man: document new ratelimiting APIs
This commit is contained in:
Lennart Poettering
parent
d586f642fd
commit
a303686fc1
|
|
@ -582,6 +582,10 @@ manpages = [
|
|||
'SD_EVENT_PRIORITY_NORMAL',
|
||||
'sd_event_source_get_priority'],
|
||||
''],
|
||||
['sd_event_source_set_ratelimit',
|
||||
'3',
|
||||
['sd_event_source_get_ratelimit', 'sd_event_source_is_ratelimited'],
|
||||
''],
|
||||
['sd_event_source_set_userdata', '3', ['sd_event_source_get_userdata'], ''],
|
||||
['sd_event_source_unref',
|
||||
'3',
|
||||
|
|
|
|||
|
|
@ -56,6 +56,7 @@
|
|||
<citerefentry><refentrytitle>sd_event_source_get_pending</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||||
<citerefentry><refentrytitle>sd_event_source_set_description</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||||
<citerefentry><refentrytitle>sd_event_source_set_prepare</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||||
<citerefentry><refentrytitle>sd_event_source_set_ratelimit</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||||
<citerefentry><refentrytitle>sd_event_wait</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||||
<citerefentry><refentrytitle>sd_event_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||||
<citerefentry><refentrytitle>sd_event_set_watchdog</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||||
|
|
@ -147,6 +148,7 @@
|
|||
<citerefentry><refentrytitle>sd_event_source_get_pending</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||||
<citerefentry><refentrytitle>sd_event_source_set_description</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||||
<citerefentry><refentrytitle>sd_event_source_set_prepare</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||||
<citerefentry><refentrytitle>sd_event_source_set_ratelimit</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||||
<citerefentry><refentrytitle>sd_event_wait</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||||
<citerefentry><refentrytitle>sd_event_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||||
<citerefentry><refentrytitle>sd_event_set_watchdog</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||||
|
|
|
|||
|
|
@ -147,7 +147,8 @@
|
|||
<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>,
|
||||
<citerefentry><refentrytitle>sd_event_source_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
||||
<citerefentry><refentrytitle>sd_event_source_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||||
<citerefentry><refentrytitle>sd_event_source_set_ratelimit</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
||||
</para>
|
||||
</refsect1>
|
||||
|
||||
|
|
|
|||
|
|
@ -0,0 +1,148 @@
|
|||
<?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_source_set_ratelimit" xmlns:xi="http://www.w3.org/2001/XInclude">
|
||||
|
||||
<refentryinfo>
|
||||
<title>sd_event_source_set_ratelimit</title>
|
||||
<productname>systemd</productname>
|
||||
</refentryinfo>
|
||||
|
||||
<refmeta>
|
||||
<refentrytitle>sd_event_source_set_ratelimit</refentrytitle>
|
||||
<manvolnum>3</manvolnum>
|
||||
</refmeta>
|
||||
|
||||
<refnamediv>
|
||||
<refname>sd_event_source_set_ratelimit</refname>
|
||||
<refname>sd_event_source_get_ratelimit</refname>
|
||||
<refname>sd_event_source_is_ratelimited</refname>
|
||||
|
||||
<refpurpose>Configure rate limiting on event sources</refpurpose>
|
||||
</refnamediv>
|
||||
|
||||
<refsynopsisdiv>
|
||||
<funcsynopsis>
|
||||
<funcsynopsisinfo>#include <systemd/sd-event.h></funcsynopsisinfo>
|
||||
|
||||
<funcprototype>
|
||||
<funcdef>int <function>sd_event_source_set_ratelimit</function></funcdef>
|
||||
<paramdef>sd_event_source *<parameter>source</parameter></paramdef>
|
||||
<paramdef>uint64_t <parameter>interval_usec</parameter></paramdef>
|
||||
<paramdef>unsigned <parameter>burst</parameter></paramdef>
|
||||
</funcprototype>
|
||||
|
||||
<funcprototype>
|
||||
<funcdef>int <function>sd_event_source_get_ratelimit</function></funcdef>
|
||||
<paramdef>sd_event_source *<parameter>source</parameter></paramdef>
|
||||
<paramdef>uint64_t* <parameter>ret_interval_usec</parameter></paramdef>
|
||||
<paramdef>unsigned* <parameter>ret_burst</parameter></paramdef>
|
||||
</funcprototype>
|
||||
|
||||
<funcprototype>
|
||||
<funcdef>int <function>sd_event_source_is_ratelimited</function></funcdef>
|
||||
<paramdef>sd_event_source *<parameter>source</parameter></paramdef>
|
||||
</funcprototype>
|
||||
|
||||
</funcsynopsis>
|
||||
</refsynopsisdiv>
|
||||
|
||||
<refsect1>
|
||||
<title>Description</title>
|
||||
|
||||
<para><function>sd_event_source_set_ratelimit()</function> may be used to enforce rate limiting on an
|
||||
event source. When used an event source will be temporarily turned off when it fires more often then a
|
||||
specified burst number within a specified time interval. This is useful as simple mechanism to avoid
|
||||
event source starvation if high priority event sources fire very frequently.</para>
|
||||
|
||||
<para>Pass the event source to operate on as first argument, a time interval in microseconds as second
|
||||
argument and a maximum dispatch limit ("burst") as third parameter. Whenever the event source is
|
||||
dispatched more often than the specified burst within the specified interval it is placed in a mode
|
||||
similar to being disabled with
|
||||
<citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
||||
and the <constant>SD_EVENT_OFF</constant> parameter. However it is disabled only temporarily – once the
|
||||
specified interval is over regular operation resumes. It is again disabled temporarily once the specified rate
|
||||
limiting is hit the next time. If either the interval or the burst value are specified as zero, rate
|
||||
limiting is turned off. By default event sources do not have rate limiting enabled. Note that rate
|
||||
limiting and disabling via <function>sd_event_source_set_enabled()</function> are independent of each
|
||||
other, and an event source will only effect event loop wake-ups and is dispatched while it both is
|
||||
enabled and rate limiting is not in effect.</para>
|
||||
|
||||
<para><function>sd_event_source_get_ratelimit()</function> may be used to query the current rate limiting
|
||||
parameters set on the event source object <parameter>source</parameter>. The previously set interval and
|
||||
burst vales are returned in the second and third argument.</para>
|
||||
|
||||
<para><function>sd_event_source_is_ratelimited()</function> may be used to query whether the event source
|
||||
is currently affected by rate limiting, i.e. it has recently hit the rate limit and is currently
|
||||
temporarily disabled due to that.</para>
|
||||
|
||||
<para>Rate limiting is currently implemented for I/O, timer, signal, defer and inotify event
|
||||
sources.</para>
|
||||
</refsect1>
|
||||
|
||||
<refsect1>
|
||||
<title>Return Value</title>
|
||||
|
||||
<para>On success, <function>sd_event_source_set_ratelimit()</function> and
|
||||
<function>sd_event_source_get_ratelimit()</function> return a non-negative integer. On failure, they
|
||||
return a negative errno-style error code. <function>sd_event_source_is_ratelimited</function> returns
|
||||
zero if rate limiting is currently not in effect and greater than zero if it is in effect; it returns a
|
||||
negative errno-style error code on failure.</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>-ECHILD</constant></term>
|
||||
|
||||
<listitem><para>The event loop has been created in a different process.</para></listitem>
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term><constant>-EDOM</constant></term>
|
||||
|
||||
<listitem><para>It was attempted to use the rate limiting feature on an event source type that does
|
||||
not support rate limiting.</para></listitem>
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term><constant>-ENOEXEC</constant></term>
|
||||
|
||||
<listitem><para><function>sd_event_source_get_ratelimit()</function> was called on a event source
|
||||
that doesn't have rate limiting configured.</para></listitem>
|
||||
</varlistentry>
|
||||
|
||||
</variablelist>
|
||||
</refsect2>
|
||||
</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_inotify</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||||
<citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||||
<citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
||||
</para>
|
||||
</refsect1>
|
||||
|
||||
</refentry>
|
||||
Loading…
Reference in New Issue