Commit aef97245450bbe11debc5335bb9d3abc4e0d9479
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 2ed3574..805d2c3 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 147a160..22d057b 100644
--- a/tests/odb/sorting.c
+++ b/tests/odb/sorting.c
@@ -56,14 +56,14 @@ 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);
}