Commit a0a1b19ab043f3579aabfb7602b4c4ac4dd69e72
2015-10-14T19:31:54
odb: Prioritize alternate backends For most real use cases, repositories with alternates use them as main object storage. Checking the alternate for objects before the main repository should result in measurable speedups. Because of this, we're changing the sorting algorithm to prioritize alternates *in cases where two backends have the same priority*. This means that the pack backend for the alternate will be checked before the pack backend for the main repository *but* both of them will be checked before any loose backends.
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diff --git a/src/odb.c b/src/odb.c
index af1ff7f..1c877c9 100644
--- a/src/odb.c
+++ b/src/odb.c
@@ -374,10 +374,14 @@ static int backend_sort_cmp(const void *a, const void *b)
const backend_internal *backend_a = (const backend_internal *)(a);
const backend_internal *backend_b = (const backend_internal *)(b);
- if (backend_a->is_alternate == backend_b->is_alternate)
- return (backend_b->priority - backend_a->priority);
-
- return backend_a->is_alternate ? 1 : -1;
+ if (backend_b->priority == backend_a->priority) {
+ if (backend_a->is_alternate)
+ return -1;
+ if (backend_b->is_alternate)
+ return 1;
+ return 0;
+ }
+ return (backend_b->priority - backend_a->priority);
}
int git_odb_new(git_odb **out)
diff --git a/tests/odb/sorting.c b/tests/odb/sorting.c
index d24c49c..6af8b0d 100644
--- a/tests/odb/sorting.c
+++ b/tests/odb/sorting.c
@@ -57,14 +57,14 @@ void test_odb_sorting__basic_backends_sorting(void)
void test_odb_sorting__alternate_backends_sorting(void)
{
- cl_git_pass(git_odb_add_backend(_odb, new_backend(0), 5));
- cl_git_pass(git_odb_add_backend(_odb, new_backend(2), 3));
- cl_git_pass(git_odb_add_backend(_odb, new_backend(1), 4));
- cl_git_pass(git_odb_add_backend(_odb, new_backend(3), 1));
- cl_git_pass(git_odb_add_alternate(_odb, new_backend(4), 5));
- cl_git_pass(git_odb_add_alternate(_odb, new_backend(6), 3));
- cl_git_pass(git_odb_add_alternate(_odb, new_backend(5), 4));
- cl_git_pass(git_odb_add_alternate(_odb, new_backend(7), 1));
+ cl_git_pass(git_odb_add_backend(_odb, new_backend(1), 5));
+ cl_git_pass(git_odb_add_backend(_odb, new_backend(5), 3));
+ cl_git_pass(git_odb_add_backend(_odb, new_backend(3), 4));
+ cl_git_pass(git_odb_add_backend(_odb, new_backend(7), 1));
+ cl_git_pass(git_odb_add_alternate(_odb, new_backend(0), 5));
+ cl_git_pass(git_odb_add_alternate(_odb, new_backend(4), 3));
+ cl_git_pass(git_odb_add_alternate(_odb, new_backend(2), 4));
+ cl_git_pass(git_odb_add_alternate(_odb, new_backend(6), 1));
check_backend_sorting(_odb);
}