granicus.if.org Git - apache/blob - docs/manual/mod/mod_mem_cache.html.en

   1 <?xml version="1.0" encoding="ISO-8859-1"?>
   2 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
   3 <html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head><!--
   4         XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
   5               This file is generated from xml source: DO NOT EDIT
   6         XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
   7       -->
   8 <title>mod_mem_cache - Apache HTTP Server</title>
   9 <link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" />
  10 <link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" />
  11 <link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" />
  12 <link href="../images/favicon.ico" rel="shortcut icon" /></head>
  13 <body>
  14 <div id="page-header">
  15 <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>
  16 <p class="apache">Apache HTTP Server Version 2.1</p>
  17 <img alt="" src="../images/feather.gif" /></div>
  18 <div class="up"><a href="./"><img title="&lt;-" alt="&lt;-" src="../images/left.gif" /></a></div>
  19 <div id="path">
  20 <a href="http://www.apache.org/">Apache</a> &gt; <a href="http://httpd.apache.org/">HTTP Server</a> &gt; <a href="http://httpd.apache.org/docs-project/">Documentation</a> &gt; <a href="../">Version 2.1</a> &gt; <a href="./">Modules</a></div>
  21 <div id="page-content">
  22 <div id="preamble"><h1>Apache Module mod_mem_cache</h1>
  23 <div class="toplang">
  24 <p><span>Available Languages: </span><a href="../en/mod/mod_mem_cache.html" title="English">&nbsp;en&nbsp;</a></p>
  25 </div>
  26 <table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Content cache keyed to URIs</td></tr>
  27 <tr><th><a href="module-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
  28 <tr><th><a href="module-dict.html#ModuleIdentifier">Module Identifier:</a></th><td>mem_cache_module</td></tr>
  29 <tr><th><a href="module-dict.html#SourceFile">Source File:</a></th><td>mod_mem_cache.c</td></tr></table>
  30 <h3>Summary</h3>
  31
  32     <div class="warning">
  33       This module is experimental. Documentation is still under
  34       development...
  35     </div>
  36
  37     <p>This module <em>requires</em> the service of <code class="module"><a href="../mod/mod_cache.html">mod_cache</a></code>. It acts as a support module for <code class="module"><a href="../mod/mod_cache.html">mod_cache</a></code> and provides a memory based storage manager.
  38     <code class="module"><a href="../mod/mod_mem_cache.html">mod_mem_cache</a></code> can be configured to operate in two
  39     modes: caching open file descriptors or caching objects in heap storage.
  40     <code class="module"><a href="../mod/mod_mem_cache.html">mod_mem_cache</a></code> is most useful when used to cache locally
  41     generated content or to cache backend server content for <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> configured for <code class="directive"><a href="../mod/mod_proxy.html#proxypass">ProxyPass</a></code> (aka <dfn>reverse proxy</dfn>).</p>
  42
  43     <p>Content is stored in and retrieved from the cache using URI based
  44     keys. Content with access protection is not cached.</p>
  45 </div>
  46 <div id="quickview"><h3 class="directives">Directives</h3>
  47 <ul id="toc">
  48 <li><img alt="" src="../images/down.gif" /> <a href="#mcachemaxobjectcount">MCacheMaxObjectCount</a></li>
  49 <li><img alt="" src="../images/down.gif" /> <a href="#mcachemaxobjectsize">MCacheMaxObjectSize</a></li>
  50 <li><img alt="" src="../images/down.gif" /> <a href="#mcachemaxstreamingbuffer">MCacheMaxStreamingBuffer</a></li>
  51 <li><img alt="" src="../images/down.gif" /> <a href="#mcacheminobjectsize">MCacheMinObjectSize</a></li>
  52 <li><img alt="" src="../images/down.gif" /> <a href="#mcacheremovalalgorithm">MCacheRemovalAlgorithm</a></li>
  53 <li><img alt="" src="../images/down.gif" /> <a href="#mcachesize">MCacheSize</a></li>
  54 </ul>
  55 <h3>See also</h3>
  56 <ul class="seealso">
  57 <li><code class="module"><a href="../mod/mod_cache.html">mod_cache</a></code></li>
  58 <li><code class="module"><a href="../mod/mod_disk_cache.html">mod_disk_cache</a></code></li>
  59 </ul></div>
  60
  61 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
  62 <div class="directive-section"><h2><a name="MCacheMaxObjectCount" id="MCacheMaxObjectCount">MCacheMaxObjectCount</a> <a name="mcachemaxobjectcount" id="mcachemaxobjectcount">Directive</a></h2>
  63 <table class="directive">
  64 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>The maximum number of objects allowed to be placed in the
  65 cache</td></tr>
  66 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MCacheMaxObjectCount <var>value</var></code></td></tr>
  67 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MCacheMaxObjectCount 1009</code></td></tr>
  68 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
  69 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
  70 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_mem_cache</td></tr>
  71 </table>
  72     <p>The <code class="directive">MCacheMaxObjectCount</code> directive sets the
  73     maximum number of objects to be cached. The value is used to create the
  74     open hash table. If a new object needs to be inserted in the cache and
  75     the maximum number of objects has been reached, an object will be
  76     removed to allow the new object to be cached. The object to be removed
  77     is selected using the algorithm specified by <code class="directive"><a href="#mcacheremovalalgorithm">MCacheRemovalAlgorithm</a></code>.</p>
  78
  79     <div class="example"><h3>Example</h3><p><code>
  80       MCacheMaxObjectCount 13001
  81     </code></p></div>
  82
  83 </div>
  84 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
  85 <div class="directive-section"><h2><a name="MCacheMaxObjectSize" id="MCacheMaxObjectSize">MCacheMaxObjectSize</a> <a name="mcachemaxobjectsize" id="mcachemaxobjectsize">Directive</a></h2>
  86 <table class="directive">
  87 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>The maximum size (in bytes) of a document allowed in the
  88 cache</td></tr>
  89 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MCacheMaxObjectSize <var>bytes</var></code></td></tr>
  90 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MCacheMaxObjectSize 10000</code></td></tr>
  91 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
  92 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
  93 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_mem_cache</td></tr>
  94 </table>
  95     <p>The <code class="directive">MCacheMaxObjectSize</code> directive sets the
  96     maximum allowable size, in bytes, of a document for it to be considered
  97     cacheable.</p>
  98
  99     <div class="example"><h3>Example</h3><p><code>
 100       MCacheMaxObjectSize 6400000
 101     </code></p></div>
 102
 103     <div class="note"><h3>Note</h3>
 104       <p>The value of <code class="directive">MCacheMaxObjectSize</code> must be
 105       greater than the value specified by the <code class="directive"><a href="#mcacheminobjectsize">MCacheMinObjectSize</a></code> directive.</p>
 106     </div>
 107
 108 </div>
 109 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 110 <div class="directive-section"><h2><a name="MCacheMaxStreamingBuffer" id="MCacheMaxStreamingBuffer">MCacheMaxStreamingBuffer</a> <a name="mcachemaxstreamingbuffer" id="mcachemaxstreamingbuffer">Directive</a></h2>
 111 <table class="directive">
 112 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximum amount of a streamed response to buffer in memory
 113 before declaring the response uncacheable</td></tr>
 114 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MCacheMaxStreamingBuffer <var>size_in_bytes</var></code></td></tr>
 115 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MCacheMaxStreamingBuffer the smaller of 100000 or MCacheMaxObjectSize</code></td></tr>
 116 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
 117 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
 118 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_mem_cache</td></tr>
 119 </table>
 120     <p>The <code class="directive">MCacheMaxStreamingBuffer</code> directive
 121     specifies the maximum number of bytes of a streamed response to
 122     buffer before deciding that the response is too big to cache.
 123     A streamed response is one in which the entire content is not
 124     immediately available and in which the <code>Content-Length</code>
 125     may not be known. Sources of streaming responses include proxied
 126     responses and the output of CGI scripts. By default, a streamed
 127     response will <em>not</em> be cached unless it has a
 128     <code>Content-Length</code> header. The reason for this is to
 129     avoid using a large amount of memory to buffer a partial response
 130     that might end up being too large to fit in the cache.
 131     The <code class="directive">MCacheMaxStreamingBuffer</code> directive allows
 132     buffering of streamed responses that don't contain a
 133     <code>Content-Length</code> up to the specified maximum amount of
 134     space. If the maximum buffer space is reached, the buffered
 135     content is discarded and the attempt to cache is abandoned.</p>
 136
 137     <div class="note"><h3>Note:</h3>
 138       <p>Using a nonzero value for <code class="directive">MCacheMaxStreamingBuffer</code>
 139       will not delay the transmission of the response to the client.
 140       As soon as <code class="module"><a href="../mod/mod_mem_cache.html">mod_mem_cache</a></code> copies a block of streamed
 141       content into a buffer, it sends the block on to the next output
 142       filter for delivery to the client.</p>
 143     </div>
 144
 145     <div class="example"><p><code>
 146       # Enable caching of streamed responses up to 64KB:<br />
 147       MCacheMaxStreamingBuffer 65536
 148     </code></p></div>
 149
 150 </div>
 151 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 152 <div class="directive-section"><h2><a name="MCacheMinObjectSize" id="MCacheMinObjectSize">MCacheMinObjectSize</a> <a name="mcacheminobjectsize" id="mcacheminobjectsize">Directive</a></h2>
 153 <table class="directive">
 154 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>The minimum size (in bytes) of a document to be allowed in the
 155 cache</td></tr>
 156 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MCacheMinObjectSize <var>bytes</var></code></td></tr>
 157 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MCacheMinObjectSize 0</code></td></tr>
 158 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
 159 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
 160 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_mem_cache</td></tr>
 161 </table>
 162     <p>The <code class="directive">MCacheMinObjectSize</code> directive sets the
 163     minimum size in bytes of a document for it to be considered
 164     cacheable.</p>
 165
 166     <div class="example"><h3>Example</h3><p><code>
 167       MCacheMinObjectSize 10000
 168     </code></p></div>
 169
 170 </div>
 171 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 172 <div class="directive-section"><h2><a name="MCacheRemovalAlgorithm" id="MCacheRemovalAlgorithm">MCacheRemovalAlgorithm</a> <a name="mcacheremovalalgorithm" id="mcacheremovalalgorithm">Directive</a></h2>
 173 <table class="directive">
 174 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>The algorithm used to select documents for removal from the
 175 cache</td></tr>
 176 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MCacheRemovalAlgorithm LRU|GDSF</code></td></tr>
 177 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MCacheRemovalAlgorithm GDSF</code></td></tr>
 178 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
 179 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
 180 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_mem_cache</td></tr>
 181 </table>
 182     <p>The <code class="directive">MCacheRemovalAlgorithm</code> directive specifies
 183     the algorithm used to select documents for removal from the cache.
 184     Two choices are available:</p>
 185
 186     <dl>
 187       <dt><code>LRU</code> (Least Recently Used)</dt>
 188       <dd><code>LRU</code> removes the documents that have not been accessed
 189       for the longest time.</dd>
 190
 191       <dt><code>GDSF</code> (GreadyDual-Size)</dt>
 192       <dd><code>GDSF</code> assigns a priority to cached documents based
 193       on the cost of a cache miss and the size of the document. Documents
 194       with the lowest priority are removed first.</dd>
 195     </dl>
 196
 197     <div class="example"><h3>Example</h3><p><code>
 198       MCacheRemovalAlgorithm GDSF<br />
 199       MCacheRemovalAlgorithm LRU
 200     </code></p></div>
 201
 202 </div>
 203 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 204 <div class="directive-section"><h2><a name="MCacheSize" id="MCacheSize">MCacheSize</a> <a name="mcachesize" id="mcachesize">Directive</a></h2>
 205 <table class="directive">
 206 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>The maximum amount of memory used by the cache in
 207 KBytes</td></tr>
 208 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MCacheSize <var>KBytes</var></code></td></tr>
 209 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MCacheSize 100</code></td></tr>
 210 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
 211 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
 212 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_mem_cache</td></tr>
 213 </table>
 214     <p>The <code class="directive">MCacheSize</code> directive sets the maximum
 215     amount of memory to be used by the cache, in KBytes (1024-byte units).
 216     If a new object needs to be inserted in the cache and the size of the
 217     object is greater than the remaining memory, objects will be removed
 218     until the new object can be cached. The object to be removed is
 219     selected using the algorithm specified by <code class="directive"><a href="#mcacheremovalalgorithm">MCacheRemovalAlgorithm</a></code>.</p>
 220
 221     <div class="example"><h3>Example</h3><p><code>
 222       MCacheSize 700000
 223     </code></p></div>
 224
 225     <div class="note"><h3>Note</h3>
 226       <p>The <code class="directive">MCacheSize</code> value must be greater than
 227       the value specified by the <code class="directive"><a href="#mcachemaxobjectsize">MCacheMaxObjectSize</a></code> directive.</p>
 228     </div>
 229
 230 </div>
 231 </div>
 232 <div class="bottomlang">
 233 <p><span>Available Languages: </span><a href="../en/mod/mod_mem_cache.html" title="English">&nbsp;en&nbsp;</a></p>
 234 </div><div id="footer">
 235 <p class="apache">Copyright 1999-2004 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>
 236 <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>
 237 </body></html>