<alpine.DEB.1.00.0903031008580.6399@intel-tinevez-2-302>

Requested by Sverre Rabbelier.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---

	Actually, I did not think things through.  Of _course_ we need
	that rev-parse, to determine the parent of the to-be-picked
	commit.

	Changes since v1: use only one loop instead of counting the number 
	of skipped commits first, and then actually skipping them.

 git-rebase--interactive.sh    |   26 ++++++++++++++++++++++++++
 t/t3404-rebase-interactive.sh |   11 +++++++++++
 2 files changed, 37 insertions(+), 0 deletions(-)

diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index 3dc659d..72f7fc7 100755
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -442,6 +442,30 @@ do_rest () {
 	done
 }
 
+# skip picking commits whose parents are unchanged
+skip_unnecessary_picks () {
+	fd=3
+	while read command sha1 rest
+	do
+		# fd=3 means we skip the command
+		case "$fd,$command,$(git rev-parse --verify --quiet $sha1^)" in
+		3,pick,"$ONTO"*|t,p,"$ONTO"*)
+			# pick a commit whose parent is current $ONTO -> skip
+			ONTO=$sha1
+			;;
+		3,#*|3,,*)
+			# copy comments
+			;;
+		*)
+			fd=1
+			;;
+		esac
+		echo "$command${sha1:+ }$sha1${rest:+ }$rest" >&$fd
+	done < "$TODO" > "$TODO.new" 3>> "$DONE" &&
+	mv -f "$TODO".new "$TODO" ||
+	die "Could not skip unnecessary pick commands"
+}
+
 # check if no other options are set
 is_standalone () {
 	test $# -eq 2 -a "$2" = '--' &&
@@ -746,6 +770,8 @@ EOF
 		has_action "$TODO" ||
 			die_abort "Nothing to do"
 
+		test -d "$REWRITTEN" || skip_unnecessary_picks
+
 		git update-ref ORIG_HEAD $HEAD
 		output git checkout $ONTO && do_rest
 		;;
diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index 603b003..c32ff66 100755
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -459,4 +459,15 @@ test_expect_success 'submodule rebase -i' '
 	FAKE_LINES="1 squash 2 3" git rebase -i A
 '
 
+test_expect_success 'avoid unnecessary reset' '
+	git checkout master &&
+	test-chmtime =123456789 file3 &&
+	git update-index --refresh &&
+	HEAD=$(git rev-parse HEAD) &&
+	git rebase -i HEAD~4 &&
+	test $HEAD = $(git rev-parse HEAD) &&
+	MTIME=$(test-chmtime -v +0 file3 | sed 's/[^0-9].*$//') &&
+	test 123456789 = $MTIME
+'
+
 test_done

-- 
1.6.2.rc1.456.g3dbe7