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systemd/man/sd_event_add_time.xml
Filipe Brandenburger 681eb9cf2b man: generate configured paths in manpages
In particular, use /lib/systemd instead of /usr/lib/systemd in distributions
like Debian which still have not adopted a /usr merge setup.

Use XML entities from man/custom-entities.ent to replace configured paths while
doing XSLT processing of the original XML files. There was precedent of some
files (such as systemd.generator.xml) which were already using this approach.

This addresses most of the (manual) fixes from this patch:
http://anonscm.debian.org/cgit/pkg-systemd/systemd.git/tree/debian/patches/Fix-paths-in-man-pages.patch?h=experimental-220

The idea of using generic XML entities was presented here:
http://lists.freedesktop.org/archives/systemd-devel/2015-May/032240.html

This patch solves almost all the issues, with the exception of:
- Path to /bin/mount and /bin/umount.
- Generic statements about preference of /lib over /etc.

These will be handled separately by follow up patches.

Tested:
- With default configure settings, ran "make install" to two separate
  directories and compared the output to confirm they matched exactly.
- Used a set of configure flags including $CONFFLAGS from Debian:
  http://anonscm.debian.org/cgit/pkg-systemd/systemd.git/tree/debian/rules
  Installed the tree and confirmed the paths use /lib/systemd instead of
  /usr/lib/systemd and that no other unexpected differences exist.
- Confirmed that `make distcheck` still passes.
2015-05-28 19:28:19 +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" [
<!ENTITY % entities SYSTEM "custom-entities.ent" >
%entities;
]>
<!--
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 &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>