The get_merge_bases_many() function reduces the result returned by
the merge_bases_many() function, which is a set of possible merge
bases, by excluding commits that can be reached from other commits.
We used to do N*(N-1) traversals for this, but we can check if one
commit reaches which other (N-1) commits by a single traversal, and
repeat it for all the candidates to find the answer.
Introduce remove_redundant() helper function to do this painting; we
should be able to use it to reimplement reduce_heads() as well.
---
commit.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++-----------------
1 file changed, 58 insertions(+), 21 deletions(-)
diff --git a/commit.c b/commit.c
index d39a9e9..2ff5061 100644
--- a/commit.c
+++ b/commit.c
@@ -692,6 +692,60 @@ struct commit_list *get_octopus_merge_bases(struct commit_list *in)
return ret;
}
+static int remove_redundant(struct commit **array, int cnt)
+{
+ /*
+ * Some commit in the array may be an ancestor of
+ * another commit. Move such commit to the end of
+ * the array, and return the number of commits that
+ * are independent from each other.
+ */
+ struct commit **work;
+ unsigned char *redundant;
+ int *filled_index;
+ int i, j, filled;
+
+ work = xcalloc(cnt, sizeof(*work));
+ redundant = xcalloc(cnt, 1);
+ filled_index = xmalloc(sizeof(*filled_index) * (cnt - 1));
+
+ for (i = 0; i < cnt; i++) {
+ struct commit_list *common;
+
+ if (redundant[i])
+ continue;
+ for (j = filled = 0; j < cnt; j++) {
+ if (i == j || redundant[j])
+ continue;
+ filled_index[filled] = j;
+ work[filled++] = array[j];
+ }
+ common = paint_down_to_common(array[i], filled, work);
+ if (array[i]->object.flags & PARENT2)
+ redundant[i] = 1;
+ for (j = 0; j < filled; j++)
+ if (work[j]->object.flags & PARENT1)
+ redundant[filled_index[j]] = 1;
+ clear_commit_marks(array[i], all_flags);
+ for (j = 0; j < filled; j++)
+ clear_commit_marks(work[j], all_flags);
+ free_commit_list(common);
+ }
+
+ /* Now collect the result */
+ memcpy(work, array, sizeof(*array) * cnt);
+ for (i = filled = 0; i < cnt; i++)
+ if (!redundant[i])
+ array[filled++] = work[i];
+ for (j = filled, i = 0; i < cnt; i++)
+ if (redundant[i])
+ array[j++] = work[i];
+ free(work);
+ free(redundant);
+ free(filled_index);
+ return filled;
+}
+
struct commit_list *get_merge_bases_many(struct commit *one,
int n,
struct commit **twos,
@@ -700,7 +754,7 @@ struct commit_list *get_merge_bases_many(struct commit *one,
struct commit_list *list;
struct commit **rslt;
struct commit_list *result;
- int cnt, i, j;
+ int cnt, i;
result = merge_bases_many(one, n, twos);
for (i = 0; i < n; i++) {
@@ -731,28 +785,11 @@ struct commit_list *get_merge_bases_many(struct commit *one,
clear_commit_marks(one, all_flags);
for (i = 0; i < n; i++)
clear_commit_marks(twos[i], all_flags);
- for (i = 0; i < cnt - 1; i++) {
- for (j = i+1; j < cnt; j++) {
- if (!rslt[i] || !rslt[j])
- continue;
- result = merge_bases_many(rslt[i], 1, &rslt[j]);
- clear_commit_marks(rslt[i], all_flags);
- clear_commit_marks(rslt[j], all_flags);
- for (list = result; list; list = list->next) {
- if (rslt[i] == list->item)
- rslt[i] = NULL;
- if (rslt[j] == list->item)
- rslt[j] = NULL;
- }
- }
- }
- /* Surviving ones in rslt[] are the independent results */
+ cnt = remove_redundant(rslt, cnt);
result = NULL;
- for (i = 0; i < cnt; i++) {
- if (rslt[i])
- commit_list_insert_by_date(rslt[i], &result);
- }
+ for (i = 0; i < cnt; i++)
+ commit_list_insert_by_date(rslt[i], &result);
free(rslt);
return result;
}
--
1.7.12.293.g6aeebca
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