[gnome-software: 21/25] gs-category: Lazily create child categories array

[Philip Withnall <pwithnall src gnome org>]

commit c50844b416548bd365d7aaac8ad098cc39ea9fe0
Author: Philip Withnall <pwithnall endlessos org>
Date:   Tue Feb 2 00:58:03 2021 +0000

    gs-category: Lazily create child categories array
    
    It’s only needed in parent categories, so there’s no point in creating it
    for child categories. This will save a small amount of memory.
    
    Signed-off-by: Philip Withnall <pwithnall endlessos org>

 lib/gs-category.c | 29 ++++++++++++++++++++++-------
 1 file changed, 22 insertions(+), 7 deletions(-)
---
diff --git a/lib/gs-category.c b/lib/gs-category.c
index 7c1aa5a68..b311c4941 100644
--- a/lib/gs-category.c
+++ b/lib/gs-category.c
@@ -33,7 +33,7 @@ struct _GsCategory
        GPtrArray       *desktop_groups;  /* potentially NULL if empty */
        GsCategory      *parent;
        guint            size;
-       GPtrArray       *children;
+       GPtrArray       *children;  /* potentially NULL if empty */
 };
 
 G_DEFINE_TYPE (GsCategory, gs_category, G_TYPE_OBJECT)
@@ -84,11 +84,10 @@ gs_category_to_string (GsCategory *category)
                                        gs_category_get_id (category->parent));
        }
        g_string_append_printf (str, "  score: %i\n", gs_category_get_score (category));
-       if (category->children->len == 0) {
-               g_string_append_printf (str, "  children: %u\n",
-                                       category->children->len);
+       if (category->children == NULL || category->children->len == 0) {
+               g_string_append_printf (str, "  children: %u\n", 0u);
        } else {
-               g_string_append (str, "  children:\n");
+               g_string_append_printf (str, "  children: %u\n", category->children->len);
                for (i = 0; i < category->children->len; i++) {
                        GsCategory *child = g_ptr_array_index (category->children, i);
                        g_string_append_printf (str, "  - %s\n",
@@ -379,6 +378,9 @@ gs_category_find_child (GsCategory *category, const gchar *id)
        GsCategory *tmp;
        guint i;
 
+       if (category->children == NULL)
+               return NULL;
+
        /* find the subcategory */
        for (i = 0; i < category->children->len; i++) {
                tmp = GS_CATEGORY (g_ptr_array_index (category->children, i));
@@ -419,6 +421,10 @@ GPtrArray *
 gs_category_get_children (GsCategory *category)
 {
        g_return_val_if_fail (GS_IS_CATEGORY (category), NULL);
+
+       if (category->children == NULL)
+               category->children = g_ptr_array_new_with_free_func ((GDestroyNotify) g_object_unref);
+
        return category->children;
 }
 
@@ -437,6 +443,11 @@ gs_category_add_child (GsCategory *category, GsCategory *subcategory)
        g_return_if_fail (GS_IS_CATEGORY (category));
        g_return_if_fail (GS_IS_CATEGORY (subcategory));
 
+       /* lazily create the array to save memory in subcategories, which don’t
+        * recursively have children */
+       if (category->children == NULL)
+               category->children = g_ptr_array_new_with_free_func ((GDestroyNotify) g_object_unref);
+
        /* FIXME: do we need this? */
        subcategory->parent = category;
        g_object_add_weak_pointer (G_OBJECT (subcategory->parent),
@@ -482,6 +493,9 @@ gs_category_sort_children_cb (gconstpointer a, gconstpointer b)
 void
 gs_category_sort_children (GsCategory *category)
 {
+       if (category->children == NULL)
+               return;
+
        g_ptr_array_sort (category->children,
                          gs_category_sort_children_cb);
 }
@@ -547,7 +561,7 @@ gs_category_finalize (GObject *object)
        if (category->parent != NULL)
                g_object_remove_weak_pointer (G_OBJECT (category->parent),
                                              (gpointer *) &category->parent);
-       g_ptr_array_unref (category->children);
+       g_clear_pointer (&category->children, g_ptr_array_unref);
        g_clear_pointer (&category->desktop_groups, g_ptr_array_unref);
 
        G_OBJECT_CLASS (gs_category_parent_class)->finalize (object);
@@ -647,7 +661,6 @@ gs_category_class_init (GsCategoryClass *klass)
 static void
 gs_category_init (GsCategory *category)
 {
-       category->children = g_ptr_array_new_with_free_func ((GDestroyNotify) g_object_unref);
 }
 
 /**
@@ -687,6 +700,8 @@ gs_category_new_for_desktop_data (const GsDesktopData *data)
        /* set up the ‘all’ subcategory specially, adding all the desktop groups
         * from all other child categories to it */
        if (subcategory_all != NULL) {
+               g_assert (category->children != NULL);
+
                for (guint i = 0; i < category->children->len; i++) {
                        GPtrArray *desktop_groups;
                        GsCategory *child;