pack-objects: enable multi-pack reuse via `feature.experimental`

Now that multi-pack reuse is supported, enable it via the
feature.experimental configuration in addition to the classic
`pack.allowPackReuse`.

This will allow more users to experiment with the new behavior who might
not otherwise be aware of the existing `pack.allowPackReuse`
configuration option.

The enum with values NO_PACK_REUSE, SINGLE_PACK_REUSE, and
MULTI_PACK_REUSE is defined statically in builtin/pack-objects.c's
compilation unit. We could hoist that enum into a scope visible from the
repository_settings struct, and then use that enum value in
pack-objects. Instead, define a single int that indicates what
pack-objects's default value should be to avoid additional unnecessary
code movement.

Though `feature.experimental` implies `pack.allowPackReuse=multi`, this
can still be overridden by explicitly setting the latter configuration
to either "single" or "false". Tests covering all of these cases are
showin t5332.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/t/t5332-multi-pack-reuse.sh b/t/t5332-multi-pack-reuse.sh
index d516062f84..b925a81d37 100755
--- a/t/t5332-multi-pack-reuse.sh
+++ b/t/t5332-multi-pack-reuse.sh
@@ -58,6 +58,22 @@ test_expect_success 'preferred pack is reused for single-pack reuse' '
 	test_pack_objects_reused_all 3 1
 '
 
+test_expect_success 'multi-pack reuse is disabled by default' '
+	test_pack_objects_reused_all 3 1
+'
+
+test_expect_success 'feature.experimental implies multi-pack reuse' '
+	test_config feature.experimental true &&
+
+	test_pack_objects_reused_all 6 2
+'
+
+test_expect_success 'multi-pack reuse can be disabled with feature.experimental' '
+	test_config feature.experimental true &&
+	test_config pack.allowPackReuse single &&
+
+	test_pack_objects_reused_all 3 1
+'
 
 test_expect_success 'enable multi-pack reuse' '
 	git config pack.allowPackReuse multi