mirror of
https://github.com/systemd/systemd.git
synced 2024-12-26 03:22:00 +03:00
3802a3d3d7
In the long run we really should figure out if we want to stick with 8ch or 2ch indenting, and not continue with half-and-half. For now, just make emacs aware of the files that use 2ch indenting.
260 lines
11 KiB
XML
260 lines
11 KiB
XML
<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
|
||
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
|
||
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
|
||
|
||
<!--
|
||
This file is part of systemd.
|
||
|
||
Copyright 2014 Lennart Poettering
|
||
|
||
systemd is free software; you can redistribute it and/or modify it
|
||
under the terms of the GNU Lesser General Public License as published by
|
||
the Free Software Foundation; either version 2.1 of the License, or
|
||
(at your option) any later version.
|
||
|
||
systemd is distributed in the hope that it will be useful, but
|
||
WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||
Lesser General Public License for more details.
|
||
|
||
You should have received a copy of the GNU Lesser General Public License
|
||
along with systemd; If not, see <http://www.gnu.org/licenses/>.
|
||
-->
|
||
|
||
<refentry id="sd_event_add_time" conditional="ENABLE_KDBUS">
|
||
|
||
<refentryinfo>
|
||
<title>sd_event_add_time</title>
|
||
<productname>systemd</productname>
|
||
|
||
<authorgroup>
|
||
<author>
|
||
<contrib>Developer</contrib>
|
||
<firstname>Lennart</firstname>
|
||
<surname>Poettering</surname>
|
||
<email>lennart@poettering.net</email>
|
||
</author>
|
||
</authorgroup>
|
||
</refentryinfo>
|
||
|
||
<refmeta>
|
||
<refentrytitle>sd_event_add_time</refentrytitle>
|
||
<manvolnum>3</manvolnum>
|
||
</refmeta>
|
||
|
||
<refnamediv>
|
||
<refname>sd_event_add_time</refname>
|
||
<refname>sd_event_source_get_time</refname>
|
||
<refname>sd_event_source_set_time</refname>
|
||
<refname>sd_event_source_get_time_accuracy</refname>
|
||
<refname>sd_event_source_set_time_accuracy</refname>
|
||
<refname>sd_event_source_get_time_clock</refname>
|
||
|
||
<refpurpose>Add a timer event source to an event loop</refpurpose>
|
||
</refnamediv>
|
||
|
||
<refsynopsisdiv>
|
||
<funcsynopsis>
|
||
<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
|
||
|
||
<funcprototype>
|
||
<funcdef>int <function>sd_event_add_time</function></funcdef>
|
||
<paramdef>sd_event *<parameter>event</parameter></paramdef>
|
||
<paramdef>sd_event_source **<parameter>source</parameter></paramdef>
|
||
<paramdef>clockid_t <parameter>clock</parameter></paramdef>
|
||
<paramdef>uint64_t <parameter>usec</parameter></paramdef>
|
||
<paramdef>uint64_t <parameter>accuracy</parameter></paramdef>
|
||
<paramdef>sd_event_time_handler_t <parameter>handler</parameter></paramdef>
|
||
<paramdef>void *<parameter>userdata</parameter></paramdef>
|
||
</funcprototype>
|
||
|
||
<funcprototype>
|
||
<funcdef>typedef int (*<function>sd_event_time_handler_t</function>)</funcdef>
|
||
<paramdef>sd_event_source *<parameter>s</parameter></paramdef>
|
||
<paramdef>uint64_t <parameter>usec</parameter></paramdef>
|
||
<paramdef>void *<parameter>userdata</parameter></paramdef>
|
||
</funcprototype>
|
||
|
||
<funcprototype>
|
||
<funcdef>int <function>sd_event_source_get_time</function></funcdef>
|
||
<paramdef>sd_event_source *<parameter>source</parameter></paramdef>
|
||
<paramdef>usec_t *<parameter>usec</parameter></paramdef>
|
||
</funcprototype>
|
||
|
||
<funcprototype>
|
||
<funcdef>int <function>sd_event_source_set_time</function></funcdef>
|
||
<paramdef>sd_event_source *<parameter>source</parameter></paramdef>
|
||
<paramdef>usec_t <parameter>usec</parameter></paramdef>
|
||
</funcprototype>
|
||
|
||
<funcprototype>
|
||
<funcdef>int <function>sd_event_source_get_time_accuracy</function></funcdef>
|
||
<paramdef>sd_event_source *<parameter>source</parameter></paramdef>
|
||
<paramdef>usec_t *<parameter>usec</parameter></paramdef>
|
||
</funcprototype>
|
||
|
||
<funcprototype>
|
||
<funcdef>int <function>sd_event_source_set_time_accuracy</function></funcdef>
|
||
<paramdef>sd_event_source *<parameter>source</parameter></paramdef>
|
||
<paramdef>usec_t <parameter>usec</parameter></paramdef>
|
||
</funcprototype>
|
||
|
||
<funcprototype>
|
||
<funcdef>int <function>sd_event_source_get_time_clock</function></funcdef>
|
||
<paramdef>sd_event_source *<parameter>source</parameter></paramdef>
|
||
<paramdef>clockid_t *<parameter>clock</parameter></paramdef>
|
||
</funcprototype>
|
||
|
||
</funcsynopsis>
|
||
</refsynopsisdiv>
|
||
|
||
<refsect1>
|
||
<title>Description</title>
|
||
|
||
<para><function>sd_event_add_time()</function> adds a new timer
|
||
event source to an event loop object. The event loop is specified
|
||
in <parameter>event</parameter>, the event source is returned in
|
||
the <parameter>source</parameter> parameter. The
|
||
<parameter>clock</parameter> parameter takes a clock identifier,
|
||
one of <constant>CLOCK_REALTIME</constant>,
|
||
<constant>CLOCK_MONOTONIC</constant> and
|
||
<constant>CLOCK_BOOTTIME_ALARM</constant>. See
|
||
<citerefentry><refentrytitle>timerfd_create</refentrytitle><manvolnum>2</manvolnum></citerefentry>
|
||
for details regarding the various types of clocks. The
|
||
<parameter>usec</parameter> parameter takes a time value in
|
||
microseconds, relative to the clock's epoch specifying when the
|
||
timer shall elapse the earliest. The
|
||
<parameter>accuracy</parameter> parameter takes an additional
|
||
accuracy value in microseconds specifying a time the timer event
|
||
may be delayed. Specify 0 for selecting the default accuracy
|
||
(250ms). Specify 1 for most accurate timers. Consider specifying
|
||
60000000 or larger (1h) for long-running events that may be
|
||
delayed substantially. Picking higher accuracy values allows the
|
||
system to coalesce timer events more aggressively, thus improving
|
||
power efficiency. The <parameter>handler</parameter> shall
|
||
reference a function to call when the timer elapses. The handler
|
||
function will be passed the <parameter>userdata</parameter>
|
||
pointer, which may be chosen freely by the caller. The handler is
|
||
also passed the configured time it was triggered, however it might
|
||
actually have been called at a slightly later time, subject to the
|
||
specified accuracy value, the kernel timer slack (see
|
||
<citerefentry><refentrytitle>prctl</refentrytitle><manvolnum>2</manvolnum></citerefentry>)
|
||
and additional scheduling latencies.</para>
|
||
|
||
<para>By default, the timer will elapse once
|
||
(<constant>SD_EVENT_ONESHOT</constant>), but this may be changed
|
||
with
|
||
<citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
|
||
If the handler function returns a negative error code, it will be
|
||
disabled after the invocation, even if
|
||
<constant>SD_EVENT_ON</constant> mode is set.
|
||
</para>
|
||
|
||
<para><function>sd_event_source_get_time()</function> retrieves
|
||
the configured time value of a timer event source created
|
||
previously with <function>sd_event_add_time()</function>. It takes
|
||
the event source object and a pointer to a variable to store the
|
||
time in microseconds in.</para>
|
||
|
||
<para><function>sd_event_source_set_time()</function> changes the
|
||
configured time value of a timer event source created previously
|
||
with <function>sd_event_add_time()</function>. It takes the event
|
||
source object and a time relative to the selected clock's
|
||
epoch, in microseconds.</para>
|
||
|
||
<para><function>sd_event_source_get_time_accuracy()</function>
|
||
retrieves the configured accuracy value of a timer event source
|
||
created previously with <function>sd_event_add_time()</function>. It
|
||
takes the event source object and a pointer to a variable to store
|
||
the accuracy in microseconds in.</para>
|
||
|
||
<para><function>sd_event_source_set_time_accuracy()</function>
|
||
changes the configured accuracy of a timer event source created
|
||
previously with <function>sd_event_add_time()</function>. It takes
|
||
the event source object and an accuracy, in microseconds.</para>
|
||
|
||
<para><function>sd_event_source_get_time_clock()</function>
|
||
retrieves the configured clock of a timer event source created
|
||
previously with <function>sd_event_add_time()</function>. It takes
|
||
the event source object and a pointer to a variable to store the
|
||
clock identifier in.</para>
|
||
|
||
</refsect1>
|
||
|
||
<refsect1>
|
||
<title>Return Value</title>
|
||
|
||
<para>On success, these functions return 0 or a positive
|
||
integer. On failure, they return a negative errno-style error
|
||
code. </para>
|
||
</refsect1>
|
||
|
||
<refsect1>
|
||
<title>Errors</title>
|
||
|
||
<para>Returned errors may indicate the following problems:</para>
|
||
|
||
<variablelist>
|
||
<varlistentry>
|
||
<term><constant>-ENOMEM</constant></term>
|
||
|
||
<listitem><para>Not enough memory to allocate an object.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><constant>-EINVAL</constant></term>
|
||
|
||
<listitem><para>An invalid argument has been passed.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><constant>-ESTALE</constant></term>
|
||
|
||
<listitem><para>The event loop is already terminated.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><constant>-ECHILD</constant></term>
|
||
|
||
<listitem><para>The event loop has been created in a different process.</para></listitem>
|
||
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><constant>-ENOTSUP</constant></term>
|
||
|
||
<listitem><para>The selected clock is not supported by the event loop implementation.</para></listitem>
|
||
|
||
</varlistentry>
|
||
</variablelist>
|
||
</refsect1>
|
||
|
||
<refsect1>
|
||
<title>Notes</title>
|
||
|
||
<para><function>sd_event_add_time()</function> and the other functions
|
||
described here are available as a shared library, which can be
|
||
compiled and linked to with the
|
||
<constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
|
||
file.</para>
|
||
</refsect1>
|
||
|
||
<refsect1>
|
||
<title>See Also</title>
|
||
|
||
<para>
|
||
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>sd_event_new</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_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>clock_gettime</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
||
</para>
|
||
</refsect1>
|
||
|
||
</refentry>
|