Adding upstream version 241.upstream/241upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 172 insertions, 0 deletions

diff --git a/man/sd_event_source_set_priority.xml b/man/sd_event_source_set_priority.xml
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+<?xml version='1.0'?>
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+
+<!--
+  SPDX-License-Identifier: LGPL-2.1+
+-->
+
+<refentry id="sd_event_source_set_priority" xmlns:xi="http://www.w3.org/2001/XInclude">
+
+  <refentryinfo>
+    <title>sd_event_source_set_priority</title>
+    <productname>systemd</productname>
+  </refentryinfo>
+
+  <refmeta>
+    <refentrytitle>sd_event_source_set_priority</refentrytitle>
+    <manvolnum>3</manvolnum>
+  </refmeta>
+
+  <refnamediv>
+    <refname>sd_event_source_set_priority</refname>
+    <refname>sd_event_source_get_priority</refname>
+    <refname>SD_EVENT_PRIORITY_IMPORTANT</refname>
+    <refname>SD_EVENT_PRIORITY_NORMAL</refname>
+    <refname>SD_EVENT_PRIORITY_IDLE</refname>
+
+    <refpurpose>Set or retrieve the priority of event sources</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <funcsynopsis>
+      <funcsynopsisinfo>#include &lt;systemd/sd-event.h&gt;</funcsynopsisinfo>
+
+      <funcsynopsisinfo><token>enum</token> {
+        <constant>SD_EVENT_PRIORITY_IMPORTANT</constant> = -100,
+        <constant>SD_EVENT_PRIORITY_NORMAL</constant> = 0,
+        <constant>SD_EVENT_PRIORITY_IDLE</constant> = 100,
+};</funcsynopsisinfo>
+
+      <funcprototype>
+        <funcdef>int <function>sd_event_source_set_priority</function></funcdef>
+        <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
+        <paramdef>int64_t <parameter>priority</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>int <function>sd_event_source_get_priority</function></funcdef>
+        <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
+        <paramdef>int64_t *<parameter>priority</parameter></paramdef>
+      </funcprototype>
+
+    </funcsynopsis>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Description</title>
+
+    <para><function>sd_event_source_set_priority()</function> may be
+    used to set the priority for the event source object specified as
+    <parameter>source</parameter>. The priority is specified as an
+    arbitrary signed 64bit integer. The priority is initialized to
+    <constant>SD_EVENT_PRIORITY_NORMAL</constant> (0) when the event
+    source is allocated with a call such as
+    <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+    or
+    <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+    and may be changed with this call. If multiple event sources have seen events at the same time, they are dispatched in the order indicated by the
+    event sources' priorities. Event sources with smaller priority
+    values are dispatched first. As well-known points of reference,
+    the constants <constant>SD_EVENT_PRIORITY_IMPORTANT</constant>
+    (-100), <constant>SD_EVENT_PRIORITY_NORMAL</constant> (0) and
+    <constant>SD_EVENT_PRIORITY_IDLE</constant> (100) may be used to
+    indicate event sources that shall be dispatched early, normally or
+    late. It is recommended to specify priorities based on these
+    definitions, and relative to them — however, the full 64bit
+    signed integer range is available for ordering event
+    sources.</para>
+
+    <para>Priorities define the order in which event sources that have
+    seen events are dispatched. Care should be taken to ensure that
+    high-priority event sources (those with negative priority values
+    assigned) do not cause starvation of low-priority event sources
+    (those with positive priority values assigned).</para>
+
+    <para>The order in which event sources with the same priority are
+    dispatched is undefined, but the event loop generally tries to
+    dispatch them in the order it learnt about events on them. As the
+    backing kernel primitives do not provide accurate information
+    about the order in which events occurred this is not necessarily
+    reliable. However, it is guaranteed that if events are seen on
+    multiple same-priority event sources at the same time, each one is
+    not dispatched again until all others have been dispatched
+    once. This behavior guarantees that within each priority
+    particular event sources do not starve or dominate the event
+    loop.</para>
+
+    <para>The priority of event sources may be changed at any time of their lifetime, with the exception of inotify
+    event sources (i.e. those created with
+    <citerefentry><refentrytitle>sd_event_add_inotify</refentrytitle><manvolnum>3</manvolnum></citerefentry>) whose
+    priority may only be changed in the time between their initial creation and the first subsequent event loop
+    iteration.</para>
+
+    <para><function>sd_event_source_get_priority()</function> may be
+    used to query the current priority assigned to the event source
+    object <parameter>source</parameter>.</para>
+  </refsect1>
+
+  <refsect1>
+    <title>Return Value</title>
+
+    <para>On success,
+    <function>sd_event_source_set_priority()</function> and
+    <function>sd_event_source_get_priority()</function> return a
+    non-negative integer. On failure, they return a negative
+    errno-style error code.</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>source</parameter> is not a valid
+        pointer to an <structname>sd_event_source</structname>
+        object.</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.</para></listitem>
+
+      </varlistentry>
+
+    </variablelist>
+  </refsect1>
+
+  <xi:include href="libsystemd-pkgconfig.xml" />
+
+  <refsect1>
+    <title>See Also</title>
+
+    <para>
+      <citerefentry><refentrytitle>sd-event</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_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+    </para>
+  </refsect1>
+
+</refentry>