diff options
Diffstat (limited to 'man/sd_event_wait.xml')
| -rw-r--r-- | man/sd_event_wait.xml | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/man/sd_event_wait.xml b/man/sd_event_wait.xml new file mode 100644 index 0000000000..4b7cf50b6d --- /dev/null +++ b/man/sd_event_wait.xml @@ -0,0 +1,213 @@ +<?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. + + 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> |