merges from the resulting history, as there are no selected
commits contributing to this merge.
+--ancestry-path::
+
+ When given a range of commits to display (e.g. 'commit1..commit2'
+ or 'commit2 {caret}commit1'), only display commits that exist
+ directly on the ancestry chain between the 'commit1' and
+ 'commit2', i.e. commits that are both descendants of 'commit1',
+ and ancestors of 'commit2'.
+
A more detailed explanation follows.
Suppose you specified `foo` as the <paths>. We shall call commits
+
-----------------------------------------------------------------------
.-A---N---O
- / /
+ / / /
I---------D
-----------------------------------------------------------------------
+
one of the parents is TREESAME, we follow only that one, so the other
sides of the merge are never walked.
-Finally, there is a fourth simplification mode available:
-
--simplify-merges::
First, build a history graph in the same way that
removed completely, because it had one parent and is TREESAME.
--
+Finally, there is a fifth simplification mode available:
+
+--ancestry-path::
+
+ Limit the displayed commits to those directly on the ancestry
+ chain between the "from" and "to" commits in the given commit
+ range. I.e. only display commits that are ancestor of the "to"
+ commit, and descendants of the "from" commit.
++
+As an example use case, consider the following commit history:
++
+-----------------------------------------------------------------------
+ D---E-------F
+ / \ \
+ B---C---G---H---I---J
+ / \
+ A-------K---------------L--M
+-----------------------------------------------------------------------
++
+A regular 'D..M' computes the set of commits that are ancestors of `M`,
+but excludes the ones that are ancestors of `D`. This is useful to see
+what happened to the history leading to `M` since `D`, in the sense
+that "what does `M` have that did not exist in `D`". The result in this
+example would be all the commits, except `A` and `B` (and `D` itself,
+of course).
++
+When we want to find out what commits in `M` are contaminated with the
+bug introduced by `D` and need fixing, however, we might want to view
+only the subset of 'D..M' that are actually descendants of `D`, i.e.
+excluding `C` and `K`. This is exactly what the '\--ancestry-path'
+option does. Applied to the 'D..M' range, it results in:
++
+-----------------------------------------------------------------------
+ E-------F
+ \ \
+ G---H---I---J
+ \
+ L--M
+-----------------------------------------------------------------------
+
The '\--simplify-by-decoration' option allows you to view only the
big picture of the topology of the history, by omitting commits
that are not referenced by tags. Commits are marked as !TREESAME
return slop-1;
}
+/*
+ * "rev-list --ancestry-path A..B" computes commits that are ancestors
+ * of B but not ancestors of A but further limits the result to those
+ * that are descendants of A. This takes the list of bottom commits and
+ * the result of "A..B" without --ancestry-path, and limits the latter
+ * further to the ones that can reach one of the commits in "bottom".
+ */
+static void limit_to_ancestry(struct commit_list *bottom, struct commit_list *list)
+{
+ struct commit_list *p;
+ struct commit_list *rlist = NULL;
+ int made_progress;
+
+ /*
+ * Reverse the list so that it will be likely that we would
+ * process parents before children.
+ */
+ for (p = list; p; p = p->next)
+ commit_list_insert(p->item, &rlist);
+
+ for (p = bottom; p; p = p->next)
+ p->item->object.flags |= TMP_MARK;
+
+ /*
+ * Mark the ones that can reach bottom commits in "list",
+ * in a bottom-up fashion.
+ */
+ do {
+ made_progress = 0;
+ for (p = rlist; p; p = p->next) {
+ struct commit *c = p->item;
+ struct commit_list *parents;
+ if (c->object.flags & (TMP_MARK | UNINTERESTING))
+ continue;
+ for (parents = c->parents;
+ parents;
+ parents = parents->next) {
+ if (!(parents->item->object.flags & TMP_MARK))
+ continue;
+ c->object.flags |= TMP_MARK;
+ made_progress = 1;
+ break;
+ }
+ }
+ } while (made_progress);
+
+ /*
+ * NEEDSWORK: decide if we want to remove parents that are
+ * not marked with TMP_MARK from commit->parents for commits
+ * in the resulting list. We may not want to do that, though.
+ */
+
+ /*
+ * The ones that are not marked with TMP_MARK are uninteresting
+ */
+ for (p = list; p; p = p->next) {
+ struct commit *c = p->item;
+ if (c->object.flags & TMP_MARK)
+ continue;
+ c->object.flags |= UNINTERESTING;
+ }
+
+ /* We are done with the TMP_MARK */
+ for (p = list; p; p = p->next)
+ p->item->object.flags &= ~TMP_MARK;
+ for (p = bottom; p; p = p->next)
+ p->item->object.flags &= ~TMP_MARK;
+ free_commit_list(rlist);
+}
+
+/*
+ * Before walking the history, keep the set of "negative" refs the
+ * caller has asked to exclude.
+ *
+ * This is used to compute "rev-list --ancestry-path A..B", as we need
+ * to filter the result of "A..B" further to the ones that can actually
+ * reach A.
+ */
+static struct commit_list *collect_bottom_commits(struct commit_list *list)
+{
+ struct commit_list *elem, *bottom = NULL;
+ for (elem = list; elem; elem = elem->next)
+ if (elem->item->object.flags & UNINTERESTING)
+ commit_list_insert(elem->item, &bottom);
+ return bottom;
+}
+
static int limit_list(struct rev_info *revs)
{
int slop = SLOP;
struct commit_list *list = revs->commits;
struct commit_list *newlist = NULL;
struct commit_list **p = &newlist;
+ struct commit_list *bottom = NULL;
+
+ if (revs->ancestry_path) {
+ bottom = collect_bottom_commits(list);
+ if (!bottom)
+ die("--ancestry-path given but there are no bottom commits");
+ }
while (list) {
struct commit_list *entry = list;
if (revs->cherry_pick)
cherry_pick_list(newlist, revs);
+ if (bottom) {
+ limit_to_ancestry(bottom, newlist);
+ free_commit_list(bottom);
+ }
+
revs->commits = newlist;
return 0;
}
revs->min_age = approxidate(arg + 8);
} else if (!strcmp(arg, "--first-parent")) {
revs->first_parent_only = 1;
+ } else if (!strcmp(arg, "--ancestry-path")) {
+ revs->ancestry_path = 1;
+ revs->simplify_history = 0;
+ revs->limited = 1;
} else if (!strcmp(arg, "-g") || !strcmp(arg, "--walk-reflogs")) {
init_reflog_walk(&revs->reflog_info);
} else if (!strcmp(arg, "--default")) {
--- /dev/null
+#!/bin/sh
+
+test_description='--ancestry-path'
+
+# D---E-------F
+# / \ \
+# B---C---G---H---I---J
+# / \
+# A-------K---------------L--M
+#
+# D..M == E F G H I J K L M
+# --ancestry-path D..M == E F H I J L M
+#
+# D..M -- M.t == M
+# --ancestry-path D..M -- M.t == M
+
+. ./test-lib.sh
+
+test_merge () {
+ test_tick &&
+ git merge -s ours -m "$2" "$1" &&
+ git tag "$2"
+}
+
+test_expect_success setup '
+ test_commit A &&
+ test_commit B &&
+ test_commit C &&
+ test_commit D &&
+ test_commit E &&
+ test_commit F &&
+ git reset --hard C &&
+ test_commit G &&
+ test_merge E H &&
+ test_commit I &&
+ test_merge F J &&
+ git reset --hard A &&
+ test_commit K &&
+ test_merge J L &&
+ test_commit M
+'
+
+test_expect_success 'rev-list D..M' '
+ for c in E F G H I J K L M; do echo $c; done >expect &&
+ git rev-list --format=%s D..M |
+ sed -e "/^commit /d" |
+ sort >actual &&
+ test_cmp expect actual
+'
+
+test_expect_success 'rev-list --ancestry-path D..M' '
+ for c in E F H I J L M; do echo $c; done >expect &&
+ git rev-list --ancestry-path --format=%s D..M |
+ sed -e "/^commit /d" |
+ sort >actual &&
+ test_cmp expect actual
+'
+
+test_expect_success 'rev-list D..M -- M.t' '
+ echo M >expect &&
+ git rev-list --format=%s D..M -- M.t |
+ sed -e "/^commit /d" >actual &&
+ test_cmp expect actual
+'
+
+test_expect_success 'rev-list --ancestry-patch D..M -- M.t' '
+ echo M >expect &&
+ git rev-list --ancestry-path --format=%s D..M -- M.t |
+ sed -e "/^commit /d" >actual &&
+ test_cmp expect actual
+'
+
+test_done