sd_bus_get_n_queued_read, sd_bus_get_n_queued_write — Get the number of pending bus messages in the read and write queues of a bus connection object
sd_bus_get_n_queued_read() may be used to query the number of bus messages in the read queue
of a bus connection object. The read queue contains all messages read from the transport medium (e.g. network
socket) but not yet processed locally. The function expects two arguments: the bus object to query, and a pointer
to a 64bit counter variable to write the current queue size to. Use
order to process queued messages, i.e. to reduce the size of the read queue (as well as, in fact, the write
queue, see below).
sd_bus_get_n_queued_write() may be used to query the number of currently pending
bus messages in the write queue of a bus connection object. The write queue contains all messages enqueued into
the connection with a call such as
sd_bus_send() but not yet written to the transport
medium. The expected arguments are similar to
sd_bus_get_n_queued_read(). Here too, use
sd_bus_process() to reduce the size of the write queue. Alternatively, use
sd_bus_flush() to synchronously write out any pending bus messages until the write queue is
On success, these functions return 0 or a positive integer. On failure, they return a negative errno-style error code.
Returned errors may indicate the following problems:
The bus connection was created in a different process.