man/sd_bus_set_connected_signal.xml

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   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4
   5 <!--
   6   SPDX-License-Identifier: LGPL-2.1+
   7
   8   Copyright 2017 Lennart Poettering
   9 -->
  10
  11 <refentry id="sd_bus_set_connected_signal">
  12
  13   <refentryinfo>
  14     <title>sd_bus_set_connected_signal</title>
  15     <productname>elogind</productname>
  16
  17     <authorgroup>
  18       <author>
  19         <contrib>Developer</contrib>
  20         <firstname>Lennart</firstname>
  21         <surname>Poettering</surname>
  22         <email>lennart@poettering.net</email>
  23       </author>
  24     </authorgroup>
  25   </refentryinfo>
  26
  27   <refmeta>
  28     <refentrytitle>sd_bus_set_connected_signal</refentrytitle>
  29     <manvolnum>3</manvolnum>
  30   </refmeta>
  31
  32   <refnamediv>
  33     <refname>sd_bus_set_connected_signal</refname>
  34     <refname>sd_bus_get_connected_signal</refname>
  35
  36     <refpurpose>Control emmission of local connection establishment signal on bus connections</refpurpose>
  37   </refnamediv>
  38
  39   <refsynopsisdiv>
  40     <funcsynopsis>
  41       <funcsynopsisinfo>#include &lt;elogind/sd-bus.h&gt;</funcsynopsisinfo>
  42
  43       <funcprototype>
  44         <funcdef>int <function>sd_bus_set_connected_signal</function></funcdef>
  45         <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
  46         <paramdef>int <parameter>b</parameter></paramdef>
  47       </funcprototype>
  48
  49       <funcprototype>
  50         <funcdef>int <function>sd_bus_get_connected_signal</function></funcdef>
  51         <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
  52       </funcprototype>
  53
  54     </funcsynopsis>
  55   </refsynopsisdiv>
  56
  57   <refsect1>
  58     <title>Description</title>
  59
  60     <para><function>sd_bus_set_connected_signal()</function> may be used to control whether a local, synthetic
  61     <function>Connected()</function> signal message shall be generated and enqueued for dispatching when the connection
  62     is fully established. If the <parameter>b</parameter> parameter is zero the message is not generated (the default),
  63     otherwise it is generated.</para>
  64
  65     <para><function>sd_bus_get_connected_signal()</function> may be used to query whether this feature is enabled. It
  66     returns zero if not, positive otherwise.</para>
  67
  68     <para>The <function>Connected()</function> signal message is generated from the
  69     <literal>org.freedesktop.DBus.Local</literal> service and interface, and
  70     <literal>/org/freedesktop/DBus/Local</literal> object path. Use
  71     <citerefentry><refentrytitle>sd_bus_match_signal_async</refentrytitle><manvolnum>3</manvolnum></citerefentry> to
  72     match on this signal.</para>
  73
  74     <para>This message is particularly useful on slow transports where connections take a long time to be
  75     established. This is especially the case when
  76     <citerefentry><refentrytitle>sd_bus_set_watch_bind</refentrytitle><manvolnum>3</manvolnum></citerefentry> is
  77     used. The signal is generated when the
  78     <citerefentry><refentrytitle>sd_bus_is_ready</refentrytitle><manvolnum>3</manvolnum></citerefentry> returns
  79     positive for the first time.</para>
  80
  81     <para>The <function>Connected()</function> signal corresponds with the <function>Disconnected()</function> signal
  82     that is synthesized locally when the connection is terminated. The latter is generated unconditionally however,
  83     unlike the former which needs to be enabled explicitly before it is generated, with
  84     <function>sd_bus_set_connected_signal()</function>.</para>
  85   </refsect1>
  86
  87   <refsect1>
  88     <title>Return Value</title>
  89
  90     <para>On success, these functions return 0 or a positive integer. On failure, they return a negative errno-style
  91     error code.</para>
  92   </refsect1>
  93
  94   <refsect1>
  95     <title>Errors</title>
  96
  97     <para>Returned errors may indicate the following problems:</para>
  98
  99     <variablelist>
 100       <varlistentry>
 101         <term><constant>-ECHILD</constant></term>
 102
 103         <listitem><para>The bus connection has been created in a different process.</para></listitem>
 104       </varlistentry>
 105     </variablelist>
 106   </refsect1>
 107
 108   <refsect1>
 109     <title>Notes</title>
 110
 111     <para><function>sd_bus_set_connected_signal()</function> and <function>sd_bus_get_connected_signal()</function> are available as
 112     a shared library, which can be compiled and linked to with the <constant>libelogind</constant> <citerefentry
 113     project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> file.</para>
 114   </refsect1>
 115
 116   <refsect1>
 117     <title>See Also</title>
 118
 119     <para>
 120       <citerefentry><refentrytitle>elogind</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 121       <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 122       <citerefentry><refentrytitle>sd_bus_match_signal_async</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 123       <citerefentry><refentrytitle>sd_bus_set_watch_bind</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 124       <citerefentry><refentrytitle>sd_bus_is_ready</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 125     </para>
 126   </refsect1>
 127
 128 </refentry>