Merge branch 'backport-3213-variant-text-performance-glib-2-74' into 'glib-2-74'

Backport !3213 “gvariant: Optimise g_variant_print() for nested maybes” to glib-2-74

See merge request GNOME/glib!3214

glib/gvariant-core.c

@@ -1138,11 +1138,13 @@ GVariant *
 g_variant_get_child_value (GVariant *value,
                            gsize     index_)
 {
-  g_return_val_if_fail (index_ < g_variant_n_children (value), NULL);
   g_return_val_if_fail (value->depth < G_MAXSIZE, NULL);
 
   if (~g_atomic_int_get (&value->state) & STATE_SERIALISED)
     {
+      /* g_variant_serialised_get_child() does its own checks on index_ */
+      g_return_val_if_fail (index_ < g_variant_n_children (value), NULL);
+
       g_variant_lock (value);
 
       if (~value->state & STATE_SERIALISED)
@@ -1233,11 +1235,13 @@ GVariant *
 g_variant_maybe_get_child_value (GVariant *value,
                                  gsize     index_)
 {
-  g_return_val_if_fail (index_ < g_variant_n_children (value), NULL);
   g_return_val_if_fail (value->depth < G_MAXSIZE, NULL);
 
   if (~g_atomic_int_get (&value->state) & STATE_SERIALISED)
     {
+      /* g_variant_serialised_get_child() does its own checks on index_ */
+      g_return_val_if_fail (index_ < g_variant_n_children (value), NULL);
+
       g_variant_lock (value);
 
       if (~value->state & STATE_SERIALISED)

glib/gvariant.c

@@ -2213,20 +2213,22 @@ g_variant_print_string (GVariant *value,
                         GString  *string,
                         gboolean  type_annotate)
 {
+  const gchar *value_type_string = g_variant_get_type_string (value);
+
   if G_UNLIKELY (string == NULL)
     string = g_string_new (NULL);
 
-  switch (g_variant_classify (value))
+  switch (value_type_string[0])
     {
     case G_VARIANT_CLASS_MAYBE:
       if (type_annotate)
-        g_string_append_printf (string, "@%s ",
+        g_string_append_printf (string, "@%s ", value_type_string);
-                                g_variant_get_type_string (value));
 
       if (g_variant_n_children (value))
         {
-          gchar *printed_child;
+          const GVariantType *base_type;
-          GVariant *element;
+          guint i, depth;
+          GVariant *element = NULL;
 
           /* Nested maybes:
            *
@@ -2240,19 +2242,36 @@ g_variant_print_string (GVariant *value,
            * "just" is actually exactly the case where we have a nested
            * Nothing.
            *
-           * Instead of searching for that nested Nothing, we just print
+           * Search for the nested Nothing, to save a lot of recursion if there
-           * the contained value into a separate string and see if we
+           * are multiple levels of maybes.
-           * end up with "nothing" at the end of it.  If so, we need to
-           * add "just" at our level.
            */
-          element = g_variant_get_child_value (value, 0);
+          for (depth = 0, base_type = g_variant_get_type (value);
-          printed_child = g_variant_print (element, FALSE);
+               g_variant_type_is_maybe (base_type);
-          g_variant_unref (element);
+               depth++, base_type = g_variant_type_element (base_type));
 
-          if (g_str_has_suffix (printed_child, "nothing"))
+          element = g_variant_ref (value);
-            g_string_append (string, "just ");
+          for (i = 0; i < depth && element != NULL; i++)
-          g_string_append (string, printed_child);
+            {
-          g_free (printed_child);
+              GVariant *new_element = g_variant_n_children (element) ? g_variant_get_child_value (element, 0) : NULL;
+              g_variant_unref (element);
+              element = g_steal_pointer (&new_element);
+            }
+
+          if (element == NULL)
+            {
+              /* One of the maybes was Nothing, so print out the right number of
+               * justs. */
+              for (; i > 1; i--)
+                g_string_append (string, "just ");
+              g_string_append (string, "nothing");
+            }
+          else
+            {
+              /* There are no Nothings, so print out the child with no prefixes. */
+              g_variant_print_string (element, string, FALSE);
+            }
+
+          g_clear_pointer (&element, g_variant_unref);
         }
       else
         g_string_append (string, "nothing");
@@ -2265,7 +2284,7 @@ g_variant_print_string (GVariant *value,
        * if the first two characters are 'ay' then it's a bytestring.
        * under certain conditions we print those as strings.
        */
-      if (g_variant_get_type_string (value)[1] == 'y')
+      if (value_type_string[1] == 'y')
         {
           const gchar *str;
           gsize size;
@@ -2307,7 +2326,7 @@ g_variant_print_string (GVariant *value,
        * dictionary entries (ie: a dictionary) so we print that
        * differently.
        */
-      if (g_variant_get_type_string (value)[1] == '{')
+      if (value_type_string[1] == '{')
         /* dictionary */
         {
           const gchar *comma = "";
@@ -2316,8 +2335,7 @@ g_variant_print_string (GVariant *value,
           if ((n = g_variant_n_children (value)) == 0)
             {
               if (type_annotate)
-                g_string_append_printf (string, "@%s ",
+                g_string_append_printf (string, "@%s ", value_type_string);
-                                        g_variant_get_type_string (value));
               g_string_append (string, "{}");
               break;
             }
@@ -2353,8 +2371,7 @@ g_variant_print_string (GVariant *value,
           if ((n = g_variant_n_children (value)) == 0)
             {
               if (type_annotate)
-                g_string_append_printf (string, "@%s ",
+                g_string_append_printf (string, "@%s ", value_type_string);
-                                        g_variant_get_type_string (value));
               g_string_append (string, "[]");
               break;
             }

glib/gvarianttypeinfo.c

@@ -247,8 +247,6 @@ g_variant_type_info_query (GVariantTypeInfo *info,
                            guint            *alignment,
                            gsize            *fixed_size)
 {
-  g_variant_type_info_check (info, 0);
-
   if (alignment)
     *alignment = info->alignment;