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514094f9 | 1 | <?xml version='1.0'?> |
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2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> | |
0307f791 | 4 | <!-- SPDX-License-Identifier: LGPL-2.1+ --> |
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5 | |
6 | <refentry id="sd_event_source_unref" xmlns:xi="http://www.w3.org/2001/XInclude"> | |
7 | ||
8 | <refentryinfo> | |
9 | <title>sd_event_source_unref</title> | |
10 | <productname>systemd</productname> | |
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11 | </refentryinfo> |
12 | ||
13 | <refmeta> | |
14 | <refentrytitle>sd_event_source_unref</refentrytitle> | |
15 | <manvolnum>3</manvolnum> | |
16 | </refmeta> | |
17 | ||
18 | <refnamediv> | |
19 | <refname>sd_event_source_unref</refname> | |
4afd3348 | 20 | <refname>sd_event_source_unrefp</refname> |
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21 | <refname>sd_event_source_ref</refname> |
22 | ||
23 | <refpurpose>Increase or decrease event source reference counters</refpurpose> | |
24 | </refnamediv> | |
25 | ||
26 | <refsynopsisdiv> | |
27 | <funcsynopsis> | |
28 | <funcsynopsisinfo>#include <systemd/sd-event.h></funcsynopsisinfo> | |
29 | ||
30 | <funcprototype> | |
31 | <funcdef>sd_event_source* <function>sd_event_source_unref</function></funcdef> | |
32 | <paramdef>sd_event_source *<parameter>source</parameter></paramdef> | |
33 | </funcprototype> | |
34 | ||
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35 | <funcprototype> |
36 | <funcdef>void <function>sd_event_source_unrefp</function></funcdef> | |
37 | <paramdef>sd_event_source **<parameter>source</parameter></paramdef> | |
38 | </funcprototype> | |
39 | ||
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40 | <funcprototype> |
41 | <funcdef>sd_event_source* <function>sd_event_source_ref</function></funcdef> | |
42 | <paramdef>sd_event_source *<parameter>source</parameter></paramdef> | |
43 | </funcprototype> | |
44 | ||
45 | </funcsynopsis> | |
46 | </refsynopsisdiv> | |
47 | ||
48 | <refsect1> | |
49 | <title>Description</title> | |
50 | ||
51 | <para><function>sd_event_source_unref()</function> may be used to | |
52 | decrement by one the reference counter of the event source object | |
53 | specified as <parameter>source</parameter>. The reference counter | |
54 | is initially set to one, when the event source is created with calls | |
55 | such as | |
56 | <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
57 | or | |
58 | <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>. When | |
59 | the reference counter reaches zero it is removed from its event loop | |
60 | object and destroyed.</para> | |
61 | ||
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62 | <para><function>sd_event_source_unrefp()</function> is similar to |
63 | <function>sd_event_source_unref()</function> but takes a pointer to a | |
64 | pointer to an <type>sd_event_source</type> object. This call is useful in | |
65 | conjunction with GCC's and LLVM's <ulink | |
66 | url="https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html">Clean-up | |
67 | Variable Attribute</ulink>. Note that this function is defined as | |
68 | inline function.</para> | |
69 | ||
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70 | <para><function>sd_event_source_ref()</function> may be used |
71 | to increase by one the reference counter of the event source object | |
72 | specified as <parameter>source</parameter>.</para> | |
73 | ||
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74 | <para><function>sd_event_source_unref()</function>, |
75 | <function>sd_bus_creds_unrefp()</function> and | |
76 | <function>sd_bus_creds_ref()</function> execute no operation if | |
77 | the passed event source object is | |
78 | <constant>NULL</constant>.</para> | |
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79 | |
80 | <para>Note that event source objects stay alive and may be | |
81 | dispatched as long as they have a reference counter greater than | |
82 | zero. In order to drop a reference of an event source and make | |
83 | sure the associated event source handler function is not called | |
84 | anymore it is recommended to combine a call of | |
85 | <function>sd_event_source_unref()</function> with a prior call to | |
86 | <function>sd_event_source_set_enabled()</function> with | |
87 | <constant>SD_EVENT_OFF</constant>.</para> | |
88 | </refsect1> | |
89 | ||
90 | <refsect1> | |
91 | <title>Return Value</title> | |
92 | ||
93 | <para><function>sd_event_source_unref()</function> always returns | |
94 | <constant>NULL</constant>. | |
95 | <function>sd_event_source_ref()</function> always returns the | |
96 | event source object passed in.</para> | |
97 | </refsect1> | |
98 | ||
99 | <xi:include href="libsystemd-pkgconfig.xml" /> | |
100 | ||
101 | <refsect1> | |
102 | <title>See Also</title> | |
103 | ||
104 | <para> | |
105 | <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
106 | <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
107 | <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
dc83f27a | 108 | <citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
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109 | <citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
110 | <citerefentry><refentrytitle>sd_event_add_inotify</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
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111 | <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
112 | <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
113 | </para> | |
114 | </refsect1> | |
115 | ||
116 | </refentry> |