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move get_merge_bases() to core lib. 

Signed-off-by: Junio C Hamano <junkio@cox.net>
This commit is contained in:
Johannes Schindelin 2006-06-29 15:17:32 +02:00 committed by Junio C Hamano
parent 52cab8a084
commit 7c6f8aaf6d
3 changed files with 242 additions and 238 deletions
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240
commit.c
View File

@ -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;
}

2
commit.h
View File

@ -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 */

238
merge-base.c
View File

@ -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)