1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
|
<?xml version='1.0'?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1+ -->
<refentry id="sd_event_source_set_enabled" xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sd_event_source_set_enabled</title>
<productname>elogind</productname>
</refentryinfo>
<refmeta>
<refentrytitle>sd_event_source_set_enabled</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_event_source_set_enabled</refname>
<refname>sd_event_source_get_enabled</refname>
<refname>SD_EVENT_ON</refname>
<refname>SD_EVENT_OFF</refname>
<refname>SD_EVENT_ONESHOT</refname>
<refpurpose>Enable or disable event sources</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include <elogind/sd-event.h></funcsynopsisinfo>
<funcsynopsisinfo><token>enum</token> {
<constant>SD_EVENT_OFF</constant> = 0,
<constant>SD_EVENT_ON</constant> = 1,
<constant>SD_EVENT_ONESHOT</constant> = -1,
};</funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_event_source_set_enabled</function></funcdef>
<paramdef>sd_event_source *<parameter>source</parameter></paramdef>
<paramdef>int <parameter>enabled</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_event_source_get_enabled</function></funcdef>
<paramdef>sd_event_source *<parameter>source</parameter></paramdef>
<paramdef>int *<parameter>enabled</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_event_source_set_enabled()</function> may be
used to enable or disable the event source object specified as
<parameter>source</parameter>. The <parameter>enabled</parameter>
parameter takes one of <constant>SD_EVENT_ON</constant> (to
enable), <constant>SD_EVENT_OFF</constant> (to disable) or
<constant>SD_EVENT_ONESHOT</constant>. If invoked with
<constant>SD_EVENT_ONESHOT</constant> the event source will be
enabled but automatically reset to
<constant>SD_EVENT_OFF</constant> after the event source was
dispatched once.</para>
<para>Event sources that are disabled will not result in event
loop wakeups and will not be dispatched, until they are enabled
again.</para>
<para><function>sd_event_source_get_enabled()</function> may be
used to query whether the event source object
<parameter>source</parameter> is currently enabled or not. It
returns the enablement state (one of <constant>SD_EVENT_ON</constant>,
<constant>SD_EVENT_OFF</constant>, <constant>SD_EVENT_ONESHOT</constant>)
in <parameter>enabled</parameter>, if it is not <constant>NULL</constant>.
It also returns true if the event source is not disabled.</para>
<para>Event source objects are enabled when they are first created
with calls such as
<citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>. However,
depending on the event source type they are enabled continuously
(<constant>SD_EVENT_ON</constant>) or only for a single invocation
of the event source handler
(<constant>SD_EVENT_ONESHOT</constant>). For details see the
respective manual pages.</para>
<para>As event source objects stay active and may be dispatched as
long as there is at least one reference to them, in many cases it
is a good idea to combine a call to
<citerefentry><refentrytitle>sd_event_source_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>
with a prior call to
<function>sd_event_source_set_enabled()</function> with
<constant>SD_EVENT_OFF</constant>, to ensure the event source is
not dispatched again until all other remaining references are dropped.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>On success, <function>sd_event_source_set_enabled()</function> returns a non-negative
integer. <function>sd_event_source_get_enabled()</function> returns zero if the source is disabled
(<constant>SD_EVENT_OFF</constant>) and a positive integer otherwise. On failure, they return a negative
errno-style error code.</para>
<refsect2>
<title>Errors</title>
<para>Returned errors may indicate the following problems:</para>
<variablelist>
<varlistentry>
<term><constant>-EINVAL</constant></term>
<listitem><para><parameter>source</parameter> is not a valid pointer to an
<structname>sd_event_source</structname> object.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ENOMEM</constant></term>
<listitem><para>Not enough memory.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ECHILD</constant></term>
<listitem><para>The event loop has been created in a different process.</para></listitem>
</varlistentry>
</variablelist>
</refsect2>
</refsect1>
<xi:include href="libelogind-pkgconfig.xml" />
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_event_add_inotify</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_event_source_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
|
