diff options
| -rw-r--r-- | commit.c | 240 | ||||
| -rw-r--r-- | commit.h | 2 | ||||
| -rw-r--r-- | merge-base.c | 238 |
3 files changed, 242 insertions, 238 deletions
@@ -846,3 +846,243 @@ void sort_in_topological_order_fn(struct commit_list ** list, int lifo, } free(nodes); } + +/* merge-rebase stuff */ + +#define PARENT1 1 +#define PARENT2 2 +#define UNINTERESTING 4 + +static struct commit *interesting(struct commit_list *list) +{ + while (list) { + struct commit *commit = list->item; + list = list->next; + if (commit->object.flags & UNINTERESTING) + continue; + return commit; + } + 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 + * uninteresting, 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 uninteresting. Which is + * commit B. + * + * + * Another pathological example how this thing used to fail to mark an + * ancestor of a merge base as UNINTERESTING 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 + * uninteresting, so we fail to complete the following two + * steps to fully marking uninteresting 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 uninteresting ones to list, + * so we can scan their parents. + */ + if (c->object.flags & UNINTERESTING) + 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 uninteresting, so + * mark all its parents uninteresting. 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 & UNINTERESTING)) { + p->object.flags |= UNINTERESTING; + commit_list_insert(p, &list); + } + } + } +} + +struct commit_list *get_merge_bases(struct commit *rev1, struct commit *rev2) +{ + struct commit_list *list = NULL; + struct commit_list *result = NULL; + struct commit_list *tmp = NULL; + + if (rev1 == rev2) + return commit_list_insert(rev1, &result); + + parse_commit(rev1); + parse_commit(rev2); + + rev1->object.flags |= PARENT1; + rev2->object.flags |= PARENT2; + insert_by_date(rev1, &list); + insert_by_date(rev2, &list); + + while (interesting(list)) { + struct commit *commit = list->item; + struct commit_list *parents; + int flags = commit->object.flags + & (PARENT1 | PARENT2 | UNINTERESTING); + + tmp = list; + list = list->next; + free(tmp); + if (flags == (PARENT1 | PARENT2)) { + insert_by_date(commit, &result); + + /* Mark parents of a found merge uninteresting */ + flags |= UNINTERESTING; + } + parents = commit->parents; + while (parents) { + struct commit *p = parents->item; + parents = parents->next; + if ((p->object.flags & flags) == flags) + continue; + parse_commit(p); + p->object.flags |= flags; + insert_by_date(p, &list); + } + } + + if (!result) + return NULL; + + if (result->next && list) + mark_reachable_commits(result, list); + + /* cull duplicates */ + for (tmp = result, list = NULL; tmp; ) { + struct commit *commit = tmp->item; + struct commit_list *next = tmp->next; + if (commit->object.flags & UNINTERESTING) { + if (list != NULL) + list->next = next; + free(tmp); + } else { + if (list == NULL) + result = tmp; + list = tmp; + commit->object.flags |= UNINTERESTING; + } + + tmp = next; + } + + /* reset flags */ + clear_commit_marks(rev1, PARENT1 | PARENT2 | UNINTERESTING); + clear_commit_marks(rev2, PARENT1 | PARENT2 | UNINTERESTING); + + return result; +} @@ -105,4 +105,6 @@ struct commit_graft *read_graft_line(char *buf, int len); int register_commit_graft(struct commit_graft *, int); int read_graft_file(const char *graft_file); +extern struct commit_list *get_merge_bases(struct commit *rev1, struct commit *rev2); + #endif /* COMMIT_H */ diff --git a/merge-base.c b/merge-base.c index 7d87c20b75..b41f76cb72 100644 --- a/merge-base.c +++ b/merge-base.c @@ -2,244 +2,6 @@ #include "cache.h" #include "commit.h" -#define PARENT1 1 -#define PARENT2 2 -#define UNINTERESTING 4 - -static struct commit *interesting(struct commit_list *list) -{ - while (list) { - struct commit *commit = list->item; - list = list->next; - if (commit->object.flags & UNINTERESTING) - continue; - return commit; - } - 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 - * uninteresting, 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 uninteresting. Which is - * commit B. - * - * - * Another pathological example how this thing used to fail to mark an - * ancestor of a merge base as UNINTERESTING 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 - * uninteresting, so we fail to complete the following two - * steps to fully marking uninteresting 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 uninteresting ones to list, - * so we can scan their parents. - */ - if (c->object.flags & UNINTERESTING) - 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 uninteresting, so - * mark all its parents uninteresting. 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 & UNINTERESTING)) { - p->object.flags |= UNINTERESTING; - commit_list_insert(p, &list); - } - } - } -} - -struct commit_list *get_merge_bases(struct commit *rev1, struct commit *rev2) -{ - struct commit_list *list = NULL; - struct commit_list *result = NULL; - struct commit_list *tmp = NULL; - - if (rev1 == rev2) - return commit_list_insert(rev1, &result); - - parse_commit(rev1); - parse_commit(rev2); - - rev1->object.flags |= PARENT1; - rev2->object.flags |= PARENT2; - insert_by_date(rev1, &list); - insert_by_date(rev2, &list); - - while (interesting(list)) { - struct commit *commit = list->item; - struct commit_list *parents; - int flags = commit->object.flags - & (PARENT1 | PARENT2 | UNINTERESTING); - - tmp = list; - list = list->next; - free(tmp); - if (flags == (PARENT1 | PARENT2)) { - insert_by_date(commit, &result); - - /* Mark parents of a found merge uninteresting */ - flags |= UNINTERESTING; - } - parents = commit->parents; - while (parents) { - struct commit *p = parents->item; - parents = parents->next; - if ((p->object.flags & flags) == flags) - continue; - parse_commit(p); - p->object.flags |= flags; - insert_by_date(p, &list); - } - } - - if (!result) - return NULL; - - if (result->next && list) - mark_reachable_commits(result, list); - - /* cull duplicates */ - for (tmp = result, list = NULL; tmp; ) { - struct commit *commit = tmp->item; - struct commit_list *next = tmp->next; - if (commit->object.flags & UNINTERESTING) { - if (list != NULL) - list->next = next; - free(tmp); - } else { - if (list == NULL) - result = tmp; - list = tmp; - commit->object.flags |= UNINTERESTING; - } - - tmp = next; - } - - /* reset flags */ - clear_commit_marks(rev1, PARENT1 | PARENT2 | UNINTERESTING); - clear_commit_marks(rev2, PARENT1 | PARENT2 | UNINTERESTING); - - return result; -} - static int show_all = 0; static int merge_base(struct commit *rev1, struct commit *rev2) |