[PATCH v4 3/3] gc: perform incremental repack when implictly enabled

[Glen Choo <chooglen@google.com>]

builtin/gc.c has two ways of checking if multi-pack-index is enabled:
- git_config_get_bool() in incremental_repack_auto_condition()
- the_repository->settings.core_multi_pack_index in
  maintenance_task_incremental_repack()

The two implementations have existed since the incremental-repack task
was introduced in e841a79a13 (maintenance: add incremental-repack auto
condition, 2020-09-25). These two values can diverge because
prepare_repo_settings() enables the feature in the_repository->settings
by default.

In the case where core.multiPackIndex is not set in the config, the auto
condition would fail, causing the incremental-repack task to not be
run. Because we always want to consider the default values, we should
always use the_repository->settings.

Standardize on using the_repository->settings.core_multi_pack_index to
check if multi-pack-index is enabled.

Signed-off-by: Glen Choo <chooglen@google.com>
---
 builtin/gc.c           |  5 ++---
 t/t7900-maintenance.sh | 28 ++++++++++++++++++++++++----
 2 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/builtin/gc.c b/builtin/gc.c
index 6b3de3dd51..2670931160 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -1049,12 +1049,11 @@ static int maintenance_task_loose_objects(struct maintenance_run_opts *opts)
 static int incremental_repack_auto_condition(void)
 {
 	struct packed_git *p;
-	int enabled;
 	int incremental_repack_auto_limit = 10;
 	int count = 0;
 
-	if (git_config_get_bool("core.multiPackIndex", &enabled) ||
-	    !enabled)
+	prepare_repo_settings(the_repository);
+	if (!the_repository->settings.core_multi_pack_index)
 		return 0;
 
 	git_config_get_int("maintenance.incremental-repack.auto",
diff --git a/t/t7900-maintenance.sh b/t/t7900-maintenance.sh
index 9b9f11a8e7..74aa638475 100755
--- a/t/t7900-maintenance.sh
+++ b/t/t7900-maintenance.sh
@@ -336,15 +336,15 @@ test_expect_success EXPENSIVE 'incremental-repack 2g limit' '
 		 --no-progress --batch-size=2147483647 <run-2g.txt
 '
 
-test_expect_success 'maintenance.incremental-repack.auto' '
+run_incremental_repack_and_verify () {
+	test_commit A &&
 	git repack -adk &&
-	git config core.multiPackIndex true &&
 	git multi-pack-index write &&
 	GIT_TRACE2_EVENT="$(pwd)/midx-init.txt" git \
 		-c maintenance.incremental-repack.auto=1 \
 		maintenance run --auto --task=incremental-repack 2>/dev/null &&
 	test_subcommand ! git multi-pack-index write --no-progress <midx-init.txt &&
-	test_commit A &&
+	test_commit B &&
 	git pack-objects --revs .git/objects/pack/pack <<-\EOF &&
 	HEAD
 	^HEAD~1
@@ -353,7 +353,7 @@ test_expect_success 'maintenance.incremental-repack.auto' '
 		-c maintenance.incremental-repack.auto=2 \
 		maintenance run --auto --task=incremental-repack 2>/dev/null &&
 	test_subcommand ! git multi-pack-index write --no-progress <trace-A &&
-	test_commit B &&
+	test_commit C &&
 	git pack-objects --revs .git/objects/pack/pack <<-\EOF &&
 	HEAD
 	^HEAD~1
@@ -362,6 +362,26 @@ test_expect_success 'maintenance.incremental-repack.auto' '
 		-c maintenance.incremental-repack.auto=2 \
 		maintenance run --auto --task=incremental-repack 2>/dev/null &&
 	test_subcommand git multi-pack-index write --no-progress <trace-B
+}
+
+test_expect_success 'maintenance.incremental-repack.auto' '
+	rm -rf incremental-repack-true &&
+	git init incremental-repack-true &&
+	(
+		cd incremental-repack-true &&
+		git config core.multiPackIndex true &&
+		run_incremental_repack_and_verify
+	)
+'
+
+test_expect_success 'maintenance.incremental-repack.auto (when config is unset)' '
+	rm -rf incremental-repack-unset &&
+	git init incremental-repack-unset &&
+	(
+		cd incremental-repack-unset &&
+		test_unconfig core.multiPackIndex &&
+		run_incremental_repack_and_verify
+	)
 '
 
 test_expect_success 'pack-refs task' '
-- 
2.33.0.882.g93a45727a2-goog