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3802a3d3 | 1 | <?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*--> |
b408026b | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" |
12b42c76 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
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4 | |
5 | <!-- | |
b975b0d5 | 6 | This file is part of systemd. |
b408026b | 7 | |
b975b0d5 | 8 | Copyright 2014 Lennart Poettering |
b408026b | 9 | |
b975b0d5 ZJS |
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. | |
b408026b | 14 | |
b975b0d5 ZJS |
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. | |
b408026b | 19 | |
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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/>. | |
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22 | --> |
23 | ||
48f69d8f | 24 | <refentry id="sd_event_add_time"> |
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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 | ||
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71 | <funcprototype> |
72 | <funcdef>typedef int (*<function>sd_event_time_handler_t</function>)</funcdef> | |
73 | <paramdef>sd_event_source *<parameter>s</parameter></paramdef> | |
74 | <paramdef>uint64_t <parameter>usec</parameter></paramdef> | |
75 | <paramdef>void *<parameter>userdata</parameter></paramdef> | |
76 | </funcprototype> | |
77 | ||
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78 | <funcprototype> |
79 | <funcdef>int <function>sd_event_source_get_time</function></funcdef> | |
80 | <paramdef>sd_event_source *<parameter>source</parameter></paramdef> | |
3b3d7d06 | 81 | <paramdef>usec_t *<parameter>usec</parameter></paramdef> |
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82 | </funcprototype> |
83 | ||
84 | <funcprototype> | |
85 | <funcdef>int <function>sd_event_source_set_time</function></funcdef> | |
86 | <paramdef>sd_event_source *<parameter>source</parameter></paramdef> | |
87 | <paramdef>usec_t <parameter>usec</parameter></paramdef> | |
88 | </funcprototype> | |
89 | ||
90 | <funcprototype> | |
91 | <funcdef>int <function>sd_event_source_get_time_accuracy</function></funcdef> | |
92 | <paramdef>sd_event_source *<parameter>source</parameter></paramdef> | |
93 | <paramdef>usec_t *<parameter>usec</parameter></paramdef> | |
94 | </funcprototype> | |
95 | ||
96 | <funcprototype> | |
97 | <funcdef>int <function>sd_event_source_set_time_accuracy</function></funcdef> | |
98 | <paramdef>sd_event_source *<parameter>source</parameter></paramdef> | |
99 | <paramdef>usec_t <parameter>usec</parameter></paramdef> | |
100 | </funcprototype> | |
101 | ||
102 | <funcprototype> | |
103 | <funcdef>int <function>sd_event_source_get_time_clock</function></funcdef> | |
104 | <paramdef>sd_event_source *<parameter>source</parameter></paramdef> | |
105 | <paramdef>clockid_t *<parameter>clock</parameter></paramdef> | |
106 | </funcprototype> | |
107 | ||
108 | </funcsynopsis> | |
109 | </refsynopsisdiv> | |
110 | ||
111 | <refsect1> | |
112 | <title>Description</title> | |
113 | ||
114 | <para><function>sd_event_add_time()</function> adds a new timer | |
115 | event source to an event loop object. The event loop is specified | |
116 | in <parameter>event</parameter>, the event source is returned in | |
117 | the <parameter>source</parameter> parameter. The | |
118 | <parameter>clock</parameter> parameter takes a clock identifier, | |
119 | one of <constant>CLOCK_REALTIME</constant>, | |
120 | <constant>CLOCK_MONOTONIC</constant> and | |
121 | <constant>CLOCK_BOOTTIME_ALARM</constant>. See | |
122 | <citerefentry><refentrytitle>timerfd_create</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
123 | for details regarding the various types of clocks. The | |
124 | <parameter>usec</parameter> parameter takes a time value in | |
125 | microseconds, relative to the clock's epoch specifying when the | |
126 | timer shall elapse the earliest. The | |
127 | <parameter>accuracy</parameter> parameter takes an additional | |
128 | accuracy value in microseconds specifying a time the timer event | |
129 | may be delayed. Specify 0 for selecting the default accuracy | |
130 | (250ms). Specify 1 for most accurate timers. Consider specifying | |
b8bde116 | 131 | 60000000 or larger (1h) for long-running events that may be |
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132 | delayed substantially. Picking higher accuracy values allows the |
133 | system to coalesce timer events more aggressively, thus improving | |
134 | power efficiency. The <parameter>handler</parameter> shall | |
135 | reference a function to call when the timer elapses. The handler | |
136 | function will be passed the <parameter>userdata</parameter> | |
137 | pointer, which may be chosen freely by the caller. The handler is | |
138 | also passed the configured time it was triggered, however it might | |
139 | actually have been called at a slightly later time, subject to the | |
140 | specified accuracy value, the kernel timer slack (see | |
141 | <citerefentry><refentrytitle>prctl</refentrytitle><manvolnum>2</manvolnum></citerefentry>) | |
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142 | and additional scheduling latencies.</para> |
143 | ||
144 | <para>By default, the timer will elapse once | |
145 | (<constant>SD_EVENT_ONESHOT</constant>), but this may be changed | |
146 | with | |
147 | <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>. | |
148 | If the handler function returns a negative error code, it will be | |
149 | disabled after the invocation, even if | |
150 | <constant>SD_EVENT_ON</constant> mode is set. | |
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151 | </para> |
152 | ||
153 | <para><function>sd_event_source_get_time()</function> retrieves | |
154 | the configured time value of a timer event source created | |
155 | previously with <function>sd_event_add_time()</function>. It takes | |
156 | the event source object and a pointer to a variable to store the | |
157 | time in microseconds in.</para> | |
158 | ||
159 | <para><function>sd_event_source_set_time()</function> changes the | |
160 | configured time value of a timer event source created previously | |
161 | with <function>sd_event_add_time()</function>. It takes the event | |
162 | source object and a time relative to the selected clock's | |
163 | epoch, in microseconds.</para> | |
164 | ||
165 | <para><function>sd_event_source_get_time_accuracy()</function> | |
166 | retrieves the configured accuracy value of a timer event source | |
167 | created previously with <function>sd_event_add_time()</function>. It | |
168 | takes the event source object and a pointer to a variable to store | |
169 | the accuracy in microseconds in.</para> | |
170 | ||
171 | <para><function>sd_event_source_set_time_accuracy()</function> | |
172 | changes the configured accuracy of a timer event source created | |
173 | previously with <function>sd_event_add_time()</function>. It takes | |
174 | the event source object and an accuracy, in microseconds.</para> | |
175 | ||
176 | <para><function>sd_event_source_get_time_clock()</function> | |
177 | retrieves the configured clock of a timer event source created | |
178 | previously with <function>sd_event_add_time()</function>. It takes | |
179 | the event source object and a pointer to a variable to store the | |
180 | clock identifier in.</para> | |
181 | ||
182 | </refsect1> | |
183 | ||
184 | <refsect1> | |
185 | <title>Return Value</title> | |
186 | ||
187 | <para>On success, these functions return 0 or a positive | |
188 | integer. On failure, they return a negative errno-style error | |
189 | code. </para> | |
190 | </refsect1> | |
191 | ||
192 | <refsect1> | |
193 | <title>Errors</title> | |
194 | ||
195 | <para>Returned errors may indicate the following problems:</para> | |
196 | ||
197 | <variablelist> | |
198 | <varlistentry> | |
8474b70c | 199 | <term><constant>-ENOMEM</constant></term> |
b408026b | 200 | |
3144ebca | 201 | <listitem><para>Not enough memory to allocate an object.</para></listitem> |
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202 | </varlistentry> |
203 | ||
204 | <varlistentry> | |
8474b70c | 205 | <term><constant>-EINVAL</constant></term> |
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206 | |
207 | <listitem><para>An invalid argument has been passed.</para></listitem> | |
208 | ||
209 | </varlistentry> | |
210 | ||
211 | <varlistentry> | |
8474b70c | 212 | <term><constant>-ESTALE</constant></term> |
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213 | |
214 | <listitem><para>The event loop is already terminated.</para></listitem> | |
215 | ||
216 | </varlistentry> | |
217 | ||
218 | <varlistentry> | |
8474b70c | 219 | <term><constant>-ECHILD</constant></term> |
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220 | |
221 | <listitem><para>The event loop has been created in a different process.</para></listitem> | |
222 | ||
223 | </varlistentry> | |
224 | ||
225 | <varlistentry> | |
15411c0c | 226 | <term><constant>-EOPNOTSUPP</constant></term> |
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227 | |
228 | <listitem><para>The selected clock is not supported by the event loop implementation.</para></listitem> | |
229 | ||
230 | </varlistentry> | |
231 | </variablelist> | |
232 | </refsect1> | |
233 | ||
234 | <refsect1> | |
235 | <title>Notes</title> | |
236 | ||
237 | <para><function>sd_event_add_time()</function> and the other functions | |
238 | described here are available as a shared library, which can be | |
239 | compiled and linked to with the | |
5aded369 | 240 | <constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> |
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241 | file.</para> |
242 | </refsect1> | |
243 | ||
244 | <refsect1> | |
245 | <title>See Also</title> | |
246 | ||
247 | <para> | |
248 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
249 | <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
250 | <citerefentry><refentrytitle>sd_event_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
3144ebca | 251 | <citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
edf25737 | 252 | <citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
4dfefc19 | 253 | <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
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254 | <citerefentry><refentrytitle>clock_gettime</refentrytitle><manvolnum>2</manvolnum></citerefentry>, |
255 | <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
256 | </para> | |
257 | </refsect1> | |
258 | ||
259 | </refentry> |