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git/commit-reach.c
Derrick Stolee cb99a34e23 commit-graph: fix writing first commit-graph during fetch
The previous commit includes a failing test for an issue around
fetch.writeCommitGraph and fetching in a repo with a submodule. Here, we
fix that bug and set the test to "test_expect_success".

The problem arises with this set of commands when the remote repo at
<url> has a submodule. Note that --recurse-submodules is not needed to
demonstrate the bug.

	$ git clone <url> test
	$ cd test
	$ git -c fetch.writeCommitGraph=true fetch origin
	Computing commit graph generation numbers: 100% (12/12), done.
	BUG: commit-graph.c:886: missing parent <hash1> for commit <hash2>
	Aborted (core dumped)

As an initial fix, I converted the code in builtin/fetch.c that calls
write_commit_graph_reachable() to instead launch a "git commit-graph
write --reachable --split" process. That code worked, but is not how we
want the feature to work long-term.

That test did demonstrate that the issue must be something to do with
internal state of the 'git fetch' process.

The write_commit_graph() method in commit-graph.c ensures the commits we
plan to write are "closed under reachability" using close_reachable().
This method walks from the input commits, and uses the UNINTERESTING
flag to mark which commits have already been visited. This allows the
walk to take O(N) time, where N is the number of commits, instead of
O(P) time, where P is the number of paths. (The number of paths can be
exponential in the number of commits.)

However, the UNINTERESTING flag is used in lots of places in the
codebase. This flag usually means some barrier to stop a commit walk,
such as in revision-walking to compare histories. It is not often
cleared after the walk completes because the starting points of those
walks do not have the UNINTERESTING flag, and clear_commit_marks() would
stop immediately.

This is happening during a 'git fetch' call with a remote. The fetch
negotiation is comparing the remote refs with the local refs and marking
some commits as UNINTERESTING.

I tested running clear_commit_marks_many() to clear the UNINTERESTING
flag inside close_reachable(), but the tips did not have the flag, so
that did nothing.

It turns out that the calculate_changed_submodule_paths() method is at
fault. Thanks, Peff, for pointing out this detail! More specifically,
for each submodule, the collect_changed_submodules() runs a revision
walk to essentially do file-history on the list of submodules. That
revision walk marks commits UNININTERESTING if they are simplified away
by not changing the submodule.

Instead, I finally arrived on the conclusion that I should use a flag
that is not used in any other part of the code. In commit-reach.c, a
number of flags were defined for commit walk algorithms. The REACHABLE
flag seemed like it made the most sense, and it seems it was not
actually used in the file. The REACHABLE flag was used in early versions
of commit-reach.c, but was removed by 4fbcca4 (commit-reach: make
can_all_from_reach... linear, 2018-07-20).

Add the REACHABLE flag to commit-graph.c and use it instead of
UNINTERESTING in close_reachable(). This fixes the bug in manual
testing.

Reported-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Helped-by: Jeff King <peff@peff.net>
Helped-by: Szeder Gábor <szeder.dev@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-10-25 11:19:16 +09:00

773 lines
19 KiB
C

#include "cache.h"
#include "commit.h"
#include "commit-graph.h"
#include "decorate.h"
#include "prio-queue.h"
#include "tree.h"
#include "ref-filter.h"
#include "revision.h"
#include "tag.h"
#include "commit-reach.h"
/* Remember to update object flag allocation in object.h */
#define PARENT1 (1u<<16)
#define PARENT2 (1u<<17)
#define STALE (1u<<18)
#define RESULT (1u<<19)
static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
static int queue_has_nonstale(struct prio_queue *queue)
{
int i;
for (i = 0; i < queue->nr; i++) {
struct commit *commit = queue->array[i].data;
if (!(commit->object.flags & STALE))
return 1;
}
return 0;
}
/* all input commits in one and twos[] must have been parsed! */
static struct commit_list *paint_down_to_common(struct repository *r,
struct commit *one, int n,
struct commit **twos,
int min_generation)
{
struct prio_queue queue = { compare_commits_by_gen_then_commit_date };
struct commit_list *result = NULL;
int i;
uint32_t last_gen = GENERATION_NUMBER_INFINITY;
if (!min_generation)
queue.compare = compare_commits_by_commit_date;
one->object.flags |= PARENT1;
if (!n) {
commit_list_append(one, &result);
return result;
}
prio_queue_put(&queue, one);
for (i = 0; i < n; i++) {
twos[i]->object.flags |= PARENT2;
prio_queue_put(&queue, twos[i]);
}
while (queue_has_nonstale(&queue)) {
struct commit *commit = prio_queue_get(&queue);
struct commit_list *parents;
int flags;
if (min_generation && commit->generation > last_gen)
BUG("bad generation skip %8x > %8x at %s",
commit->generation, last_gen,
oid_to_hex(&commit->object.oid));
last_gen = commit->generation;
if (commit->generation < min_generation)
break;
flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
if (flags == (PARENT1 | PARENT2)) {
if (!(commit->object.flags & RESULT)) {
commit->object.flags |= RESULT;
commit_list_insert_by_date(commit, &result);
}
/* Mark parents of a found merge stale */
flags |= STALE;
}
parents = commit->parents;
while (parents) {
struct commit *p = parents->item;
parents = parents->next;
if ((p->object.flags & flags) == flags)
continue;
if (repo_parse_commit(r, p))
return NULL;
p->object.flags |= flags;
prio_queue_put(&queue, p);
}
}
clear_prio_queue(&queue);
return result;
}
static struct commit_list *merge_bases_many(struct repository *r,
struct commit *one, int n,
struct commit **twos)
{
struct commit_list *list = NULL;
struct commit_list *result = NULL;
int i;
for (i = 0; i < n; i++) {
if (one == twos[i])
/*
* We do not mark this even with RESULT so we do not
* have to clean it up.
*/
return commit_list_insert(one, &result);
}
if (repo_parse_commit(r, one))
return NULL;
for (i = 0; i < n; i++) {
if (repo_parse_commit(r, twos[i]))
return NULL;
}
list = paint_down_to_common(r, one, n, twos, 0);
while (list) {
struct commit *commit = pop_commit(&list);
if (!(commit->object.flags & STALE))
commit_list_insert_by_date(commit, &result);
}
return result;
}
struct commit_list *get_octopus_merge_bases(struct commit_list *in)
{
struct commit_list *i, *j, *k, *ret = NULL;
if (!in)
return ret;
commit_list_insert(in->item, &ret);
for (i = in->next; i; i = i->next) {
struct commit_list *new_commits = NULL, *end = NULL;
for (j = ret; j; j = j->next) {
struct commit_list *bases;
bases = get_merge_bases(i->item, j->item);
if (!new_commits)
new_commits = bases;
else
end->next = bases;
for (k = bases; k; k = k->next)
end = k;
}
ret = new_commits;
}
return ret;
}
static int remove_redundant(struct repository *r, struct commit **array, int cnt)
{
/*
* Some commit in the array may be an ancestor of
* another commit. Move such commit to the end of
* the array, and return the number of commits that
* are independent from each other.
*/
struct commit **work;
unsigned char *redundant;
int *filled_index;
int i, j, filled;
work = xcalloc(cnt, sizeof(*work));
redundant = xcalloc(cnt, 1);
ALLOC_ARRAY(filled_index, cnt - 1);
for (i = 0; i < cnt; i++)
repo_parse_commit(r, array[i]);
for (i = 0; i < cnt; i++) {
struct commit_list *common;
uint32_t min_generation = array[i]->generation;
if (redundant[i])
continue;
for (j = filled = 0; j < cnt; j++) {
if (i == j || redundant[j])
continue;
filled_index[filled] = j;
work[filled++] = array[j];
if (array[j]->generation < min_generation)
min_generation = array[j]->generation;
}
common = paint_down_to_common(r, array[i], filled,
work, min_generation);
if (array[i]->object.flags & PARENT2)
redundant[i] = 1;
for (j = 0; j < filled; j++)
if (work[j]->object.flags & PARENT1)
redundant[filled_index[j]] = 1;
clear_commit_marks(array[i], all_flags);
clear_commit_marks_many(filled, work, all_flags);
free_commit_list(common);
}
/* Now collect the result */
COPY_ARRAY(work, array, cnt);
for (i = filled = 0; i < cnt; i++)
if (!redundant[i])
array[filled++] = work[i];
for (j = filled, i = 0; i < cnt; i++)
if (redundant[i])
array[j++] = work[i];
free(work);
free(redundant);
free(filled_index);
return filled;
}
static struct commit_list *get_merge_bases_many_0(struct repository *r,
struct commit *one,
int n,
struct commit **twos,
int cleanup)
{
struct commit_list *list;
struct commit **rslt;
struct commit_list *result;
int cnt, i;
result = merge_bases_many(r, one, n, twos);
for (i = 0; i < n; i++) {
if (one == twos[i])
return result;
}
if (!result || !result->next) {
if (cleanup) {
clear_commit_marks(one, all_flags);
clear_commit_marks_many(n, twos, all_flags);
}
return result;
}
/* There are more than one */
cnt = commit_list_count(result);
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_many(n, twos, all_flags);
cnt = remove_redundant(r, rslt, cnt);
result = NULL;
for (i = 0; i < cnt; i++)
commit_list_insert_by_date(rslt[i], &result);
free(rslt);
return result;
}
struct commit_list *repo_get_merge_bases_many(struct repository *r,
struct commit *one,
int n,
struct commit **twos)
{
return get_merge_bases_many_0(r, one, n, twos, 1);
}
struct commit_list *repo_get_merge_bases_many_dirty(struct repository *r,
struct commit *one,
int n,
struct commit **twos)
{
return get_merge_bases_many_0(r, one, n, twos, 0);
}
struct commit_list *repo_get_merge_bases(struct repository *r,
struct commit *one,
struct commit *two)
{
return get_merge_bases_many_0(r, one, 1, &two, 1);
}
/*
* Is "commit" a descendant of one of the elements on the "with_commit" list?
*/
int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
{
if (!with_commit)
return 1;
if (generation_numbers_enabled(the_repository)) {
struct commit_list *from_list = NULL;
int result;
commit_list_insert(commit, &from_list);
result = can_all_from_reach(from_list, with_commit, 0);
free_commit_list(from_list);
return result;
} else {
while (with_commit) {
struct commit *other;
other = with_commit->item;
with_commit = with_commit->next;
if (in_merge_bases(other, commit))
return 1;
}
return 0;
}
}
/*
* Is "commit" an ancestor of one of the "references"?
*/
int repo_in_merge_bases_many(struct repository *r, struct commit *commit,
int nr_reference, struct commit **reference)
{
struct commit_list *bases;
int ret = 0, i;
uint32_t min_generation = GENERATION_NUMBER_INFINITY;
if (repo_parse_commit(r, commit))
return ret;
for (i = 0; i < nr_reference; i++) {
if (repo_parse_commit(r, reference[i]))
return ret;
if (reference[i]->generation < min_generation)
min_generation = reference[i]->generation;
}
if (commit->generation > min_generation)
return ret;
bases = paint_down_to_common(r, commit,
nr_reference, reference,
commit->generation);
if (commit->object.flags & PARENT2)
ret = 1;
clear_commit_marks(commit, all_flags);
clear_commit_marks_many(nr_reference, reference, all_flags);
free_commit_list(bases);
return ret;
}
/*
* Is "commit" an ancestor of (i.e. reachable from) the "reference"?
*/
int repo_in_merge_bases(struct repository *r,
struct commit *commit,
struct commit *reference)
{
return repo_in_merge_bases_many(r, commit, 1, &reference);
}
struct commit_list *reduce_heads(struct commit_list *heads)
{
struct commit_list *p;
struct commit_list *result = NULL, **tail = &result;
struct commit **array;
int num_head, i;
if (!heads)
return NULL;
/* Uniquify */
for (p = heads; p; p = p->next)
p->item->object.flags &= ~STALE;
for (p = heads, num_head = 0; p; p = p->next) {
if (p->item->object.flags & STALE)
continue;
p->item->object.flags |= STALE;
num_head++;
}
array = xcalloc(num_head, sizeof(*array));
for (p = heads, i = 0; p; p = p->next) {
if (p->item->object.flags & STALE) {
array[i++] = p->item;
p->item->object.flags &= ~STALE;
}
}
num_head = remove_redundant(the_repository, array, num_head);
for (i = 0; i < num_head; i++)
tail = &commit_list_insert(array[i], tail)->next;
free(array);
return result;
}
void reduce_heads_replace(struct commit_list **heads)
{
struct commit_list *result = reduce_heads(*heads);
free_commit_list(*heads);
*heads = result;
}
int ref_newer(const struct object_id *new_oid, const struct object_id *old_oid)
{
struct object *o;
struct commit *old_commit, *new_commit;
struct commit_list *old_commit_list = NULL;
/*
* Both new_commit and old_commit must be commit-ish and new_commit is descendant of
* old_commit. Otherwise we require --force.
*/
o = deref_tag(the_repository, parse_object(the_repository, old_oid),
NULL, 0);
if (!o || o->type != OBJ_COMMIT)
return 0;
old_commit = (struct commit *) o;
o = deref_tag(the_repository, parse_object(the_repository, new_oid),
NULL, 0);
if (!o || o->type != OBJ_COMMIT)
return 0;
new_commit = (struct commit *) o;
if (parse_commit(new_commit) < 0)
return 0;
commit_list_insert(old_commit, &old_commit_list);
return is_descendant_of(new_commit, old_commit_list);
}
/*
* Mimicking the real stack, this stack lives on the heap, avoiding stack
* overflows.
*
* At each recursion step, the stack items points to the commits whose
* ancestors are to be inspected.
*/
struct contains_stack {
int nr, alloc;
struct contains_stack_entry {
struct commit *commit;
struct commit_list *parents;
} *contains_stack;
};
static int in_commit_list(const struct commit_list *want, struct commit *c)
{
for (; want; want = want->next)
if (oideq(&want->item->object.oid, &c->object.oid))
return 1;
return 0;
}
/*
* Test whether the candidate is contained in the list.
* Do not recurse to find out, though, but return -1 if inconclusive.
*/
static enum contains_result contains_test(struct commit *candidate,
const struct commit_list *want,
struct contains_cache *cache,
uint32_t cutoff)
{
enum contains_result *cached = contains_cache_at(cache, candidate);
/* If we already have the answer cached, return that. */
if (*cached)
return *cached;
/* or are we it? */
if (in_commit_list(want, candidate)) {
*cached = CONTAINS_YES;
return CONTAINS_YES;
}
/* Otherwise, we don't know; prepare to recurse */
parse_commit_or_die(candidate);
if (candidate->generation < cutoff)
return CONTAINS_NO;
return CONTAINS_UNKNOWN;
}
static void push_to_contains_stack(struct commit *candidate, struct contains_stack *contains_stack)
{
ALLOC_GROW(contains_stack->contains_stack, contains_stack->nr + 1, contains_stack->alloc);
contains_stack->contains_stack[contains_stack->nr].commit = candidate;
contains_stack->contains_stack[contains_stack->nr++].parents = candidate->parents;
}
static enum contains_result contains_tag_algo(struct commit *candidate,
const struct commit_list *want,
struct contains_cache *cache)
{
struct contains_stack contains_stack = { 0, 0, NULL };
enum contains_result result;
uint32_t cutoff = GENERATION_NUMBER_INFINITY;
const struct commit_list *p;
for (p = want; p; p = p->next) {
struct commit *c = p->item;
load_commit_graph_info(the_repository, c);
if (c->generation < cutoff)
cutoff = c->generation;
}
result = contains_test(candidate, want, cache, cutoff);
if (result != CONTAINS_UNKNOWN)
return result;
push_to_contains_stack(candidate, &contains_stack);
while (contains_stack.nr) {
struct contains_stack_entry *entry = &contains_stack.contains_stack[contains_stack.nr - 1];
struct commit *commit = entry->commit;
struct commit_list *parents = entry->parents;
if (!parents) {
*contains_cache_at(cache, commit) = CONTAINS_NO;
contains_stack.nr--;
}
/*
* If we just popped the stack, parents->item has been marked,
* therefore contains_test will return a meaningful yes/no.
*/
else switch (contains_test(parents->item, want, cache, cutoff)) {
case CONTAINS_YES:
*contains_cache_at(cache, commit) = CONTAINS_YES;
contains_stack.nr--;
break;
case CONTAINS_NO:
entry->parents = parents->next;
break;
case CONTAINS_UNKNOWN:
push_to_contains_stack(parents->item, &contains_stack);
break;
}
}
free(contains_stack.contains_stack);
return contains_test(candidate, want, cache, cutoff);
}
int commit_contains(struct ref_filter *filter, struct commit *commit,
struct commit_list *list, struct contains_cache *cache)
{
if (filter->with_commit_tag_algo)
return contains_tag_algo(commit, list, cache) == CONTAINS_YES;
return is_descendant_of(commit, list);
}
static int compare_commits_by_gen(const void *_a, const void *_b)
{
const struct commit *a = *(const struct commit * const *)_a;
const struct commit *b = *(const struct commit * const *)_b;
if (a->generation < b->generation)
return -1;
if (a->generation > b->generation)
return 1;
return 0;
}
int can_all_from_reach_with_flag(struct object_array *from,
unsigned int with_flag,
unsigned int assign_flag,
time_t min_commit_date,
uint32_t min_generation)
{
struct commit **list = NULL;
int i;
int nr_commits;
int result = 1;
ALLOC_ARRAY(list, from->nr);
nr_commits = 0;
for (i = 0; i < from->nr; i++) {
struct object *from_one = from->objects[i].item;
if (!from_one || from_one->flags & assign_flag)
continue;
from_one = deref_tag(the_repository, from_one,
"a from object", 0);
if (!from_one || from_one->type != OBJ_COMMIT) {
/*
* no way to tell if this is reachable by
* looking at the ancestry chain alone, so
* leave a note to ourselves not to worry about
* this object anymore.
*/
from->objects[i].item->flags |= assign_flag;
continue;
}
list[nr_commits] = (struct commit *)from_one;
if (parse_commit(list[nr_commits]) ||
list[nr_commits]->generation < min_generation) {
result = 0;
goto cleanup;
}
nr_commits++;
}
QSORT(list, nr_commits, compare_commits_by_gen);
for (i = 0; i < nr_commits; i++) {
/* DFS from list[i] */
struct commit_list *stack = NULL;
list[i]->object.flags |= assign_flag;
commit_list_insert(list[i], &stack);
while (stack) {
struct commit_list *parent;
if (stack->item->object.flags & (with_flag | RESULT)) {
pop_commit(&stack);
if (stack)
stack->item->object.flags |= RESULT;
continue;
}
for (parent = stack->item->parents; parent; parent = parent->next) {
if (parent->item->object.flags & (with_flag | RESULT))
stack->item->object.flags |= RESULT;
if (!(parent->item->object.flags & assign_flag)) {
parent->item->object.flags |= assign_flag;
if (parse_commit(parent->item) ||
parent->item->date < min_commit_date ||
parent->item->generation < min_generation)
continue;
commit_list_insert(parent->item, &stack);
break;
}
}
if (!parent)
pop_commit(&stack);
}
if (!(list[i]->object.flags & (with_flag | RESULT))) {
result = 0;
goto cleanup;
}
}
cleanup:
clear_commit_marks_many(nr_commits, list, RESULT | assign_flag);
free(list);
for (i = 0; i < from->nr; i++)
from->objects[i].item->flags &= ~assign_flag;
return result;
}
int can_all_from_reach(struct commit_list *from, struct commit_list *to,
int cutoff_by_min_date)
{
struct object_array from_objs = OBJECT_ARRAY_INIT;
time_t min_commit_date = cutoff_by_min_date ? from->item->date : 0;
struct commit_list *from_iter = from, *to_iter = to;
int result;
uint32_t min_generation = GENERATION_NUMBER_INFINITY;
while (from_iter) {
add_object_array(&from_iter->item->object, NULL, &from_objs);
if (!parse_commit(from_iter->item)) {
if (from_iter->item->date < min_commit_date)
min_commit_date = from_iter->item->date;
if (from_iter->item->generation < min_generation)
min_generation = from_iter->item->generation;
}
from_iter = from_iter->next;
}
while (to_iter) {
if (!parse_commit(to_iter->item)) {
if (to_iter->item->date < min_commit_date)
min_commit_date = to_iter->item->date;
if (to_iter->item->generation < min_generation)
min_generation = to_iter->item->generation;
}
to_iter->item->object.flags |= PARENT2;
to_iter = to_iter->next;
}
result = can_all_from_reach_with_flag(&from_objs, PARENT2, PARENT1,
min_commit_date, min_generation);
while (from) {
clear_commit_marks(from->item, PARENT1);
from = from->next;
}
while (to) {
clear_commit_marks(to->item, PARENT2);
to = to->next;
}
object_array_clear(&from_objs);
return result;
}
struct commit_list *get_reachable_subset(struct commit **from, int nr_from,
struct commit **to, int nr_to,
unsigned int reachable_flag)
{
struct commit **item;
struct commit *current;
struct commit_list *found_commits = NULL;
struct commit **to_last = to + nr_to;
struct commit **from_last = from + nr_from;
uint32_t min_generation = GENERATION_NUMBER_INFINITY;
int num_to_find = 0;
struct prio_queue queue = { compare_commits_by_gen_then_commit_date };
for (item = to; item < to_last; item++) {
struct commit *c = *item;
parse_commit(c);
if (c->generation < min_generation)
min_generation = c->generation;
if (!(c->object.flags & PARENT1)) {
c->object.flags |= PARENT1;
num_to_find++;
}
}
for (item = from; item < from_last; item++) {
struct commit *c = *item;
if (!(c->object.flags & PARENT2)) {
c->object.flags |= PARENT2;
parse_commit(c);
prio_queue_put(&queue, *item);
}
}
while (num_to_find && (current = prio_queue_get(&queue)) != NULL) {
struct commit_list *parents;
if (current->object.flags & PARENT1) {
current->object.flags &= ~PARENT1;
current->object.flags |= reachable_flag;
commit_list_insert(current, &found_commits);
num_to_find--;
}
for (parents = current->parents; parents; parents = parents->next) {
struct commit *p = parents->item;
parse_commit(p);
if (p->generation < min_generation)
continue;
if (p->object.flags & PARENT2)
continue;
p->object.flags |= PARENT2;
prio_queue_put(&queue, p);
}
}
clear_commit_marks_many(nr_to, to, PARENT1);
clear_commit_marks_many(nr_from, from, PARENT2);
return found_commits;
}