fix(msg): able to create/delete msgs during notify (#3847)

Co-authored-by: wrgallo <28547933+wrgallo@users.noreply.github.com>

Kconfig

@@ -338,6 +338,11 @@ menu "LVGL configuration"
 				bool "Enable/Disable LV_LOG_TRACE in anim module"
 				default y
 				depends on LV_USE_LOG
+			
+			config LV_LOG_TRACE_MSG
+				bool "Enable/Disable LV_LOG_TRACE in msg module"
+				default y
+				depends on LV_USE_LOG
 		endmenu
 
 		menu "Asserts"

lv_conf_template.h

@@ -242,6 +242,7 @@
     #define LV_LOG_TRACE_OBJ_CREATE 1
     #define LV_LOG_TRACE_LAYOUT     1
     #define LV_LOG_TRACE_ANIM       1
+	#define LV_LOG_TRACE_MSG		1
 
 #endif  /*LV_USE_LOG*/
 

src/lv_conf_internal.h

@@ -724,6 +724,17 @@
             #define LV_LOG_TRACE_ANIM       1
         #endif
     #endif
+	#ifndef LV_LOG_TRACE_MSG
+	    #ifdef _LV_KCONFIG_PRESENT
+	        #ifdef CONFIG_LV_LOG_TRACE_MSG
+	            #define LV_LOG_TRACE_MSG CONFIG_LV_LOG_TRACE_MSG
+	        #else
+	            #define LV_LOG_TRACE_MSG 0
+	        #endif
+	    #else
+	        #define LV_LOG_TRACE_MSG		1
+	    #endif
+	#endif
 
 #endif  /*LV_USE_LOG*/
 

src/others/msg/lv_msg.c

@@ -26,6 +26,7 @@ typedef struct {
     lv_msg_subscribe_cb_t callback;
     void * user_data;
     void * _priv_data;      /*Internal: used only store 'obj' in lv_obj_subscribe*/
+    uint8_t _checked : 1;   /*Internal: used to prevent multiple notifications*/
 } sub_dsc_t;
 
 /**********************
@@ -39,6 +40,7 @@ static void obj_delete_event_cb(lv_event_t * e);
 /**********************
  *  STATIC VARIABLES
  **********************/
+static bool restart_notify;
 
 /**********************
  *  GLOBAL VARIABLES
@@ -47,6 +49,11 @@ static void obj_delete_event_cb(lv_event_t * e);
 /**********************
  *      MACROS
  **********************/
+#if LV_LOG_TRACE_MSG
+    #define MSG_TRACE(...) LV_LOG_TRACE(__VA_ARGS__)
+#else
+    #define MSG_TRACE(...)
+#endif
 
 /**********************
  *   GLOBAL FUNCTIONS
@@ -68,6 +75,8 @@ void * lv_msg_subscribe(lv_msg_id_t msg_id, lv_msg_subscribe_cb_t cb, void * use
     s->msg_id = msg_id;
     s->callback = cb;
     s->user_data = user_data;
+    s->_checked = 1; // if subsribed during `notify`, it won't be notified immediately
+    restart_notify = true;
     return s;
 }
 
@@ -89,6 +98,7 @@ void lv_msg_unsubscribe(void * s)
 {
     LV_ASSERT_NULL(s);
     _lv_ll_remove(&LV_GC_ROOT(_subs_ll), s);
+    restart_notify = true;
     lv_free(s);
 }
 
@@ -138,14 +148,48 @@ lv_msg_t * lv_event_get_msg(lv_event_t * e)
 
 static void notify(lv_msg_t * m)
 {
+    static unsigned int _recursion_counter = 0;
+    _recursion_counter++;
+
+    /*First clear all _checked flags*/
     sub_dsc_t * s;
+    if(_recursion_counter == 1) {
         _LV_LL_READ(&LV_GC_ROOT(_subs_ll), s) {
+            s->_checked = 0;
+        }
+    }
+
+    /*Run all sub_dsc_t from the list*/
+    do {
+        restart_notify = false;
+        s = _lv_ll_get_head(&LV_GC_ROOT(_subs_ll));
+        while(s) {
+            /*get next element while current is surely valid*/
+            sub_dsc_t * next = _lv_ll_get_next(&LV_GC_ROOT(_subs_ll), s);
+
+            /*Notify only once*/
+            if(!s->_checked) {
+                /*Check if this sub_dsc_t is about this msg_id*/
                 if(s->msg_id == m->id && s->callback) {
+                    // Set this flag and notify
+                    s->_checked = 1;
                     m->user_data = s->user_data;
                     m->_priv_data = s->_priv_data;
                     s->callback(m);
                 }
             }
+
+            /*restart or load next*/
+            if(restart_notify) {
+                MSG_TRACE("Start from the first sub_dsc_t again because _subs_ll may have changed");
+                break;
+            }
+            s = next;
+        }
+    } while(s);
+
+    _recursion_counter--;
+    restart_notify = (_recursion_counter > 0);
 }
 
 static void obj_notify_cb(lv_msg_t * m)