#define PARENT1 (1u<< 8)
#define PARENT2 (1u<< 9)
#define STALE (1u<<10)
+#define RESULT (1u<<11)
static struct commit *interesting(struct commit_list *list)
{
return NULL;
}
-/*
- * A pathological example of how this thing works.
- *
- * Suppose we had this commit graph, where chronologically
- * the timestamp on the commit are A <= B <= C <= D <= E <= F
- * and we are trying to figure out the merge base for E and F
- * commits.
- *
- * F
- * / \
- * E A D
- * \ / /
- * B /
- * \ /
- * C
- *
- * First we push E and F to list to be processed. E gets bit 1
- * and F gets bit 2. The list becomes:
- *
- * list=F(2) E(1), result=empty
- *
- * Then we pop F, the newest commit, from the list. Its flag is 2.
- * We scan its parents, mark them reachable from the side that F is
- * reachable from, and push them to the list:
- *
- * list=E(1) D(2) A(2), result=empty
- *
- * Next pop E and do the same.
- *
- * list=D(2) B(1) A(2), result=empty
- *
- * Next pop D and do the same.
- *
- * list=C(2) B(1) A(2), result=empty
- *
- * Next pop C and do the same.
- *
- * list=B(1) A(2), result=empty
- *
- * Now it is B's turn. We mark its parent, C, reachable from B's side,
- * and push it to the list:
- *
- * list=C(3) A(2), result=empty
- *
- * Now pop C and notice it has flags==3. It is placed on the result list,
- * and the list now contains:
- *
- * list=A(2), result=C(3)
- *
- * We pop A and do the same.
- *
- * list=B(3), result=C(3)
- *
- * Next, we pop B and something very interesting happens. It has flags==3
- * so it is also placed on the result list, and its parents are marked
- * stale, retroactively, and placed back on the list:
- *
- * list=C(7), result=C(7) B(3)
- *
- * Now, list does not have any interesting commit. So we find the newest
- * commit from the result list that is not marked stale. Which is
- * commit B.
- *
- *
- * Another pathological example how this thing used to fail to mark an
- * ancestor of a merge base as STALE before we introduced the
- * postprocessing phase (mark_reachable_commits).
- *
- * 2
- * H
- * 1 / \
- * G A \
- * |\ / \
- * | B \
- * | \ \
- * \ C F
- * \ \ /
- * \ D /
- * \ | /
- * \| /
- * E
- *
- * list A B C D E F G H
- * G1 H2 - - - - - - 1 2
- * H2 E1 B1 - 1 - - 1 - 1 2
- * F2 E1 B1 A2 2 1 - - 1 2 1 2
- * E3 B1 A2 2 1 - - 3 2 1 2
- * B1 A2 2 1 - - 3 2 1 2
- * C1 A2 2 1 1 - 3 2 1 2
- * D1 A2 2 1 1 1 3 2 1 2
- * A2 2 1 1 1 3 2 1 2
- * B3 2 3 1 1 3 2 1 2
- * C7 2 3 7 1 3 2 1 2
- *
- * At this point, unfortunately, everybody in the list is
- * stale, so we fail to complete the following two
- * steps to fully marking stale commits.
- *
- * D7 2 3 7 7 3 2 1 2
- * E7 2 3 7 7 7 2 1 2
- *
- * and we ended up showing E as an interesting merge base.
- * The postprocessing phase re-injects C and continues traversal
- * to contaminate D and E.
- */
-
-static void mark_reachable_commits(struct commit_list *result,
- struct commit_list *list)
-{
- struct commit_list *tmp;
-
- /*
- * Postprocess to fully contaminate the well.
- */
- for (tmp = result; tmp; tmp = tmp->next) {
- struct commit *c = tmp->item;
- /* Reinject stale ones to list,
- * so we can scan their parents.
- */
- if (c->object.flags & STALE)
- commit_list_insert(c, &list);
- }
- while (list) {
- struct commit *c = list->item;
- struct commit_list *parents;
-
- tmp = list;
- list = list->next;
- free(tmp);
-
- /* Anything taken out of the list is stale, so
- * mark all its parents stale. We do not
- * parse new ones (we already parsed all the relevant
- * ones).
- */
- parents = c->parents;
- while (parents) {
- struct commit *p = parents->item;
- parents = parents->next;
- if (!(p->object.flags & STALE)) {
- p->object.flags |= STALE;
- commit_list_insert(p, &list);
- }
- }
- }
-}
-
-struct commit_list *get_merge_bases(struct commit *rev1, struct commit *rev2,
- int cleanup)
+static struct commit_list *merge_bases(struct commit *one, struct commit *two)
{
struct commit_list *list = NULL;
struct commit_list *result = NULL;
- struct commit_list *tmp = NULL;
- if (rev1 == rev2)
- return commit_list_insert(rev1, &result);
+ if (one == two)
+ /* We do not mark this even with RESULT so we do not
+ * have to clean it up.
+ */
+ return commit_list_insert(one, &result);
- parse_commit(rev1);
- parse_commit(rev2);
+ parse_commit(one);
+ parse_commit(two);
- rev1->object.flags |= PARENT1;
- rev2->object.flags |= PARENT2;
- insert_by_date(rev1, &list);
- insert_by_date(rev2, &list);
+ one->object.flags |= PARENT1;
+ two->object.flags |= PARENT2;
+ insert_by_date(one, &list);
+ insert_by_date(two, &list);
while (interesting(list)) {
- struct commit *commit = list->item;
+ struct commit *commit;
struct commit_list *parents;
- int flags = commit->object.flags
- & (PARENT1 | PARENT2 | STALE);
+ struct commit_list *n;
+ int flags;
- tmp = list;
- list = list->next;
- free(tmp);
- if (flags == (PARENT1 | PARENT2)) {
- insert_by_date(commit, &result);
+ commit = list->item;
+ n = list->next;
+ free(list);
+ list = n;
+ flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
+ if (flags == (PARENT1 | PARENT2)) {
+ if (!(commit->object.flags & RESULT)) {
+ commit->object.flags |= RESULT;
+ insert_by_date(commit, &result);
+ }
/* Mark parents of a found merge stale */
flags |= STALE;
}
}
}
- if (!result)
- goto finish;
-
- if (result->next && list)
- mark_reachable_commits(result, list);
+ /* Clean up the result to remove stale ones */
+ list = result; result = NULL;
+ while (list) {
+ struct commit_list *n = list->next;
+ if (!(list->item->object.flags & STALE))
+ insert_by_date(list->item, &result);
+ free(list);
+ list = n;
+ }
+ return result;
+}
- /* cull duplicates */
- for (tmp = result, list = NULL; tmp; ) {
- struct commit *commit = tmp->item;
- struct commit_list *next = tmp->next;
- if (commit->object.flags & STALE) {
- if (list != NULL)
- list->next = next;
- free(tmp);
- } else {
- if (list == NULL)
- result = tmp;
- list = tmp;
- commit->object.flags |= STALE;
+struct commit_list *get_merge_bases(struct commit *one,
+ struct commit *two,
+ int cleanup)
+{
+ const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
+ struct commit_list *list;
+ struct commit **rslt;
+ struct commit_list *result;
+ int cnt, i, j;
+
+ result = merge_bases(one, two);
+ if (one == two)
+ return result;
+ if (!result || !result->next) {
+ if (cleanup) {
+ clear_commit_marks(one, all_flags);
+ clear_commit_marks(two, all_flags);
}
-
- tmp = next;
+ return result;
}
- finish:
- if (cleanup) {
- clear_commit_marks(rev1, PARENT1 | PARENT2 | STALE);
- clear_commit_marks(rev2, PARENT1 | PARENT2 | STALE);
+ /* There are more than one */
+ cnt = 0;
+ list = result;
+ while (list) {
+ list = list->next;
+ cnt++;
+ }
+ rslt = xcalloc(cnt, sizeof(*rslt));
+ for (list = result, i = 0; list; list = list->next)
+ rslt[i++] = list->item;
+ free_commit_list(result);
+
+ clear_commit_marks(one, all_flags);
+ clear_commit_marks(two, 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(rslt[i], 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 */
+ result = NULL;
+ for (i = 0; i < cnt; i++) {
+ if (rslt[i])
+ insert_by_date(rslt[i], &result);
+ }
+ free(rslt);
return result;
}
projects / git.git / commitdiff