git-commit-vandalism/git-resolve-script
Junio C Hamano 9585e40622 Try to find the optimum merge base while resolving.
The merge-base command acquires a new option, '--all', that causes it
to output all the common ancestor candidates.  The "git resolve"
command then uses it to pick the optimum merge base by picking the one
that results in the smallest number of nontrivial merges.

Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-08-23 21:08:59 -07:00

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#!/bin/sh
#
# Copyright (c) 2005 Linus Torvalds
#
# Resolve two trees.
#
. git-sh-setup-script || die "Not a git archive"
usage () {
die "git-resolve-script <head> <remote> <merge-message>"
}
dropheads() {
rm -f -- "$GIT_DIR/MERGE_HEAD" \
"$GIT_DIR/LAST_MERGE" || exit 1
}
head=$(git-rev-parse --verify "$1"^0) &&
merge=$(git-rev-parse --verify "$2"^0) &&
merge_msg="$3" || usage
#
# The remote name is just used for the message,
# but we do want it.
#
if [ -z "$head" -o -z "$merge" -o -z "$merge_msg" ]; then
usage
fi
dropheads
echo $head > "$GIT_DIR"/ORIG_HEAD
echo $merge > "$GIT_DIR"/LAST_MERGE
common=$(git-merge-base $head $merge)
if [ -z "$common" ]; then
die "Unable to find common commit between" $merge $head
fi
if [ "$common" == "$merge" ]; then
echo "Already up-to-date. Yeeah!"
dropheads
exit 0
fi
if [ "$common" == "$head" ]; then
echo "Updating from $head to $merge."
git-read-tree -u -m $head $merge || exit 1
echo $merge > "$GIT_DIR"/HEAD
git-diff-tree -p $head $merge | git-apply --stat
dropheads
exit 0
fi
# Find an optimum merge base if there are more than one candidates.
LF='
'
common=$(git-merge-base -a $head $merge)
case "$common" in
?*"$LF"?*)
echo "Trying to find the optimum merge base."
G=.tmp-index$$
best=
best_cnt=-1
for c in $common
do
rm -f $G
GIT_INDEX_FILE=$G git-read-tree -m $c $head $merge \
2>/dev/null || continue
# Count the paths that are unmerged.
cnt=`GIT_INDEX_FILE=$G git-ls-files --unmerged | wc -l`
if test $best_cnt -le 0 -o $cnt -le $best_cnt
then
best=$c
best_cnt=$cnt
if test "$best_cnt" -eq 0
then
# Cannot do any better than all trivial merge.
break
fi
fi
done
rm -f $G
common="$best"
esac
echo "Trying to merge $merge into $head using $common."
git-update-cache --refresh 2>/dev/null
git-read-tree -u -m $common $head $merge || exit 1
result_tree=$(git-write-tree 2> /dev/null)
if [ $? -ne 0 ]; then
echo "Simple merge failed, trying Automatic merge"
git-merge-cache -o git-merge-one-file-script -a
if [ $? -ne 0 ]; then
echo $merge > "$GIT_DIR"/MERGE_HEAD
die "Automatic merge failed, fix up by hand"
fi
result_tree=$(git-write-tree) || exit 1
fi
result_commit=$(echo "$merge_msg" | git-commit-tree $result_tree -p $head -p $merge)
echo "Committed merge $result_commit"
echo $result_commit > "$GIT_DIR"/HEAD
git-diff-tree -p $head $result_commit | git-apply --stat
dropheads