man-pages/man3/sd_bus_get_n_queued_read.3.html
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<H1>SD_BUS_GET_N_QUEUED_READ</H1>
Section: sd_bus_get_fd (3)<BR>Updated: <BR><A HREF="#index">Index</A>
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<H2>NAME</H2>
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
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<H2>SYNOPSIS</H2>
<P>
<B>
</B><PRE>
#include &lt;<A HREF="file:///usr/include/systemd/sd-bus.h">systemd/sd-bus.h</A>&gt;
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<DL COMPACT>
<DT id="1">
<B>int sd_bus_get_n_queued_read(sd_bus&nbsp;*</B><I>bus</I><B>, uint64_t&nbsp;*</B><I>ret</I><B>);</B>
<DT id="2">
<B>int sd_bus_get_n_queued_write(sd_bus&nbsp;*</B><I>bus</I><B>, uint64_t&nbsp;*</B><I>ret</I><B>);</B>
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<H2>DESCRIPTION</H2>
<P>
<B>sd_bus_get_n_queued_read()</B>
<DD>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
<B>sd_bus_process()</B>
in 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).
<P>
Similarly,
<B>sd_bus_get_n_queued_write()</B>
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
<B>sd_bus_send()</B>
but not yet written to the transport medium. The expected arguments are similar to
<B>sd_bus_get_n_queued_read()</B>. Here too, use
<B>sd_bus_process()</B>
to reduce the size of the write queue. Alternatively, use
<B>sd_bus_flush()</B>
to synchronously write out any pending bus messages until the write queue is empty.
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<H2>RETURN VALUE</H2>
<P>
On success, these functions return 0 or a positive integer. On failure, they return a negative errno-style error code.
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<H3>Errors</H3>
<P>
Returned errors may indicate the following problems:
<P>
<B>-ECHILD</B>
<DL COMPACT><DT id="3"><DD>
The bus connection was created in a different process.
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<H2>SEE ALSO</H2>
<P>
<B><A HREF="/cgi-bin/man/man2html?1+systemd">systemd</A></B>(1),
<B><A HREF="/cgi-bin/man/man2html?3+sd-bus">sd-bus</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?3+sd_bus_process">sd_bus_process</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?3+sd_bus_send">sd_bus_send</A></B>(3),
<B><A HREF="/cgi-bin/man/man2html?3+sd_bus_flush">sd_bus_flush</A></B>(3)
<P>
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<A NAME="index">&nbsp;</A><H2>Index</H2>
<DL>
<DT id="4"><A HREF="#lbAB">NAME</A><DD>
<DT id="5"><A HREF="#lbAC">SYNOPSIS</A><DD>
<DT id="6"><A HREF="#lbAD">DESCRIPTION</A><DD>
<DT id="7"><A HREF="#lbAE">RETURN VALUE</A><DD>
<DL>
<DT id="8"><A HREF="#lbAF">Errors</A><DD>
</DL>
<DT id="9"><A HREF="#lbAG">SEE ALSO</A><DD>
</DL>
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