clapper: Add ability to enable/disable creation of given enhancer

Allow apps to enable or disable given enhancer instances from being created.
Also as a safely measure, by default only enable enhancers that work
on-demand (extractables) and disable others (reactables).

src/lib/clapper/clapper-enhancer-proxy.c

@@ -86,6 +86,8 @@ struct _ClapperEnhancerProxy
   ClapperEnhancerParamFlags scope;
   GstStructure *local_config;
 
+  gboolean allowed;
+
   /* GSettings are not thread-safe,
    * so store schema instead */
   GSettingsSchema *schema;
@@ -100,6 +102,7 @@ enum
   PROP_MODULE_DIR,
   PROP_DESCRIPTION,
   PROP_VERSION,
+  PROP_TARGET_CREATION_ALLOWED,
   PROP_LAST
 };
 
@@ -229,6 +232,8 @@ clapper_enhancer_proxy_copy (ClapperEnhancerProxy *src_proxy, const gchar *copy_
   if (src_proxy->local_config)
     copy->local_config = gst_structure_copy (src_proxy->local_config);
 
+  copy->allowed = src_proxy->allowed;
+
   GST_OBJECT_UNLOCK (src_proxy);
 
   gst_object_ref_sink (copy);
@@ -359,6 +364,8 @@ clapper_enhancer_proxy_fill_from_cache (ClapperEnhancerProxy *self)
       if (G_UNLIKELY ((self->ifaces[i] = clapper_cache_read_iface (&data)) == 0))
         goto abort_reading;
     }
+    /* Reactable type is always last */
+    self->allowed = (self->ifaces[self->n_ifaces - 1] != CLAPPER_TYPE_REACTABLE);
   }
 
   /* Restore ParamSpecs */
@@ -456,6 +463,7 @@ clapper_enhancer_proxy_export_to_cache (ClapperEnhancerProxy *self)
 gboolean
 clapper_enhancer_proxy_fill_from_instance (ClapperEnhancerProxy *self, GObject *enhancer)
 {
+  /* NOTE: REACTABLE must be last for "allowed" to work as expected */
   const GType enhancer_types[] = { CLAPPER_TYPE_EXTRACTABLE, CLAPPER_TYPE_REACTABLE };
   GType *ifaces;
   GParamSpec **pspecs;
@@ -465,9 +473,12 @@ clapper_enhancer_proxy_fill_from_instance (ClapperEnhancerProxy *self, GObject *
   /* Filter to only Clapper interfaces */
   ifaces = g_type_interfaces (G_OBJECT_TYPE (enhancer), &n);
   for (i = 0; i < n; ++i) {
-    for (j = 0; j < G_N_ELEMENTS (enhancer_types); ++j) {
+    const guint n_types = G_N_ELEMENTS (enhancer_types);
+
+    for (j = 0; j < n_types; ++j) {
       if (ifaces[i] == enhancer_types[j]) {
         ifaces[write_index++] = ifaces[i];
+        self->allowed = (j < n_types - 1);
         break; // match found, do next iface
       }
     }
@@ -1088,6 +1099,58 @@ clapper_enhancer_proxy_set_locally_with_table (ClapperEnhancerProxy *self, GHash
     gst_structure_free (structure);
 }
 
+/**
+ * clapper_enhancer_proxy_set_target_creation_allowed:
+ * @proxy: a #ClapperEnhancerProxy
+ * @allowed: whether allowed
+ *
+ * Set whether to allow instances of proxy target to be created.
+ *
+ * See [property@Clapper.EnhancerProxy:target-creation-allowed] for
+ * detailed descripton what this does.
+ *
+ * Since: 0.10
+ */
+void
+clapper_enhancer_proxy_set_target_creation_allowed (ClapperEnhancerProxy *self, gboolean allowed)
+{
+  gboolean changed;
+
+  g_return_if_fail (CLAPPER_IS_ENHANCER_PROXY (self));
+
+  GST_OBJECT_LOCK (self);
+  if ((changed = self->allowed != allowed))
+    self->allowed = allowed;
+  GST_OBJECT_UNLOCK (self);
+
+  if (changed)
+    g_object_notify_by_pspec (G_OBJECT (self), param_specs[PROP_TARGET_CREATION_ALLOWED]);
+}
+
+/**
+ * clapper_enhancer_proxy_get_target_creation_allowed:
+ * @proxy: a #ClapperEnhancerProxy
+ *
+ * Get whether it is allowed to create instances of enhancer that this proxy targets.
+ *
+ * Returns: whether target creation is allowed.
+ *
+ * Since: 0.10
+ */
+gboolean
+clapper_enhancer_proxy_get_target_creation_allowed (ClapperEnhancerProxy *self)
+{
+  gboolean allowed;
+
+  g_return_val_if_fail (CLAPPER_IS_ENHANCER_PROXY (self), FALSE);
+
+  GST_OBJECT_LOCK (self);
+  allowed = self->allowed;
+  GST_OBJECT_UNLOCK (self);
+
+  return allowed;
+}
+
 static void
 clapper_enhancer_proxy_init (ClapperEnhancerProxy *self)
 {
@@ -1137,6 +1200,25 @@ clapper_enhancer_proxy_get_property (GObject *object, guint prop_id,
     case PROP_VERSION:
       g_value_set_string (value, clapper_enhancer_proxy_get_version (self));
       break;
+    case PROP_TARGET_CREATION_ALLOWED:
+      g_value_set_boolean (value, clapper_enhancer_proxy_get_target_creation_allowed (self));
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+  }
+}
+
+static void
+clapper_enhancer_proxy_set_property (GObject *object, guint prop_id,
+    const GValue *value, GParamSpec *pspec)
+{
+  ClapperEnhancerProxy *self = CLAPPER_ENHANCER_PROXY_CAST (object);
+
+  switch (prop_id) {
+    case PROP_TARGET_CREATION_ALLOWED:
+      clapper_enhancer_proxy_set_target_creation_allowed (self, g_value_get_boolean (value));
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
@@ -1152,6 +1234,7 @@ clapper_enhancer_proxy_class_init (ClapperEnhancerProxyClass *klass)
       "Clapper Enhancer Proxy");
 
   gobject_class->get_property = clapper_enhancer_proxy_get_property;
+  gobject_class->set_property = clapper_enhancer_proxy_set_property;
   gobject_class->finalize = clapper_enhancer_proxy_finalize;
 
   /**
@@ -1209,5 +1292,29 @@ clapper_enhancer_proxy_class_init (ClapperEnhancerProxyClass *klass)
       NULL, NULL, NULL,
       G_PARAM_READABLE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS);
 
+  /**
+   * ClapperEnhancerProxy:target-creation-allowed:
+   *
+   * Whether to allow instances of proxy target to be created.
+   *
+   * This effectively means whether the given enhancer can be used.
+   *
+   * By default all enhancers that work on-demand such as [iface@Clapper.Extractable]
+   * are allowed while enhancers implementing [iface@Clapper.Reactable] are not.
+   *
+   * Value of this property from a `GLOBAL` [class@Clapper.EnhancerProxyList] will carry
+   * over to all newly created [class@Clapper.Player] objects, while altering this on
+   * `LOCAL` proxy list will only influence given player instance that list belongs to.
+   *
+   * Changing this property will not remove already created enhancer instances, thus
+   * it is usually best practice to allow/disallow creation of given enhancer plugin
+   * right after [class@Clapper.Player] is created (before it or its queue are used).
+   *
+   * Since: 0.10
+   */
+  param_specs[PROP_TARGET_CREATION_ALLOWED] = g_param_spec_boolean ("target-creation-allowed",
+      NULL, NULL, FALSE,
+      G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS);
+
   g_object_class_install_properties (gobject_class, PROP_LAST, param_specs);
 }

src/lib/clapper/clapper-enhancer-proxy.h

@@ -76,4 +76,10 @@ void clapper_enhancer_proxy_set_locally (ClapperEnhancerProxy *proxy, const gcha
 CLAPPER_API
 void clapper_enhancer_proxy_set_locally_with_table (ClapperEnhancerProxy *proxy, GHashTable *table);
 
+CLAPPER_API
+void clapper_enhancer_proxy_set_target_creation_allowed (ClapperEnhancerProxy *proxy, gboolean allowed);
+
+CLAPPER_API
+gboolean clapper_enhancer_proxy_get_target_creation_allowed (ClapperEnhancerProxy *proxy);
+
 G_END_DECLS

src/lib/clapper/clapper-enhancers-loader.c

@@ -54,6 +54,28 @@ _import_enhancers (const gchar *enhancers_path)
   g_strfreev (dir_paths);
 }
 
+static GObject *
+_force_create_enhancer (ClapperEnhancerProxy *proxy, GType iface_type)
+{
+  GObject *enhancer = NULL;
+  PeasPluginInfo *info = (PeasPluginInfo *) clapper_enhancer_proxy_get_peas_info (proxy);
+
+  g_mutex_lock (&load_lock);
+
+  if (!peas_plugin_info_is_loaded (info) && !peas_engine_load_plugin (_engine, info)) {
+    GST_ERROR ("Could not load enhancer: %s", peas_plugin_info_get_module_name (info));
+  } else if (!peas_engine_provides_extension (_engine, info, iface_type)) {
+    GST_LOG ("No \"%s\" enhancer in module: %s", g_type_name (iface_type),
+        peas_plugin_info_get_module_name (info));
+  } else {
+    enhancer = peas_engine_create_extension (_engine, info, iface_type, NULL);
+  }
+
+  g_mutex_unlock (&load_lock);
+
+  return enhancer;
+}
+
 /*
  * clapper_enhancers_loader_initialize:
  *
@@ -155,7 +177,7 @@ clapper_enhancers_loader_initialize (ClapperEnhancerProxyList *proxies)
 
       /* We cannot ask libpeas for "any" of our main interfaces, so try each one until found */
       for (j = 0; j < G_N_ELEMENTS (main_types); ++j) {
-        if ((enhancer = clapper_enhancers_loader_create_enhancer (proxy, main_types[j]))) {
+        if ((enhancer = _force_create_enhancer (proxy, main_types[j]))) {
           filled = clapper_enhancer_proxy_fill_from_instance (proxy, enhancer);
           g_object_unref (enhancer);
 
@@ -200,21 +222,8 @@ clapper_enhancers_loader_initialize (ClapperEnhancerProxyList *proxies)
 GObject *
 clapper_enhancers_loader_create_enhancer (ClapperEnhancerProxy *proxy, GType iface_type)
 {
-  GObject *enhancer = NULL;
-  PeasPluginInfo *info = (PeasPluginInfo *) clapper_enhancer_proxy_get_peas_info (proxy);
+  if (!clapper_enhancer_proxy_get_target_creation_allowed (proxy))
+    return NULL;
 
-  g_mutex_lock (&load_lock);
-
-  if (!peas_plugin_info_is_loaded (info) && !peas_engine_load_plugin (_engine, info)) {
-    GST_ERROR ("Could not load enhancer: %s", peas_plugin_info_get_module_name (info));
-  } else if (!peas_engine_provides_extension (_engine, info, iface_type)) {
-    GST_LOG ("No \"%s\" enhancer in module: %s", g_type_name (iface_type),
-        peas_plugin_info_get_module_name (info));
-  } else {
-    enhancer = peas_engine_create_extension (_engine, info, iface_type, NULL);
-  }
-
-  g_mutex_unlock (&load_lock);
-
-  return enhancer;
+  return _force_create_enhancer (proxy, iface_type);
 }

src/lib/clapper/clapper-player.c

@@ -2339,8 +2339,6 @@ clapper_player_init (ClapperPlayer *self)
   if (clapper_enhancer_proxy_list_has_proxy_with_interface (self->enhancer_proxies, CLAPPER_TYPE_REACTABLE)) {
     self->reactables_manager = clapper_reactables_manager_new ();
     gst_object_set_parent (GST_OBJECT_CAST (self->reactables_manager), GST_OBJECT_CAST (self));
-
-    clapper_reactables_manager_trigger_prepare (self->reactables_manager);
   }
 
   self->position_query = gst_query_new_position (GST_FORMAT_TIME);

src/lib/clapper/clapper-reactables-manager-private.h

@@ -36,9 +36,6 @@ void clapper_reactables_manager_initialize (void);
 G_GNUC_INTERNAL
 ClapperReactablesManager * clapper_reactables_manager_new (void);
 
-G_GNUC_INTERNAL
-void clapper_reactables_manager_trigger_prepare (ClapperReactablesManager *manager);
-
 G_GNUC_INTERNAL
 void clapper_reactables_manager_trigger_configure_take_config (ClapperReactablesManager *manager, ClapperEnhancerProxy *proxy, GstStructure *config);
 

src/lib/clapper/clapper-reactables-manager.c

@@ -43,6 +43,8 @@ struct _ClapperReactablesManager
 
   GstBus *bus;
   GPtrArray *array;
+
+  gboolean prepare_called;
 };
 
 #define parent_class clapper_reactables_manager_parent_class
@@ -74,15 +76,13 @@ enum
 
 enum
 {
-  CLAPPER_REACTABLES_MANAGER_QUARK_PREPARE = 0,
-  CLAPPER_REACTABLES_MANAGER_QUARK_CONFIGURE,
+  CLAPPER_REACTABLES_MANAGER_QUARK_CONFIGURE = 0,
   CLAPPER_REACTABLES_MANAGER_QUARK_EVENT,
   CLAPPER_REACTABLES_MANAGER_QUARK_VALUE,
   CLAPPER_REACTABLES_MANAGER_QUARK_EXTRA_VALUE
 };
 
 static ClapperBusQuark _quarks[] = {
-  {"prepare", 0},
   {"configure", 0},
   {"event", 0},
   {"value", 0},
@@ -161,7 +161,7 @@ clapper_reactables_manager_handle_prepare (ClapperReactablesManager *self)
           clapper_enhancers_loader_create_enhancer (proxy, CLAPPER_TYPE_REACTABLE));
 #endif
 
-      if (G_LIKELY (reactable != NULL)) {
+      if (reactable) {
         ClapperReactableManagerData *data;
         GstStructure *config;
 
@@ -216,11 +216,9 @@ clapper_reactables_manager_handle_configure (ClapperReactablesManager *self, con
     if (data->proxy == proxy) {
       clapper_enhancer_proxy_apply_config_to_enhancer (data->proxy,
           config, (GObject *) data->reactable);
-      return;
+      break;
     }
   }
-
-  GST_ERROR_OBJECT (self, "Triggered configure, but no matching enhancer proxy found");
 }
 
 static inline void
@@ -319,9 +317,11 @@ _bus_message_func (GstBus *bus, GstMessage *msg, gpointer user_data G_GNUC_UNUSE
     GQuark quark = gst_structure_get_name_id (structure);
 
     if (quark == _QUARK (EVENT)) {
+      if (G_UNLIKELY (!self->prepare_called)) {
+        clapper_reactables_manager_handle_prepare (self);
+        self->prepare_called = TRUE;
+      }
       clapper_reactables_manager_handle_event (self, structure);
-    } else if (quark == _QUARK (PREPARE)) {
-      clapper_reactables_manager_handle_prepare (self);
     } else if (quark == _QUARK (CONFIGURE)) {
       clapper_reactables_manager_handle_configure (self, structure);
     } else {
@@ -365,15 +365,6 @@ clapper_reactables_manager_new (void)
   return reactables_manager;
 }
 
-void
-clapper_reactables_manager_trigger_prepare (ClapperReactablesManager *self)
-{
-  GstStructure *structure = gst_structure_new_id_empty (_QUARK (PREPARE));
-
-  gst_bus_post (self->bus, gst_message_new_application (
-      GST_OBJECT_CAST (self), structure));
-}
-
 void
 clapper_reactables_manager_trigger_configure_take_config (ClapperReactablesManager *self,
     ClapperEnhancerProxy *proxy, GstStructure *config)

src/lib/clapper/gst/clapper-enhancer-director.c

@@ -93,7 +93,7 @@ clapper_enhancer_director_extract_in_thread (ClapperEnhancerDirectorData *data)
         clapper_enhancers_loader_create_enhancer (proxy, CLAPPER_TYPE_EXTRACTABLE));
 #endif
 
-    if (G_LIKELY (extractable != NULL)) {
+    if (extractable) {
       if (config)
         clapper_enhancer_proxy_apply_config_to_enhancer (proxy, config, (GObject *) extractable);