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fmt-merge-msg: discard needless merge parents
This is used by "git pull" to construct a merge message from list of remote refs. When pulling redundant set of refs, however, it did not filter them even though the merge itself discards them as unnecessary. Teach the command to do the same for consistency. Signed-off-by: Junio C Hamano <[email protected]>
1 parent e78cbf8 commit 5802f81

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2 files changed

+149
-10
lines changed

2 files changed

+149
-10
lines changed

‎builtin/fmt-merge-msg.c

Lines changed: 119 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -53,14 +53,56 @@ static void init_src_data(struct src_data *data)
5353
static struct string_list srcs = STRING_LIST_INIT_DUP;
5454
static struct string_list origins = STRING_LIST_INIT_DUP;
5555

56-
static int handle_line(char *line)
56+
struct merge_parents {
57+
int alloc, nr;
58+
struct merge_parent {
59+
unsigned char given[20];
60+
unsigned char commit[20];
61+
unsigned char used;
62+
} *item;
63+
};
64+
65+
/*
66+
* I know, I know, this is inefficient, but you won't be pulling and merging
67+
* hundreds of heads at a time anyway.
68+
*/
69+
static struct merge_parent *find_merge_parent(struct merge_parents *table,
70+
unsigned char *given,
71+
unsigned char *commit)
72+
{
73+
int i;
74+
for (i = 0; i < table->nr; i++) {
75+
if (given && hashcmp(table->item[i].given, given))
76+
continue;
77+
if (commit && hashcmp(table->item[i].commit, commit))
78+
continue;
79+
return &table->item[i];
80+
}
81+
return NULL;
82+
}
83+
84+
static void add_merge_parent(struct merge_parents *table,
85+
unsigned char *given,
86+
unsigned char *commit)
87+
{
88+
if (table->nr && find_merge_parent(table, given, commit))
89+
return;
90+
ALLOC_GROW(table->item, table->nr + 1, table->alloc);
91+
hashcpy(table->item[table->nr].given, given);
92+
hashcpy(table->item[table->nr].commit, commit);
93+
table->item[table->nr].used = 0;
94+
table->nr++;
95+
}
96+
97+
static int handle_line(char *line, struct merge_parents *merge_parents)
5798
{
5899
int i, len = strlen(line);
59100
struct origin_data *origin_data;
60101
char *src, *origin;
61102
struct src_data *src_data;
62103
struct string_list_item *item;
63104
int pulling_head = 0;
105+
unsigned char sha1[20];
64106

65107
if (len < 43 || line[40] != '\t')
66108
return 1;
@@ -71,14 +113,15 @@ static int handle_line(char *line)
71113
if (line[41] != '\t')
72114
return 2;
73115

74-
line[40] = 0;
75-
origin_data = xcalloc(1, sizeof(struct origin_data));
76-
i = get_sha1(line, origin_data->sha1);
77-
line[40] = '\t';
78-
if (i) {
79-
free(origin_data);
116+
i = get_sha1_hex(line, sha1);
117+
if (i)
80118
return 3;
81-
}
119+
120+
if (!find_merge_parent(merge_parents, sha1, NULL))
121+
return 0; /* subsumed by other parents */
122+
123+
origin_data = xcalloc(1, sizeof(struct origin_data));
124+
hashcpy(origin_data->sha1, sha1);
82125

83126
if (line[len - 1] == '\n')
84127
line[len - 1] = 0;
@@ -366,13 +409,77 @@ static void fmt_merge_msg_sigs(struct strbuf *out)
366409
strbuf_release(&tagbuf);
367410
}
368411

412+
static void find_merge_parents(struct merge_parents *result,
413+
struct strbuf *in, unsigned char *head)
414+
{
415+
struct commit_list *parents, *next;
416+
struct commit *head_commit;
417+
int pos = 0, i, j;
418+
419+
parents = NULL;
420+
while (pos < in->len) {
421+
int len;
422+
char *p = in->buf + pos;
423+
char *newline = strchr(p, '\n');
424+
unsigned char sha1[20];
425+
struct commit *parent;
426+
struct object *obj;
427+
428+
len = newline ? newline - p : strlen(p);
429+
pos += len + !!newline;
430+
431+
if (len < 43 ||
432+
get_sha1_hex(p, sha1) ||
433+
p[40] != '\t' ||
434+
p[41] != '\t')
435+
continue; /* skip not-for-merge */
436+
/*
437+
* Do not use get_merge_parent() here; we do not have
438+
* "name" here and we do not want to contaminate its
439+
* util field yet.
440+
*/
441+
obj = parse_object(sha1);
442+
parent = (struct commit *)peel_to_type(NULL, 0, obj, OBJ_COMMIT);
443+
if (!parent)
444+
continue;
445+
commit_list_insert(parent, &parents);
446+
add_merge_parent(result, obj->sha1, parent->object.sha1);
447+
}
448+
head_commit = lookup_commit(head);
449+
if (head_commit)
450+
commit_list_insert(head_commit, &parents);
451+
parents = reduce_heads(parents);
452+
453+
while (parents) {
454+
for (i = 0; i < result->nr; i++)
455+
if (!hashcmp(result->item[i].commit,
456+
parents->item->object.sha1))
457+
result->item[i].used = 1;
458+
next = parents->next;
459+
free(parents);
460+
parents = next;
461+
}
462+
463+
for (i = j = 0; i < result->nr; i++) {
464+
if (result->item[i].used) {
465+
if (i != j)
466+
result->item[j] = result->item[i];
467+
j++;
468+
}
469+
}
470+
result->nr = j;
471+
}
472+
369473
int fmt_merge_msg(struct strbuf *in, struct strbuf *out,
370474
struct fmt_merge_msg_opts *opts)
371475
{
372476
int i = 0, pos = 0;
373477
unsigned char head_sha1[20];
374478
const char *current_branch;
375479
void *current_branch_to_free;
480+
struct merge_parents merge_parents;
481+
482+
memset(&merge_parents, 0, sizeof(merge_parents));
376483

377484
/* get current branch */
378485
current_branch = current_branch_to_free =
@@ -382,6 +489,8 @@ int fmt_merge_msg(struct strbuf *in, struct strbuf *out,
382489
if (!prefixcmp(current_branch, "refs/heads/"))
383490
current_branch += 11;
384491

492+
find_merge_parents(&merge_parents, in, head_sha1);
493+
385494
/* get a line */
386495
while (pos < in->len) {
387496
int len;
@@ -392,7 +501,7 @@ int fmt_merge_msg(struct strbuf *in, struct strbuf *out,
392501
pos += len + !!newline;
393502
i++;
394503
p[len] = 0;
395-
if (handle_line(p))
504+
if (handle_line(p, &merge_parents))
396505
die ("Error in line %d: %.*s", i, len, p);
397506
}
398507

@@ -423,6 +532,7 @@ int fmt_merge_msg(struct strbuf *in, struct strbuf *out,
423532

424533
strbuf_complete_line(out);
425534
free(current_branch_to_free);
535+
free(merge_parents.item);
426536
return 0;
427537
}
428538

‎t/t7603-merge-reduce-heads.sh

Lines changed: 30 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -57,7 +57,36 @@ test_expect_success 'merge c1 with c2, c3, c4, c5' '
5757
test -f c2.c &&
5858
test -f c3.c &&
5959
test -f c4.c &&
60-
test -f c5.c
60+
test -f c5.c &&
61+
git show --format=%s -s >actual &&
62+
! grep c1 actual &&
63+
grep c2 actual &&
64+
grep c3 actual &&
65+
! grep c4 actual &&
66+
grep c5 actual
67+
'
68+
69+
test_expect_success 'pull c2, c3, c4, c5 into c1' '
70+
git reset --hard c1 &&
71+
git pull . c2 c3 c4 c5 &&
72+
test "$(git rev-parse c1)" != "$(git rev-parse HEAD)" &&
73+
test "$(git rev-parse c1)" = "$(git rev-parse HEAD^1)" &&
74+
test "$(git rev-parse c2)" = "$(git rev-parse HEAD^2)" &&
75+
test "$(git rev-parse c3)" = "$(git rev-parse HEAD^3)" &&
76+
test "$(git rev-parse c5)" = "$(git rev-parse HEAD^4)" &&
77+
git diff --exit-code &&
78+
test -f c0.c &&
79+
test -f c1.c &&
80+
test -f c2.c &&
81+
test -f c3.c &&
82+
test -f c4.c &&
83+
test -f c5.c &&
84+
git show --format=%s -s >actual &&
85+
! grep c1 actual &&
86+
grep c2 actual &&
87+
grep c3 actual &&
88+
! grep c4 actual &&
89+
grep c5 actual
6190
'
6291

6392
test_expect_success 'setup' '

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