read-cache: add post-index-change hook

Add a post-index-change hook that is invoked after the index is written in
do_write_locked_index().

This hook is meant primarily for notification, and cannot affect
the outcome of git commands that trigger the index write.

The hook is passed a flag to indicate whether the working directory was
updated or not and a flag indicating if a skip-worktree bit could have
changed.  These flags enable the hook to optimize its response to the
index change notification.

Signed-off-by: Ben Peart <benpeart@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/cache.h b/cache.h
index 27fe635..46eb862 100644
--- a/cache.h
+++ b/cache.h
@@ -338,7 +338,9 @@ struct index_state {
 	struct cache_time timestamp;
 	unsigned name_hash_initialized : 1,
 		 initialized : 1,
-		 drop_cache_tree : 1;
+		 drop_cache_tree : 1,
+		 updated_workdir : 1,
+		 updated_skipworktree : 1;
 	struct hashmap name_hash;
 	struct hashmap dir_hash;
 	struct object_id oid;