config: create core.multiPackIndex setting

The core.multiPackIndex config setting controls the multi-pack-
index (MIDX) feature. If false, the setting will disable all reads
from the multi-pack-index file.

Read this config setting in the new prepare_multi_pack_index_one()
which is called during prepare_packed_git(). This check is run once
per repository.

Add comparison commands in t5319-multi-pack-index.sh to check
typical Git behavior remains the same as the config setting is turned
on and off. This currently includes 'git rev-list' and 'git log'
commands to trigger several object database reads. Currently, these
would only catch an error in the prepare_multi_pack_index_one(), but
with later commits will catch errors in object lookups, abbreviations,
and approximate object counts.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/midx.h b/midx.h
index e15966272f..9bcfc82d2e 100644
--- a/midx.h
+++ b/midx.h
@@ -1,7 +1,11 @@
 #ifndef __MIDX_H__
 #define __MIDX_H__
 
+#include "repository.h"
+
 struct multi_pack_index {
+	struct multi_pack_index *next;
+
 	int fd;
 
 	const unsigned char *data;
@@ -25,6 +29,7 @@ struct multi_pack_index {
 };
 
 struct multi_pack_index *load_multi_pack_index(const char *object_dir);
+int prepare_multi_pack_index_one(struct repository *r, const char *object_dir);
 
 int write_midx_file(const char *object_dir);