man: add sd_event_{run,wait,prepare,dispatch,loop}

This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2015-03-13 21:35:32 -04:00
parent 02d30981b1
commit 42f1ab5009
3 changed files with 414 additions and 0 deletions

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@ -810,7 +810,9 @@ MANPAGES += \
man/sd_event_add_time.3 \
man/sd_event_get_fd.3 \
man/sd_event_new.3 \
man/sd_event_run.3 \
man/sd_event_set_name.3 \
man/sd_event_wait.3 \
man/systemd-bus-proxyd.8 \
man/systemd-bus-proxyd@.service.8
MANPAGES_ALIAS += \
@ -871,7 +873,10 @@ MANPAGES_ALIAS += \
man/sd_event_add_exit.3 \
man/sd_event_add_post.3 \
man/sd_event_default.3 \
man/sd_event_dispatch.3 \
man/sd_event_get_name.3 \
man/sd_event_loop.3 \
man/sd_event_prepare.3 \
man/sd_event_ref.3 \
man/sd_event_source_get_child_pid.3 \
man/sd_event_source_get_signal.3 \
@ -939,7 +944,10 @@ man/sd_bus_unref.3: man/sd_bus_new.3
man/sd_event_add_exit.3: man/sd_event_add_defer.3
man/sd_event_add_post.3: man/sd_event_add_defer.3
man/sd_event_default.3: man/sd_event_new.3
man/sd_event_dispatch.3: man/sd_event_wait.3
man/sd_event_get_name.3: man/sd_event_set_name.3
man/sd_event_loop.3: man/sd_event_run.3
man/sd_event_prepare.3: man/sd_event_wait.3
man/sd_event_ref.3: man/sd_event_new.3
man/sd_event_source_get_child_pid.3: man/sd_event_add_child.3
man/sd_event_source_get_signal.3: man/sd_event_add_signal.3
@ -1121,9 +1129,18 @@ man/sd_event_add_post.html: man/sd_event_add_defer.html
man/sd_event_default.html: man/sd_event_new.html
$(html-alias)
man/sd_event_dispatch.html: man/sd_event_wait.html
$(html-alias)
man/sd_event_get_name.html: man/sd_event_set_name.html
$(html-alias)
man/sd_event_loop.html: man/sd_event_run.html
$(html-alias)
man/sd_event_prepare.html: man/sd_event_wait.html
$(html-alias)
man/sd_event_ref.html: man/sd_event_new.html
$(html-alias)
@ -1693,7 +1710,9 @@ EXTRA_DIST += \
man/sd_event_add_time.xml \
man/sd_event_get_fd.xml \
man/sd_event_new.xml \
man/sd_event_run.xml \
man/sd_event_set_name.xml \
man/sd_event_wait.xml \
man/sd_get_seats.xml \
man/sd_id128_get_machine.xml \
man/sd_id128_randomize.xml \

182
man/sd_event_run.xml Normal file
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@ -0,0 +1,182 @@
<?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_run" conditional="ENABLE_KDBUS">
<refentryinfo>
<title>sd_event_run</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_run</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_event_run</refname>
<refname>sd_event_loop</refname>
<refpurpose>Run libsystemd event loop</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include &lt;systemd/sd-event.h&gt;</funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_event_run</function></funcdef>
<paramdef>sd_event *<parameter>event</parameter></paramdef>
<paramdef>uint64_t <parameter>timeout</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_event_loop</function></funcdef>
<paramdef>sd_event *<parameter>event</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_event_run()</function> can be used to run one
iteration of the event loop of libsystemd. This function waits
until an event to process is available and dispatches a handler
for it. Parameter <parameter>timeout</parameter> specifices the
maximum time (in microseconds) to wait. <constant>(uint64_t)
-1</constant> may be used to specify an infinite timeout.</para>
<para><function>sd_event_loop</function> runs
<function>sd_event_wait</function> in a loop with a timeout of
infinity. This makes it suitable for the main event loop of a
program.</para>
<para>The event loop object <parameter>event</parameter> is
created with
<function>sd_event_new</function>.
Events to wait for and their handlers can be registered with
<function>sd_event_add_time</function>,
<function>sd_event_add_child</function>,
<function>sd_event_add_signal</function>,
<function>sd_event_add_defer</function>,
<function>sd_event_add_exit</function>,
and
<function>sd_event_add_post</function>.
</para>
<para>For more fine-grained control,
<function>sd_event_prepare</function>,
<function>sd_event_wait</function>, and
<function>sd_event_dispatch</function> may be used. Along with
<function>sd_event_get_fd</function>, those functions make it
possible to integrate the libsystemd loop inside of another event
loop.</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.
<function>sd_event_run</function> returns 0 if the event loop is
finished, and a positive value if it can be continued.</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 (see
<citerefentry><refentrytitle>sd_event_prepare</refentrytitle><manvolnum>3</manvolnum></citerefentry>
for an explanation of possible states).</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><function>sd_event_run()</function> and
<function>sd_event_loop()</function> 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_wait</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>

213
man/sd_event_wait.xml Normal file
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@ -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 &lt;systemd/sd-event.h&gt;</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>