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

2 files changed, 395 insertions, 0 deletions

diff --git a/man/sd_event_run.xml b/man/sd_event_run.xml
new file mode 100644
index 0000000000..d9ffe46bda
--- /dev/null
+++ b/man/sd_event_run.xml
@@ -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>
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 &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>