<?xml version='1.0'?> <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd"> <!-- SPDX-License-Identifier: LGPL-2.1-or-later --> <refentry id="sd_event_source_get_pending" xmlns:xi="http://www.w3.org/2001/XInclude"> <refentryinfo> <title>sd_event_source_get_pending</title> <productname>systemd</productname> </refentryinfo> <refmeta> <refentrytitle>sd_event_source_get_pending</refentrytitle> <manvolnum>3</manvolnum> </refmeta> <refnamediv> <refname>sd_event_source_get_pending</refname> <refpurpose>Determine pending state of event sources</refpurpose> </refnamediv> <refsynopsisdiv> <funcsynopsis> <funcsynopsisinfo>#include <systemd/sd-event.h></funcsynopsisinfo> <funcprototype> <funcdef>int <function>sd_event_source_get_pending</function></funcdef> <paramdef>sd_event_source *<parameter>source</parameter></paramdef> </funcprototype> </funcsynopsis> </refsynopsisdiv> <refsect1> <title>Description</title> <para><function>sd_event_source_get_pending()</function> may be used to determine whether the event source object specified as <parameter>source</parameter> has seen events but has not been dispatched yet (and thus is marked "pending").</para> <para>Event source objects initially are not marked pending, when they are created with calls such as <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>, <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>, with the exception of those created with <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry> which are immediately marked pending, and <citerefentry><refentrytitle>sd_event_add_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry> for which the "pending" concept is not defined. For details see the respective manual pages.</para> <para>In each event loop iteration one event source of those marked pending is dispatched, in the order defined by the event source priority, as set with <citerefentry><refentrytitle>sd_event_source_set_priority</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para> <para>For I/O event sources, as created with <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>, the call <citerefentry><refentrytitle>sd_event_source_get_io_revents</refentrytitle><manvolnum>3</manvolnum></citerefentry> may be used to query the type of event pending in more detail.</para> </refsect1> <refsect1> <title>Return Value</title> <para>On success, <function>sd_event_source_get_pending()</function> returns an integer greater than zero when the event source is marked pending, and zero when the event source is not marked pending. On failure, it returns a negative errno-style error code.</para> <refsect2> <title>Errors</title> <para>Returned errors may indicate the following problems:</para> <variablelist> <varlistentry> <term><constant>-EINVAL</constant></term> <listitem><para><parameter>source</parameter> is not a valid pointer to an <structname>sd_event_source</structname> object.</para></listitem> </varlistentry> <varlistentry> <term><constant>-EDOM</constant></term> <listitem><para><parameter>source</parameter> refers to an event source object created with <citerefentry><refentrytitle>sd_event_add_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem> </varlistentry> <varlistentry> <term><constant>-ENOMEM</constant></term> <listitem><para>Not enough memory.</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_source_get_pending()</function> was added in version 229.</para> </refsect1> <refsect1> <title>See Also</title> <para><simplelist type="inline"> <member><citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> <member><citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> <member><citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> <member><citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> <member><citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> <member><citerefentry><refentrytitle>sd_event_add_inotify</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> <member><citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> <member><citerefentry><refentrytitle>sd_event_source_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry></member> </simplelist></para> </refsect1> </refentry>