core: introduce the notion of provided features on components

Each component can optionally "provide" a feature, which is basically
a string that describes the feature (ex. "support.dbus"). If the
component loads successfully, the feature is marked as provided and
can be tested for its presence with wp_core_test_feature()

lib/wp/component-loader.c

@@ -95,6 +95,8 @@ on_component_loader_load_done (WpComponentLoader * cl, GAsyncResult * res,
   g_autoptr (GError) error = NULL;
   g_autoptr (GObject) o = NULL;
   WpCore *core = g_task_get_source_object (task);
+  WpRegistry *reg = wp_core_get_registry (core);
+  gchar *provides = g_task_get_task_data (task);
 
   o = wp_component_loader_load_finish (cl, res, &error);
   if (error) {
@@ -102,11 +104,14 @@ on_component_loader_load_done (WpComponentLoader * cl, GAsyncResult * res,
     return;
   }
 
+  if (provides)
+    wp_registry_mark_feature_provided (reg, provides);
+
   if (o) {
     wp_trace_object (cl, "loaded object " WP_OBJECT_FORMAT, WP_OBJECT_ARGS (o));
 
     /* store object in the registry */
-    wp_registry_register_object (wp_core_get_registry (core), g_object_ref (o));
+    wp_registry_register_object (reg, g_object_ref (o));
 
     if (WP_IS_OBJECT (o)) {
       /* WpObject needs to be activated */
@@ -132,18 +137,21 @@ on_component_loader_load_done (WpComponentLoader * cl, GAsyncResult * res,
  *
  * \ingroup wpcomponentloader
  * \param self the core
- * \param component the module name or file name
+ * \param component (nullable): the module name or file name
  * \param type the type of the component
  * \param args (transfer none)(nullable): additional arguments for the component,
  *   expected to be a JSON object
+ * \param provides (nullable): the name of the feature that this component will
+ *   provide if it loads successfully; this can be queried later with
+ *   wp_core_test_feature()
  * \param cancellable (nullable): optional GCancellable
  * \param callback (scope async): the callback to call when the operation is done
  * \param data (closure): data to pass to \a callback
  */
 void
 wp_core_load_component (WpCore * self, const gchar * component,
-    const gchar * type, WpSpaJson * args, GCancellable * cancellable,
+    const gchar * type, WpSpaJson * args, const gchar * provides,
-    GAsyncReadyCallback callback, gpointer data)
+    GCancellable * cancellable, GAsyncReadyCallback callback, gpointer data)
 {
   g_autoptr (GTask) task = NULL;
   g_autoptr (WpComponentLoader) cl = NULL;
@@ -151,6 +159,9 @@ wp_core_load_component (WpCore * self, const gchar * component,
   task = g_task_new (self, cancellable, callback, data);
   g_task_set_source_tag (task, wp_core_load_component);
 
+  if (provides)
+    g_task_set_task_data (task, g_strdup (provides), g_free);
+
   /* find a component loader for that type and load the component */
   cl = wp_component_loader_find (self, type);
   if (!cl) {

lib/wp/component-loader.h

@@ -42,8 +42,8 @@ struct _WpComponentLoaderInterface
 
 WP_API
 void wp_core_load_component (WpCore * self, const gchar * component,
-    const gchar * type, WpSpaJson * args, GCancellable * cancellable,
+    const gchar * type, WpSpaJson * args, const gchar * provides,
-    GAsyncReadyCallback callback, gpointer data);
+    GCancellable * cancellable, GAsyncReadyCallback callback, gpointer data);
 
 WP_API
 gboolean wp_core_load_component_finish (WpCore * self, GAsyncResult * res,

lib/wp/core.c

@@ -1052,6 +1052,21 @@ wp_core_sync_finish (WpCore * self, GAsyncResult * res, GError ** error)
   return g_task_propagate_boolean (G_TASK (res), error);
 }
 
+/*!
+ * \brief Test if a global feature is provided
+ *
+ * \ingroup wpcore
+ * \param self the core
+ * \param feature the feature name
+ * \returns TRUE if the feature is provided, FALSE otherwise
+ */
+gboolean
+wp_core_test_feature (WpCore * self, const gchar * feature)
+{
+  return g_ptr_array_find_with_equal_func (self->registry.features, feature,
+      g_str_equal, NULL);
+}
+
 WpRegistry *
 wp_core_get_registry (WpCore * self)
 {

lib/wp/core.h

@@ -120,6 +120,11 @@ gboolean wp_core_sync_finish (WpCore * self, GAsyncResult * res,
 WP_API
 void wp_core_install_object_manager (WpCore * self, WpObjectManager * om);
 
+/* Global Features */
+
+WP_API
+gboolean wp_core_test_feature (WpCore * self, const gchar * feature);
+
 G_END_DECLS
 
 #endif

lib/wp/object-manager.c

@@ -961,6 +961,7 @@ wp_registry_init (WpRegistry *self)
       g_ptr_array_new_with_free_func ((GDestroyNotify) wp_global_unref);
   self->objects = g_ptr_array_new_with_free_func (g_object_unref);
   self->object_managers = g_ptr_array_new ();
+  self->features = g_ptr_array_new_with_free_func (g_free);
 }
 
 void
@@ -969,6 +970,7 @@ wp_registry_clear (WpRegistry *self)
   wp_registry_detach (self);
   g_clear_pointer (&self->globals, g_ptr_array_unref);
   g_clear_pointer (&self->tmp_globals, g_ptr_array_unref);
+  g_clear_pointer (&self->features, g_ptr_array_unref);
 
   /* remove all the registered objects
      this will normally also destroy the object managers, eventually, since

lib/wp/private/internal-comp-loader.c

@@ -292,7 +292,7 @@ wp_component_array_load_task_execute_step (WpTransition * transition, guint step
         self->curr_component->name, self->curr_component->type,
         self->curr_component->priority, self->curr_component->flags);
     wp_core_load_component (core, self->curr_component->name,
-        self->curr_component->type, NULL, NULL,
+        self->curr_component->type, NULL, NULL, NULL,
         (GAsyncReadyCallback) on_component_loaded, self);
     break;
 

lib/wp/private/registry.h

@@ -30,6 +30,7 @@ struct _WpRegistry
   GPtrArray *tmp_globals; // elementy-type: WpGlobal*
   GPtrArray *objects; // element-type: GObject*
   GPtrArray *object_managers; // element-type: WpObjectManager*
+  GPtrArray *features; // element-type: gchar*
 };
 
 void wp_registry_init (WpRegistry *self);
@@ -47,6 +48,12 @@ gpointer wp_registry_find_object (WpRegistry *reg, GEqualFunc func,
 void wp_registry_register_object (WpRegistry *reg, gpointer obj);
 void wp_registry_remove_object (WpRegistry *reg, gpointer obj);
 
+static inline void
+wp_registry_mark_feature_provided (WpRegistry * reg, const gchar * feature)
+{
+  g_ptr_array_add (reg->features, g_strdup (feature));
+}
+
 WpCore * wp_registry_get_core (WpRegistry * self) G_GNUC_CONST;
 
 /* core */

modules/module-lua-scripting/api/require.c

@@ -92,7 +92,7 @@ wp_require_api_transition_execute_step (WpTransition * transition, guint step)
             "libwireplumber-module-%s", api_name);
 
         self->pending_plugins++;
-        wp_core_load_component (core, module_name, "module", NULL, NULL,
+        wp_core_load_component (core, module_name, "module", NULL, NULL, NULL,
             (GAsyncReadyCallback) on_plugin_loaded, self);
       }
     }

src/main.c

@@ -190,7 +190,7 @@ wp_init_transition_execute_step (WpTransition * transition, guint step)
 
     /* Load components that are defined in the configuration section */
     json_comps = wp_conf_get_section (conf, "wireplumber.components", NULL);
-    wp_core_load_component (core, NULL, "array", json_comps, NULL,
+    wp_core_load_component (core, NULL, "array", json_comps, NULL, NULL,
         (GAsyncReadyCallback) on_components_loaded, self);
     break;
   }

src/tools/wpctl.c

@@ -1407,10 +1407,10 @@ main (gint argc, gchar **argv)
   /* load required API modules */
   ctl.pending_plugins++;
   wp_core_load_component (ctl.core, "libwireplumber-module-default-nodes-api",
-      "module", NULL, NULL, (GAsyncReadyCallback) on_plugin_loaded, &ctl);
+      "module", NULL, NULL, NULL, (GAsyncReadyCallback) on_plugin_loaded, &ctl);
   ctl.pending_plugins++;
   wp_core_load_component (ctl.core, "libwireplumber-module-mixer-api",
-      "module", NULL, NULL, (GAsyncReadyCallback) on_plugin_loaded, &ctl);
+      "module", NULL, NULL, NULL, (GAsyncReadyCallback) on_plugin_loaded, &ctl);
 
   /* connect */
   if (!wp_core_connect (ctl.core)) {

src/tools/wpexec.c

@@ -138,14 +138,14 @@ wp_init_transition_execute_step (WpTransition * transition, guint step)
 
   case STEP_ACTIVATE_PLUGINS: {
     wp_core_load_component (core, "libwireplumber-module-lua-scripting",
-        "module", NULL, NULL, (GAsyncReadyCallback) on_plugin_loaded, self);
+        "module", NULL, NULL, NULL, (GAsyncReadyCallback) on_plugin_loaded, self);
     wp_core_load_component (core, "libwireplumber-module-standard-event-source",
-        "module", NULL, NULL, (GAsyncReadyCallback) on_plugin_loaded, self);
+        "module", NULL, NULL, NULL, (GAsyncReadyCallback) on_plugin_loaded, self);
     break;
   }
 
   case STEP_ACTIVATE_SCRIPT: {
-    wp_core_load_component (core, exec_script, "script/lua", exec_args, NULL,
+    wp_core_load_component (core, exec_script, "script/lua", exec_args, NULL, NULL,
           (GAsyncReadyCallback) on_plugin_loaded, self);
     break;
   }

tests/modules/dbus-connection.c

@@ -62,7 +62,7 @@ test_dbus_connection (TestFixture *f, gconstpointer user_data)
   WpDBusConnectionState state = -1;
 
   wp_core_load_component (f->base.core,
-      "libwireplumber-module-dbus-connection", "module", NULL, NULL,
+      "libwireplumber-module-dbus-connection", "module", NULL, NULL, NULL,
       (GAsyncReadyCallback) on_plugin_loaded, f);
   g_main_loop_run (f->base.loop);
 

tests/modules/file-monitor.c

@@ -38,7 +38,7 @@ test_file_monitor_setup (TestFixture * f, gconstpointer user_data)
   wp_base_test_fixture_setup (&f->base, WP_BASE_TEST_FLAG_DONT_CONNECT);
 
   wp_core_load_component (f->base.core,
-      "libwireplumber-module-file-monitor-api", "module", NULL, NULL,
+      "libwireplumber-module-file-monitor-api", "module", NULL, NULL, NULL,
       (GAsyncReadyCallback) on_plugin_loaded, f);
   g_main_loop_run (f->base.loop);
 

tests/modules/reserve-device.c

@@ -47,25 +47,25 @@ test_rd_setup (RdTestFixture *f, gconstpointer data)
 
   {
     wp_core_load_component (f->base.core,
-        "libwireplumber-module-dbus-connection", "module", NULL, NULL,
+        "libwireplumber-module-dbus-connection", "module", NULL, NULL, NULL,
         (GAsyncReadyCallback) on_plugin_loaded, f);
     g_main_loop_run (f->base.loop);
   }
   {
     wp_core_load_component (f->base.client_core,
-        "libwireplumber-module-dbus-connection", "module", NULL, NULL,
+        "libwireplumber-module-dbus-connection", "module", NULL, NULL, NULL,
         (GAsyncReadyCallback) on_plugin_loaded, f);
     g_main_loop_run (f->base.loop);
   }
   {
     wp_core_load_component (f->base.core,
-        "libwireplumber-module-reserve-device", "module", NULL, NULL,
+        "libwireplumber-module-reserve-device", "module", NULL, NULL, NULL,
         (GAsyncReadyCallback) on_plugin_loaded, f);
     g_main_loop_run (f->base.loop);
   }
   {
     wp_core_load_component (f->base.client_core,
-        "libwireplumber-module-reserve-device", "module", NULL, NULL,
+        "libwireplumber-module-reserve-device", "module", NULL, NULL, NULL,
         (GAsyncReadyCallback) on_plugin_loaded, f);
     g_main_loop_run (f->base.loop);
   }

tests/modules/si-audio-adapter.c

@@ -44,7 +44,7 @@ test_si_audio_adapter_setup (TestFixture * f, gconstpointer user_data)
   }
   {
     wp_core_load_component (f->base.core,
-        "libwireplumber-module-si-audio-adapter", "module", NULL, NULL,
+        "libwireplumber-module-si-audio-adapter", "module", NULL, NULL, NULL,
         (GAsyncReadyCallback) on_plugin_loaded, f);
     g_main_loop_run (f->base.loop);
   }

tests/modules/si-audio-virtual.c

@@ -42,13 +42,13 @@ test_si_audio_virtual_setup (TestFixture * f, gconstpointer user_data)
   }
   {
     wp_core_load_component (f->base.core,
-        "libwireplumber-module-si-audio-adapter", "module", NULL, NULL,
+        "libwireplumber-module-si-audio-adapter", "module", NULL, NULL, NULL,
         (GAsyncReadyCallback) on_plugin_loaded, f);
     g_main_loop_run (f->base.loop);
   }
   {
     wp_core_load_component (f->base.core,
-        "libwireplumber-module-si-audio-virtual", "module", NULL, NULL,
+        "libwireplumber-module-si-audio-virtual", "module", NULL, NULL, NULL,
         (GAsyncReadyCallback) on_plugin_loaded, f);
     g_main_loop_run (f->base.loop);
   }

tests/modules/si-node.c

@@ -50,7 +50,7 @@ test_si_node_setup (TestFixture * f, gconstpointer user_data)
   }
   {
     wp_core_load_component (f->base.core,
-        "libwireplumber-module-si-node", "module", NULL, NULL,
+        "libwireplumber-module-si-node", "module", NULL, NULL, NULL,
         (GAsyncReadyCallback) on_plugin_loaded, f);
     g_main_loop_run (f->base.loop);
   }

tests/modules/si-standard-link.c

@@ -97,12 +97,12 @@ test_si_standard_link_setup (TestFixture * f, gconstpointer user_data)
   }
   {
     wp_core_load_component (f->base.core,
-        "libwireplumber-module-si-audio-adapter", "module", NULL, NULL,
+        "libwireplumber-module-si-audio-adapter", "module", NULL, NULL, NULL,
         (GAsyncReadyCallback) on_plugin_loaded, f);
     g_main_loop_run (f->base.loop);
 
     wp_core_load_component (f->base.core,
-        "libwireplumber-module-si-standard-link", "module", NULL, NULL,
+        "libwireplumber-module-si-standard-link", "module", NULL, NULL, NULL,
         (GAsyncReadyCallback) on_plugin_loaded, f);
     g_main_loop_run (f->base.loop);
   }

tests/script-tester.c

@@ -204,7 +204,7 @@ load_component (ScriptRunnerFixture *f, const gchar *name, const gchar *type)
     plugin_name = g_strdup (name);
   }
 
-  wp_core_load_component (f->base.core, component_name, type, NULL, NULL,
+  wp_core_load_component (f->base.core, component_name, type, NULL, NULL, NULL,
       (GAsyncReadyCallback) on_plugin_loaded, f);
   g_main_loop_run (f->base.loop);
 }