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<!DOCTYPE modulesynopsis SYSTEM "../style/modulesynopsis.dtd">
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<modulesynopsis metafile="mod_disk_cache.xml.meta">

<name>mod_disk_cache</name>
<description>Content cache storage manager keyed to URIs</description>
<status>Experimental</status>
<sourcefile>mod_disk_cache.c</sourcefile>
<identifier>disk_cache_module</identifier>

<summary>
    <note type="warning">
      This module is experimental. Documentation is still under development...
    </note>

    <p><module>mod_disk_cache</module> implements a disk based storage
    manager. It is primarily of use in conjunction with
    <module>mod_proxy</module>.</p>

    <p>Content is stored in and retrieved from the cache using URI based
    keys. Content with access protection is not cached.</p>

    <note><title>Note:</title>
      <p><module>mod_disk_cache</module> requires the services of
      <module>mod_cache</module>.</p>
    </note>
</summary>

<directivesynopsis>
<name>CacheRoot</name>
<description>The directory root under which cache files are
stored</description>
<syntax>CacheRoot <var>directory</var></syntax>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>

<usage>
    <p>The <directive>CacheRoot</directive> directive defines the name of
    the directory on the disk to contain cache files. If the <module
    >mod_disk_cache</module> module has been loaded or compiled in to the
    Apache server, this directive <em>must</em> be defined. Failing to
    provide a value for <directive>CacheRoot</directive> will result in
    a configuration file processing error. The <directive
    module="mod_disk_cache">CacheDirLevels</directive> and <directive
    module="mod_disk_cache">CacheDirLength</directive> directives define
    the structure of the directories under the specified root directory.</p>

    <example>
      CacheRoot c:/cacheroot
    </example>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>CacheSize</name>
<description>The maximum amount of disk space that will be used by the
cache in KBytes</description>
<syntax>CacheSize <var>KBytes</var></syntax>
<default>CacheSize 1000000</default>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>

<usage>
    <p>The <directive>CacheSize</directive> directive sets the desired
    disk space usage of the cache, in KBytes (1024-byte units). This
    directive does not put a  hard limit on the size of the cache. The
    garbage collector will delete files until the usage is at or below the
    settings. Always use a value that is lower than the available disk
    space.</p>

    <example>
      CacheSize  5000000
    </example>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>CacheGcInterval</name>
<description>The interval between garbage collection attempts.</description>
<syntax>CacheGcInterval <var>hours</var></syntax>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>

<usage>
    <p>The <directive>CacheGcInterval</directive> directive specifies the
    number of hours to wait between attempts to free up disk space.</p>
    <p>More detail will be added here, when the function is implemented.</p>

    <example>
      CacheGcInterval  24<br />
    </example>

    <note type="warning">
      The <directive>CacheGcInterval</directive> directive is currently
      <em>not</em> implemented.
    </note>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>CacheDirLevels</name>
<description>The number of levels of subdirectories in the
cache.</description>
<syntax>CacheDirLevels <var>levels</var></syntax>
<default>CacheDirLevels 3</default>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>

<usage>
    <p>The <directive>CacheDirLevels</directive> directive sets the number
    of subdirectory levels in the cache. Cached data will be saved this
    many directory levels below the <directive module="mod_disk_cache"
    >CacheRoot</directive> directory.</p>

    <note>
      <p>The result of <directive>CacheDirLevels</directive>*
      <directive module="mod_disk_cache">CacheDirLength</directive> must
      not be higher than 20.</p>
    </note>

    <example>
      CacheDirLevels  5
    </example>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>CacheDirLength</name>
<description>The number of characters in subdirectory names</description>
<syntax>CacheDirLength <var>length</var></syntax>
<default>CacheDirLength 2</default>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>

<usage>
    <p>The <directive>CacheDirLength</directive> directive sets the number
    of characters for each subdirectory name in the cache hierarchy.</p>

    <note>
      <p>The result of <directive module="mod_disk_cache"
      >CacheDirLevels</directive>* <directive>CacheDirLength</directive>
      must not be higher than 20.</p>
    </note>

    <example>
      CacheDirLength  4
    </example>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>CacheExpiryCheck</name>
<description>Indicates if the cache observes Expires dates when seeking
files</description>
<syntax>CacheExpiryCheck On|Off</syntax>
<default>CacheExpiryCheck On</default>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>

<usage>
    <p>More detail will be added here, when the function is implemented.</p>

    <example>
      CacheExpiryCheck Off<br />
    </example>

    <note type="warning">
      The <directive>CacheExpiryCheck</directive> directive is currently
      <em>not</em> implemented.
    </note>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>CacheMinFileSize</name>
<description>The minimum size (in bytes) of a document to be placed in the
cache</description>
<syntax>CacheMinFileSize <var>bytes</var></syntax>
<default>CacheMinFileSize 1</default>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>

<usage>
    <p>The <directive>CacheMinFileSize</directive> directive sets the
    minimum size, in bytes, for a document to be considered for storage
    in the cache.</p>

    <example>
      CacheMinFileSize 64
    </example>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>CacheMaxFileSize</name>
<description>The maximum size (in bytes) of a document to be placed in the
cache</description>
<syntax>CacheMaxFileSize <var>bytes</var></syntax>
<default>CacheMaxFileSize 1000000</default>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>

<usage>
    <p>The <directive>CacheMaxFileSize</directive> directive sets the
    maximum size, in bytes, for a document to be considered for storage in
    the cache.</p>

    <example>
      CacheMaxFileSize 64000
    </example>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>CacheTimeMargin</name>
<description>The minimum time margin to cache a document</description>
<syntax>CacheTimeMargin <var>?</var></syntax>
<default>CacheTimeMargin ?</default>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>

<usage>
    <p>More detail will be added here, when the function is implemented.</p>

    <example>
      CacheTimeMargin X
    </example>

    <note type="warning">
      The <directive>CacheTimeMargin</directive> directive is currently
      <em>not</em> implemented.
    </note>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>CacheGcDaily</name>
<description>The recurring time each day for garbage collection to be run.
(24 hour clock)</description>
<syntax>CacheGcDaily <var>time</var></syntax>
<default>CacheGcDaily ?</default>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>

<usage>
    <p>More detail will be added here, when the function is implemented.</p>

    <example>
      CacheGcDaily 23:59
    </example>

    <note type="warning">
      The <directive>CacheGcDaily</directive> directive is currently
      <em>not</em> implemented.
    </note>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>CacheGcUnused</name>
<description>The time to retain unreferenced cached files that match a
URL.</description>
<syntax>CacheGcUnused <var>hours</var> <var>url-string</var></syntax>
<default>CacheGcUnused ?</default>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>

<usage>
    <p>More detail will be added here, when the function is implemented.</p>

    <example>
      CacheGcUnused 12 /local_images
    </example>

    <note type="warning">
      The <directive>CacheGcUnused</directive> directive is currently
      <em>not</em> implemented.
    </note>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>CacheGcClean</name>
<description>The time to retain unchanged cached files that match a
URL</description>
<syntax>CacheGcClean <var>hours</var> <var>url-string</var></syntax>
<default>CacheGcClean ?</default>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>

<usage>
    <p>More detail will be added here, when the function is implemented.</p>

    <example>
      CacheGcClean 12 /daily_scripts
    </example>

    <note type="warning">
      The <directive>CacheGcClean</directive> directive is currently
      <em>not</em> implemented.
    </note>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>CacheGcMemUsage</name>
<description>The maximum kilobytes of memory used for garbage
collection</description>
<syntax>CacheGcMemUsage <var>KBytes</var></syntax>
<default>CacheGcMemUsage ?</default>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>

<usage>
    <p>More detail will be added here, when the function is implemented.</p>

    <example>
      CacheGcMemUsage 16
    </example>

    <note type="warning">
      The <directive>CacheGcMemUsage</directive> directive is currently
      <em>not</em> implemented.
    </note>
</usage>
</directivesynopsis>

</modulesynopsis>
