packfile: split up responsibilities of `reprepare_packed_git()`

In `reprepare_packed_git()` we perform a couple of operations:

  - We reload alternate object directories.

  - We clear the loose object cache.

  - We reprepare packfiles.

While the logic is hosted in "packfile.c", it clearly reaches into other
subsystems that aren't related to packfiles.

Split up the responsibility and introduce `odb_reprepare()` which now
becomes responsible for repreparing the whole object database. The
existing `reprepare_packed_git()` function is refactored accordingly and
only cares about reloading the packfile store now.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/backfill.c

@@ -53,7 +53,7 @@ static void download_batch(struct backfill_context *ctx)
 	 * We likely have a new packfile. Add it to the packed list to
 	 * avoid possible duplicate downloads of the same objects.
 	 */
-	reprepare_packed_git(ctx->repo);
+	odb_reprepare(ctx->repo->objects);
 }
 
 static int fill_missing_blobs(const char *path UNUSED,

builtin/gc.c

@@ -1042,7 +1042,7 @@ int cmd_gc(int argc,
 		die(FAILED_RUN, "rerere");
 
 	report_garbage = report_pack_garbage;
-	reprepare_packed_git(the_repository);
+	odb_reprepare(the_repository->objects);
 	if (pack_garbage.nr > 0) {
 		close_object_store(the_repository->objects);
 		clean_pack_garbage();
@@ -1491,7 +1491,7 @@ static off_t get_auto_pack_size(void)
 	struct packed_git *p;
 	struct repository *r = the_repository;
 
-	reprepare_packed_git(r);
+	odb_reprepare(r->objects);
 	for (p = get_all_packs(r); p; p = p->next) {
 		if (p->pack_size > max_size) {
 			second_largest_size = max_size;

builtin/receive-pack.c

@@ -2389,7 +2389,7 @@ static const char *unpack(int err_fd, struct shallow_info *si)
 		status = finish_command(&child);
 		if (status)
 			return "index-pack abnormal exit";
-		reprepare_packed_git(the_repository);
+		odb_reprepare(the_repository->objects);
 	}
 	return NULL;
 }

builtin/repack.c

@@ -1685,7 +1685,7 @@ int cmd_repack(int argc,
 			goto cleanup;
 	}
 
-	reprepare_packed_git(the_repository);
+	odb_reprepare(the_repository->objects);
 
 	if (delete_redundant) {
 		int opts = 0;

bulk-checkin.c

@@ -90,7 +90,7 @@ clear_exit:
 
 	strbuf_release(&packname);
 	/* Make objects we just wrote available to ourselves */
-	reprepare_packed_git(the_repository);
+	odb_reprepare(the_repository->objects);
 }
 
 /*

connected.c

@@ -72,7 +72,7 @@ int check_connected(oid_iterate_fn fn, void *cb_data,
 		 * Before checking for promisor packs, be sure we have the
 		 * latest pack-files loaded into memory.
 		 */
-		reprepare_packed_git(the_repository);
+		odb_reprepare(the_repository->objects);
 		do {
 			struct packed_git *p;
 

fetch-pack.c

@@ -1983,7 +1983,7 @@ static void update_shallow(struct fetch_pack_args *args,
 		 * remote is shallow, but this is a clone, there are
 		 * no objects in repo to worry about. Accept any
 		 * shallow points that exist in the pack (iow in repo
-		 * after get_pack() and reprepare_packed_git())
+		 * after get_pack() and odb_reprepare())
 		 */
 		struct oid_array extra = OID_ARRAY_INIT;
 		struct object_id *oid = si->shallow->oid;
@@ -2108,7 +2108,7 @@ struct ref *fetch_pack(struct fetch_pack_args *args,
 		ref_cpy = do_fetch_pack(args, fd, ref, sought, nr_sought,
 					&si, pack_lockfiles);
 	}
-	reprepare_packed_git(the_repository);
+	odb_reprepare(the_repository->objects);
 
 	if (!args->cloning && args->deepen) {
 		struct check_connected_options opt = CHECK_CONNECTED_INIT;

object-name.c

@@ -596,7 +596,7 @@ static enum get_oid_result get_short_oid(struct repository *r,
 	 * or migrated from loose to packed.
 	 */
 	if (status == MISSING_OBJECT) {
-		reprepare_packed_git(r);
+		odb_reprepare(r->objects);
 		find_short_object_filename(&ds);
 		find_short_packed_object(&ds);
 		status = finish_object_disambiguation(&ds, oid);

odb.c

@@ -694,7 +694,7 @@ static int do_oid_object_info_extended(struct object_database *odb,
 
 		/* Not a loose object; someone else may have just packed it. */
 		if (!(flags & OBJECT_INFO_QUICK)) {
-			reprepare_packed_git(odb->repo);
+			odb_reprepare(odb->repo->objects);
 			if (find_pack_entry(odb->repo, real, &e))
 				break;
 		}
@@ -1040,3 +1040,28 @@ void odb_clear(struct object_database *o)
 
 	string_list_clear(&o->submodule_source_paths, 0);
 }
+
+void odb_reprepare(struct object_database *o)
+{
+	struct odb_source *source;
+
+	obj_read_lock();
+
+	/*
+	 * Reprepare alt odbs, in case the alternates file was modified
+	 * during the course of this process. This only _adds_ odbs to
+	 * the linked list, so existing odbs will continue to exist for
+	 * the lifetime of the process.
+	 */
+	o->loaded_alternates = 0;
+	odb_prepare_alternates(o);
+
+	for (source = o->sources; source; source = source->next)
+		odb_clear_loose_cache(source);
+
+	o->approximate_object_count_valid = 0;
+
+	packfile_store_reprepare(o->packfiles);
+
+	obj_read_unlock();
+}

odb.h

@@ -161,6 +161,12 @@ struct object_database {
 struct object_database *odb_new(struct repository *repo);
 void odb_clear(struct object_database *o);
 
+/*
+ * Clear caches, reload alternates and then reload object sources so that new
+ * objects may become accessible.
+ */
+void odb_reprepare(struct object_database *o);
+
 /*
  * Find source by its object directory path. Returns a `NULL` pointer in case
  * the source could not be found.

packfile.c

@@ -1002,28 +1002,10 @@ static void packfile_store_prepare(struct packfile_store *store)
 	store->initialized = true;
 }
 
-void reprepare_packed_git(struct repository *r)
+void packfile_store_reprepare(struct packfile_store *store)
 {
-	struct odb_source *source;
-
-	obj_read_lock();
-
-	/*
-	 * Reprepare alt odbs, in case the alternates file was modified
-	 * during the course of this process. This only _adds_ odbs to
-	 * the linked list, so existing odbs will continue to exist for
-	 * the lifetime of the process.
-	 */
-	r->objects->loaded_alternates = 0;
-	odb_prepare_alternates(r->objects);
-
-	for (source = r->objects->sources; source; source = source->next)
-		odb_clear_loose_cache(source);
-
-	r->objects->approximate_object_count_valid = 0;
-	r->objects->packfiles->initialized = false;
-	packfile_store_prepare(r->objects->packfiles);
-	obj_read_unlock();
+	store->initialized = false;
+	packfile_store_prepare(store);
 }
 
 struct packed_git *get_packed_git(struct repository *r)
@@ -1144,7 +1126,7 @@ unsigned long get_size_from_delta(struct packed_git *p,
 		 *
 		 * Other worrying sections could be the call to close_pack_fd(),
 		 * which can close packs even with in-use windows, and to
-		 * reprepare_packed_git(). Regarding the former, mmap doc says:
+		 * odb_reprepare(). Regarding the former, mmap doc says:
 		 * "closing the file descriptor does not unmap the region". And
 		 * for the latter, it won't re-open already available packs.
 		 */

packfile.h

@@ -112,6 +112,14 @@ void packfile_store_free(struct packfile_store *store);
  */
 void packfile_store_close(struct packfile_store *store);
 
+/*
+ * Clear the packfile caches and try to look up any new packfiles that have
+ * appeared since last preparing the packfiles store.
+ *
+ * This function must be called under the `odb_read_lock()`.
+ */
+void packfile_store_reprepare(struct packfile_store *store);
+
 struct pack_window {
 	struct pack_window *next;
 	unsigned char *base;
@@ -188,7 +196,6 @@ int for_each_packed_object(struct repository *repo, each_packed_object_fn cb,
 #define PACKDIR_FILE_GARBAGE 4
 extern void (*report_garbage)(unsigned seen_bits, const char *path);
 
-void reprepare_packed_git(struct repository *r);
 void install_packed_git(struct repository *r, struct packed_git *pack);
 
 struct packed_git *get_packed_git(struct repository *r);

transport-helper.c

@@ -450,7 +450,7 @@ static int fetch_with_fetch(struct transport *transport,
 	}
 	strbuf_release(&buf);
 
-	reprepare_packed_git(the_repository);
+	odb_reprepare(the_repository->objects);
 	return 0;
 }