[gobject-introspection/wip/carlosg/cache-misses] girepository: Also store GType cache misses

[Carlos Garnacho <carlosg src gnome org>]

commit d908039aca36ddb13068600ce3df7ad0c943ea09
Author: Carlos Garnacho <carlosg gnome org>
Date:   Wed Nov 13 19:37:00 2019 +0100

    girepository: Also store GType cache misses
    
    There are notably 3 classes of GTypes where a girepository lookup
    might fail:
    - GTypes from private interfaces in public objects (eg. MetaCullable in
      mutter)
    - GTypes for private base objects with public interfaces (eg. GLocalFile
      in GLib)
    - GTypes registered from the language, and presumably not coming from the
      GIR
    
    It is moot to look for those over and over again, and a full lookup can
    be taxing if looking up for a method/property on objects with those
    characteristics.
    
    It seems we can cache the misses too, so next lookups are just as quick
    as an introspected GType.

 girepository/girepository.c | 28 ++++++++++++++++++++++------
 1 file changed, 22 insertions(+), 6 deletions(-)
---
diff --git a/girepository/girepository.c b/girepository/girepository.c
index fd668c5a..90045540 100644
--- a/girepository/girepository.c
+++ b/girepository/girepository.c
@@ -120,6 +120,13 @@ DllMain (HINSTANCE hinstDLL,
 
 #endif
 
+static void
+check_base_info_unref (GIBaseInfo *base_info)
+{
+  if (base_info)
+    g_base_info_unref (base_info);
+}
+
 static void
 g_irepository_init (GIRepository *repository)
 {
@@ -135,7 +142,7 @@ g_irepository_init (GIRepository *repository)
   repository->priv->info_by_gtype
     = g_hash_table_new_full (g_direct_hash, g_direct_equal,
                              (GDestroyNotify) NULL,
-                             (GDestroyNotify) g_base_info_unref);
+                             (GDestroyNotify) check_base_info_unref);
   repository->priv->info_by_error_domain
     = g_hash_table_new_full (g_direct_hash, g_direct_equal,
                              (GDestroyNotify) NULL,
@@ -808,11 +815,15 @@ g_irepository_find_by_gtype (GIRepository *repository,
 
   repository = get_repository (repository);
 
-  cached = g_hash_table_lookup (repository->priv->info_by_gtype,
-                               (gpointer)gtype);
+  if (g_hash_table_lookup_extended (repository->priv->info_by_gtype,
+                                    (gpointer)gtype,
+                                    NULL, (gpointer*)&cached))
+    {
+      if (!cached)
+        return NULL;
 
-  if (cached != NULL)
-    return g_base_info_ref (cached);
+      return g_base_info_ref (cached);
+    }
 
   data.gtype_name = g_type_name (gtype);
   data.result_typelib = NULL;
@@ -849,7 +860,12 @@ g_irepository_find_by_gtype (GIRepository *repository,
                           g_base_info_ref (cached));
       return cached;
     }
-  return NULL;
+  else
+    {
+      g_hash_table_insert (repository->priv->info_by_gtype,
+                           (gpointer) gtype, NULL);
+      return NULL;
+    }
 }
 
 /**