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b1de39dec8
Logically, this is better, because we're describing a subset of possible return values. Visually this also looks quite good because groff renders refsect2 much less prominently. Also rewrap things, add <constant> in various places, fix some typos.
138 lines
5.3 KiB
XML
138 lines
5.3 KiB
XML
<?xml version='1.0'?>
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!-- SPDX-License-Identifier: LGPL-2.1+ -->
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<refentry id="sd_event_source_get_pending" xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>sd_event_source_get_pending</title>
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<productname>systemd</productname>
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</refentryinfo>
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<refmeta>
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<refentrytitle>sd_event_source_get_pending</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_event_source_get_pending</refname>
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<refpurpose>Determine pending state of event sources</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <systemd/sd-event.h></funcsynopsisinfo>
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<funcprototype>
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<funcdef>int <function>sd_event_source_get_pending</function></funcdef>
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<paramdef>sd_event_source *<parameter>source</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><function>sd_event_source_get_pending()</function> may be
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used to determine whether the event source object specified as
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<parameter>source</parameter> has seen events but has not been
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dispatched yet (and thus is marked "pending").</para>
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<para>Event source objects initially are not marked pending, when
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they are created with calls such as
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<citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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with the exception of those created with
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<citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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which are immediately marked pending, and
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<citerefentry><refentrytitle>sd_event_add_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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for which the "pending" concept is not defined. For details see
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the respective manual pages.</para>
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<para>In each event loop iteration one event source of those
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marked pending is dispatched, in the order defined by the event
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source priority, as set with
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<citerefentry><refentrytitle>sd_event_source_set_priority</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
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<para>For I/O event sources, as created with
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<citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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the call
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<citerefentry><refentrytitle>sd_event_source_get_io_revents</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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may be used to query the type of event pending in more
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detail.</para>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para>On success, <function>sd_event_source_get_pending()</function> returns an integer greater than zero
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when the event source is marked pending, and zero when the event source is not marked pending. On
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failure, it returns a negative errno-style error code.</para>
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<refsect2>
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<title>Errors</title>
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<para>Returned errors may indicate the following problems:</para>
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<variablelist>
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<varlistentry>
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<term><constant>-EINVAL</constant></term>
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<listitem><para><parameter>source</parameter> is not a valid pointer to an
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<structname>sd_event_source</structname> object.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-EDOM</constant></term>
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<listitem><para><parameter>source</parameter> refers to an event source object created with
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<citerefentry><refentrytitle>sd_event_add_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ENOMEM</constant></term>
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<listitem><para>Not enough memory.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ESTALE</constant></term>
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<listitem><para>The event loop is already terminated.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ECHILD</constant></term>
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<listitem><para>The event loop has been created in a different process.</para></listitem>
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</varlistentry>
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</variablelist>
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</refsect2>
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</refsect1>
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<xi:include href="libsystemd-pkgconfig.xml" />
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_event_add_inotify</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_event_source_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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