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authorJunio C Hamano <junkio@cox.net>2005-09-08 20:47:12 (GMT)
committerJunio C Hamano <junkio@cox.net>2005-09-11 01:30:41 (GMT)
commit91063bbc6c4187184e94ebc4ab2b807e6d53cd0a (patch)
tree473b699f8570ca750aa44689ca63875ff10136bf /git-merge.sh
parentbb97a2a804e0afdd686ed9f18fed2ddc15833540 (diff)
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Multi-backend merge driver.
The new command 'git merge' takes the current head and one or more remote heads, with the commit log message for the automated case. If the heads being merged are simple fast-forwards, it acts the same way as the current 'git resolve'. Otherwise, it tries different merge strategies and takes the result from the one that succeeded auto-merging, if there is any. If no merge strategy succeeds auto-merging, their results are evaluated for number of paths needed for hand resolving, and the one with the least number of such paths is left in the working tree. The user is asked to resolve them by hand and make a commit manually. The calling convention from the 'git merge' driver to merge strategy programs is very simple: - A strategy program is to be called 'git-merge-<strategy>'. - They take input of this form: <common1> <common2> ... '--' <head> <remote1> <remote2>... That is, one or more the common ancestors, double dash, the current head, and one or more remote heads being merged into the current branch. - Before a strategy program is called, the working tree is matched to the current <head>. - The strategy program exits with status code 0 when it successfully auto-merges the given heads. It should do update-cache for all the merged paths when it does so -- the index file will be used to record the merge result as a commit by the driver. - The strategy program exits with status code 1 when it leaves conflicts behind. It should do update-cache for all the merged paths that it successfully auto-merged, and leave the cache entry in the index file as the same as <head> for paths it could not auto-merge, and leave its best-effort result with conflict markers in the working tree when it does so. - The strategy program exists with status code other than 0 or 1 if it does not handle the given merge at all. As examples, this commit comes with merge strategies based on 'git resolve' and 'git octopus'. Signed-off-by: Junio C Hamano <junkio@cox.net>
Diffstat (limited to 'git-merge.sh')
-rwxr-xr-xgit-merge.sh212
1 files changed, 212 insertions, 0 deletions
diff --git a/git-merge.sh b/git-merge.sh
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+++ b/git-merge.sh
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+#!/bin/sh
+#
+# Copyright (c) 2005 Junio C Hamano
+#
+
+. git-sh-setup || die "Not a git archive"
+
+LF='
+'
+
+usage () {
+ die "git-merge [-n] [-s <strategy>]... <merge-message> <head> <remote>+"
+}
+
+# all_strategies='resolve multibase fredrik octopus'
+
+all_strategies='resolve multibase octopus'
+default_strategies='resolve multibase octopus'
+use_strategies=
+
+dropheads() {
+ rm -f -- "$GIT_DIR/MERGE_HEAD" || exit 1
+}
+
+summary() {
+ case "$no_summary" in
+ '')
+ git-diff-tree -p -M $head "$1" |
+ git-apply --stat --summary
+ ;;
+ esac
+}
+
+while case "$#" in 0) break ;; esac
+do
+ case "$1" in
+ -n|--n|--no|--no-|--no-s|--no-su|--no-sum|--no-summ|\
+ --no-summa|--no-summar|--no-summary)
+ no_summary=t ;;
+ -s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
+ --strateg=*|--strategy=*|\
+ -s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
+ case "$#,$1" in
+ *,*=*)
+ strategy=`expr "$1" : '-[^=]*=\(.*\)'` ;;
+ 0,*)
+ usage ;;
+ *)
+ strategy="$2"
+ shift ;;
+ esac
+ case " $all_strategies " in
+ *" $strategy "*)
+ use_strategies="$use_strategies$strategy " ;;
+ *)
+ die "available strategies are: $all_strategies" ;;
+ esac
+ ;;
+ -*) usage ;;
+ *) break ;;
+ esac
+ shift
+done
+
+case "$use_strategies" in
+'')
+ use_strategies=$default_strategies
+ ;;
+esac
+test "$#" -le 2 && usage ;# we need at least two heads.
+
+merge_msg="$1"
+shift
+head=$(git-rev-parse --verify "$1"^0) || usage
+shift
+
+# All the rest are remote heads
+for remote
+do
+ git-rev-parse --verify "$remote"^0 >/dev/null ||
+ die "$remote - not something we can merge"
+done
+
+common=$(git-show-branch --merge-base $head "$@")
+echo "$head" >"$GIT_DIR/ORIG_HEAD"
+
+case "$#,$common" in
+*,'')
+ die "Unable to find common commit between $head and $*"
+ ;;
+1,"$1")
+ # If head can reach all the merge then we are up to date.
+ # but first the most common case of merging one remote
+ echo "Already up-to-date. Yeeah!"
+ dropheads
+ exit 0
+ ;;
+1,"$head")
+ # Again the most common case of merging one remote.
+ echo "Updating from $head to $1."
+ git-update-index --refresh 2>/dev/null
+ git-read-tree -u -m $head "$1" || exit 1
+ git-rev-parse --verify "$1^0" > "$GIT_DIR/HEAD"
+ summary "$1"
+ dropheads
+ exit 0
+ ;;
+1,*)
+ # We are not doing octopus and not fast forward. Need a
+ # real merge.
+ ;;
+*)
+ # An octopus. If we can reach all the remote we are up to date.
+ up_to_date=t
+ for remote
+ do
+ common_one=$(git-merge-base $head $remote)
+ if test "$common_one" != "$remote"
+ then
+ up_to_date=f
+ break
+ fi
+ done
+ if test "$up_to_date" = t
+ then
+ echo "Already up-to-date. Yeeah!"
+ dropheads
+ exit 0
+ fi
+ ;;
+esac
+
+# At this point we need a real merge. Require that the tree matches
+# exactly our head.
+
+git-update-index --refresh &&
+test '' = "`git-diff-index --cached --name-only $head`" || {
+ die "Need real merge but the working tree has local changes."
+}
+
+result_tree= best_cnt=-1 best_strategy= wt_strategy=
+for strategy in $use_strategies
+do
+ test "$wt_strategy" = '' || {
+ echo "Rewinding the tree to pristine..."
+ git reset --hard $head
+ }
+ echo "Trying merge strategy $strategy..."
+ wt_strategy=$strategy
+ git-merge-$strategy $common -- $head "$@" || {
+
+ # The backend exits with 1 when conflicts are left to be resolved,
+ # with 2 when it does not handle the given merge at all.
+
+ exit=$?
+ if test "$exit" -eq 1
+ then
+ cnt=`{
+ git-diff-files --name-only
+ git-ls-files --unmerged
+ } | wc -l`
+ if test $best_cnt -le 0 -o $cnt -le $best_cnt
+ then
+ best_strategy=$strategy
+ best_cnt=$cnt
+ fi
+ fi
+ continue
+ }
+
+ # Automerge succeeded.
+ result_tree=$(git-write-tree) && break
+done
+
+# If we have a resulting tree, that means the strategy module
+# auto resolved the merge cleanly.
+if test '' != "$result_tree"
+then
+ parents="-p $head"
+ for remote
+ do
+ parents="$parents -p $remote"
+ done
+ result_commit=$(echo "$merge_msg" | git-commit-tree $result_tree $parents)
+ echo "Committed merge $result_commit, made by $wt_strategy."
+ echo $result_commit >"$GIT_DIR/HEAD"
+ summary $result_commit
+ dropheads
+ exit 0
+fi
+
+# Pick the result from the best strategy and have the user fix it up.
+case "$best_strategy" in
+'')
+ git reset --hard $head
+ die "No merge strategy handled the merge."
+ ;;
+"$wt_strategy")
+ # We already have its result in the working tree.
+ ;;
+*)
+ echo "Rewinding the tree to pristine..."
+ git reset --hard $head
+ echo "Using the $best_strategy to prepare resolving by hand."
+ git-merge-$best_strategy $common -- $head "$@"
+ ;;
+esac
+for remote
+do
+ echo $remote
+done >"$GIT_DIR/MERGE_HEAD"
+die "Automatic merge failed; fix up by hand"