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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/
*/
/**
* Memcache wrapper class.
* @author Curverider Ltd <info@elgg.com>
*/
class ElggMemcache extends ElggSharedMemoryCache
{
/**
* Minimum version of memcached needed to run
*
*/
private static $MINSERVERVERSION = '1.1.12';
/**
* Memcache object
*/
private $memcache;
/**
* Expiry of saved items (default timeout after a day to prevent anything getting too stale)
*/
private $expires = 86400;
/**
* 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;
$this->setNamespace($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'));
if (is_callable($this->memcache, 'addServer'))
{
foreach ($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);
}
}
else
{
if ((isset($CONFIG->debug)) && ($CONFIG->debug == true))
error_log(elgg_echo('memcache:noaddserver'));
$server = $CONFIG->memcache_servers[0];
if (is_array($server))
{
$this->memcache->connect($server[0], $server[1]);
}
else
$this->memcache->addServer($server, 11211);
}
// Get version
$this->version = $this->memcache->getversion();
if (version_compare($this->version, ElggMemcache::$MINSERVERVERSION, '<'))
throw new ConfigurationException(sprintf(elgg_echo('memcache:versiontoolow'), ElggMemcache::$MINSERVERVERSION, $this->version));
// Set some defaults
if (isset($CONFIG->memcache_expires))
$this->expires = $CONFIG->memcache_expires;
}
/**
* Set the default expiry.
*
* @param int $expires The lifetime as a unix timestamp or time from now. Defaults forever.
*/
public function setDefaultExpiry($expires = 0)
{
$this->expires = $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 = $this->getNamespace() . ":";
if (strlen($prefix.$key)> 250)
$key = md5($key);
return $prefix.$key;
}
public function save($key, $data)
{
$key = $this->make_memcache_key($key);
$this->keys_so_far[$key] = time();
//$this->save_persistent_keylist();
$result = $this->memcache->set($key, $data, null, $this->expires);
if ((isset($CONFIG->debug)) && ($CONFIG->debug == true) && (!$result))
error_log("MEMCACHE: FAILED TO SAVE $key");
return $result;
}
public function load($key, $offset = 0, $limit = null)
{
$key = $this->make_memcache_key($key);
$this->keys_so_far[$key] = time();
//$this->save_persistent_keylist();
$result = $this->memcache->get($key);
if ((isset($CONFIG->debug)) && ($CONFIG->debug == true) && (!$result))
error_log("MEMCACHE: FAILED TO LOAD $key");
return $result;
}
public function delete($key)
{
$key = $this->make_memcache_key($key);
return $this->memcache->delete($key, 0);
}
public function clear()
{
// DISABLE clearing for now - you must use delete on a specific key.
return true;
foreach ($this->keys_so_far as $key => $ts)
$this->memcache->delete($key, 0);
//$this->clear_persistent_keylist();
$this->keys_so_far = array();
return true;
}
/*private function load_persistent_keylist()
{
return $this->memcache->get($this->getNamespace().':keys_so_far');
}
private function save_persistent_keylist()
{
$stored = $this->load_persistent_keylist();
if ($stored) $this->keys_so_far = array_merge($this->keys_so_far, $stored);
return $this->memcache->set($this->getNamespace().':keys_so_far', $this->keys_so_far, null, 0);
}
private function clear_persistent_keylist()
{
return $this->memcache->delete($this->getNamespace().':keys_so_far', 0);
}
public function __destruct()
{
$this->save_persistent_keylist();
}*/
}
/**
* Return true if memcache is available and configured.
*
* @return bool
*/
function is_memcache_available()
{
global $CONFIG;
static $memcache_available;
if ((!isset($CONFIG->memcache)) || (!$CONFIG->memcache))
return false;
if (($memcache_available!==true) && ($memcache_available!==false)) // If we haven't set variable to something
{
try {
$tmp = new ElggMemcache();
$memcache_available = true; // No exception thrown so we have memcache available
} catch (Exception $e) { $memcache_available = false; }
}
return $memcache_available;
}
?>
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