systemd/man/sd_event_add_time.xml
Tom Gundersen 12b42c7667 man: revert dynamic paths for split-usr setups
This did not really work out as we had hoped. Trying to do this upstream
introduced several problems that probably makes it better suited as a
downstream patch after all. At any rate, it is not releaseable in the
current state, so we at least need to revert this before the release.

 * by adjusting the path to binaries, but not do the same thing to the
   search path we end up with inconsistent man-pages. Adjusting the search
   path too would be quite messy, and it is not at all obvious that this is
   worth the effort, but at any rate it would have to be done before we
   could ship this.

 * this means that distributed man-pages does not make sense as they depend
   on config options, and for better or worse we are still distributing
   man pages, so that is something that definitely needs sorting out before
   we could ship with this patch.

 * we have long held that split-usr is only minimally supported in order
   to boot, and something we hope will eventually go away. So before we start
   adding even more magic/effort in order to make this work nicely, we should
   probably question if it makes sense at all.
2015-06-18 19:47:44 +02:00

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<?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
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-->
<refentry id="sd_event_add_time">
<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 &lt;systemd/sd-bus.h&gt;</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>-EOPNOTSUPP</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>