[glib/wip/baedert/gparam: 6/6] giomodule: Don't allocate GHashTable for no entries

[Timm Bäder <baedert src gnome org>]

commit fe441c8ca5a2ba92a17dc7d6cc408480a63f5681
Author: Timm Bäder <mail baedert org>
Date:   Thu Dec 31 14:48:31 2020 +0100

    giomodule: Don't allocate GHashTable for no entries
    
    This seems to happen in 3 out of 4 cases when calling gtk_init(), so
    avoid allocating the GHashTable in that case.

 gio/giomodule.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)
---
diff --git a/gio/giomodule.c b/gio/giomodule.c
index e27f1ab76..f20b64875 100644
--- a/gio/giomodule.c
+++ b/gio/giomodule.c
@@ -477,9 +477,7 @@ g_io_modules_scan_all_in_directory_with_scope (const char     *dirname,
 
   filename = g_build_filename (dirname, "giomodule.cache", NULL);
 
-  cache = g_hash_table_new_full (g_str_hash, g_str_equal,
-                                g_free, (GDestroyNotify)g_strfreev);
-
+  cache = NULL;
   cache_time = 0;
   if (g_stat (filename, &statbuf) == 0 &&
       g_file_get_contents (filename, &data, NULL, NULL))
@@ -523,6 +521,10 @@ g_io_modules_scan_all_in_directory_with_scope (const char     *dirname,
          while (g_ascii_isspace (*colon))
            colon++;
 
+          if (G_UNLIKELY (!cache))
+            cache = g_hash_table_new_full (g_str_hash, g_str_equal,
+                                           g_free, (GDestroyNotify)g_strfreev);
+
          extension_points = g_strsplit (colon, ",", -1);
          g_hash_table_insert (cache, file, extension_points);
        }
@@ -536,13 +538,15 @@ g_io_modules_scan_all_in_directory_with_scope (const char     *dirname,
          GIOExtensionPoint *extension_point;
          GIOModule *module;
          gchar *path;
-         char **extension_points;
+         char **extension_points = NULL;
          int i;
 
          path = g_build_filename (dirname, name, NULL);
          module = g_io_module_new (path);
 
-         extension_points = g_hash_table_lookup (cache, name);
+          if (cache)
+            extension_points = g_hash_table_lookup (cache, name);
+
          if (extension_points != NULL &&
              g_stat (path, &statbuf) == 0 &&
              statbuf.st_ctime <= cache_time)
@@ -577,7 +581,8 @@ g_io_modules_scan_all_in_directory_with_scope (const char     *dirname,
 
   g_dir_close (dir);
 
-  g_hash_table_destroy (cache);
+  if (cache)
+    g_hash_table_destroy (cache);
 
   g_free (filename);
 }