mirror of
https://github.com/sigmasternchen/php-doc-en
synced 2025-03-27 06:18:56 +00:00
742f5f2c5b
Patch provided by Joshua Facemyer. git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@342892 c90b9560-bf6c-de11-be94-00142212c4b1
132 lines
3.6 KiB
XML
132 lines
3.6 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<!-- $Revision$ -->
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<refentry xmlns="http://docbook.org/ns/docbook" xml:id="function.session-gc">
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<refnamediv>
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<refname>session_gc</refname>
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<refpurpose>Perform session data garbage collection</refpurpose>
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</refnamediv>
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<refsect1 role="description">
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&reftitle.description;
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<methodsynopsis>
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<type>int</type><methodname>session_gc</methodname>
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<void />
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</methodsynopsis>
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<para>
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<function>session_gc</function> is used to perform session data
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GC(garbage collection). PHP does probability based session GC by
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default.
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</para>
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<para>
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Probability based GC works somewhat but it has few problems. 1) Low
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traffic sites' session data may not be deleted within the preferred
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duration. 2) High traffic sites' GC may be too frequent GC. 3) GC is
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performed on the user's request and the user will experience a GC
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delay.
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</para>
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<para>
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Therefore, it is recommended to execute GC periodically for
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production systems using, e.g., "cron" for UNIX-like systems.
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Make sure to disable probability based GC by setting
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<link linkend="ini.session.gc-probability">session.gc_probability</link>
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to 0.
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</para>
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</refsect1>
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<refsect1 role="returnvalues">
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&reftitle.returnvalues;
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<para>
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<function>session_gc</function> returns number of deleted session
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data for success, &false; for failure.
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</para>
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<para>
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Old save handlers do not return number of deleted session data, but
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only success/failure flag. If this is the case, number of deleted
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session data became 1 regardless of actually deleted data.
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</para>
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</refsect1>
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<refsect1 role="examples">
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&reftitle.examples;
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<para>
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<example>
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<title><function>session_gc</function> example for task managers like cron</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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// Note: This script should be executed by the same user of web server process.
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// Need active session to initialize session data storage access.
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session_start();
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// Executes GC immediately
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session_gc();
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// Clean up session ID created by session_gc()
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session_destroy();
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?>
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]]>
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</programlisting>
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</example>
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<example>
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<title><function>session_gc</function> example for user accessible script</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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// Note: session_gc() is recommended to be used by task manager script, but
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// it may be used as follows.
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// Used for last GC time check
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$gc_time = '/tmp/php_session_last_gc';
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$gc_period = 1800;
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session_start();
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// Execute GC only when GC period elapsed.
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// i.e. Calling session_gc() every request is waste of resources.
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if (file_exists($gc_time)) {
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if (filemtime($gc_time) < time() - $gc_period) {
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session_gc();
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touch($gc_time);
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}
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} else {
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touch($gc_time);
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}
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?>
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]]>
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</programlisting>
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</example>
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</para>
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</refsect1>
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<refsect1 role="seealso">
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&reftitle.seealso;
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<para>
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<simplelist>
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<member><function>session_start</function></member>
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<member><function>session_destroy</function></member>
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<member><link linkend="ini.session.gc-probability">session.gc_probability</link></member>
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</simplelist>
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</para>
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</refsect1>
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</refentry>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-omittag:t
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sgml-shorttag:t
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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indent-tabs-mode:nil
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sgml-parent-document:nil
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sgml-default-dtd-file:"~/.phpdoc/manual.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:nil
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sgml-local-ecat-files:nil
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End:
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vim600: syn=xml fen fdm=syntax fdl=2 si
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vim: et tw=78 syn=sgml
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vi: ts=1 sw=1
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-->
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