};
struct sd_bus_message {
- unsigned n_ref;
+ /* Caveat: a message can be referenced in two different ways: the main (user-facing) way will also
+ * pin the bus connection object the message is associated with. The secondary way ("queued") is used
+ * when a message is in the read or write queues of the bus connection object, which will not pin the
+ * bus connection object. This is necessary so that we don't have to have a pair of cyclic references
+ * between a message that is queued and its connection: as soon as a message is only referenced by
+ * the connection (by means of being queued) and the connection itself has no other references it
+ * will be freed. */
+
+ unsigned n_ref; /* Counter of references that pin the connection */
+ unsigned n_queued; /* Counter of references that do not pin the connection */
sd_bus *bus;
void bus_message_set_sender_driver(sd_bus *bus, sd_bus_message *m);
void bus_message_set_sender_local(sd_bus *bus, sd_bus_message *m);
+
+sd_bus_message* bus_message_ref_queued(sd_bus_message *m, sd_bus *bus);
+sd_bus_message* bus_message_unref_queued(sd_bus_message *m, sd_bus *bus);