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diff --git a/man/sd_event_add_defer.xml b/man/sd_event_add_defer.xml new file mode 100644 index 0000000..de9125f --- /dev/null +++ b/man/sd_event_add_defer.xml @@ -0,0 +1,210 @@ +<?xml version='1.0'?> +<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" + "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> +<!-- SPDX-License-Identifier: LGPL-2.1-or-later --> + +<refentry id="sd_event_add_defer" xmlns:xi="http://www.w3.org/2001/XInclude"> + + <refentryinfo> + <title>sd_event_add_defer</title> + <productname>systemd</productname> + </refentryinfo> + + <refmeta> + <refentrytitle>sd_event_add_defer</refentrytitle> + <manvolnum>3</manvolnum> + </refmeta> + + <refnamediv> + <refname>sd_event_add_defer</refname> + <refname>sd_event_add_post</refname> + <refname>sd_event_add_exit</refname> + <refname>sd_event_handler_t</refname> + + <refpurpose>Add static event sources to an event loop</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcsynopsisinfo>#include <systemd/sd-event.h></funcsynopsisinfo> + + <funcsynopsisinfo><token>typedef</token> struct sd_event_source sd_event_source;</funcsynopsisinfo> + + <funcprototype> + <funcdef>typedef int (*<function>sd_event_handler_t</function>)</funcdef> + <paramdef>sd_event_source *<parameter>s</parameter></paramdef> + <paramdef>void *<parameter>userdata</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef>int <function>sd_event_add_defer</function></funcdef> + <paramdef>sd_event *<parameter>event</parameter></paramdef> + <paramdef>sd_event_source **<parameter>source</parameter></paramdef> + <paramdef>sd_event_handler_t <parameter>handler</parameter></paramdef> + <paramdef>void *<parameter>userdata</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef>int <function>sd_event_add_post</function></funcdef> + <paramdef>sd_event *<parameter>event</parameter></paramdef> + <paramdef>sd_event_source **<parameter>source</parameter></paramdef> + <paramdef>sd_event_handler_t <parameter>handler</parameter></paramdef> + <paramdef>void *<parameter>userdata</parameter></paramdef> + </funcprototype> + + <funcprototype> + <funcdef>int <function>sd_event_add_exit</function></funcdef> + <paramdef>sd_event *<parameter>event</parameter></paramdef> + <paramdef>sd_event_source **<parameter>source</parameter></paramdef> + <paramdef>sd_event_handler_t <parameter>handler</parameter></paramdef> + <paramdef>void *<parameter>userdata</parameter></paramdef> + </funcprototype> + + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Description</title> + + <para>These three functions add new static event sources to an event loop. The event loop object is + specified in the <parameter>event</parameter> parameter, the event source object is returned in the + <parameter>source</parameter> parameter. The event sources are enabled statically and will "fire" when + the event loop is run and the conditions described below are met.</para> + + <para>The <parameter>handler</parameter> is a function to call or <constant>NULL</constant>. The handler + function will be passed the <parameter>userdata</parameter> pointer, which may be chosen freely by the + caller. The handler may return negative to signal an error (see below), other return values are + ignored. If <parameter>handler</parameter> is <constant>NULL</constant>, a default handler that calls + <citerefentry><refentrytitle>sd_event_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry> will be + used.</para> + + <para><function>sd_event_add_defer()</function> adds a new event + source that will be dispatched instantly, before the event loop + goes to sleep again and waits for new events. By default, the + handler will be called once + (<constant>SD_EVENT_ONESHOT</constant>). Note that if the event + source is set to <constant>SD_EVENT_ON</constant> the event loop + will never go to sleep again, but continuously call the handler, + possibly interleaved with other event sources.</para> + + <para><function>sd_event_add_post()</function> adds a new event + source that is run before the event loop will sleep and wait + for new events, but only after at least one other non-post event + source was dispatched. By default, the source is enabled + permanently (<constant>SD_EVENT_ON</constant>). Note that this + event source type will still allow the event loop to go to sleep + again, even if set to <constant>SD_EVENT_ON</constant>, as long as + no other event source is ever triggered.</para> + + <para><function>sd_event_add_exit()</function> adds a new event + source that will be dispatched when the event loop is terminated + with <citerefentry><refentrytitle>sd_event_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para> + + <para>The + <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry> + function may be used to enable the event source permanently + (<constant>SD_EVENT_ON</constant>) or to make it fire just once + (<constant>SD_EVENT_ONESHOT</constant>).</para> + + <para>If the handler function returns a negative error code, it will either be disabled after the + invocation, even if the <constant>SD_EVENT_ON</constant> mode was requested before, or it will cause the + loop to terminate, see + <citerefentry><refentrytitle>sd_event_source_set_exit_on_failure</refentrytitle><manvolnum>3</manvolnum></citerefentry>. + </para> + + <para>To destroy an event source object use + <citerefentry><refentrytitle>sd_event_source_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + but note that the event source is only removed from the event loop + when all references to the event source are dropped. To make sure + an event source does not fire anymore, even when there's still a + reference to it kept, consider setting the event source to + <constant>SD_EVENT_OFF</constant> with + <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para> + + <para>If the second parameter of these functions is passed as <constant>NULL</constant> no reference to + the event source object is returned. In this case the event source is considered "floating", and will be + destroyed implicitly when the event loop itself is destroyed.</para> + + <para>If the <parameter>handler</parameter> parameter to <function>sd_event_add_defer()</function> or + <function>sd_event_add_post()</function> is <constant>NULL</constant>, and the event source fires, this + will be considered a request to exit the event loop. In this case, the <parameter>userdata</parameter> + parameter, cast to an integer, is passed as the exit code parameter to + <citerefentry><refentrytitle>sd_event_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>. Similar + functionality is not available for <function>sd_event_add_exit()</function>, as these types of event + sources are only dispatched when exiting anyway.</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> + + <refsect2> + <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, library or module instance.</para></listitem> + </varlistentry> + + </variablelist> + </refsect2> + </refsect1> + + <xi:include href="libsystemd-pkgconfig.xml" /> + + <refsect1> + <title>History</title> + <para><function>sd_event_add_defer()</function>, + <function>sd_event_add_post()</function>, + <function>sd_event_add_exit()</function>, and + <function>sd_event_handler_t()</function> were added in version 217.</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_now</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_child</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_event_add_inotify</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_event_source_set_priority</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_event_source_set_userdata</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_event_source_set_description</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_event_source_set_floating</refentrytitle><manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sd_event_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry> + </para> + </refsect1> + +</refentry> |