man/sd_bus_set_connected_signal.xml

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  10   Copyright 2017 Lennart Poettering
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  25
  26 <refentry id="sd_bus_set_connected_signal">
  27
  28   <refentryinfo>
  29     <title>sd_bus_set_connected_signal</title>
  30     <productname>elogind</productname>
  31
  32     <authorgroup>
  33       <author>
  34         <contrib>Developer</contrib>
  35         <firstname>Lennart</firstname>
  36         <surname>Poettering</surname>
  37         <email>lennart@poettering.net</email>
  38       </author>
  39     </authorgroup>
  40   </refentryinfo>
  41
  42   <refmeta>
  43     <refentrytitle>sd_bus_set_connected_signal</refentrytitle>
  44     <manvolnum>3</manvolnum>
  45   </refmeta>
  46
  47   <refnamediv>
  48     <refname>sd_bus_set_connected_signal</refname>
  49     <refname>sd_bus_get_connected_signal</refname>
  50
  51     <refpurpose>Control emmission of local connection establishment signal on bus connections</refpurpose>
  52   </refnamediv>
  53
  54   <refsynopsisdiv>
  55     <funcsynopsis>
  56       <funcsynopsisinfo>#include &lt;elogind/sd-bus.h&gt;</funcsynopsisinfo>
  57
  58       <funcprototype>
  59         <funcdef>int <function>sd_bus_set_connected_signal</function></funcdef>
  60         <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
  61         <paramdef>int <parameter>b</parameter></paramdef>
  62       </funcprototype>
  63
  64       <funcprototype>
  65         <funcdef>int <function>sd_bus_get_connected_signal</function></funcdef>
  66         <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
  67       </funcprototype>
  68
  69     </funcsynopsis>
  70   </refsynopsisdiv>
  71
  72   <refsect1>
  73     <title>Description</title>
  74
  75     <para><function>sd_bus_set_connected_signal()</function> may be used to control whether a local, synthetic
  76     <function>Connected()</function> signal message shall be generated and enqueued for dispatching when the connection
  77     is fully established. If the <parameter>b</parameter> parameter is zero the message is not generated (the default),
  78     otherwise it is generated.</para>
  79
  80     <para><function>sd_bus_get_connected_signal()</function> may be used to query whether this feature is enabled. It
  81     returns zero if not, positive otherwise.</para>
  82
  83     <para>The <function>Connected()</function> signal message is generated from the
  84     <literal>org.freedesktop.DBus.Local</literal> service and interface, and
  85     <literal>/org/freedesktop/DBus/Local</literal> object path. Use
  86     <citerefentry><refentrytitle>sd_bus_match_signal_async</refentrytitle><manvolnum>3</manvolnum></citerefentry> to
  87     match on this signal.</para>
  88
  89     <para>This message is particularly useful on slow transports where connections take a long time to be
  90     established. This is especially the case when
  91     <citerefentry><refentrytitle>sd_bus_set_watch_bind</refentrytitle><manvolnum>3</manvolnum></citerefentry> is
  92     used. The signal is generated when the
  93     <citerefentry><refentrytitle>sd_bus_is_ready</refentrytitle><manvolnum>3</manvolnum></citerefentry> returns
  94     positive for the first time.</para>
  95
  96     <para>The <function>Connected()</function> signal corresponds with the <function>Disconnected()</function> signal
  97     that is synthesized locally when the connection is terminated. The latter is generated unconditionally however,
  98     unlike the former which needs to be enabled explicitly before it is generated, with
  99     <function>sd_bus_set_connected_signal()</function>.</para>
 100   </refsect1>
 101
 102   <refsect1>
 103     <title>Return Value</title>
 104
 105     <para>On success, these functions return 0 or a positive integer. On failure, they return a negative errno-style
 106     error code.</para>
 107   </refsect1>
 108
 109   <refsect1>
 110     <title>Errors</title>
 111
 112     <para>Returned errors may indicate the following problems:</para>
 113
 114     <variablelist>
 115       <varlistentry>
 116         <term><constant>-ECHILD</constant></term>
 117
 118         <listitem><para>The bus connection has been created in a different process.</para></listitem>
 119       </varlistentry>
 120     </variablelist>
 121   </refsect1>
 122
 123   <refsect1>
 124     <title>Notes</title>
 125
 126     <para><function>sd_bus_set_connected_signal()</function> and <function>sd_bus_get_connected_signal()</function> are available as
 127     a shared library, which can be compiled and linked to with the <constant>libelogind</constant> <citerefentry
 128     project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> file.</para>
 129   </refsect1>
 130
 131   <refsect1>
 132     <title>See Also</title>
 133
 134     <para>
 135       <citerefentry><refentrytitle>elogind</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 136       <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 137       <citerefentry><refentrytitle>sd_bus_match_signal_async</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 138       <citerefentry><refentrytitle>sd_bus_set_watch_bind</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 139       <citerefentry><refentrytitle>sd_bus_is_ready</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 140     </para>
 141   </refsect1>
 142
 143 </refentry>