diff options
| -rw-r--r-- | commit.c | 280 |
1 files changed, 90 insertions, 190 deletions
@@ -854,6 +854,7 @@ void sort_in_topological_order_fn(struct commit_list ** list, int lifo, #define PARENT1 (1u<< 8) #define PARENT2 (1u<< 9) #define STALE (1u<<10) +#define RESULT (1u<<11) static struct commit *interesting(struct commit_list *list) { @@ -867,183 +868,42 @@ 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; } @@ -1059,35 +919,75 @@ struct commit_list *get_merge_bases(struct commit *rev1, struct commit *rev2, } } - 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; } |