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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 2015 Zbigniew Jędrzejewski-Szmek
-
- 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.
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- 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_wait" conditional="ENABLE_KDBUS">
-
- <refentryinfo>
- <title>sd_event_wait</title>
- <productname>systemd</productname>
-
- <authorgroup>
- <author>
- <contrib>Developer</contrib>
- <firstname>Tom</firstname>
- <surname>Gundersen</surname>
- <email>teg@jklm.no</email>
- </author>
- </authorgroup>
- </refentryinfo>
-
- <refmeta>
- <refentrytitle>sd_event_wait</refentrytitle>
- <manvolnum>3</manvolnum>
- </refmeta>
-
- <refnamediv>
- <refname>sd_event_wait</refname>
- <refname>sd_event_prepare</refname>
- <refname>sd_event_dispatch</refname>
-
- <refpurpose>Run parts of libsystemd event loop</refpurpose>
- </refnamediv>
-
- <refsynopsisdiv>
- <funcsynopsis>
- <funcsynopsisinfo>#include <systemd/sd-event.h></funcsynopsisinfo>
-
- <funcprototype>
- <funcdef>int <function>sd_event_prepare</function></funcdef>
- <paramdef>sd_event *<parameter>event</parameter></paramdef>
- </funcprototype>
-
- <funcprototype>
- <funcdef>int <function>sd_event_wait</function></funcdef>
- <paramdef>sd_event *<parameter>event</parameter></paramdef>
- <paramdef>uint64_t <parameter>timeout</parameter></paramdef>
- </funcprototype>
-
- <funcprototype>
- <funcdef>int <function>sd_event_dispatch</function></funcdef>
- <paramdef>sd_event *<parameter>event</parameter></paramdef>
- </funcprototype>
-
- </funcsynopsis>
- </refsynopsisdiv>
-
- <refsect1>
- <title>Description</title>
-
- <para>Functions described here form parts of an event loop.</para>
-
- <para><function>sd_event_prepare</function> checks for pending
- events and arms necessary timers. If any events are ready to be
- processed, it returns a positive value, and the events should be
- processed with <function>sd_event_dispatch</function>.
- <function>sd_event_dispatch</function> runs a handler for one of
- the events from the sources with the highest priority. On success,
- <function>sd_event_dispatch</function> returns either 0, which
- means that the loop is finished, or a positive value, which means
- that the loop is again in the initial state and
- <function>sd_event_prepare</function> should be called again.
- </para>
-
- <para>In case <function>sd_event_prepare</function> returned 0,
- <function>sd_event_wait</function> should be called to wait for
- events or a timeout. If any events are ready to be processed, it
- returns a positive value, and the events should be processed with
- <function>sd_event_dispatch</function>. Otherwise, the loop is
- back in the inital state and <function>sd_event_prepare</function>
- should be called again.</para>
-
- <programlisting>
- ┌──────────┐
- │ initial ├──←←←←←←←←←←←←←←←←←←←─┐
- └───┬──────┘ ↑
- │ ↑
- sd_event_prepare ┌─────────┐ ↑
- ├ 0 →→→→→→→──┤ armed │ ↑
- 1 └───┬─────┘ ↑
- ↓ │ ↑
- ↓ sd_event_wait ↑
- ├───←←←←←←←─── 1 ┴─ 0 →→→→→→→─┘
- ┌───┴──────┐ ↑
- │ pending │ ↑
- └───┬──────┘ ↑
- │ ↑
- sd_event_dispatch ↑
- ↓ ↑
- ├ 1 ──────────→→→→→→→─────────┘
- 0
- ↓
- ┌───┴──────┐
- │ finished │
- └──────────┘
- </programlisting>
-
- <para>All three functions as the first argument take the event
- loop object <parameter>event</parameter> that is created with with
- <function>sd_event_new</function>. The timeout for
- <function>sd_event_wait</function> is specified with
- <parameter>timeout</parameter> in milliseconds.
- <constant>(uint64_t) -1</constant> may be used to specify an
- infinite timeout.</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. In case
- of <function>sd_event_prepare</function> and
- <function>sd_event_wait</function> a positive value means that
- events are ready to be processed and 0 means that no events are
- ready. In case of <function>sd_event_dispatch</function> a
- positive value means that the loop is again in the initial state
- and 0 means the loop is finished. For any of those functions, a
- negative return value means the loop must be aborted.</para>
- </refsect1>
-
- <refsect1>
- <title>Errors</title>
-
- <para>Returned errors may indicate the following problems:</para>
-
- <variablelist>
- <varlistentry>
- <term><constant>-EINVAL</constant></term>
-
- <listitem><para>Parameter <parameter>event</parameter> is
- <constant>NULL</constant>.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><constant>-EBUSY</constant></term>
-
- <listitem><para>The event loop object is not in the right
- state.</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>
-
- </variablelist>
-
- <para>Other errors are possible too.</para>
- </refsect1>
-
- <refsect1>
- <title>Notes</title>
-
- <para>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_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>sd_event_run</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>sd_event_add_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>sd_event_add_post</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
- </para>
- </refsect1>
-
-</refentry>
~ianmdlvl / elogind.git / blobdiff