mirror of
https://github.com/apache/httpd.git
synced 2025-04-18 22:24:07 +03:00
01055edef2
git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1907148 13f79535-47bb-0310-9956-ffa450edef68
238 lines
16 KiB
XML
238 lines
16 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
|
||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
|
||
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head>
|
||
<meta content="text/html; charset=UTF-8" http-equiv="Content-Type" />
|
||
<!--
|
||
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
|
||
This file is generated from xml source: DO NOT EDIT
|
||
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
|
||
-->
|
||
<title>mod_file_cache - Apache HTTP Server Version 2.5</title>
|
||
<link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" />
|
||
<link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" />
|
||
<link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /><link rel="stylesheet" type="text/css" href="../style/css/prettify.css" />
|
||
<script src="../style/scripts/prettify.min.js" type="text/javascript">
|
||
</script>
|
||
|
||
<link href="../images/favicon.ico" rel="shortcut icon" /></head>
|
||
<body>
|
||
<div id="page-header">
|
||
<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/quickreference.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p>
|
||
<p class="apache">Apache HTTP Server Version 2.5</p>
|
||
<img alt="" src="../images/feather.png" /></div>
|
||
<div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div>
|
||
<div id="path">
|
||
<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="../">Version 2.5</a> > <a href="./">Modules</a></div>
|
||
<div id="page-content">
|
||
<div id="preamble"><h1>Apache Module mod_file_cache</h1>
|
||
<div class="toplang">
|
||
<p><span>Available Languages: </span><a href="../en/mod/mod_file_cache.html" title="English"> en </a> |
|
||
<a href="../fr/mod/mod_file_cache.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
|
||
<a href="../ko/mod/mod_file_cache.html" hreflang="ko" rel="alternate" title="Korean"> ko </a></p>
|
||
</div>
|
||
<table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Caches a static list of files in memory</td></tr>
|
||
<tr><th><a href="module-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
|
||
<tr><th><a href="module-dict.html#ModuleIdentifier">Module Identifier:</a></th><td>file_cache_module</td></tr>
|
||
<tr><th><a href="module-dict.html#SourceFile">Source File:</a></th><td>mod_file_cache.c</td></tr></table>
|
||
<h3>Summary</h3>
|
||
|
||
|
||
<div class="warning">
|
||
This module should be used with care. You can easily create a broken
|
||
site using <code class="module"><a href="../mod/mod_file_cache.html">mod_file_cache</a></code>, so read this document
|
||
carefully.
|
||
</div>
|
||
|
||
<p><em>Caching</em> frequently requested files that change very
|
||
infrequently is a technique for reducing server load.
|
||
<code class="module"><a href="../mod/mod_file_cache.html">mod_file_cache</a></code> provides two techniques for caching
|
||
frequently requested <em>static</em> files. Through configuration
|
||
directives, you can direct <code class="module"><a href="../mod/mod_file_cache.html">mod_file_cache</a></code> to either
|
||
open then <code>mmap()</code> a file, or to pre-open a file and save
|
||
the file's open <em>file handle</em>. Both techniques reduce server
|
||
load when processing requests for these files by doing part of the work
|
||
(specifically, the file I/O) for serving the file when the
|
||
server is started rather than during each request.</p>
|
||
|
||
<p>Notice: You cannot use this for speeding up CGI programs or
|
||
other files which are served by special content handlers. It
|
||
can only be used for regular files which are usually served by
|
||
the Apache core content handler.</p>
|
||
|
||
<p>This module is an extension of and borrows heavily from the
|
||
<code>mod_mmap_static</code> module in Apache 1.3.</p>
|
||
</div>
|
||
<div id="quickview"><h3>Topics</h3>
|
||
<ul id="topics">
|
||
<li><img alt="" src="../images/down.gif" /> <a href="#using">Using mod_file_cache</a></li>
|
||
</ul><h3 class="directives">Directives</h3>
|
||
<ul id="toc">
|
||
<li><img alt="" src="../images/down.gif" /> <a href="#cachefile">CacheFile</a></li>
|
||
<li><img alt="" src="../images/down.gif" /> <a href="#mmapfile">MMapFile</a></li>
|
||
</ul>
|
||
<h3>Bugfix checklist</h3><ul class="seealso"><li><a href="https://www.apache.org/dist/httpd/CHANGES_2.4">httpd changelog</a></li><li><a href="https://bz.apache.org/bugzilla/buglist.cgi?bug_status=__open__&list_id=144532&product=Apache%20httpd-2&query_format=specific&order=changeddate%20DESC%2Cpriority%2Cbug_severity&component=mod_file_cache">Known issues</a></li><li><a href="https://bz.apache.org/bugzilla/enter_bug.cgi?product=Apache%20httpd-2&component=mod_file_cache">Report a bug</a></li></ul><h3>See also</h3>
|
||
<ul class="seealso">
|
||
<li><a href="#comments_section">Comments</a></li></ul></div>
|
||
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
|
||
<div class="section">
|
||
<h2><a name="using" id="using">Using mod_file_cache</a> <a title="Permanent link" href="#using" class="permalink">¶</a></h2>
|
||
|
||
<p><code class="module"><a href="../mod/mod_file_cache.html">mod_file_cache</a></code> caches a list of statically
|
||
configured files via <code class="directive"><a href="#mmapfile">MMapFile</a></code> or <code class="directive"><a href="#cachefile">CacheFile</a></code> directives in the main server configuration.</p>
|
||
|
||
<p>Not all platforms support both directives. You will receive an error
|
||
message in the server error log if you attempt to use an
|
||
unsupported directive. If given an unsupported directive, the
|
||
server will start but the file will not be cached. On platforms
|
||
that support both directives, you should experiment with both to
|
||
see which works best for you.</p>
|
||
|
||
<h3>MMapFile Directive</h3>
|
||
|
||
<p>The <code class="directive"><a href="#mmapfile">MMapFile</a></code>
|
||
directive of <code class="module"><a href="../mod/mod_file_cache.html">mod_file_cache</a></code> maps a list of
|
||
statically configured files into memory through the system call
|
||
<code>mmap()</code>. This system call is available on most modern
|
||
Unix derivatives, but not on all. There are sometimes system-specific
|
||
limits on the size and number of files that can be
|
||
<code>mmap()</code>ed, experimentation is probably the easiest way
|
||
to find out.</p>
|
||
|
||
<p>This <code>mmap()</code>ing is done once at server start or
|
||
restart, only. So whenever one of the mapped files changes on the
|
||
filesystem you <em>have</em> to restart the server (see the <a href="../stopping.html">Stopping and Restarting</a> documentation).
|
||
To reiterate that point: if the files are modified <em>in place</em>
|
||
without restarting the server you may end up serving requests that
|
||
are completely bogus. You should update files by unlinking the old
|
||
copy and putting a new copy in place. Most tools such as
|
||
<code>rdist</code> and <code>mv</code> do this. The reason why this
|
||
modules doesn't take care of changes to the files is that this check
|
||
would need an extra <code>stat()</code> every time which is a waste
|
||
and against the intent of I/O reduction.</p>
|
||
|
||
|
||
<h3>CacheFile Directive</h3>
|
||
|
||
<p>The <code class="directive"><a href="#cachefile">CacheFile</a></code>
|
||
directive of <code class="module"><a href="../mod/mod_file_cache.html">mod_file_cache</a></code> opens an active
|
||
<em>handle</em> or <em>file descriptor</em> to the file (or files)
|
||
listed in the configuration directive and places these open file
|
||
handles in the cache. When the file is requested, the server
|
||
retrieves the handle from the cache and passes it to the
|
||
<code>sendfile()</code> (or <code>TransmitFile()</code> on Windows),
|
||
socket API.</p>
|
||
|
||
|
||
|
||
<p>This file handle caching is done once at server start or
|
||
restart, only. So whenever one of the cached files changes on
|
||
the filesystem you <em>have</em> to restart the server (see the
|
||
<a href="../stopping.html">Stopping and Restarting</a>
|
||
documentation). To reiterate that point: if the files are
|
||
modified <em>in place</em> without restarting the server you
|
||
may end up serving requests that are completely bogus. You
|
||
should update files by unlinking the old copy and putting a new
|
||
copy in place. Most tools such as <code>rdist</code> and
|
||
<code>mv</code> do this.</p>
|
||
|
||
|
||
<div class="note"><h3>Note</h3>
|
||
<p>Don't bother asking for a directive which recursively
|
||
caches all the files in a directory. Try this instead... See the
|
||
<code class="directive"><a href="../mod/core.html#include">Include</a></code> directive, and consider
|
||
this command:</p>
|
||
|
||
<div class="example"><p><code>
|
||
find /www/htdocs -type f -print \<br />
|
||
| sed -e 's/.*/mmapfile &/' > /www/conf/mmap.conf
|
||
</code></p></div>
|
||
</div>
|
||
</div>
|
||
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
|
||
<div class="directive-section"><h2><a name="CacheFile" id="CacheFile">CacheFile</a> <a name="cachefile" id="cachefile">Directive</a> <a title="Permanent link" href="#cachefile" class="permalink">¶</a></h2>
|
||
<table class="directive">
|
||
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Cache a list of file handles at startup time</td></tr>
|
||
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CacheFile <var>file-path</var> [<var>file-path</var>] ...</code></td></tr>
|
||
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
|
||
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
|
||
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_file_cache</td></tr>
|
||
</table>
|
||
<p>The <code class="directive">CacheFile</code> directive opens handles to
|
||
one or more files (given as whitespace separated arguments) and
|
||
places these handles into the cache at server startup
|
||
time. Handles to cached files are automatically closed on a server
|
||
shutdown. When the files have changed on the filesystem, the
|
||
server should be restarted to re-cache them.</p>
|
||
|
||
<p>Be careful with the <var>file-path</var> arguments: They have
|
||
to literally match the filesystem path Apache's URL-to-filename
|
||
translation handlers create. We cannot compare inodes or other
|
||
stuff to match paths through symbolic links <em>etc.</em>
|
||
because that again would cost extra <code>stat()</code> system
|
||
calls which is not acceptable. This module may or may not work
|
||
with filenames rewritten by <code class="module"><a href="../mod/mod_alias.html">mod_alias</a></code> or
|
||
<code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>.</p>
|
||
|
||
<div class="example"><h3>Example</h3><pre class="prettyprint lang-config">CacheFile /usr/local/apache/htdocs/index.html</pre>
|
||
</div>
|
||
|
||
</div>
|
||
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
|
||
<div class="directive-section"><h2><a name="MMapFile" id="MMapFile">MMapFile</a> <a name="mmapfile" id="mmapfile">Directive</a> <a title="Permanent link" href="#mmapfile" class="permalink">¶</a></h2>
|
||
<table class="directive">
|
||
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Map a list of files into memory at startup time</td></tr>
|
||
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MMapFile <var>file-path</var> [<var>file-path</var>] ...</code></td></tr>
|
||
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
|
||
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
|
||
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_file_cache</td></tr>
|
||
</table>
|
||
<p>The <code class="directive">MMapFile</code> directive maps one or more files
|
||
(given as whitespace separated arguments) into memory at server
|
||
startup time. They are automatically unmapped on a server
|
||
shutdown. When the files have changed on the filesystem at
|
||
least a <code>HUP</code> or <code>USR1</code> signal should be send to
|
||
the server to re-<code>mmap()</code> them.</p>
|
||
|
||
<p>Be careful with the <var>file-path</var> arguments: They have
|
||
to literally match the filesystem path Apache's URL-to-filename
|
||
translation handlers create. We cannot compare inodes or other
|
||
stuff to match paths through symbolic links <em>etc.</em>
|
||
because that again would cost extra <code>stat()</code> system
|
||
calls which is not acceptable. This module may or may not work
|
||
with filenames rewritten by <code class="module"><a href="../mod/mod_alias.html">mod_alias</a></code> or
|
||
<code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>.</p>
|
||
|
||
<div class="example"><h3>Example</h3><pre class="prettyprint lang-config">MMapFile /usr/local/apache/htdocs/index.html</pre>
|
||
</div>
|
||
|
||
</div>
|
||
</div>
|
||
<div class="bottomlang">
|
||
<p><span>Available Languages: </span><a href="../en/mod/mod_file_cache.html" title="English"> en </a> |
|
||
<a href="../fr/mod/mod_file_cache.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
|
||
<a href="../ko/mod/mod_file_cache.html" hreflang="ko" rel="alternate" title="Korean"> ko </a></p>
|
||
</div><div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div><div class="section"><h2><a id="comments_section" name="comments_section">Comments</a></h2><div class="warning"><strong>Notice:</strong><br />This is not a Q&A section. Comments placed here should be pointed towards suggestions on improving the documentation or server, and may be removed by our moderators if they are either implemented or considered invalid/off-topic. Questions on how to manage the Apache HTTP Server should be directed at either our IRC channel, #httpd, on Libera.chat, or sent to our <a href="https://httpd.apache.org/lists.html">mailing lists</a>.</div>
|
||
<script type="text/javascript"><!--//--><![CDATA[//><!--
|
||
var comments_shortname = 'httpd';
|
||
var comments_identifier = 'http://httpd.apache.org/docs/trunk/mod/mod_file_cache.html';
|
||
(function(w, d) {
|
||
if (w.location.hostname.toLowerCase() == "httpd.apache.org") {
|
||
d.write('<div id="comments_thread"><\/div>');
|
||
var s = d.createElement('script');
|
||
s.type = 'text/javascript';
|
||
s.async = true;
|
||
s.src = 'https://comments.apache.org/show_comments.lua?site=' + comments_shortname + '&page=' + comments_identifier;
|
||
(d.getElementsByTagName('head')[0] || d.getElementsByTagName('body')[0]).appendChild(s);
|
||
}
|
||
else {
|
||
d.write('<div id="comments_thread">Comments are disabled for this page at the moment.<\/div>');
|
||
}
|
||
})(window, document);
|
||
//--><!]]></script></div><div id="footer">
|
||
<p class="apache">Copyright 2023 The Apache Software Foundation.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p>
|
||
<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/quickreference.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p></div><script type="text/javascript"><!--//--><![CDATA[//><!--
|
||
if (typeof(prettyPrint) !== 'undefined') {
|
||
prettyPrint();
|
||
}
|
||
//--><!]]></script>
|
||
</body></html> |