| <?xml version="1.0" encoding="ISO-8859-1"?> |
| <!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=ISO-8859-1" http-equiv="Content-Type" /> |
| <meta content="noindex, nofollow" name="robots" /> |
| <!-- |
| XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX |
| This file is generated from xml source: DO NOT EDIT |
| XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX |
| --> |
| <title>mod_file_cache - Apache HTTP Server</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 href="../images/favicon.ico" rel="shortcut icon" /><link href="http://httpd.apache.org/docs/current/mod/mod_file_cache.html" rel="canonical" /></head> |
| <body> |
| <div id="page-header"> |
| <p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p> |
| <p class="apache">Apache HTTP Server Version 2.0</p> |
| <img alt="" src="../images/feather.gif" /></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 2.0</a> > <a href="./">Modules</a></div> |
| <div id="page-content"> |
| <div class="retired"><h4>Please note</h4> |
| <p>This document refers to the <strong>2.0</strong> version of Apache httpd, which <strong>is no longer maintained</strong>. Upgrade, and refer to the current version of httpd instead, documented at:</p> |
| <ul><li><a href="http://httpd.apache.org/docs/current/">Current release version of Apache HTTP Server documentation</a></li></ul><p>You may follow <a href="http://httpd.apache.org/docs/current/mod/mod_file_cache.html">this link</a> to go to the current version of this document.</p></div><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="../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 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>Topics</h3> |
| <ul id="topics"> |
| <li><img alt="" src="../images/down.gif" /> <a href="#using">Using mod_file_cache</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></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. For example, Apache |
| on Windows does not currently support the <code class="directive"><a href="#mmapstatic">MMapStatic</a></code> directive, while |
| other platforms, like AIX, support both. 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 derivates, 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></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 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><p><code> |
| CacheFile /usr/local/apache/htdocs/index.html |
| </code></p></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></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><p><code> |
| MMapFile /usr/local/apache/htdocs/index.html |
| </code></p></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="../ko/mod/mod_file_cache.html" hreflang="ko" rel="alternate" title="Korean"> ko </a></p> |
| </div><div id="footer"> |
| <p class="apache">Copyright 2013 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/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p></div> |
| </body></html> |