Add support for deferred settings changes, defer audio latency

frontend/menu/menu_common.c

@@ -309,6 +309,61 @@ static unsigned input_frame(uint64_t trigger_state)
    return MENU_ACTION_NOOP;
 }
 
+void apply_deferred_settings()
+{
+   rarch_setting_t *setting = driver.menu->list_settings;
+   bool change = false;
+
+   for (; setting->type != ST_NONE; setting++)
+   {
+      if ((setting->type < ST_GROUP) && (setting->flags & SD_FLAG_IS_DEFERRED))
+      {
+         switch (setting->type)
+         {
+            case ST_BOOL:
+               if (*setting->value.boolean != setting->original_value.boolean)
+               {
+                  setting->original_value.boolean = *setting->value.boolean;
+                  change = true;
+               }
+               break;
+            case ST_INT:
+               if (*setting->value.integer != setting->original_value.integer)
+               {
+                  setting->original_value.integer = *setting->value.integer;
+                  change = true;
+               }
+               break;
+            case ST_UINT:
+               if (*setting->value.unsigned_integer != setting->original_value.unsigned_integer)
+               {
+                  setting->original_value.unsigned_integer = *setting->value.unsigned_integer;
+                  change = true;
+               }
+               break;
+            case ST_FLOAT:
+               if (*setting->value.fraction != setting->original_value.fraction)
+               {
+                  setting->original_value.fraction = *setting->value.fraction;
+                  change = true;
+               }
+               break;
+            case ST_PATH:
+            case ST_DIR:
+            case ST_STRING:
+            case ST_BIND:
+               /* always run the deferred write handler */
+               change = true;
+               break;
+            default:
+               break;
+         }
+         if (change)
+            setting->deferred_handler(setting);
+      }
+   }
+}
+
 /* Returns:
  *  0  -  Forcibly wake up the loop.
  * -1  -  Quit out of iteration loop.

frontend/menu/menu_common.h

@@ -160,6 +160,8 @@ int menu_common_core_setting_toggle(unsigned setting, unsigned action);
 int menu_common_setting_set_perf(unsigned setting, unsigned action,
       struct retro_perf_counter **counters, unsigned offset);
 
+void apply_deferred_settings();
+
 #ifdef __cplusplus
 }
 #endif

retroarch.c

@@ -2015,6 +2015,8 @@ void rarch_main_set_state(unsigned cmd)
          break;
       case RARCH_ACTION_STATE_MENU_RUNNING_FINISHED:
 #ifdef HAVE_MENU
+         apply_deferred_settings();
+
          g_extern.is_menu = false;
 
          driver_set_nonblock_state(driver.nonblock_state);

settings_data.c

@@ -703,6 +703,7 @@ rarch_setting_t setting_data_float_setting(const char* name,
    result.change_handler = change_handler;
    result.read_handler = read_handler;
    result.value.fraction = target;
+   result.original_value.fraction = *target;
    result.default_value.fraction = default_value;
    return result;
 }
@@ -718,6 +719,7 @@ rarch_setting_t setting_data_bool_setting(const char* name,
    result.change_handler = change_handler;
    result.read_handler = read_handler;
    result.value.boolean = target;
+   result.original_value.boolean = *target;
    result.default_value.boolean = default_value;
    result.boolean.off_label = off;
    result.boolean.on_label = on;
@@ -735,6 +737,7 @@ rarch_setting_t setting_data_int_setting(const char* name,
    result.change_handler = change_handler;
    result.read_handler = read_handler;
    result.value.integer = target;
+   result.original_value.integer = *target;
    result.default_value.integer = default_value;
    return result;
 }
@@ -750,6 +753,7 @@ rarch_setting_t setting_data_uint_setting(const char* name,
    result.change_handler = change_handler;
    result.read_handler = read_handler;
    result.value.unsigned_integer = target;
+   result.original_value.unsigned_integer = *target;
    result.default_value.unsigned_integer = default_value;
 
    return result;
@@ -3631,7 +3635,7 @@ bool setting_data_append_list_audio_options(
          general_write_handler,
          general_read_handler);
    settings_list_current_add_range(list, list_info, 1, 256, 1.0, true, true);
-
+   settings_list_current_add_flags(list, list_info, SD_FLAG_IS_DEFERRED);
 
    CONFIG_FLOAT(
          g_settings.audio.rate_control_delta,

settings_list.c

@@ -56,12 +56,24 @@ bool settings_list_append(rarch_setting_t **list,
    return true;
 }
 
+static void null_write_handler(void *data)
+{
+   return;
+}
+
 void settings_list_current_add_flags(
       rarch_setting_t **list,
       rarch_setting_info_t *list_info,
       unsigned values)
 {
+
    (*list)[list_info->index - 1].flags |= values;
+
+   if (values & SD_FLAG_IS_DEFERRED)
+   {
+      (*list)[list_info->index - 1].deferred_handler = (*list)[list_info->index - 1].change_handler;
+      (*list)[list_info->index - 1].change_handler = null_write_handler;
+   }
 }
 
 void settings_list_current_add_range(

settings_list.h

@@ -56,6 +56,7 @@ enum setting_flags
    SD_FLAG_EXIT           = (1 << 8),
    SD_FLAG_CMD_APPLY_AUTO = (1 << 9),
    SD_FLAG_IS_CATEGORY    = (1 << 10),
+   SD_FLAG_IS_DEFERRED    = (1 << 11),
 };
 
 enum setting_list_flags
@@ -112,6 +113,7 @@ typedef struct rarch_setting
    uint64_t flags;
    
    change_handler_t change_handler;
+   change_handler_t deferred_handler;
    change_handler_t read_handler;
    
    union
@@ -134,6 +136,14 @@ typedef struct rarch_setting
       struct retro_keybind* keybind;
    } value;
 
+   union
+   {
+      bool boolean;
+      int integer;
+      unsigned int unsigned_integer;
+      float fraction;
+   } original_value;
+
    struct
    {
       const char *empty_path;