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<?php
/**
* Elgg memcache support.
*
* Requires php5-memcache to work.
*
* @package Elgg
* @subpackage API
* @license http://www.gnu.org/licenses/old-licenses/gpl-2.0.html GNU Public License version 2
* @author Curverider Ltd <info@elgg.com>
* @copyright Curverider Ltd 2008
* @link http://elgg.org/
*/
class ElggMemcache extends ElggCache
{
/**
* Namespace variable used for key
*
* @var string
*/
private $namespace;
/**
* Memcache object
*/
private $memcache;
/**
* Expiry of saved items (defaults forever)
*/
private $expires = 0;
/**
* The version of memcache running
*/
private $version = 0;
/**
* Keys so far.
* This variable holds a list of keys we have seen so that when we call ->clear() we invalidate only those keys.
* TODO: Could this be done better?
*/
private $keys_so_far = array();
/**
* Connect to memcache.
*
* @param string $cache_id The namespace for this cache to write to - note, namespaces of the same name are shared!
*/
function __construct($namespace = 'default')
{
global $CONFIG;
$this->namespace = $namespace;
// Do we have memcache?
if (!class_exists('Memcache'))
throw new ConfigurationException(elgg_echo('memcache:notinstalled'));
// Create memcache object
$this->memcache = new Memcache;
// Now add servers
if (!$CONFIG->memcache_servers)
throw new ConfigurationException(elgg_echo('memcache:noservers'));
foreach ($CONFIG->memcache_servers as $server)
{
if (is_array($server))
{
$this->memcache->addServer(
$server[0],
isset($server[1]) ? $server[1] : 11211,
isset($server[2]) ? $server[2] : true,
isset($server[3]) ? $server[3] : null,
isset($server[4]) ? $server[4] : 1,
isset($server[5]) ? $server[5] : 15,
isset($server[6]) ? $server[6] : true
);
}
else
$this->memcache->addServer($server, 11211);
}
// Get version
$this->version = $this->memcache->getversion();
if (version_compare($this->version, '2.0.0', '<'))
throw new ConfigurationException(sprintf(elgg_echo('memcache:versiontoolow'), $this->version));
// Set some defaults
if (isset($CONFIG->memcache_expires))
$this->expires = $CONFIG->memcache_expires;
}
/**
* Combine a key with the namespace.
* Memcache can only accept <250 char key. If the given key is too long it is shortened.
*
* @param string $key The key
* @return string The new key.
*/
private function make_memcache_key($key)
{
$prefix = $this->namespace . ":";
if (strlen($prefix.$key)> 250)
$key = md5($key);
return $prefix.$key;
}
public function save($key, $data)
{
$key = $this->make_memcache_key($key);
return $this->memcache->add($key, $data, null, $this->expires);
}
public function load($key, $offset = 0, $limit = null)
{
$key = $this->make_memcache_key($key);
return $this->memcache->get($key);
}
public function delete($key)
{
$key = $this->make_memcache_key($key);
return $this->memcache->delete($key, 0);
}
public function clear()
{
foreach ($this->keys_so_far as $key)
$this->memcache->delete($key, 0);
$this->keys_so_far = array();
return true;
}
}
?>
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