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<?php
// +----------------------------------------------------------------------+
// | PEAR :: Cache |
// +----------------------------------------------------------------------+
// | Copyright (c) 1997-2003 The PHP Group |
// +----------------------------------------------------------------------+
// | This source file is subject to version 2.0 of the PHP license, |
// | that is bundled with this package in the file LICENSE, and is |
// | available at through the world-wide-web at |
// | http://www.php.net/license/2_02.txt. |
// | If you did not receive a copy of the PHP license and are unable to |
// | obtain it through the world-wide-web, please send a note to |
// | license@php.net so we can mail you a copy immediately. |
// +----------------------------------------------------------------------+
// | Authors: Ulf Wendel <ulf.wendel@phpdoc.de> |
// | Sebastian Bergmann <sb@sebastian-bergmann.de> |
// +----------------------------------------------------------------------+
//
// $Id: Cache.php 267047 2008-10-07 08:58:46Z dufuz $
require_once 'PEAR.php';
require_once 'Cache/Error.php';
/**
* Cache is a base class for cache implementations.
*
* The pear cache module is a generic data cache which can be used to
* cache script runs. The idea behind the cache is quite simple. If you have
* the same input parameters for whatever tasks/algorithm you use you'll
* usually get the same output. So why not caching templates, functions calls,
* graphic generation etc. Caching certain actions e.g. XSLT tranformations
* saves you lots of time.
*
* The design of the cache reminds of PHPLibs session implementation. A
* (PHPLib: session) controller uses storage container (PHPLib: ct_*.inc) to save
* certain data (PHPLib: session data). In contrast to the session stuff it's up to
* you to generate an ID for the data to cache. If you're using the output cache
* you might use the script name as a seed for cache::generateID(), if your using the
* function cache you'd use an array with all function parameters.
*
* Usage example of the generic data cache:
*
* require_once('Cache.php');
*
* $cache = new Cache('file', array('cache_dir' => 'cache/') );
* $id = $cache->generateID('testentry');
*
* if ($data = $cache->get($id)) {
* print "Cache hit.<br>Data: $data";
*
* } else {
* $data = 'data of any kind';
* $cache->save($id, $data);
* print 'Cache miss.<br>';
* }
*
* WARNING: No File/DB-Table-Row locking is implemented yet,
* it's possible, that you get corrupted data-entries under
* bad circumstances (especially with the file container)
*
* @author Ulf Wendel <ulf.wendel@phpdoc.de>
* @version $Id: Cache.php 267047 2008-10-07 08:58:46Z dufuz $
* @package Cache
* @access public
*/
class Cache extends PEAR
{
/**
* Enables / disables caching.
*
* TODO: Add explanation what this is good for.
*
* @var boolean
* @access private
*/
var $caching = true;
/**
* Garbage collection: probability in seconds
*
* If set to a value above 0 a garbage collection will
* flush all cache entries older than the specified number
* of seconds.
*
* @var integer
* @see $gc_probability, $gc_maxlifetime
* @access public
*/
var $gc_time = 1;
/**
* Garbage collection: probability in percent
*
* TODO: Add an explanation.
*
* @var integer 0 => never
* @see $gc_time, $gc_maxlifetime
* @access public
*/
var $gc_probability = 1;
/**
* Garbage collection: delete all entries not use for n seconds.
*
* Default is one day, 60 * 60 * 24 = 86400 seconds.
*
* @var integer
* @see $gc_probability, $gc_time
*/
var $gc_maxlifetime = 86400;
/**
* Storage container object.
*
* @var object Cache_Container
*/
var $container;
//
// public methods
//
/**
*
* @param string Name of container class
* @param array Array with container class options
*/
function Cache($container, $container_options = '')
{
$this->PEAR();
$container = strtolower($container);
$container_class = 'Cache_Container_' . $container;
$container_classfile = 'Cache/Container/' . $container . '.php';
include_once $container_classfile;
$this->container = new $container_class($container_options);
}
//deconstructor
function _Cache()
{
$this->garbageCollection();
}
/**
* Returns the current caching state.
*
* @return boolean The current caching state.
* @access public
*/
function getCaching()
{
return $this->caching;
}
/**
* Enables or disables caching.
*
* @param boolean The new caching state.
* @access public
*/
function setCaching($state)
{
$this->caching = $state;
}
/**
* Returns the requested dataset it if exists and is not expired
*
* @param string dataset ID
* @param string cache group
* @return mixed cached data or null on failure
* @access public
*/
function get($id, $group = 'default')
{
if (!$this->caching) {
return '';
}
if ($this->isCached($id, $group) && !$this->isExpired($id, $group)) {
return $this->load($id, $group);
}
return null;
} // end func get
/**
* Stores the given data in the cache.
*
* @param string dataset ID used as cache identifier
* @param mixed data to cache
* @param integer lifetime of the cached data in seconds - 0 for endless
* @param string cache group
* @return boolean
* @access public
*/
function save($id, $data, $expires = 0, $group = 'default')
{
if (!$this->caching) {
return true;
}
return $this->extSave($id, $data, '',$expires, $group);
} // end func save
/**
* Stores a dataset with additional userdefined data.
*
* @param string dataset ID
* @param mixed data to store
* @param string additional userdefined data
* @param mixed userdefined expire date
* @param string cache group
* @return boolean
* @throws Cache_Error
* @access public
* @see getUserdata()
*/
function extSave($id, $cachedata, $userdata, $expires = 0, $group = 'default')
{
if (!$this->caching) {
return true;
}
return $this->container->save($id, $cachedata, $expires, $group, $userdata);
} // end func extSave
/**
* Loads the given ID from the cache.
*
* @param string dataset ID
* @param string cache group
* @return mixed cached data or null on failure
* @access public
*/
function load($id, $group = 'default')
{
if (!$this->caching) {
return '';
}
return $this->container->load($id, $group);
} // end func load
/**
* Returns the userdata field of a cached data set.
*
* @param string dataset ID
* @param string cache group
* @return string userdata
* @access public
* @see extSave()
*/
function getUserdata($id, $group = 'default')
{
if (!$this->caching) {
return '';
}
return $this->container->getUserdata($id, $group);
} // end func getUserdata
/**
* Removes the specified dataset from the cache.
*
* @param string dataset ID
* @param string cache group
* @return boolean
* @access public
*/
function remove($id, $group = 'default')
{
if (!$this->caching) {
return true;
}
return $this->container->remove($id, $group);
} // end func remove
/**
* Flushes the cache - removes all data from it
*
* @param string cache group, if empty all groups will be flashed
* @return integer number of removed datasets
*/
function flush($group = 'default')
{
if (!$this->caching) {
return true;
}
return $this->container->flush($group);
} // end func flush
/**
* Checks if a dataset exists.
*
* Note: this does not say that the cached data is not expired!
*
* @param string dataset ID
* @param string cache group
* @return boolean
* @access public
*/
function isCached($id, $group = 'default')
{
if (!$this->caching) {
return false;
}
return $this->container->isCached($id, $group);
} // end func isCached
/**
* Checks if a dataset is expired
*
* @param string dataset ID
* @param string cache group
* @param integer maximum age for the cached data in seconds - 0 for endless
* If the cached data is older but the given lifetime it will
* be removed from the cache. You don't have to provide this
* argument if you call isExpired(). Every dataset knows
* it's expire date and will be removed automatically. Use
* this only if you know what you're doing...
* @return boolean
* @access public
*/
function isExpired($id, $group = 'default', $max_age = 0)
{
if (!$this->caching) {
return true;
}
return $this->container->isExpired($id, $group, $max_age);
} // end func isExpired
/**
* Generates a "unique" ID for the given value
*
* This is a quick but dirty hack to get a "unique" ID for a any kind of variable.
* ID clashes might occur from time to time although they are extreme unlikely!
*
* @param mixed variable to generate a ID for
* @return string "unique" ID
* @access public
*/
function generateID($variable)
{
// WARNING: ID clashes are possible although unlikely
return md5(serialize($variable));
}
/**
* Calls the garbage collector of the storage object with a certain probability
*
* @param boolean Force a garbage collection run?
* @see $gc_probability, $gc_time
*/
function garbageCollection($force = false)
{
static $last_run = 0;
if (!$this->caching) {
return;
}
// time and probability based
if (($force) || ($last_run && $last_run < time() + $this->gc_time) || (rand(1, 100) < $this->gc_probability)) {
$this->container->garbageCollection($this->gc_maxlifetime);
$last_run = time();
}
} // end func garbageCollection
} // end class cache
?>
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