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Merge branch 'jc/rev-list-ancestry-path'
* jc/rev-list-ancestry-path: revision: Turn off history simplification in --ancestry-path mode revision: Fix typo in --ancestry-path error message Documentation/rev-list-options.txt: Explain --ancestry-path Documentation/rev-list-options.txt: Fix missing line in example history graph revision: --ancestry-path
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‎Documentation/rev-list-options.txt‎

Lines changed: 49 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -384,6 +384,14 @@ Default mode::
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merges from the resulting history, as there are no selected
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commits contributing to this merge.
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--ancestry-path::
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When given a range of commits to display (e.g. 'commit1..commit2'
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or 'commit2 {caret}commit1'), only display commits that exist
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directly on the ancestry chain between the 'commit1' and
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'commit2', i.e. commits that are both descendants of 'commit1',
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and ancestors of 'commit2'.
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A more detailed explanation follows.
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Suppose you specified `foo` as the <paths>. We shall call commits
@@ -440,7 +448,7 @@ This results in:
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+
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-----------------------------------------------------------------------
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.-A---N---O
443-
/ /
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/ / /
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I---------D
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-----------------------------------------------------------------------
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+
@@ -511,8 +519,6 @@ Note that without '\--full-history', this still simplifies merges: if
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one of the parents is TREESAME, we follow only that one, so the other
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sides of the merge are never walked.
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514-
Finally, there is a fourth simplification mode available:
515-
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--simplify-merges::
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First, build a history graph in the same way that
@@ -554,6 +560,46 @@ Note the major differences in `N` and `P` over '\--full-history':
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removed completely, because it had one parent and is TREESAME.
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--
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Finally, there is a fifth simplification mode available:
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--ancestry-path::
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Limit the displayed commits to those directly on the ancestry
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chain between the "from" and "to" commits in the given commit
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range. I.e. only display commits that are ancestor of the "to"
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commit, and descendants of the "from" commit.
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+
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As an example use case, consider the following commit history:
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+
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-----------------------------------------------------------------------
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D---E-------F
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/ \ \
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B---C---G---H---I---J
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/ \
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A-------K---------------L--M
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-----------------------------------------------------------------------
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+
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A regular 'D..M' computes the set of commits that are ancestors of `M`,
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but excludes the ones that are ancestors of `D`. This is useful to see
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what happened to the history leading to `M` since `D`, in the sense
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that "what does `M` have that did not exist in `D`". The result in this
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example would be all the commits, except `A` and `B` (and `D` itself,
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of course).
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+
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When we want to find out what commits in `M` are contaminated with the
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bug introduced by `D` and need fixing, however, we might want to view
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only the subset of 'D..M' that are actually descendants of `D`, i.e.
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excluding `C` and `K`. This is exactly what the '\--ancestry-path'
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option does. Applied to the 'D..M' range, it results in:
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+
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-----------------------------------------------------------------------
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E-------F
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\ \
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G---H---I---J
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\
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L--M
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-----------------------------------------------------------------------
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The '\--simplify-by-decoration' option allows you to view only the
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big picture of the topology of the history, by omitting commits
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that are not referenced by tags. Commits are marked as !TREESAME

‎revision.c‎

Lines changed: 103 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -646,13 +646,107 @@ static int still_interesting(struct commit_list *src, unsigned long date, int sl
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return slop-1;
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}
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/*
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* "rev-list --ancestry-path A..B" computes commits that are ancestors
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* of B but not ancestors of A but further limits the result to those
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* that are descendants of A. This takes the list of bottom commits and
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* the result of "A..B" without --ancestry-path, and limits the latter
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* further to the ones that can reach one of the commits in "bottom".
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*/
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static void limit_to_ancestry(struct commit_list *bottom, struct commit_list *list)
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{
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struct commit_list *p;
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struct commit_list *rlist = NULL;
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int made_progress;
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/*
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* Reverse the list so that it will be likely that we would
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* process parents before children.
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*/
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for (p = list; p; p = p->next)
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commit_list_insert(p->item, &rlist);
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for (p = bottom; p; p = p->next)
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p->item->object.flags |= TMP_MARK;
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/*
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* Mark the ones that can reach bottom commits in "list",
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* in a bottom-up fashion.
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*/
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do {
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made_progress = 0;
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for (p = rlist; p; p = p->next) {
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struct commit *c = p->item;
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struct commit_list *parents;
681+
if (c->object.flags & (TMP_MARK | UNINTERESTING))
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continue;
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for (parents = c->parents;
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parents;
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parents = parents->next) {
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if (!(parents->item->object.flags & TMP_MARK))
687+
continue;
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c->object.flags |= TMP_MARK;
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made_progress = 1;
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break;
691+
}
692+
}
693+
} while (made_progress);
694+
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/*
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* NEEDSWORK: decide if we want to remove parents that are
697+
* not marked with TMP_MARK from commit->parents for commits
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* in the resulting list. We may not want to do that, though.
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*/
700+
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/*
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* The ones that are not marked with TMP_MARK are uninteresting
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*/
704+
for (p = list; p; p = p->next) {
705+
struct commit *c = p->item;
706+
if (c->object.flags & TMP_MARK)
707+
continue;
708+
c->object.flags |= UNINTERESTING;
709+
}
710+
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/* We are done with the TMP_MARK */
712+
for (p = list; p; p = p->next)
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p->item->object.flags &= ~TMP_MARK;
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for (p = bottom; p; p = p->next)
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p->item->object.flags &= ~TMP_MARK;
716+
free_commit_list(rlist);
717+
}
718+
719+
/*
720+
* Before walking the history, keep the set of "negative" refs the
721+
* caller has asked to exclude.
722+
*
723+
* This is used to compute "rev-list --ancestry-path A..B", as we need
724+
* to filter the result of "A..B" further to the ones that can actually
725+
* reach A.
726+
*/
727+
static struct commit_list *collect_bottom_commits(struct commit_list *list)
728+
{
729+
struct commit_list *elem, *bottom = NULL;
730+
for (elem = list; elem; elem = elem->next)
731+
if (elem->item->object.flags & UNINTERESTING)
732+
commit_list_insert(elem->item, &bottom);
733+
return bottom;
734+
}
735+
649736
static int limit_list(struct rev_info *revs)
650737
{
651738
int slop = SLOP;
652739
unsigned long date = ~0ul;
653740
struct commit_list *list = revs->commits;
654741
struct commit_list *newlist = NULL;
655742
struct commit_list **p = &newlist;
743+
struct commit_list *bottom = NULL;
744+
745+
if (revs->ancestry_path) {
746+
bottom = collect_bottom_commits(list);
747+
if (!bottom)
748+
die("--ancestry-path given but there are no bottom commits");
749+
}
656750

657751
while (list) {
658752
struct commit_list *entry = list;
@@ -694,6 +788,11 @@ static int limit_list(struct rev_info *revs)
694788
if (revs->cherry_pick)
695789
cherry_pick_list(newlist, revs);
696790

791+
if (bottom) {
792+
limit_to_ancestry(bottom, newlist);
793+
free_commit_list(bottom);
794+
}
795+
697796
revs->commits = newlist;
698797
return 0;
699798
}
@@ -1089,6 +1188,10 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg
10891188
revs->min_age = approxidate(arg + 8);
10901189
} else if (!strcmp(arg, "--first-parent")) {
10911190
revs->first_parent_only = 1;
1191+
} else if (!strcmp(arg, "--ancestry-path")) {
1192+
revs->ancestry_path = 1;
1193+
revs->simplify_history = 0;
1194+
revs->limited = 1;
10921195
} else if (!strcmp(arg, "-g") || !strcmp(arg, "--walk-reflogs")) {
10931196
init_reflog_walk(&revs->reflog_info);
10941197
} else if (!strcmp(arg, "--default")) {

‎revision.h‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -66,6 +66,7 @@ struct rev_info {
6666
reverse_output_stage:1,
6767
cherry_pick:1,
6868
bisect:1,
69+
ancestry_path:1,
6970
first_parent_only:1;
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/* Diff flags */

‎t/t6019-rev-list-ancestry-path.sh‎

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,73 @@
1+
#!/bin/sh
2+
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test_description='--ancestry-path'
4+
5+
# D---E-------F
6+
# / \ \
7+
# B---C---G---H---I---J
8+
# / \
9+
# A-------K---------------L--M
10+
#
11+
# D..M == E F G H I J K L M
12+
# --ancestry-path D..M == E F H I J L M
13+
#
14+
# D..M -- M.t == M
15+
# --ancestry-path D..M -- M.t == M
16+
17+
. ./test-lib.sh
18+
19+
test_merge () {
20+
test_tick &&
21+
git merge -s ours -m "$2" "$1" &&
22+
git tag "$2"
23+
}
24+
25+
test_expect_success setup '
26+
test_commit A &&
27+
test_commit B &&
28+
test_commit C &&
29+
test_commit D &&
30+
test_commit E &&
31+
test_commit F &&
32+
git reset --hard C &&
33+
test_commit G &&
34+
test_merge E H &&
35+
test_commit I &&
36+
test_merge F J &&
37+
git reset --hard A &&
38+
test_commit K &&
39+
test_merge J L &&
40+
test_commit M
41+
'
42+
43+
test_expect_success 'rev-list D..M' '
44+
for c in E F G H I J K L M; do echo $c; done >expect &&
45+
git rev-list --format=%s D..M |
46+
sed -e "/^commit /d" |
47+
sort >actual &&
48+
test_cmp expect actual
49+
'
50+
51+
test_expect_success 'rev-list --ancestry-path D..M' '
52+
for c in E F H I J L M; do echo $c; done >expect &&
53+
git rev-list --ancestry-path --format=%s D..M |
54+
sed -e "/^commit /d" |
55+
sort >actual &&
56+
test_cmp expect actual
57+
'
58+
59+
test_expect_success 'rev-list D..M -- M.t' '
60+
echo M >expect &&
61+
git rev-list --format=%s D..M -- M.t |
62+
sed -e "/^commit /d" >actual &&
63+
test_cmp expect actual
64+
'
65+
66+
test_expect_success 'rev-list --ancestry-patch D..M -- M.t' '
67+
echo M >expect &&
68+
git rev-list --ancestry-path --format=%s D..M -- M.t |
69+
sed -e "/^commit /d" >actual &&
70+
test_cmp expect actual
71+
'
72+
73+
test_done

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