[gnome-software] Fix threadsafety issues with gtk icon theme use

[Kalev Lember <klember src gnome org>]

commit 199757279be079ae8c4317a6a078eb58c5f71649
Author: Kalev Lember <kalevlember gmail com>
Date:   Tue Apr 22 11:45:19 2014 +0200

    Fix threadsafety issues with gtk icon theme use
    
    Instead of using global icon theme, create our own icon theme singleton
    and use that. Having our own makes it easy to serialize access to it
    when we need to load icons from several threads at a time.

 src/gs-utils.c |   16 +++++++++++++++-
 1 files changed, 15 insertions(+), 1 deletions(-)
---
diff --git a/src/gs-utils.c b/src/gs-utils.c
index aba511f..4b4edee 100644
--- a/src/gs-utils.c
+++ b/src/gs-utils.c
@@ -247,6 +247,18 @@ gs_mkdir_parent (const gchar *path, GError **error)
        return ret;
 }
 
+static GtkIconTheme *icon_theme_singleton;
+static GMutex        icon_theme_lock;
+
+static GtkIconTheme *
+icon_theme_get (void)
+{
+       if (icon_theme_singleton == NULL)
+               icon_theme_singleton = gtk_icon_theme_new ();
+
+       return icon_theme_singleton;
+}
+
 /**
  * gs_pixbuf_load:
  **/
@@ -269,12 +281,14 @@ gs_pixbuf_load (const gchar *icon_name, guint icon_size, GError **error)
                                                           icon_size,
                                                           error);
        } else if (g_strstr_len (icon_name, -1, ".") == NULL) {
-               pixbuf = gtk_icon_theme_load_icon (gtk_icon_theme_get_default (),
+               g_mutex_lock (&icon_theme_lock);
+               pixbuf = gtk_icon_theme_load_icon (icon_theme_get (),
                                                   icon_name,
                                                   icon_size,
                                                   GTK_ICON_LOOKUP_USE_BUILTIN |
                                                   GTK_ICON_LOOKUP_FORCE_SIZE,
                                                   error);
+               g_mutex_unlock (&icon_theme_lock);
        } else {
                g_set_error (error,
                             GS_PLUGIN_ERROR,