Switch to a plugin API that only allows one cache backend at a time.

Tumbler will now only check for the file

  $(libdir)/tumbler-1/plugins/cache/tumbler-cache-plugin.so

which is supposed to link to the cache backend that is being used. If
the XDG cache is built, tumbler-cache-plugin.so is set up to link to
this plugin.

The fact that we only have a singleton cache makes things much less
ambiguous.

6 files changed, 82 insertions, 74 deletions

diff --git a/tumbler/Makefile.am b/tumbler/Makefile.am
index 3d32f4d..12f8d0b 100644
--- a/tumbler/Makefile.am
+++ b/tumbler/Makefile.am
@@ -30,7 +30,7 @@ libtumbler_built_sources =						\
 libtumbler_headers =							\
 	tumbler-abstract-thumbnailer.h					\
 	tumbler-cache.h							\
-	tumbler-cache-provider.h					\
+	tumbler-cache-plugin.h						\
 	tumbler-config.h						\
 	tumbler-enum-types.h						\
 	tumbler-error.h							\
@@ -48,7 +48,7 @@ libtumbler_headers =							\
 libtumbler_sources =							\
 	tumbler-abstract-thumbnailer.c					\
 	tumbler-cache.c							\
-	tumbler-cache-provider.c					\
+	tumbler-cache-plugin.c						\
 	tumbler-config.c						\
 	tumbler-enum-types.c						\
 	tumbler-file-info.c						\
diff --git a/tumbler/tumbler-cache.c b/tumbler/tumbler-cache.c
index d1232b1..cdb5156 100644
--- a/tumbler/tumbler-cache.c
+++ b/tumbler/tumbler-cache.c
@@ -25,6 +25,7 @@
 #include <glib-object.h>
 
 #include <tumbler/tumbler-cache.h>
+#include <tumbler/tumbler-cache-plugin.h>
 
 
 
@@ -54,6 +55,33 @@ tumbler_cache_get_type (void)
 
 
 
+TumblerCache *
+tumbler_cache_get_default (void)
+{
+  static TumblerCache *cache = NULL;
+  GTypeModule         *plugin;
+
+  if (cache == NULL)
+    {
+      plugin = tumbler_cache_plugin_get_default ();
+
+      if (plugin != NULL)
+        {
+          cache = tumbler_cache_plugin_get_cache (TUMBLER_CACHE_PLUGIN (plugin));
+          g_object_add_weak_pointer (G_OBJECT (cache), (gpointer) &cache);
+          g_type_module_unuse (plugin);
+        }
+    }
+  else
+    {
+      g_object_ref (cache);
+    }
+     
+  return cache;
+}
+
+
+
 GList *
 tumbler_cache_get_thumbnails (TumblerCache *cache,
                               const gchar  *uri)
diff --git a/tumbler/tumbler-cache.h b/tumbler/tumbler-cache.h
index c1a1e42..7e42539 100644
--- a/tumbler/tumbler-cache.h
+++ b/tumbler/tumbler-cache.h
@@ -61,23 +61,25 @@ struct _TumblerCacheIface
                               const gchar  *uri);
 };
 
-GType    tumbler_cache_get_type (void) G_GNUC_CONST;
+GType         tumbler_cache_get_type (void) G_GNUC_CONST;
 
-GList   *tumbler_cache_get_thumbnails (TumblerCache *cache,
-                                       const gchar  *uri) G_GNUC_MALLOC G_GNUC_WARN_UNUSED_RESULT;
-void     tumbler_cache_cleanup        (TumblerCache *cache,
-                                       const gchar  *uri_prefix,
-                                       guint64       since);
-void     tumbler_cache_delete         (TumblerCache *cache,
-                                       const GStrv   uris);
-void     tumbler_cache_copy           (TumblerCache *cache,
-                                       const GStrv   from_uris,
-                                       const GStrv   to_uris);
-void     tumbler_cache_move           (TumblerCache *cache,
-                                       const GStrv   from_uris,
-                                       const GStrv   to_uris);
-gboolean tumbler_cache_is_thumbnail   (TumblerCache *cache,
-                                       const gchar  *uri);
+TumblerCache *tumbler_cache_get_default    (void) G_GNUC_WARN_UNUSED_RESULT;
+
+GList        *tumbler_cache_get_thumbnails (TumblerCache *cache,
+                                            const gchar  *uri) G_GNUC_MALLOC G_GNUC_WARN_UNUSED_RESULT;
+void          tumbler_cache_cleanup        (TumblerCache *cache,
+                                            const gchar  *uri_prefix,
+                                            guint64       since);
+void          tumbler_cache_delete         (TumblerCache *cache,
+                                            const GStrv   uris);
+void          tumbler_cache_copy           (TumblerCache *cache,
+                                            const GStrv   from_uris,
+                                            const GStrv   to_uris);
+void          tumbler_cache_move           (TumblerCache *cache,
+                                            const GStrv   from_uris,
+                                            const GStrv   to_uris);
+gboolean      tumbler_cache_is_thumbnail   (TumblerCache *cache,
+                                            const gchar  *uri);
 
 G_END_DECLS
 
diff --git a/tumbler/tumbler-file-info.c b/tumbler/tumbler-file-info.c
index 80b8d69..c2cbde8 100644
--- a/tumbler/tumbler-file-info.c
+++ b/tumbler/tumbler-file-info.c
@@ -193,15 +193,14 @@ tumbler_file_info_load (TumblerFileInfo *info,
                         GError         **error)
 {
   TumblerProviderFactory *provider_factory;
-  GFileInfo *file_info;
-  GError    *err = NULL;
-  GFile     *file;
-  GList     *caches;
-  GList     *cp;
-  GList     *lp;
-  GList     *providers;
-  GList     *thumbnails;
-  GList     *tp;
+  TumblerCache           *cache;
+  GFileInfo              *file_info;
+  GError                 *err = NULL;
+  GFile                  *file;
+  GList                  *cp;
+  GList                  *lp;
+  GList                  *thumbnails;
+  GList                  *tp;
 
   g_return_val_if_fail (TUMBLER_IS_FILE_INFO (info), FALSE);
   g_return_val_if_fail (cancellable == NULL || G_IS_CANCELLABLE (cancellable), FALSE);
@@ -237,57 +236,36 @@ tumbler_file_info_load (TumblerFileInfo *info,
   g_list_free (info->thumbnails);
   info->thumbnails = NULL;
 
-  /* get the provider factory */
-  provider_factory = tumbler_provider_factory_get_default ();
-
-  /* query a list of cache providers */
-  providers = tumbler_provider_factory_get_providers (provider_factory, 
-                                                      TUMBLER_TYPE_CACHE_PROVIDER);
-
-  /* iterate over all available cache providers */
-  for (lp = providers; err == NULL && lp != NULL; lp = lp->next)
+  /* query the default cache implementation */
+  cache = tumbler_cache_get_default ();
+  if (cache != NULL)
     {
-      /* query a list of cache implementations from the current provider */
-      caches = tumbler_cache_provider_get_caches (lp->data);
+      /* check if the file itself is a thumbnail */
+      if (!tumbler_cache_is_thumbnail (cache, info->uri))
+        {
+          /* query thumbnail infos for this URI from the current cache */
+          thumbnails = tumbler_cache_get_thumbnails (cache, info->uri);
+
+          /* try to load thumbnail infos. the loop will terminate if 
+           * one of them fails */
+          for (tp = thumbnails; err == NULL && tp != NULL; tp = tp->next)
+            tumbler_thumbnail_load (tp->data, cancellable, &err);
 
-      /* iterate over all available cache implementations */
-      for (cp = caches; err == NULL && cp != NULL; cp = cp->next)
+          /* add all queried thumbnails to the list */
+          info->thumbnails = g_list_concat (info->thumbnails, 
+                                                  thumbnails);
+        }
+      else
         {
-          /* check if the file itself is a thumbnail */
-          if (!tumbler_cache_is_thumbnail (cp->data, info->uri))
-            {
-              /* query thumbnail infos for this URI from the current cache */
-              thumbnails = tumbler_cache_get_thumbnails (cp->data, info->uri);
-
-              /* try to load thumbnail infos. the loop will terminate if 
-               * one of them fails */
-              for (tp = thumbnails; err == NULL && tp != NULL; tp = tp->next)
-                tumbler_thumbnail_load (tp->data, cancellable, &err);
-
-              /* add all queried thumbnails to the list */
-              info->thumbnails = g_list_concat (info->thumbnails, 
-                                                      thumbnails);
-            }
-          else
-            {
-              /* we don't allow the generation of thumbnails for thumbnails */
-              g_set_error (&err, TUMBLER_ERROR, TUMBLER_ERROR_IS_THUMBNAIL,
-                           _("The file \"%s\" is a thumbnail itself"), info->uri);
-            }
+          /* we don't allow the generation of thumbnails for thumbnails */
+          g_set_error (&err, TUMBLER_ERROR, TUMBLER_ERROR_IS_THUMBNAIL,
+                       _("The file \"%s\" is a thumbnail itself"), info->uri);
         }
 
-      /* release cache references */
-      g_list_foreach (caches, (GFunc) g_object_unref, NULL);
-      g_list_free (caches);
+      /* release the cache */
+      g_object_unref (cache);
     }
 
-  /* release provider references */
-  g_list_foreach (providers, (GFunc) g_object_unref, NULL);
-  g_list_free (providers);
-
-  /* release the provider factory */
-  g_object_unref (provider_factory);
-
   if (err != NULL)
     {
       /* propagate errors */
diff --git a/tumbler/tumbler-provider-plugin.c b/tumbler/tumbler-provider-plugin.c
index f22babd..5e759da 100644
--- a/tumbler/tumbler-provider-plugin.c
+++ b/tumbler/tumbler-provider-plugin.c
@@ -116,7 +116,7 @@ tumbler_provider_plugin_load (GTypeModule *type_module)
   g_free (path);
 
   /* check if the load operation was successful */
-  if (G_UNLIKELY (plugin->library != NULL))
+  if (G_LIKELY (plugin->library != NULL))
     {
       /* verify that all required public symbols are present in the plugin */
       if (g_module_symbol (plugin->library, "tumbler_plugin_initialize", 
@@ -134,6 +134,7 @@ tumbler_provider_plugin_load (GTypeModule *type_module)
         {
           g_warning (_("Plugin \"%s\" lacks required symbols."), type_module->name);
           g_module_close (plugin->library);
+          plugin->library = NULL;
           return FALSE;
         }
     }
@@ -160,7 +161,6 @@ tumbler_provider_plugin_unload (GTypeModule *type_module)
   plugin->library = NULL;
 
   /* reset plugin state */
-  plugin->library = NULL;
   plugin->initialize = NULL;
   plugin->shutdown = NULL;
   plugin->get_types = NULL;
diff --git a/tumbler/tumbler.h b/tumbler/tumbler.h
index 98661a5..3f086bf 100644
--- a/tumbler/tumbler.h
+++ b/tumbler/tumbler.h
@@ -25,7 +25,7 @@
 
 #include <tumbler/tumbler-abstract-thumbnailer.h>
 #include <tumbler/tumbler-cache.h>
-#include <tumbler/tumbler-cache-provider.h>
+#include <tumbler/tumbler-cache-plugin.h>
 #include <tumbler/tumbler-config.h>
 #include <tumbler/tumbler-enum-types.h>
 #include <tumbler/tumbler-error.h>