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<?php
/**
* The Horde_Cache:: class provides a common abstracted interface into
* the various caching backends. It also provides functions for
* checking in, retrieving, and flushing a cache.
*
* $Horde: framework/Cache/Cache.php,v 1.31.10.11 2006/01/01 21:28:10 jan Exp $
*
* Copyright 1999-2006 Anil Madhavapeddy <anil@recoil.org>
* Copyright 1999-2006 Chuck Hagenbuch <chuck@horde.org>
*
* See the enclosed file COPYING for license information (LGPL). If you
* did not receive this file, see http://www.fsf.org/copyleft/lgpl.html.
*
* @author Anil Madhavapeddy <anil@recoil.org>
* @author Chuck Hagenbuch <chuck@horde.org>
* @since Horde 1.3
* @package Horde_Cache
*/
class Horde_Cache {
/**
* Construct a new Horde_Cache object.
*
* @param array $params Parameter array.
*/
function Horde_Cache($params = array())
{
/* Only do garbage collection if asked for, and then only 1% of the
* time we create an object. */
if (!empty($params['gc']) &&
(rand(0, 99) == 0)) {
$this->_doGC($params['gc']);
}
}
/**
* Attempts to retrieve a cached object and return it to the
* caller.
*
* @abstract
*
* @param string $key Object ID to query.
* @param integer $lifetime Lifetime of the object in seconds.
*
* @return mixed Cached data, or false if none was found.
*/
function get($key, $lifetime = 1)
{
return false;
}
/**
* Attempts to store an object in the cache.
*
* @abstract
*
* @param string $key Object ID used as the caching key.
* @param mixed $data Data to store in the cache.
*
* @return boolean True on success, false on failure.
*/
function set($key, $data)
{
return true;
}
/**
* Attempts to directly output a cached object.
*
* @abstract
*
* @param string $key Object ID to query.
* @param integer $lifetime Lifetime of the object in seconds.
*
* @return mixed Cached data, or false if none was found.
*/
function output($key, $lifetime = 1)
{
return false;
}
/**
* Checks if a given key exists in the cache, valid for the given
* lifetime.
*
* @abstract
*
* @param string $key Cache key to check.
* @param integer $lifetime Lifetime of the key in seconds.
*
* @return boolean Existance.
*/
function exists($key, $lifetime = 1)
{
return false;
}
/**
* Expire any existing data for the given key.
*
* @abstract
*
* @param string $key Cache key to expire.
*
* @return boolean Success or failure.
*/
function expire($key)
{
return true;
}
/**
* Do any garbage collection needed for the driver.
*
* @private
*
* @abstract
*
* @param integer $secs The minimum amount of time (in seconds) required
* before a cache item is removed.
*/
function _doGC($secs)
{
}
/**
* Attempts to return a concrete Horde_Cache instance based on $driver.
*
* @param mixed $driver The type of concrete Horde_Cache subclass to
* return. If $driver is an array, then we will look
* in $driver[0]/lib/Cache/ for the subclass
* implementation named $driver[1].php.
* @param array $params A hash containing any additional
* configuration or connection parameters a subclass
* might need.
*
* @return Horde_Cache The newly created concrete Horde_Cache instance, or
* false on error.
*/
function &factory($driver, $params = array())
{
if (is_array($driver)) {
$app = $driver[0];
$driver = $driver[1];
}
$driver = basename($driver);
if (empty($driver) || $driver == 'none') {
$cache = &new Horde_Cache($params);
return $cache;
}
if (!empty($app)) {
include_once $app . '/lib/Cache/' . $driver . '.php';
} elseif (@file_exists(dirname(__FILE__) . '/Cache/' . $driver . '.php')) {
include_once dirname(__FILE__) . '/Cache/' . $driver . '.php';
} else {
@include_once 'Horde/Cache/' . $driver . '.php';
}
$class = 'Horde_Cache_' . $driver;
if (class_exists($class)) {
$cache = &new $class($params);
} else {
$cache = PEAR::raiseError('Class definition of ' . $class . ' not found.');
}
return $cache;
}
/**
* Attempts to return a reference to a concrete Horde_Cache
* instance based on $driver. It will only create a new instance
* if no Horde_Cache instance with the same parameters currently
* exists.
*
* This should be used if multiple cache backends (and, thus,
* multiple Horde_Cache instances) are required.
*
* This method must be invoked as:
* $var = &Horde_Cache::singleton()
*
* @param mixed $driver The type of concrete Horde_Cache subclass to
* return. If $driver is an array, then we will look
* in $driver[0]/lib/Cache/ for the subclass
* implementation named $driver[1].php.
* @param array $params A hash containing any additional configuration or
* connection parameters a subclass might need.
*
* @return Horde_Cache The concrete Horde_Cache reference, or false on
* error.
*/
function &singleton($driver, $params = array())
{
static $instances = array();
$signature = serialize(array($driver, $params));
if (empty($instances[$signature])) {
$instances[$signature] = &Horde_Cache::factory($driver, $params);
}
return $instances[$signature];
}
}
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