1 files changed, 48 insertions, 12 deletions

diff --git a/submodule-config.h b/submodule-config.h
index 4dc9b0771c..42918b55e8 100644
--- a/submodule-config.h
+++ b/submodule-config.h
@@ -7,9 +7,31 @@
 #include "submodule.h"
 #include "strbuf.h"
 
+/**
+ * The submodule config cache API allows to read submodule
+ * configurations/information from specified revisions. Internally
+ * information is lazily read into a cache that is used to avoid
+ * unnecessary parsing of the same .gitmodules files. Lookups can be done by
+ * submodule path or name.
+ *
+ * Usage
+ * -----
+ *
+ * The caller can look up information about submodules by using the
+ * `submodule_from_path()` or `submodule_from_name()` functions. They return
+ * a `struct submodule` which contains the values. The API automatically
+ * initializes and allocates the needed infrastructure on-demand. If the
+ * caller does only want to lookup values from revisions the initialization
+ * can be skipped.
+ *
+ * If the internal cache might grow too big or when the caller is done with
+ * the API, all internally cached values can be freed with submodule_free().
+ *
+ */
+
 /*
  * Submodule entry containing the information about a certain submodule
- * in a certain revision.
+ * in a certain revision. It is returned by the lookup functions.
  */
 struct submodule {
 	const char *path;
@@ -30,24 +52,38 @@ struct submodule {
 struct submodule_cache;
 struct repository;
 
-extern void submodule_cache_free(struct submodule_cache *cache);
+void submodule_cache_free(struct submodule_cache *cache);
 
-extern int parse_submodule_fetchjobs(const char *var, const char *value);
-extern int parse_fetch_recurse_submodules_arg(const char *opt, const char *arg);
+int parse_submodule_fetchjobs(const char *var, const char *value);
+int parse_fetch_recurse_submodules_arg(const char *opt, const char *arg);
 struct option;
-extern int option_fetch_parse_recurse_submodules(const struct option *opt,
-						 const char *arg, int unset);
-extern int parse_update_recurse_submodules_arg(const char *opt, const char *arg);
-extern int parse_push_recurse_submodules_arg(const char *opt, const char *arg);
-extern void repo_read_gitmodules(struct repository *repo);
-extern void gitmodules_config_oid(const struct object_id *commit_oid);
+int option_fetch_parse_recurse_submodules(const struct option *opt,
+					  const char *arg, int unset);
+int parse_update_recurse_submodules_arg(const char *opt, const char *arg);
+int parse_push_recurse_submodules_arg(const char *opt, const char *arg);
+void repo_read_gitmodules(struct repository *repo);
+void gitmodules_config_oid(const struct object_id *commit_oid);
+
+/**
+ * Same as submodule_from_path but lookup by name.
+ */
 const struct submodule *submodule_from_name(struct repository *r,
 					    const struct object_id *commit_or_tree,
 					    const char *name);
+
+/**
+ * Given a tree-ish in the superproject and a path, return the submodule that
+ * is bound at the path in the named tree.
+ */
 const struct submodule *submodule_from_path(struct repository *r,
 					    const struct object_id *commit_or_tree,
 					    const char *path);
+
+/**
+ * Use these to free the internally cached values.
+ */
 void submodule_free(struct repository *r);
+
 int print_config_from_gitmodules(struct repository *repo, const char *key);
 int config_set_in_gitmodules_file_gently(const char *key, const char *value);
 
@@ -66,7 +102,7 @@ int check_submodule_name(const char *name);
  * New helpers to retrieve arbitrary configuration from the '.gitmodules' file
  * should NOT be added.
  */
-extern void fetch_config_from_gitmodules(int *max_children, int *recurse_submodules);
-extern void update_clone_config_from_gitmodules(int *max_jobs);
+void fetch_config_from_gitmodules(int *max_children, int *recurse_submodules);
+void update_clone_config_from_gitmodules(int *max_jobs);
 
 #endif /* SUBMODULE_CONFIG_H */