fix(dirmonitor): avoid calling the change callback multiple times in the same notification (#1824)

src/api/dirmonitor.c

@@ -26,7 +26,19 @@ int get_mode_dirmonitor();
 
 
 static int f_check_dir_callback(int watch_id, const char* path, void* L) {
-  // using absolute indices from f_dirmonitor_check (2: callback, 3: error_callback)
+  // using absolute indices from f_dirmonitor_check (2: callback, 3: error_callback, 4: watch_id notified table)
+
+  // Check if we already notified about this watch
+  lua_rawgeti(L, 4, watch_id);
+  bool skip = !lua_isnoneornil(L, -1);
+  lua_pop(L, 1);
+  if (skip) return 0;
+
+  // Set watch as notified
+  lua_pushboolean(L, true);
+  lua_rawseti(L, 4, watch_id);
+
+  // Prepare callback call
   lua_pushvalue(L, 2);
   if (path)
     lua_pushlstring(L, path, watch_id);
@@ -117,6 +129,9 @@ static int f_dirmonitor_check(lua_State* L) {
   if (monitor->length < 0)
     lua_pushnil(L);
   else if (monitor->length > 0) {
+    // Create a table for keeping track of what watch ids were notified in this check,
+    // so that we avoid notifying multiple times.
+    lua_newtable(L);
     if (translate_changes_dirmonitor(monitor->internal, monitor->buffer, monitor->length, f_check_dir_callback, L) == 0)
       monitor->length = 0;
     lua_pushboolean(L, 1);