2 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.2//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
6 SPDX-License-Identifier: LGPL-2.1+
9 <refentry id=
"sd_event_source_unref" xmlns:
xi=
"http://www.w3.org/2001/XInclude">
12 <title>sd_event_source_unref
</title>
13 <productname>systemd
</productname>
17 <refentrytitle>sd_event_source_unref
</refentrytitle>
18 <manvolnum>3</manvolnum>
22 <refname>sd_event_source_unref
</refname>
23 <refname>sd_event_source_unrefp
</refname>
24 <refname>sd_event_source_ref
</refname>
26 <refpurpose>Increase or decrease event source reference counters
</refpurpose>
31 <funcsynopsisinfo>#include
<systemd/sd-event.h
></funcsynopsisinfo>
34 <funcdef>sd_event_source*
<function>sd_event_source_unref
</function></funcdef>
35 <paramdef>sd_event_source *
<parameter>source
</parameter></paramdef>
39 <funcdef>void
<function>sd_event_source_unrefp
</function></funcdef>
40 <paramdef>sd_event_source **
<parameter>source
</parameter></paramdef>
44 <funcdef>sd_event_source*
<function>sd_event_source_ref
</function></funcdef>
45 <paramdef>sd_event_source *
<parameter>source
</parameter></paramdef>
52 <title>Description
</title>
54 <para><function>sd_event_source_unref()
</function> may be used to
55 decrement by one the reference counter of the event source object
56 specified as
<parameter>source
</parameter>. The reference counter
57 is initially set to one, when the event source is created with calls
59 <citerefentry><refentrytitle>sd_event_add_io
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
61 <citerefentry><refentrytitle>sd_event_add_time
</refentrytitle><manvolnum>3</manvolnum></citerefentry>. When
62 the reference counter reaches zero it is removed from its event loop
63 object and destroyed.
</para>
65 <para><function>sd_event_source_unrefp()
</function> is similar to
66 <function>sd_event_source_unref()
</function> but takes a pointer to a
67 pointer to an
<type>sd_event_source
</type> object. This call is useful in
68 conjunction with GCC's and LLVM's
<ulink
69 url=
"https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html">Clean-up
70 Variable Attribute
</ulink>. Note that this function is defined as
71 inline function.
</para>
73 <para><function>sd_event_source_ref()
</function> may be used
74 to increase by one the reference counter of the event source object
75 specified as
<parameter>source
</parameter>.
</para>
77 <para><function>sd_event_source_unref()
</function>,
78 <function>sd_bus_creds_unrefp()
</function> and
79 <function>sd_bus_creds_ref()
</function> execute no operation if
80 the passed event source object is
81 <constant>NULL
</constant>.
</para>
83 <para>Note that event source objects stay alive and may be
84 dispatched as long as they have a reference counter greater than
85 zero. In order to drop a reference of an event source and make
86 sure the associated event source handler function is not called
87 anymore it is recommended to combine a call of
88 <function>sd_event_source_unref()
</function> with a prior call to
89 <function>sd_event_source_set_enabled()
</function> with
90 <constant>SD_EVENT_OFF
</constant>.
</para>
94 <title>Return Value
</title>
96 <para><function>sd_event_source_unref()
</function> always returns
97 <constant>NULL
</constant>.
98 <function>sd_event_source_ref()
</function> always returns the
99 event source object passed in.
</para>
102 <xi:include href=
"libsystemd-pkgconfig.xml" />
105 <title>See Also
</title>
108 <citerefentry><refentrytitle>sd-event
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
109 <citerefentry><refentrytitle>sd_event_add_io
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
110 <citerefentry><refentrytitle>sd_event_add_time
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
111 <citerefentry><refentrytitle>sd_event_add_signal
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
112 <citerefentry><refentrytitle>sd_event_add_child
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
113 <citerefentry><refentrytitle>sd_event_add_inotify
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
114 <citerefentry><refentrytitle>sd_event_add_defer
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
115 <citerefentry><refentrytitle>sd_event_source_set_enabled
</refentrytitle><manvolnum>3</manvolnum></citerefentry>