php-doc-en/reference/ev/evstat.xml

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<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<phpdoc:classref xml:id="class.evstat" xmlns:phpdoc="http://php.net/ns/phpdoc" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xi="http://www.w3.org/2001/XInclude">
<title>The EvStat class</title>
<titleabbrev>EvStat</titleabbrev>
<partintro>
<!-- {{{ EvStat intro -->
<section xml:id="evstat.intro">
&reftitle.intro;
<para>
<classname>EvStat</classname>
monitors a file system path for attribute changes. It calls
<emphasis>stat()</emphasis>
on that path in regular intervals(or when the OS signals it changed) and
sees if it changed compared to the last time, invoking the callback if it
did.
</para>
<para>
The path does not need to exist: changing from "path exists" to "path does
not exist" is a status change like any other. The condition "path does not
exist" is signified by the
<constant>'nlink'</constant>
item being 0(returned by
<methodname>EvStat::attr</methodname>
method).
</para>
<para>
The path must not end in a slash or contain special components such as
<constant>'.'</constant>
or
<constant>..</constant>
. The path should be absolute: if it is relative and the working directory
changes, then the behaviour is undefined.
</para>
<para>
Since there is no portable change notification interface available, the
portable implementation simply calls
<emphasis>stat()</emphasis>
regularly on the path to see if it changed somehow. For this case a
recommended polling interval can be specified. If one specifies a polling
interval of
<constant>0.0 </constant>
(highly recommended) then a suitable, unspecified default value will be
used(which could be expected to be around 5 seconds, although this might
change dynamically).
<emphasis>libev</emphasis>
will also impose a minimum interval which is currently around
<constant>0.1</constant>
, but thats usually overkill.
</para>
<para>
This watcher type is not meant for massive numbers of
<classname>EvStat</classname>
watchers, as even with OS-supported change notifications, this can be
resource-intensive.
</para>
</section>
<!-- }}} -->
<section xml:id="evstat.synopsis">
&reftitle.classsynopsis;
<!-- {{{ Synopsis -->
<classsynopsis>
<ooclass>
<classname>EvStat</classname>
</ooclass>
<!-- {{{ Class synopsis -->
<classsynopsisinfo>
<ooclass>
<classname>EvStat</classname>
</ooclass>
<ooclass>
<modifier>extends</modifier>
<classname>EvWatcher</classname>
</ooclass>
</classsynopsisinfo>
<!-- }}} -->
<classsynopsisinfo role="comment">&Properties;</classsynopsisinfo>
<fieldsynopsis>
<modifier>public</modifier>
<varname linkend="evstat.props.path">path</varname>
</fieldsynopsis>
<fieldsynopsis>
<modifier>public</modifier>
<varname linkend="evstat.props.interval">interval</varname>
</fieldsynopsis>
<classsynopsisinfo role="comment">&InheritedProperties;</classsynopsisinfo>
<xi:include xpointer="xmlns(db=http://docbook.org/ns/docbook) xpointer(id('evwatcher.synopsis')/descendant::db:fieldsynopsis)" />
<classsynopsisinfo role="comment">&Methods;</classsynopsisinfo>
<xi:include xpointer="xmlns(db=http://docbook.org/ns/docbook) xpointer(id('class.evstat')/db:refentry/db:refsect1[@role='description']/descendant::db:methodsynopsis[1])" />
<classsynopsisinfo role="comment">&InheritedMethods;</classsynopsisinfo>
<xi:include xpointer="xmlns(db=http://docbook.org/ns/docbook) xpointer(id('class.evwatcher')/db:refentry/db:refsect1[@role='description']/descendant::db:methodsynopsis[1])" />
</classsynopsis>
<!-- }}} -->
</section>
<!-- {{{ EvStat properties -->
<section xml:id="evstat.props">
&reftitle.properties;
<variablelist>
<varlistentry xml:id="evstat.props.interval">
<term>
<varname>interval</varname>
</term>
<listitem>
<para>
<emphasis>Readonly</emphasis>
. Hint on how quickly a change is expected to be detected and should
normally be specified as
<constant>0.0</constant>
to let
<emphasis>libev</emphasis>
choose a suitable value.
</para>
</listitem>
</varlistentry>
<varlistentry xml:id="evstat.props.path">
<term>
<varname>path</varname>
</term>
<listitem>
<para>
<emphasis>Readonly</emphasis>
. The path to wait for status changes on.
</para>
</listitem>
</varlistentry>
</variablelist>
</section>
<!-- }}} -->
</partintro>
&reference.ev.entities.evstat;
</phpdoc:classref>
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