commit-reach(repo_in_merge_bases_many): optionally expect missing commits

Currently this function treats unrelated commit histories the same way
as commit histories with missing commit objects.

Typically, missing commit objects constitute a corrupt repository,
though, and should be reported as such. The next commits will make it
so, but there is one exception: In `git fetch --update-shallow` we
_expect_ commit objects to be missing, and we do want to treat the
now-incomplete commit histories as unrelated.

To allow for that, let's introduce an additional parameter that is
passed to `repo_in_merge_bases_many()` to trigger this behavior, and use
it in the two callers in `shallow.c`.

This commit changes behavior slightly: unless called from the
`shallow.c` functions that set the `ignore_missing_commits` bit, any
non-existing tip commit that is passed to `repo_in_merge_bases_many()`
will now result in an error.

Note: When encountering missing commits while traversing the commit
history in search for merge bases, with this commit there won't be a
change in behavior just yet, their children will still be interpreted as
root commits. This bug will get fixed by follow-up commits.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/commit-reach.c b/commit-reach.c
index bfa1b64..e81bee4 100644 (file)
--- a/commit-reach.c
+++ b/commit-reach.c
@@ -466,7 +466,7 @@ int repo_is_descendant_of(struct repository *r,
 
                        other = with_commit->item;
                        with_commit = with_commit->next;
-                       if (repo_in_merge_bases_many(r, other, 1, &commit))
+                       if (repo_in_merge_bases_many(r, other, 1, &commit, 0))
                                return 1;
                }
                return 0;
@@ -477,17 +477,18 @@ int repo_is_descendant_of(struct repository *r,
  * 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)
+                            int nr_reference, struct commit **reference,
+                            int ignore_missing_commits)
 {
        struct commit_list *bases;
        int ret = 0, i;
        timestamp_t generation, max_generation = GENERATION_NUMBER_ZERO;
 
        if (repo_parse_commit(r, commit))
-               return ret;
+               return ignore_missing_commits ? 0 : -1;
        for (i = 0; i < nr_reference; i++) {
                if (repo_parse_commit(r, reference[i]))
-                       return ret;
+                       return ignore_missing_commits ? 0 : -1;
 
                generation = commit_graph_generation(reference[i]);
                if (generation > max_generation)

diff --git a/commit-reach.h b/commit-reach.h
index 35c4da4..68f8154 100644 (file)
--- a/commit-reach.h
+++ b/commit-reach.h
@@ -30,7 +30,8 @@ int repo_in_merge_bases(struct repository *r,
                        struct commit *reference);
 int repo_in_merge_bases_many(struct repository *r,
                             struct commit *commit,
-                            int nr_reference, struct commit **reference);
+                            int nr_reference, struct commit **reference,
+                            int ignore_missing_commits);
 
 /*
  * Takes a list of commits and returns a new list where those

diff --git a/remote.c b/remote.c
index e07b316..b3dbdd9 100644 (file)
--- a/remote.c
+++ b/remote.c
@@ -2680,7 +2680,7 @@ static int is_reachable_in_reflog(const char *local, const struct ref *remote)
                if (MERGE_BASES_BATCH_SIZE < size)
                        size = MERGE_BASES_BATCH_SIZE;
 
-               if ((ret = repo_in_merge_bases_many(the_repository, commit, size, chunk)))
+               if ((ret = repo_in_merge_bases_many(the_repository, commit, size, chunk, 0)))
                        break;
        }
 

diff --git a/shallow.c b/shallow.c
index 7711798..998072d 100644 (file)
--- a/shallow.c
+++ b/shallow.c
@@ -796,7 +796,7 @@ static void post_assign_shallow(struct shallow_info *info,
                for (j = 0; j < bitmap_nr; j++)
                        if (bitmap[0][j] &&
                            /* Step 7, reachability test at commit level */
-                           !repo_in_merge_bases_many(the_repository, c, ca.nr, ca.commits)) {
+                           !repo_in_merge_bases_many(the_repository, c, ca.nr, ca.commits, 1)) {
                                update_refstatus(ref_status, info->ref->nr, *bitmap);
                                dst++;
                                break;
@@ -827,7 +827,8 @@ int delayed_reachability_test(struct shallow_info *si, int c)
                si->reachable[c] = repo_in_merge_bases_many(the_repository,
                                                            commit,
                                                            si->nr_commits,
-                                                           si->commits);
+                                                           si->commits,
+                                                           1);
                si->need_reachability_test[c] = 0;
        }
        return si->reachable[c];

diff --git a/t/helper/test-reach.c b/t/helper/test-reach.c
index 1e159a7..c96b62f 100644 (file)
--- a/t/helper/test-reach.c
+++ b/t/helper/test-reach.c
@@ -111,7 +111,7 @@ int cmd__reach(int ac, const char **av)
                       repo_in_merge_bases(the_repository, A, B));
        else if (!strcmp(av[1], "in_merge_bases_many"))
                printf("%s(A,X):%d\n", av[1],
-                      repo_in_merge_bases_many(the_repository, A, X_nr, X_array));
+                      repo_in_merge_bases_many(the_repository, A, X_nr, X_array, 0));
        else if (!strcmp(av[1], "is_descendant_of"))
                printf("%s(A,X):%d\n", av[1], repo_is_descendant_of(r, A, X));
        else if (!strcmp(av[1], "get_merge_bases_many")) {