settings: introduce priority for commit

A priority is introduced to allow scheduling of commit routines.

Signed-off-by: Laczen JMS <laczenjms@gmail.com>

include/zephyr/settings/settings.h

@@ -70,6 +70,9 @@ struct settings_handler {
 	const char *name;
 	/**< Name of subtree. */
 
+	int cprio;
+	/**< Priority of commit, lower value is higher priority */
+
 	int (*h_get)(const char *key, char *val, int val_len_max);
 	/**< Get values handler of settings items identified by keyword names.
 	 *
@@ -136,6 +139,9 @@ struct settings_handler_static {
 	const char *name;
 	/**< Name of subtree. */
 
+	int cprio;
+	/**< Priority of commit, lower value is higher priority */
+
 	int (*h_get)(const char *key, char *val, int val_len_max);
 	/**< Get values handler of settings items identified by keyword names.
 	 *
@@ -196,22 +202,30 @@ struct settings_handler_static {
  * @param _set set routine (can be NULL)
  * @param _commit commit routine (can be NULL)
  * @param _export export routine (can be NULL)
+ * @param _cprio commit priority (lower value is higher priority)
  *
  * This creates a variable _hname prepended by settings_handler_.
  *
  */
 
-#define SETTINGS_STATIC_HANDLER_DEFINE(_hname, _tree, _get, _set, _commit,   \
+#define SETTINGS_STATIC_HANDLER_DEFINE_WITH_CPRIO(_hname, _tree, _get, _set, \
-				       _export)				     \
+						  _commit, _export, _cprio)  \
 	const STRUCT_SECTION_ITERABLE(settings_handler_static,		     \
 				      settings_handler_ ## _hname) = {       \
 		.name = _tree,						     \
+		.cprio = _cprio,					     \
 		.h_get = _get,						     \
 		.h_set = _set,						     \
 		.h_commit = _commit,					     \
 		.h_export = _export,					     \
 	}
 
+/* Handlers without commit priority are set to priority O */
+#define SETTINGS_STATIC_HANDLER_DEFINE(_hname, _tree, _get, _set, _commit,   \
+				       _export)				     \
+	SETTINGS_STATIC_HANDLER_DEFINE_WITH_CPRIO(_hname, _tree, _get, _set, \
+		_commit, _export, 0)
+
 /**
  * Initialization of settings and backend
  *
@@ -224,7 +238,20 @@ struct settings_handler_static {
 int settings_subsys_init(void);
 
 /**
- * Register a handler for settings items stored in RAM.
+ * Register a handler for settings items stored in RAM with
+ * commit priority.
+ *
+ * @param cf   Structure containing registration info.
+ * @param cprio Commit priority (lower value is higher priority).
+ *
+ * @return 0 on success, non-zero on failure.
+ */
+int settings_register_with_cprio(struct settings_handler *cf,
+				 int cprio);
+
+/**
+ * Register a handler for settings items stored in RAM with
+ * commit priority set to default.
  *
  * @param cf Structure containing registration info.
  *

subsys/settings/src/settings.c

@@ -9,6 +9,7 @@
 #include <stdio.h>
 #include <stdbool.h>
 #include <errno.h>
+#include <limits.h>
 #include <zephyr/kernel.h>
 
 #include <zephyr/settings/settings.h>
@@ -36,7 +37,7 @@ void settings_init(void)
 }
 
 #if defined(CONFIG_SETTINGS_DYNAMIC_HANDLERS)
-int settings_register(struct settings_handler *handler)
+int settings_register_with_cprio(struct settings_handler *handler, int cprio)
 {
 	int rc = 0;
 
@@ -55,12 +56,19 @@ int settings_register(struct settings_handler *handler)
 			goto end;
 		}
 	}
+
+	handler->cprio = cprio;
 	sys_slist_append(&settings_handlers, &handler->node);
 
 end:
 	k_mutex_unlock(&settings_lock);
 	return rc;
 }
+
+int settings_register(struct settings_handler *handler)
+{
+	return settings_register_with_cprio(handler, 0);
+}
 #endif /* CONFIG_SETTINGS_DYNAMIC_HANDLERS */
 
 int settings_name_steq(const char *name, const char *key, const char **next)
@@ -234,18 +242,45 @@ int settings_commit(void)
 	return settings_commit_subtree(NULL);
 }
 
+static int set_next_cprio(int handler_cprio, int cprio, int next_cprio)
+{
+	if (handler_cprio <= cprio) {
+		return next_cprio;
+	}
+
+	/* If cprio and next_cprio are identical then next_cprio has not
+	 * yet been set to any value and its initialized to the first
+	 * handler_cprio above cprio.
+	 */
+	if (cprio == next_cprio) {
+		return handler_cprio;
+	}
+
+	return MIN(handler_cprio, next_cprio);
+}
+
 int settings_commit_subtree(const char *subtree)
 {
 	int rc;
 	int rc2;
+	int cprio = INT_MIN;
 
 	rc = 0;
 
+	while (true) {
+		int next_cprio = cprio;
+
 		STRUCT_SECTION_FOREACH(settings_handler_static, ch) {
 			if (subtree && !settings_name_steq(ch->name, subtree, NULL)) {
 				continue;
 			}
+
 			if (ch->h_commit) {
+				next_cprio = set_next_cprio(ch->cprio, cprio, next_cprio);
+				if (ch->cprio != cprio) {
+					continue;
+				}
+
 				rc2 = ch->h_commit();
 				if (!rc) {
 					rc = rc2;
@@ -253,20 +288,34 @@ int settings_commit_subtree(const char *subtree)
 			}
 		}
 
-#if defined(CONFIG_SETTINGS_DYNAMIC_HANDLERS)
+		if (IS_ENABLED(CONFIG_SETTINGS_DYNAMIC_HANDLERS)) {
 			struct settings_handler *ch;
+
 			SYS_SLIST_FOR_EACH_CONTAINER(&settings_handlers, ch, node) {
 				if (subtree && !settings_name_steq(ch->name, subtree, NULL)) {
 					continue;
 				}
+
 				if (ch->h_commit) {
+					next_cprio = set_next_cprio(ch->cprio, cprio, next_cprio);
+					if (ch->cprio != cprio) {
+						continue;
+					}
+
 					rc2 = ch->h_commit();
 					if (!rc) {
 						rc = rc2;
 					}
 				}
 			}
-#endif /* CONFIG_SETTINGS_DYNAMIC_HANDLERS */
+		}
+
+		if (cprio == next_cprio) {
+			break;
+		}
+
+		cprio = next_cprio;
+	}
 
 	return rc;
 }