core: log offset pack data accesses happened

In a workload other than "git log" (without pathspec nor any option that
causes us to inspect trees and blobs), the recency pack order is said to
cause the access jump around quite a bit. Add a hook to allow us observe
how bad it is.

"git config core.logpackaccess /var/tmp/pal.txt" will give you the log
in the specified file.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/environment.c b/environment.c
index 94d58fd244..19351024f5 100644
--- a/environment.c
+++ b/environment.c
@@ -36,6 +36,7 @@ size_t packed_git_window_size = DEFAULT_PACKED_GIT_WINDOW_SIZE;
 size_t packed_git_limit = DEFAULT_PACKED_GIT_LIMIT;
 size_t delta_base_cache_limit = 16 * 1024 * 1024;
 unsigned long big_file_threshold = 512 * 1024 * 1024;
+const char *log_pack_access;
 const char *pager_program;
 int pager_use_color = 1;
 const char *editor_program;