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1 | <?xml version='1.0'?> <!--*-nxml-*--> |
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 | This file is part of systemd. | |
7 | ||
8 | Copyright 2014 Lennart Poettering | |
9 | ||
10 | systemd is free software; you can redistribute it and/or modify it | |
11 | under the terms of the GNU Lesser General Public License as published by | |
12 | the Free Software Foundation; either version 2.1 of the License, or | |
13 | (at your option) any later version. | |
14 | ||
15 | systemd is distributed in the hope that it will be useful, but | |
16 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
18 | Lesser General Public License for more details. | |
19 | ||
20 | You should have received a copy of the GNU Lesser General Public License | |
21 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
22 | --> | |
23 | ||
24 | <refentry id="sd_event_add_time" conditional="ENABLE_KDBUS"> | |
25 | ||
26 | <refentryinfo> | |
27 | <title>sd_event_add_time</title> | |
28 | <productname>systemd</productname> | |
29 | ||
30 | <authorgroup> | |
31 | <author> | |
32 | <contrib>Developer</contrib> | |
33 | <firstname>Lennart</firstname> | |
34 | <surname>Poettering</surname> | |
35 | <email>lennart@poettering.net</email> | |
36 | </author> | |
37 | </authorgroup> | |
38 | </refentryinfo> | |
39 | ||
40 | <refmeta> | |
41 | <refentrytitle>sd_event_add_time</refentrytitle> | |
42 | <manvolnum>3</manvolnum> | |
43 | </refmeta> | |
44 | ||
45 | <refnamediv> | |
46 | <refname>sd_event_add_time</refname> | |
47 | <refname>sd_event_source_get_time</refname> | |
48 | <refname>sd_event_source_set_time</refname> | |
49 | <refname>sd_event_source_get_time_accuracy</refname> | |
50 | <refname>sd_event_source_set_time_accuracy</refname> | |
51 | <refname>sd_event_source_get_time_clock</refname> | |
52 | ||
53 | <refpurpose>Add a timer event source to an event loop</refpurpose> | |
54 | </refnamediv> | |
55 | ||
56 | <refsynopsisdiv> | |
57 | <funcsynopsis> | |
58 | <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> | |
59 | ||
60 | <funcprototype> | |
61 | <funcdef>int <function>sd_event_add_time</function></funcdef> | |
62 | <paramdef>sd_event *<parameter>event</parameter></paramdef> | |
63 | <paramdef>sd_event_source **<parameter>source</parameter></paramdef> | |
64 | <paramdef>clockid_t <parameter>clock</parameter></paramdef> | |
65 | <paramdef>uint64_t <parameter>usec</parameter></paramdef> | |
66 | <paramdef>uint64_t <parameter>accuracy</parameter></paramdef> | |
67 | <paramdef>sd_event_time_handler_t <parameter>handler</parameter></paramdef> | |
3b3d7d06 | 68 | <paramdef>void *<parameter>userdata</parameter></paramdef> |
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69 | </funcprototype> |
70 | ||
71 | <funcprototype> | |
72 | <funcdef>int <function>sd_event_source_get_time</function></funcdef> | |
73 | <paramdef>sd_event_source *<parameter>source</parameter></paramdef> | |
3b3d7d06 | 74 | <paramdef>usec_t *<parameter>usec</parameter></paramdef> |
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75 | </funcprototype> |
76 | ||
77 | <funcprototype> | |
78 | <funcdef>int <function>sd_event_source_set_time</function></funcdef> | |
79 | <paramdef>sd_event_source *<parameter>source</parameter></paramdef> | |
80 | <paramdef>usec_t <parameter>usec</parameter></paramdef> | |
81 | </funcprototype> | |
82 | ||
83 | <funcprototype> | |
84 | <funcdef>int <function>sd_event_source_get_time_accuracy</function></funcdef> | |
85 | <paramdef>sd_event_source *<parameter>source</parameter></paramdef> | |
86 | <paramdef>usec_t *<parameter>usec</parameter></paramdef> | |
87 | </funcprototype> | |
88 | ||
89 | <funcprototype> | |
90 | <funcdef>int <function>sd_event_source_set_time_accuracy</function></funcdef> | |
91 | <paramdef>sd_event_source *<parameter>source</parameter></paramdef> | |
92 | <paramdef>usec_t <parameter>usec</parameter></paramdef> | |
93 | </funcprototype> | |
94 | ||
95 | <funcprototype> | |
96 | <funcdef>int <function>sd_event_source_get_time_clock</function></funcdef> | |
97 | <paramdef>sd_event_source *<parameter>source</parameter></paramdef> | |
98 | <paramdef>clockid_t *<parameter>clock</parameter></paramdef> | |
99 | </funcprototype> | |
100 | ||
101 | </funcsynopsis> | |
102 | </refsynopsisdiv> | |
103 | ||
104 | <refsect1> | |
105 | <title>Description</title> | |
106 | ||
107 | <para><function>sd_event_add_time()</function> adds a new timer | |
108 | event source to an event loop object. The event loop is specified | |
109 | in <parameter>event</parameter>, the event source is returned in | |
110 | the <parameter>source</parameter> parameter. The | |
111 | <parameter>clock</parameter> parameter takes a clock identifier, | |
112 | one of <constant>CLOCK_REALTIME</constant>, | |
113 | <constant>CLOCK_MONOTONIC</constant> and | |
114 | <constant>CLOCK_BOOTTIME_ALARM</constant>. See | |
115 | <citerefentry><refentrytitle>timerfd_create</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
116 | for details regarding the various types of clocks. The | |
117 | <parameter>usec</parameter> parameter takes a time value in | |
118 | microseconds, relative to the clock's epoch specifying when the | |
119 | timer shall elapse the earliest. The | |
120 | <parameter>accuracy</parameter> parameter takes an additional | |
121 | accuracy value in microseconds specifying a time the timer event | |
122 | may be delayed. Specify 0 for selecting the default accuracy | |
123 | (250ms). Specify 1 for most accurate timers. Consider specifying | |
b8bde116 | 124 | 60000000 or larger (1h) for long-running events that may be |
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125 | delayed substantially. Picking higher accuracy values allows the |
126 | system to coalesce timer events more aggressively, thus improving | |
127 | power efficiency. The <parameter>handler</parameter> shall | |
128 | reference a function to call when the timer elapses. The handler | |
129 | function will be passed the <parameter>userdata</parameter> | |
130 | pointer, which may be chosen freely by the caller. The handler is | |
131 | also passed the configured time it was triggered, however it might | |
132 | actually have been called at a slightly later time, subject to the | |
133 | specified accuracy value, the kernel timer slack (see | |
134 | <citerefentry><refentrytitle>prctl</refentrytitle><manvolnum>2</manvolnum></citerefentry>) | |
b8bde116 | 135 | and additional scheduling latencies. By default, the timer will |
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136 | elapse once (SD_EVENT_ONESHOT), but this may be changed with |
137 | <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>. If | |
b8bde116 | 138 | the handler function returns a negative error code, it will be |
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139 | disabled after the invocation, even if SD_EVENT_ON mode is set. |
140 | </para> | |
141 | ||
142 | <para><function>sd_event_source_get_time()</function> retrieves | |
143 | the configured time value of a timer event source created | |
144 | previously with <function>sd_event_add_time()</function>. It takes | |
145 | the event source object and a pointer to a variable to store the | |
146 | time in microseconds in.</para> | |
147 | ||
148 | <para><function>sd_event_source_set_time()</function> changes the | |
149 | configured time value of a timer event source created previously | |
150 | with <function>sd_event_add_time()</function>. It takes the event | |
151 | source object and a time relative to the selected clock's | |
152 | epoch, in microseconds.</para> | |
153 | ||
154 | <para><function>sd_event_source_get_time_accuracy()</function> | |
155 | retrieves the configured accuracy value of a timer event source | |
156 | created previously with <function>sd_event_add_time()</function>. It | |
157 | takes the event source object and a pointer to a variable to store | |
158 | the accuracy in microseconds in.</para> | |
159 | ||
160 | <para><function>sd_event_source_set_time_accuracy()</function> | |
161 | changes the configured accuracy of a timer event source created | |
162 | previously with <function>sd_event_add_time()</function>. It takes | |
163 | the event source object and an accuracy, in microseconds.</para> | |
164 | ||
165 | <para><function>sd_event_source_get_time_clock()</function> | |
166 | retrieves the configured clock of a timer event source created | |
167 | previously with <function>sd_event_add_time()</function>. It takes | |
168 | the event source object and a pointer to a variable to store the | |
169 | clock identifier in.</para> | |
170 | ||
171 | </refsect1> | |
172 | ||
173 | <refsect1> | |
174 | <title>Return Value</title> | |
175 | ||
176 | <para>On success, these functions return 0 or a positive | |
177 | integer. On failure, they return a negative errno-style error | |
178 | code. </para> | |
179 | </refsect1> | |
180 | ||
181 | <refsect1> | |
182 | <title>Errors</title> | |
183 | ||
184 | <para>Returned errors may indicate the following problems:</para> | |
185 | ||
186 | <variablelist> | |
187 | <varlistentry> | |
188 | <term><varname>-ENOMEM</varname></term> | |
189 | ||
190 | <listitem><para>Not enough memory to allocate object.</para></listitem> | |
191 | </varlistentry> | |
192 | ||
193 | <varlistentry> | |
194 | <term><varname>-EINVAL</varname></term> | |
195 | ||
196 | <listitem><para>An invalid argument has been passed.</para></listitem> | |
197 | ||
198 | </varlistentry> | |
199 | ||
200 | <varlistentry> | |
201 | <term><varname>-ESTALE</varname></term> | |
202 | ||
203 | <listitem><para>The event loop is already terminated.</para></listitem> | |
204 | ||
205 | </varlistentry> | |
206 | ||
207 | <varlistentry> | |
208 | <term><varname>-ECHILD</varname></term> | |
209 | ||
210 | <listitem><para>The event loop has been created in a different process.</para></listitem> | |
211 | ||
212 | </varlistentry> | |
213 | ||
214 | <varlistentry> | |
215 | <term><varname>-ENOTSUP</varname></term> | |
216 | ||
217 | <listitem><para>The selected clock is not supported by the event loop implementation.</para></listitem> | |
218 | ||
219 | </varlistentry> | |
220 | </variablelist> | |
221 | </refsect1> | |
222 | ||
223 | <refsect1> | |
224 | <title>Notes</title> | |
225 | ||
226 | <para><function>sd_event_add_time()</function> and the other functions | |
227 | described here are available as a shared library, which can be | |
228 | compiled and linked to with the | |
5aded369 | 229 | <constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> |
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230 | file.</para> |
231 | </refsect1> | |
232 | ||
233 | <refsect1> | |
234 | <title>See Also</title> | |
235 | ||
236 | <para> | |
237 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
238 | <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
239 | <citerefentry><refentrytitle>sd_event_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
240 | <citerefentry><refentrytitle>clock_gettime</refentrytitle><manvolnum>2</manvolnum></citerefentry>, | |
241 | <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
242 | </para> | |
243 | </refsect1> | |
244 | ||
245 | </refentry> |