lua: add a Core.require_api() utility function

This function loads and enables "api" plugins and makes them
available in the specified callback. This is intended to be used
by interactive scripts in order to get access to "api" plugins
such as the new "default-nodes-api" and "mixer-api"

modules/module-lua-scripting/require.c

@@ -0,0 +1,201 @@
+/* WirePlumber
+ *
+ * Copyright © 2021 Collabora Ltd.
+ *    @author George Kiagiadakis <george.kiagiadakis@collabora.com>
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#include <wp/wp.h>
+#include <wplua/wplua.h>
+
+struct _WpRequireApiTransition
+{
+  WpTransition parent;
+  GPtrArray *apis;
+  guint pending_plugins;
+};
+
+enum {
+  STEP_LOAD_MODULES = WP_TRANSITION_STEP_CUSTOM_START,
+  STEP_ACTIVATE_PLUGINS,
+};
+
+G_DECLARE_FINAL_TYPE (WpRequireApiTransition, wp_require_api_transition,
+                      WP, REQUIRE_API_TRANSITION, WpTransition)
+G_DEFINE_TYPE (WpRequireApiTransition, wp_require_api_transition, WP_TYPE_TRANSITION)
+
+static void
+wp_require_api_transition_init (WpRequireApiTransition * self)
+{
+  self->apis = g_ptr_array_new_with_free_func (g_free);
+}
+
+static void
+wp_require_api_transition_finalize (GObject * object)
+{
+  WpRequireApiTransition *self = WP_REQUIRE_API_TRANSITION (object);
+
+  g_clear_pointer (&self->apis, g_ptr_array_unref);
+
+  G_OBJECT_CLASS (wp_require_api_transition_parent_class)->finalize (object);
+}
+
+static guint
+wp_require_api_transition_get_next_step (WpTransition * transition, guint step)
+{
+  WpRequireApiTransition *self = WP_REQUIRE_API_TRANSITION (transition);
+
+  switch (step) {
+  case WP_TRANSITION_STEP_NONE: return STEP_LOAD_MODULES;
+  case STEP_LOAD_MODULES:       return STEP_ACTIVATE_PLUGINS;
+  case STEP_ACTIVATE_PLUGINS:
+    return (self->pending_plugins > 0) ?
+        STEP_ACTIVATE_PLUGINS : WP_TRANSITION_STEP_NONE;
+  default:
+    g_return_val_if_reached (WP_TRANSITION_STEP_ERROR);
+  }
+}
+
+static void
+on_plugin_activated (WpObject * p, GAsyncResult * res,
+    WpRequireApiTransition *self)
+{
+  GError *error = NULL;
+
+  if (!wp_object_activate_finish (p, res, &error)) {
+    wp_transition_return_error (WP_TRANSITION (self), error);
+    return;
+  }
+
+  --self->pending_plugins;
+  wp_transition_advance (WP_TRANSITION (self));
+}
+
+static void
+wp_require_api_transition_execute_step (WpTransition * transition, guint step)
+{
+  WpRequireApiTransition *self = WP_REQUIRE_API_TRANSITION (transition);
+  WpCore *core = wp_transition_get_source_object (transition);
+
+  switch (step) {
+  case STEP_LOAD_MODULES:
+  {
+    for (guint i = 0; i < self->apis->len; i++) {
+      const gchar *api_name = g_ptr_array_index (self->apis, i);
+      g_autoptr (WpPlugin) plugin = wp_plugin_find (core, api_name);
+      if (!plugin) {
+        GError *error = NULL;
+        gchar module_name[50];
+
+        g_snprintf (module_name, sizeof (module_name),
+            "libwireplumber-module-%s", api_name);
+
+        if (!wp_core_load_component (core, module_name, "module", NULL, &error)) {
+          wp_transition_return_error (transition, error);
+          return;
+        }
+
+        plugin = wp_plugin_find (core, api_name);
+        if (!plugin) {
+          wp_transition_return_error (transition, g_error_new (
+              WP_DOMAIN_LIBRARY, WP_LIBRARY_ERROR_INVALID_ARGUMENT,
+              "API '%s' was not found in module '%s'", api_name, module_name));
+          return;
+        }
+      }
+    }
+    wp_transition_advance (transition);
+    break;
+  }
+
+  case STEP_ACTIVATE_PLUGINS:
+    wp_debug_object (self, "Activating plugins...");
+
+    for (guint i = 0; i < self->apis->len; i++) {
+      const gchar *api_name = g_ptr_array_index (self->apis, i);
+      g_autoptr (WpPlugin) plugin = wp_plugin_find (core, api_name);
+
+      self->pending_plugins++;
+      wp_object_activate (WP_OBJECT (plugin), WP_PLUGIN_FEATURE_ENABLED, NULL,
+          (GAsyncReadyCallback) on_plugin_activated, self);
+    }
+    wp_transition_advance (transition);
+    break;
+
+  case WP_TRANSITION_STEP_ERROR:
+    break;
+
+  default:
+    g_assert_not_reached ();
+  }
+}
+
+static void
+wp_require_api_transition_class_init (WpRequireApiTransitionClass * klass)
+{
+  GObjectClass * object_class = (GObjectClass *) klass;
+  WpTransitionClass * transition_class = (WpTransitionClass *) klass;
+
+  object_class->finalize = wp_require_api_transition_finalize;
+
+  transition_class->get_next_step = wp_require_api_transition_get_next_step;
+  transition_class->execute_step = wp_require_api_transition_execute_step;
+}
+
+static void
+on_require_api_transition_done (WpCore * core, GAsyncResult * res, gpointer data)
+{
+  g_autoptr (GClosure) closure = data;
+  g_autoptr (GError) error = NULL;
+
+  if (!wp_transition_finish (res, &error)) {
+    wp_warning ("Core.require_api failed: %s", error->message);
+    wp_core_idle_add (core, NULL, G_SOURCE_FUNC (core_disconnect), core, NULL);
+    return;
+  }
+
+  WpRequireApiTransition *t = WP_REQUIRE_API_TRANSITION (res);
+  g_autoptr (GArray) params = g_array_new (FALSE, TRUE, sizeof (GValue));
+
+  g_array_set_clear_func (params, (GDestroyNotify) g_value_unset);
+  g_array_set_size (params, t->apis->len);
+
+  for (guint i = 0; i < t->apis->len; i++) {
+    const gchar *api_name = g_ptr_array_index (t->apis, i);
+    g_autoptr (WpPlugin) plugin = wp_plugin_find (core, api_name);
+    g_value_init_from_instance (&g_array_index (params, GValue, i), plugin);
+  }
+
+  g_closure_invoke (closure, NULL,
+      params->len, (const GValue *) params->data, NULL);
+  g_closure_invalidate (closure);
+}
+
+static int
+wp_require_api_transition_new_from_lua (lua_State *L, WpCore * core)
+{
+  int n_args = lua_gettop (L);
+
+  wp_info("n_args = %d", n_args);
+
+  for (int i = 1; i < n_args; i++)
+    luaL_checktype (L, i, LUA_TSTRING);
+  luaL_checktype (L, n_args, LUA_TFUNCTION);
+
+  GClosure *closure = wplua_function_to_closure (L, n_args);
+  g_closure_ref (closure);
+  g_closure_sink (closure);
+
+  WpRequireApiTransition *t = (WpRequireApiTransition *)
+      wp_transition_new (wp_require_api_transition_get_type (), core, NULL,
+          (GAsyncReadyCallback) on_require_api_transition_done, closure);
+
+  for (int i = 1; i < n_args; i++) {
+    const char * api_name = lua_tostring (L, i);
+    g_ptr_array_add (t->apis, g_strdup_printf ("%s-api", api_name));
+  }
+
+  wp_transition_advance (WP_TRANSITION (t));
+  return 0;
+}