modules: implement module-session, a WpSession provider module

This keeps track of the default endpoint and selects a default
based on endpoint priorities when devices are discovered

modules/meson.build

@@ -78,3 +78,14 @@ shared_library(
   install_dir : wireplumber_module_dir,
   dependencies : [wp_dep, wptoml_dep, pipewire_dep],
 )
+
+shared_library(
+  'wireplumber-module-session',
+  [
+    'module-session.c',
+  ],
+  c_args : [common_c_args, '-DG_LOG_DOMAIN="m-session"'],
+  install : true,
+  install_dir : wireplumber_module_dir,
+  dependencies : [wp_dep, pipewire_dep],
+)

modules/module-session.c

+/* WirePlumber
+ *
+ * Copyright © 2019 Collabora Ltd.
+ *    @author George Kiagiadakis <george.kiagiadakis@collabora.com>
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#include <wp/wp.h>
+#include <pipewire/pipewire.h>
+#include <pipewire/extensions/session-manager.h>
+
+struct module_data
+{
+  WpExportedSession *session;
+  WpObjectManager *om;
+};
+
+static void
+select_new_default_ep (struct module_data * data, WpDefaultEndpointType type,
+    const gchar * media_class, guint32 blacklist_id)
+{
+  g_autoptr (GPtrArray) arr = wp_object_manager_get_objects (data->om, 0);
+  guint32 max_priority = 0;
+  guint32 best_id = 0, def_id;
+
+  for (guint i = 0; i < arr->len; i++) {
+    WpEndpoint *ep = g_ptr_array_index (arr, i);
+    guint32 id = wp_exported_endpoint_get_global_id (WP_EXPORTED_ENDPOINT (ep));
+    guint32 priority = 0;
+    const gchar *priority_str;
+
+    /* skip blacklisted */
+    if (id == blacklist_id)
+      continue;
+
+    /* skip if the endpoint is of another type */
+    if (g_strcmp0 (media_class, wp_endpoint_get_media_class (ep)) != 0)
+      continue;
+
+    g_autoptr (WpProperties) properties = wp_endpoint_get_properties (ep);
+
+    priority_str = wp_properties_get (properties, "endpoint.priority");
+    if (priority_str)
+      priority = atoi (priority_str);
+
+    if (priority >= max_priority)
+      best_id = id;
+  }
+
+  def_id = wp_session_get_default_endpoint (WP_SESSION (data->session), type);
+  if (def_id != best_id)
+    wp_session_set_default_endpoint (WP_SESSION (data->session), type, best_id);
+}
+
+static void
+on_endpoint_added (WpObjectManager * om, WpEndpoint * ep,
+    struct module_data * data)
+{
+  WpDefaultEndpointType type;
+  const gchar *media_class;
+
+  media_class = wp_endpoint_get_media_class (ep);
+  if (g_strcmp0 (media_class, "Audio/Source") == 0)
+    type = WP_DEFAULT_ENDPOINT_TYPE_AUDIO_SOURCE;
+  else if (g_strcmp0 (media_class, "Audio/Sink") == 0)
+    type = WP_DEFAULT_ENDPOINT_TYPE_AUDIO_SINK;
+  else if (g_strcmp0 (media_class, "Video/Source") == 0)
+    type = WP_DEFAULT_ENDPOINT_TYPE_VIDEO_SOURCE;
+  else
+    return;
+
+  select_new_default_ep (data, type, media_class, 0);
+}
+
+static void
+on_endpoint_removed (WpObjectManager * om, WpEndpoint * ep,
+    struct module_data * data)
+{
+  guint32 ep_id, def_id;
+  WpDefaultEndpointType type;
+  const gchar *media_class;
+
+  media_class = wp_endpoint_get_media_class (ep);
+  if (g_strcmp0 (media_class, "Audio/Source") == 0)
+    type = WP_DEFAULT_ENDPOINT_TYPE_AUDIO_SOURCE;
+  else if (g_strcmp0 (media_class, "Audio/Sink") == 0)
+    type = WP_DEFAULT_ENDPOINT_TYPE_AUDIO_SINK;
+  else if (g_strcmp0 (media_class, "Video/Source") == 0)
+    type = WP_DEFAULT_ENDPOINT_TYPE_VIDEO_SOURCE;
+  else
+    return;
+
+  ep_id = wp_exported_endpoint_get_global_id (WP_EXPORTED_ENDPOINT (ep));
+  def_id = wp_session_get_default_endpoint (WP_SESSION (data->session), type);
+
+  if (ep_id == def_id)
+    select_new_default_ep (data, type, media_class, ep_id);
+}
+
+static void
+module_destroy (gpointer d)
+{
+  struct module_data *data = d;
+
+  g_clear_object (&data->om);
+
+  wp_exported_unexport (WP_EXPORTED (data->session));
+  g_clear_object (&data->session);
+
+  g_slice_free (struct module_data, data);
+}
+
+void
+wireplumber__module_init (WpModule * module, WpCore * core, GVariant * args)
+{
+  struct module_data *data = g_slice_new0 (struct module_data);
+  wp_module_set_destroy_callback (module, module_destroy, data);
+
+  data->session = wp_exported_session_new (core);
+  wp_exported_session_set_property (data->session,
+      PW_KEY_SESSION_ID, "wireplumber");
+  wp_exported_export (WP_EXPORTED (data->session), NULL, NULL, NULL);
+
+  data->om = wp_object_manager_new ();
+  g_signal_connect (data->om, "object-added",
+      (GCallback) on_endpoint_added, data);
+  g_signal_connect (data->om, "object-removed",
+      (GCallback) on_endpoint_removed, data);
+  wp_object_manager_add_object_interest (data->om,
+      WP_TYPE_EXPORTED_ENDPOINT, NULL);
+  wp_core_install_object_manager (core, data->om);
+}

src/wireplumber.conf

@@ -9,6 +9,8 @@ add-spa-lib api.jack.* jack/libspa-jack
 # the client-device pipewire module is needed for libwireplumber-module-monitor
 load-pipewire-module libpipewire-module-client-device
 
+load-module C libwireplumber-module-session
+
 # Basic pipewire integration - do not remove
 load-module C libwireplumber-module-pipewire