refs: record the ref_store in ref_cache, not ref_dir

Instead of keeping a pointer to the `ref_store` in every `ref_dir`
entry, store it once in `struct ref_cache`, and change `struct
ref_dir` to include a pointer to its containing `ref_cache` instead.
This makes it easier to add to the information that is accessible from
a `ref_dir` without increasing the size of every `ref_dir` instance.

Note that previously, every `ref_dir` pointed at the containing
`files_ref_store` regardless of whether it was a part of the loose or
packed reference cache. Now we have to be sure to initialize the
instances to point at the correct containing `ref_cache`. So change
`create_dir_entry()` to take a `ref_cache` parameter, and change its
callers to pass the correct `ref_cache` depending on the purpose of
the new `dir_entry`.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 6 insertions, 3 deletions

diff --git a/refs/ref-cache.h b/refs/ref-cache.h
index da5388c136..83051854ff 100644
--- a/refs/ref-cache.h
+++ b/refs/ref-cache.h
@@ -3,6 +3,9 @@
 
 struct ref_cache {
 	struct ref_entry *root;
+
+	/* A pointer to the files_ref_store whose cache this is: */
+	struct files_ref_store *ref_store;
 };
 
 /*
@@ -66,8 +69,8 @@ struct ref_dir {
 	 */
 	int sorted;
 
-	/* A pointer to the files_ref_store that contains this ref_dir. */
-	struct files_ref_store *ref_store;
+	/* The ref_cache containing this entry: */
+	struct ref_cache *cache;
 
 	struct ref_entry **entries;
 };
@@ -161,7 +164,7 @@ struct ref_dir *get_ref_dir(struct ref_entry *entry);
  * dirname is the name of the directory with a trailing slash (e.g.,
  * "refs/heads/") or "" for the top-level directory.
  */
-struct ref_entry *create_dir_entry(struct files_ref_store *ref_store,
+struct ref_entry *create_dir_entry(struct ref_cache *cache,
 				   const char *dirname, size_t len,
 				   int incomplete);