2 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
4 <!-- SPDX-License-Identifier: LGPL-2.1+ -->
6 <refentry id=
"sd_bus_get_n_queued_read">
9 <title>sd_bus_get_fd
</title>
10 <productname>systemd
</productname>
14 <refentrytitle>sd_bus_get_n_queued_read
</refentrytitle>
15 <manvolnum>3</manvolnum>
19 <refname>sd_bus_get_n_queued_read
</refname>
20 <refname>sd_bus_get_n_queued_write
</refname>
22 <refpurpose>Get the number of pending bus messages in the read and write queues of a bus connection object
</refpurpose>
27 <funcsynopsisinfo>#include
<systemd/sd-bus.h
></funcsynopsisinfo>
30 <funcdef>int
<function>sd_bus_get_n_queued_read
</function></funcdef>
31 <paramdef>sd_bus *
<parameter>bus
</parameter></paramdef>
32 <paramdef>uint64_t *
<parameter>ret
</parameter></paramdef>
36 <funcdef>int
<function>sd_bus_get_n_queued_write
</function></funcdef>
37 <paramdef>sd_bus *
<parameter>bus
</parameter></paramdef>
38 <paramdef>uint64_t *
<parameter>ret
</parameter></paramdef>
44 <title>Description
</title>
47 <function>sd_bus_get_n_queued_read()
</function> may be used to query the number of bus messages in the read queue
48 of a bus connection object. The read queue contains all messages read from the transport medium (e.g. network
49 socket) but not yet processed locally. The function expects two arguments: the bus object to query, and a pointer
50 to a
64bit counter variable to write the current queue size to. Use
<function>sd_bus_process()
</function> in
51 order to process queued messages, i.e. to reduce the size of the read queue (as well as, in fact, the write
56 Similarly,
<function>sd_bus_get_n_queued_write()
</function> may be used to query the number of currently pending
57 bus messages in the write queue of a bus connection object. The write queue contains all messages enqueued into
58 the connection with a call such as
<function>sd_bus_send()
</function> but not yet written to the transport
59 medium. The expected arguments are similar to
<function>sd_bus_get_n_queued_read()
</function>. Here too, use
60 <function>sd_bus_process()
</function> to reduce the size of the write queue. Alternatively, use
61 <function>sd_bus_flush()
</function> to synchronously write out any pending bus messages until the write queue is
67 <title>Return Value
</title>
69 <para>On success, these functions return
0 or a positive integer. On failure, they return a negative errno-style
76 <para>Returned errors may indicate the following problems:
</para>
80 <term><constant>-ECHILD
</constant></term>
82 <listitem><para>The bus connection was created in a different process.
</para></listitem>
89 <title>See Also
</title>
92 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
93 <citerefentry><refentrytitle>sd-bus
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
94 <citerefentry><refentrytitle>sd_bus_process
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
95 <citerefentry><refentrytitle>sd_bus_send
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
96 <citerefentry><refentrytitle>sd_bus_flush
</refentrytitle><manvolnum>3</manvolnum></citerefentry>