Merge branch 'ps/odb-stop-registering-in-memory-sources' into jch

The mechanism to register in-memory alternate object sources has
been removed, as submodule object databases are now accessed
natively via their own repository structures.  This simplifies
object database management and prepares the codebase for migrating
alternate tracking into the files backend.

* ps/odb-stop-registering-in-memory-sources:
  odb: remove the ability to link sources ad-hoc
  t/helper: stop registering alternates in "ref-store" command
  t/helper: adapt read-midx to not link ad-hoc source anymore
  builtin/multi-pack-index: refuse unknown sources with "--object-dir="
  odb/packed: fix memory leaks when freeing source
  tmp-objdir: drop unused function to register alternate
  odb: remove infrastructure to register submodule sources
  builtin/grep: stop registering submodule ODB as source
  submodule-config: stop registering submodule sources
  submodule-config: stop using `the_hash_algo`
  submodule-config: remove uses of `the_repository`
  cache-tree: remove dependency on `the_repository`
  cache-tree: drop `the_repository` in `cache_tree_fully_valid()`

Author: gitster

builtin/checkout.c

@@ -921,7 +921,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		}
 	}
 
-	if (!cache_tree_fully_valid(the_repository->index->cache_tree))
+	if (!cache_tree_fully_valid(the_repository->index))
 		cache_tree_update(the_repository->index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 
 	if (write_locked_index(the_repository->index, &lock_file, COMMIT_LOCK))

builtin/commit.c

@@ -484,7 +484,7 @@ static const char *prepare_index(const char **argv, const char *prefix,
 				       LOCK_DIE_ON_ERROR);
 		refresh_cache_or_die(refresh_flags);
 		if (the_repository->index->cache_changed
-		    || !cache_tree_fully_valid(the_repository->index->cache_tree))
+		    || !cache_tree_fully_valid(the_repository->index))
 			cache_tree_update(the_repository->index, WRITE_TREE_SILENT);
 		if (write_locked_index(the_repository->index, &index_lock,
 				       COMMIT_LOCK | SKIP_IF_UNCHANGED))

builtin/fetch.c

@@ -2681,7 +2681,7 @@ int cmd_fetch(int argc,
 		int *rs = config.recurse_submodules == RECURSE_SUBMODULES_DEFAULT
 			  ? &config.recurse_submodules : NULL;
 
-		fetch_config_from_gitmodules(sfjc, rs);
+		fetch_config_from_gitmodules(the_repository, sfjc, rs);
 	}
 
 

builtin/grep.c

@@ -463,16 +463,6 @@ static int grep_submodule(struct grep_opt *opt,
 	ALLOC_GROW(repos_to_free, repos_to_free_nr + 1, repos_to_free_alloc);
 	repos_to_free[repos_to_free_nr++] = subrepo;
 
-	/*
-	 * NEEDSWORK: repo_read_gitmodules() might call
-	 * odb_add_to_alternates_memory() via config_from_gitmodules(). This
-	 * operation causes a race condition with concurrent object readings
-	 * performed by the worker threads. That's why we need obj_read_lock()
-	 * here. It should be removed once it's no longer necessary to add the
-	 * subrepo's odbs to the in-memory alternates list.
-	 */
-	obj_read_lock();
-
 	/*
 	 * NEEDSWORK: when reading a submodule, the sparsity settings in the
 	 * superproject are incorrectly forgotten or misused. For example:
@@ -498,18 +488,14 @@ static int grep_submodule(struct grep_opt *opt,
 	 *	ditto.
 	 *
 	 * Note that this list is not exhaustive.
+	 *
+	 * NEEDSWORK: initializing the subrepository is not thread-safe,
+	 * either, as it may cause us to race around `get_main_ref_store()`. We
+	 * thus need to hold the object-read lock to serialize all readers with
+	 * one another.
 	 */
+	obj_read_lock();
 	repo_read_gitmodules(subrepo, 0);
-
-	/*
-	 * All code paths tested by test code no longer need submodule ODBs to
-	 * be added as alternates, but add it to the list just in case.
-	 * Submodule ODBs added through add_submodule_odb_by_path() will be
-	 * lazily registered as alternates when needed (and except in an
-	 * unexpected code interaction, it won't be needed).
-	 */
-	odb_add_submodule_source_by_path(the_repository->objects,
-					 subrepo->objects->sources->path);
 	obj_read_unlock();
 
 	memcpy(&subopt, opt, sizeof(subopt));
@@ -897,7 +883,7 @@ static int grep_objects(struct grep_opt *opt, const struct pathspec *pathspec,
 		if (recurse_submodules) {
 			submodule_free(opt->repo);
 			obj_read_lock();
-			gitmodules_config_oid(&real_obj->oid);
+			gitmodules_config_oid(the_repository, &real_obj->oid);
 			obj_read_unlock();
 		}
 		if (grep_object(opt, pathspec, real_obj, list->objects[i].name,

builtin/multi-pack-index.c

@@ -90,7 +90,8 @@ static struct odb_source_files *handle_object_dir_option(struct repository *repo
 {
 	struct odb_source *source = odb_find_source(repo->objects, opts.object_dir);
 	if (!source)
-		source = odb_add_to_alternates_memory(repo->objects, opts.object_dir);
+		die(_("object directory is not an alternate of the current repository: '%s'"),
+		    opts.object_dir);
 	return odb_source_files_downcast(source);
 }
 

builtin/submodule--helper.c

@@ -3045,7 +3045,7 @@ static int module_update(int argc, const char **argv, const char *prefix,
 		NULL
 	};
 
-	update_clone_config_from_gitmodules(&opt.max_jobs);
+	update_clone_config_from_gitmodules(the_repository, &opt.max_jobs);
 	repo_config(the_repository, git_update_clone_config, &opt.max_jobs);
 
 	argc = parse_options(argc, argv, prefix, module_update_options,
@@ -3259,7 +3259,7 @@ static int module_set_url(int argc, const char **argv, const char *prefix,
 		    path);
 
 	config_name = xstrfmt("submodule.%s.url", sub->name);
-	ret = config_set_in_gitmodules_file_gently(config_name, newurl);
+	ret = config_set_in_gitmodules_file_gently(the_repository, config_name, newurl);
 
 	if (!ret) {
 		repo_read_gitmodules(the_repository, 0);
@@ -3315,7 +3315,7 @@ static int module_set_branch(int argc, const char **argv, const char *prefix,
 		    path);
 
 	config_name = xstrfmt("submodule.%s.branch", sub->name);
-	ret = config_set_in_gitmodules_file_gently(config_name, opt_branch);
+	ret = config_set_in_gitmodules_file_gently(the_repository, config_name, opt_branch);
 
 	free(config_name);
 	return !!ret;
@@ -3515,7 +3515,7 @@ static int config_submodule_in_gitmodules(const char *name, const char *var, con
 		die(_("please make sure that the .gitmodules file is in the working tree"));
 
 	key = xstrfmt("submodule.%s.%s", name, var);
-	ret = config_set_in_gitmodules_file_gently(key, value);
+	ret = config_set_in_gitmodules_file_gently(the_repository, key, value);
 	free(key);
 
 	return ret;