node: add node.priority

Add a simple priority to nodes.

src/examples/media-session/alsa-monitor.c

@@ -103,7 +103,8 @@ static struct alsa_node *alsa_create_node(struct alsa_object *obj, uint32_t id,
 	struct monitor *monitor = obj->monitor;
 	struct impl *impl = monitor->impl;
 	int res;
-	const char *dev, *subdev;
+	const char *card, *dev, *subdev;
+	int priority;
 
 	pw_log_debug("new node %u", id);
 
@@ -124,11 +125,22 @@ static struct alsa_node *alsa_create_node(struct alsa_object *obj, uint32_t id,
 
 	pw_properties_set(node->props, "factory.name", info->factory_name);
 
+	if ((card = pw_properties_get(node->props, SPA_KEY_API_ALSA_PCM_CARD)) == NULL)
+		card = "0";
 	if ((dev = pw_properties_get(node->props, SPA_KEY_API_ALSA_PCM_DEVICE)) == NULL)
 		dev = "0";
 	if ((subdev = pw_properties_get(node->props, SPA_KEY_API_ALSA_PCM_SUBDEVICE)) == NULL)
 		subdev = "0";
 
+	priority = 1000;
+	priority -= atol(card) * 64;
+	priority -= atol(dev) * 16;
+	priority -= atol(subdev);
+
+	if (pw_properties_get(node->props, PW_KEY_NODE_PRIORITY) == NULL) {
+		pw_properties_setf(node->props, PW_KEY_NODE_PRIORITY, "%d", priority);
+	}
+
 	if (pw_properties_get(node->props, SPA_KEY_NODE_NAME) == NULL) {
 		const char *devname, *stream;
 		if ((devname = pw_properties_get(obj->props, SPA_KEY_DEVICE_NAME)) == NULL)

src/examples/media-session/media-session.c

@@ -172,6 +172,7 @@ struct session {
 
 	struct impl *impl;
 	enum pw_direction direction;
+	int priority;
 	uint64_t plugged;
 
 	struct node *node;
@@ -503,6 +504,11 @@ handle_node(struct impl *impl, uint32_t id,
 		else
 			sess->plugged = SPA_TIMESPEC_TO_NSEC(&impl->now);
 
+		if ((str = spa_dict_lookup(props, PW_KEY_NODE_PRIORITY)) != NULL)
+			sess->priority = pw_properties_parse_int(str);
+		else
+			sess->priority = 0;
+
 		spa_list_init(&sess->node_list);
 		spa_list_append(&impl->session_list, &sess->l);
 
@@ -793,6 +799,7 @@ struct find_data {
 	const char *media_class;
 	struct session *sess;
 	bool exclusive;
+	int priority;
 	uint64_t plugged;
 };
 
@@ -802,6 +809,7 @@ static int find_session(void *data, struct session *sess)
 	struct impl *impl = find->impl;
 	const struct spa_dict *props;
 	const char *str;
+	int priority = 0;
 	uint64_t plugged = 0;
 
 	pw_log_debug(NAME " %p: looking at session '%d' enabled:%d busy:%d exclusive:%d",
@@ -824,6 +832,7 @@ static int find_session(void *data, struct session *sess)
 			return 0;
 
 		plugged = sess->plugged;
+		priority = sess->priority;
 	}
 
 	if ((find->exclusive && sess->busy) || sess->exclusive) {
@@ -834,9 +843,12 @@ static int find_session(void *data, struct session *sess)
 	pw_log_debug(NAME " %p: found session '%d' %" PRIu64, impl,
 			sess->id, plugged);
 
-	if (find->sess == NULL || plugged > find->plugged) {
-		pw_log_debug(NAME " %p: new best %" PRIu64, impl, plugged);
+	if (find->sess == NULL ||
+	    priority > find->priority ||
+	    (priority == find->priority && plugged > find->plugged)) {
+		pw_log_debug(NAME " %p: new best %d %" PRIu64, impl, priority, plugged);
 		find->sess = sess;
+		find->priority = priority;
 		find->plugged = plugged;
 	}
 	return 0;
@@ -953,6 +965,8 @@ static int rescan_node(struct impl *impl, struct node *node)
 		return 0;
 	}
 
+	spa_zero(find);
+
 	if ((category = spa_dict_lookup(props, PW_KEY_MEDIA_CATEGORY)) == NULL) {
 		pw_log_debug(NAME" %p: node %d find category from ports: %d %d",
 			impl, node->obj.id, info->n_input_ports, info->n_output_ports);
@@ -1041,9 +1055,8 @@ static int rescan_node(struct impl *impl, struct node *node)
 			media, category, role, exclusive, find.path_id);
 
 	find.impl = impl;
-	find.sess = NULL;
-	find.plugged = 0;
 	find.exclusive = exclusive;
+
 	spa_list_for_each(session, &impl->session_list, l)
 		find_session(&find, session);
 

src/pipewire/keys.h

@@ -115,6 +115,7 @@ extern "C" {
 								  *  description. Ex. "Foobar USB Headset" */
 #define PW_KEY_NODE_PLUGGED		"node.plugged"		/**< when the node was created. As a uint64 in
 								  *  nanoseconds. */
+#define PW_KEY_NODE_PRIORITY		"node.priority"		/**< priority of node */
 #define PW_KEY_NODE_SESSION		"node.session"		/**< the session id this node is part of */
 #define PW_KEY_NODE_EXCLUSIVE		"node.exclusive"	/**< node wants exclusive access to resources */
 #define PW_KEY_NODE_AUTOCONNECT		"node.autoconnect"	/**< node wants to be automatically connected

src/pipewire/node.c

@@ -554,6 +554,7 @@ int pw_node_register(struct pw_node *this,
 		PW_KEY_FACTORY_ID,
 		PW_KEY_CLIENT_ID,
 		PW_KEY_DEVICE_ID,
+		PW_KEY_NODE_PRIORITY,
 		PW_KEY_NODE_DESCRIPTION,
 		PW_KEY_NODE_NAME,
 		PW_KEY_NODE_NICK,