egroupware/api/src/Cache/Memcached.php
Ralf Becker 67a6a9f1f3 implement (increment|decrement)Cache to avoid race-conditions if multiple processes update a value
implemented in memcached and APCu backends, default implementation using get&set in base-class
2021-05-27 12:29:51 +02:00

301 lines
9.7 KiB
PHP

<?php
/**
* EGroupware API: Caching provider storing data in memcached via PHP's memcached extension
*
* @link http://www.egroupware.org
* @license http://opensource.org/licenses/gpl-license.php GPL - GNU General Public License
* @package api
* @subpackage cache
* @author Ralf Becker <RalfBecker-AT-outdoor-training.de>
* @copyright (c) 2009-16 by Ralf Becker <RalfBecker-AT-outdoor-training.de>
* @version $Id$
*/
namespace EGroupware\Api\Cache;
/**
* Caching provider storing data in memcached via PHP's memcached extension
*
* The provider concats all $keys with '::' to get a single string.
*
* To use this provider set in your header.inc.php:
* $GLOBALS['egw_info']['server']['cache_provider_instance'] = array('EGroupware\Api\Cache\Memcached','localhost'[,'otherhost:port']);
* and optional also $GLOBALS['egw_info']['server']['cache_provider_tree'] (defaults to instance)
*
* You can set more then one server and specify a port, if it's not the default one 11211.
*
* It allows addtional named parameters "timeout" (default 20ms), "retry" (default not) and "prefix".
*
* If igbinary extension is available, it is prefered over PHP (un)serialize.
*/
class Memcached extends Base implements ProviderMultiple
{
/**
* Instance of \Memcached
*
* @var \Memcached
*/
private $memcache;
/**
* Timeout in ms
*/
private $timeout = 20;
/**
* Use Libketama consistent hashing
*
* Off by default as for just 2 Memcached servers it creates an extreme
* unbalanced distribution favoring the 2. server and has no benefits
* as requests to the failed node can only go to the other one anyway.
*
* @var boolean
*/
private $consistent = false;
/**
* Retry on node failure: 0: no retry, 1: retry on set/add/delete, 2: always retry
*
* @var retry
*/
private $retry = 0;
/**
* Constructor, eg. opens the connection to the backend
*
* @throws Exception if connection to backend could not be established
* @param array $params eg. array('localhost'[,'localhost:11211',...])
* "timeout" in ms, "retry" on node failure 0: no retry (default), 1: retry on set/add/delete, 2: allways retry
* "prefix" prefix for keys and "consistent=1" to enable (by default disabled) consistent caching
*/
function __construct(array $params=null)
{
$this->params = $params ? $params : array('localhost'); // some reasonable default
if (isset($params['timeout']))
{
$this->timeout = (int)$params['timeout'];
unset($params['timeout']);
}
if (isset($params['retry']))
{
$this->retry = (int)$params['retry'];
unset($params['retry']);
}
if (isset($params['prefix']))
{
$prefix = $params['prefix'];
unset($params['prefix']);
}
if (isset($params['consistent']))
{
$this->consistent = !empty($params['consistent']);
}
check_load_extension('memcached',true);
// using a persitent connection for identical $params
$this->memcache = new \Memcached(md5(serialize($params)));
$this->memcache->setOptions(array(
// setting a short timeout, to better kope with failed nodes
\Memcached::OPT_CONNECT_TIMEOUT => $this->timeout,
\Memcached::OPT_SEND_TIMEOUT => $this->timeout,
\Memcached::OPT_RECV_TIMEOUT => $this->timeout,
// use more efficient binary protocol (also required for consistent hashing)
\Memcached::OPT_BINARY_PROTOCOL => true,
// Libketama compatible consistent hashing
\Memcached::OPT_LIBKETAMA_COMPATIBLE => $this->consistent,
// automatic failover and disabling of failed nodes
\Memcached::OPT_SERVER_FAILURE_LIMIT => 2,
// setting a prefix for all keys
\Memcached::OPT_PREFIX_KEY => $prefix,
));
// automatic disabling of failed nodes
if (@constant('Memcached::OPT_AUTO_EJECT_HOSTS'))
{
$this->memcache->setOption(\Memcached::OPT_AUTO_EJECT_HOSTS, true);
}
// use igbinary, if available
if (\Memcached::HAVE_IGBINARY)
{
$this->memcache->setOption(\Memcached::OPT_SERIALIZER, \Memcached::SERIALIZER_IGBINARY);
}
elseif(\Memcached::HAVE_JSON)
{
$this->memcache->setOption(\Memcached::OPT_SERIALIZER, \Memcached::SERIALIZER_JSON);
}
// with persistent connections, only add servers, if they not already added!
if (!count($this->memcache->getServerList()))
{
$ok = false;
foreach($params as $host_port)
{
$parts = explode(':',$host_port);
$host = array_shift($parts);
$port = $parts ? array_shift($parts) : 11211; // default port
$ok = $this->memcache->addServer($host,$port) || $ok;
//error_log(__METHOD__."(".array2string($params).") memcache->addServer('$host',$port) = ".(int)$ok);
}
if (!$ok)
{
throw new Exception (__METHOD__.'('.array2string($params).") Can't open connection to any memcached server!");
}
//error_log(__METHOD__."(".array2string($params).") creating new pool / persitent connection");
}
//else error_log(__METHOD__."(".array2string($params).") using existing pool / persitent connection");
}
/**
* Stores some data in the cache, if it does NOT already exists there
*
* @param array $keys eg. array($level,$app,$location)
* @param mixed $data
* @param int $expiration =0
* @return boolean true on success, false on error, incl. key already exists in cache
*/
function add(array $keys,$data,$expiration=0)
{
return $this->memcache->add(self::key($keys), $data, $expiration) ||
// if we have multiple nodes, retry on error, but not on data exists
$this->retry > 0 && $this->memcache->getResultCode() !== \Memcached::RES_DATA_EXISTS &&
$this->memcache->add(self::key($keys), $data, $expiration);
}
/**
* Stores some data in the cache
*
* @param array $keys eg. array($level,$app,$location)
* @param mixed $data
* @param int $expiration =0
* @return boolean true on success, false on error
*/
function set(array $keys,$data,$expiration=0)
{
return $this->memcache->set(self::key($keys), $data, $expiration) ||
// if we have multiple nodes, retry on error
$this->retry > 0 && $this->memcache->set(self::key($keys), $data, $expiration);
}
/**
* Get some data from the cache
*
* @param array $keys eg. array($level,$app,$location)
* @return mixed data stored or NULL if not found in cache
*/
function get(array $keys)
{
if (($data = $this->memcache->get($key=self::key($keys))) === false &&
$this->memcache->getResultCode() !== \Memcached::RES_SUCCESS ||
// if we have multiple nodes, retry on error, but not on not found
$this->retry > 1 && $this->memcache->getResultCode() !== \Memcached::RES_NOTFOUND &&
($data = $this->memcache->get($key=self::key($keys))) === false &&
$this->memcache->getResultCode() !== \Memcached::RES_SUCCESS)
{
//error_log(__METHOD__."(".array2string($keys).") key='$key' NOT found!".' $this->memcache->getResultCode()='.$this->memcache->getResultCode().')');
return null;
}
//error_log(__METHOD__."(".array2string($keys).") key='$key' found ".bytes($data)." bytes).");
return $data;
}
/**
* Get multiple data from the cache
*
* @param array $keys eg. array of array($level,$app,array $locations)
* @return array key => data stored, not found keys are NOT returned
*/
function mget(array $keys)
{
$locations = array_pop($keys);
$prefix = self::key($keys);
foreach($locations as &$location)
{
$location = $prefix.'::'.$location;
}
if (($multiple = $this->memcache->getMulti($locations)) === false ||
// if we have multiple nodes, retry on error, but not on not found
$this->retry > 1 && $this->memcache->getResultCode() !== \Memcached::RES_NOTFOUND &&
($multiple = $this->memcache->getMulti($locations)) === false)
{
return array();
}
$ret = array();
$prefix_len = strlen($prefix)+2;
foreach($multiple as $location => $data)
{
$key = substr($location,$prefix_len);
//error_log(__METHOD__."(".array2string($locations).") key='$key' found ".bytes($data)." bytes).");
$ret[$key] = $data;
}
return $ret;
}
/**
* Delete some data from the cache
*
* @param array $keys eg. array($level,$app,$location)
* @return boolean true on success, false on error (eg. $key not set)
*/
function delete(array $keys)
{
return $this->memcache->delete(self::key($keys)) ||
$this->retry > 0 && $this->memcache->getResultCode() !== \Memcached::RES_NOTFOUND &&
$this->memcache->delete(self::key($keys));
}
/**
* Increments value in cache
*
* @param array $keys
* @param int $offset =1 how much to increment by
* @param int $intial_value =0 value to set and return, if not in cache
* @param int $expiration =0
* @return false|int new value on success, false on error
*/
function increment(array $keys, int $offset=1, int $intial_value=0, int $expiration=0)
{
$ret = $this->memcache->increment($key=self::key($keys), $offset, $intial_value, $expiration);
if ($ret === false && $this->retry > 0)
{
$ret = $this->memcache->increment($key, $offset, $intial_value, $expiration);
}
// fix memcached returning strings
return $ret !== false ? (int)$ret : $ret;
}
/**
* Decrements value in cache, but never below 0
*
* If new value would be below 0, 0 will be set as new value!
*
* @param array $keys
* @param int $offset =1 how much to increment by
* @param int $intial_value =0 value to set and return, if not in cache
* @param int $expiration =0
* @return false|int new value on success, false on error
*/
function decrement(array $keys, int $offset=1, int $intial_value=0, int $expiration=0)
{
$ret = $this->memcache->decrement($key=self::key($keys), $offset, $intial_value, $expiration);
if ($ret === false && $this->retry > 0)
{
$ret = $this->memcache->decrement($key, $offset, $intial_value, $expiration);
}
// fix memcached returning strings
return $ret !== false ? (int)$ret : $ret;
}
/**
* Create a single key from $keys
*
* @param array $keys
* @return string
*/
private function key(array $keys)
{
return implode('::',$keys);
}
}