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lnkohana/modules/cache/classes/Kohana/Cache/Memcache.php

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2013-04-22 04:09:50 +00:00
<?php defined('SYSPATH') or die('No direct script access.');
/**
* [Kohana Cache](api/Kohana_Cache) Memcache driver,
*
* ### Supported cache engines
*
* * [Memcache](http://www.php.net/manual/en/book.memcache.php)
* * [Memcached-tags](http://code.google.com/p/memcached-tags/)
*
* ### Configuration example
*
* Below is an example of a _memcache_ server configuration.
*
* return array(
* 'default' => array( // Default group
* 'driver' => 'memcache', // using Memcache driver
* 'servers' => array( // Available server definitions
* // First memcache server server
* array(
* 'host' => 'localhost',
* 'port' => 11211,
* 'persistent' => FALSE
* 'weight' => 1,
* 'timeout' => 1,
* 'retry_interval' => 15,
* 'status' => TRUE,
* 'instant_death' => TRUE,
* 'failure_callback' => array('className', 'classMethod')
* ),
* // Second memcache server
* array(
* 'host' => '192.168.1.5',
* 'port' => 22122,
* 'persistent' => TRUE
* )
* ),
* 'compression' => FALSE, // Use compression?
* ),
* )
*
* In cases where only one cache group is required, if the group is named `default` there is
* no need to pass the group name when instantiating a cache instance.
*
* #### General cache group configuration settings
*
* Below are the settings available to all types of cache driver.
*
* Name | Required | Description
* -------------- | -------- | ---------------------------------------------------------------
* driver | __YES__ | (_string_) The driver type to use
* servers | __YES__ | (_array_) Associative array of server details, must include a __host__ key. (see _Memcache server configuration_ below)
* compression | __NO__ | (_boolean_) Use data compression when caching
*
* #### Memcache server configuration
*
* The following settings should be used when defining each memcache server
*
* Name | Required | Description
* ---------------- | -------- | ---------------------------------------------------------------
* host | __YES__ | (_string_) The host of the memcache server, i.e. __localhost__; or __127.0.0.1__; or __memcache.domain.tld__
* port | __NO__ | (_integer_) Point to the port where memcached is listening for connections. Set this parameter to 0 when using UNIX domain sockets. Default __11211__
* persistent | __NO__ | (_boolean_) Controls the use of a persistent connection. Default __TRUE__
* weight | __NO__ | (_integer_) Number of buckets to create for this server which in turn control its probability of it being selected. The probability is relative to the total weight of all servers. Default __1__
* timeout | __NO__ | (_integer_) Value in seconds which will be used for connecting to the daemon. Think twice before changing the default value of 1 second - you can lose all the advantages of caching if your connection is too slow. Default __1__
* retry_interval | __NO__ | (_integer_) Controls how often a failed server will be retried, the default value is 15 seconds. Setting this parameter to -1 disables automatic retry. Default __15__
* status | __NO__ | (_boolean_) Controls if the server should be flagged as online. Default __TRUE__
* failure_callback | __NO__ | (_[callback](http://www.php.net/manual/en/language.pseudo-types.php#language.types.callback)_) Allows the user to specify a callback function to run upon encountering an error. The callback is run before failover is attempted. The function takes two parameters, the hostname and port of the failed server. Default __NULL__
*
* ### System requirements
*
* * Kohana 3.0.x
* * PHP 5.2.4 or greater
* * Memcache (plus Memcached-tags for native tagging support)
* * Zlib
*
* @package Kohana/Cache
* @category Base
* @version 2.0
* @author Kohana Team
* @copyright (c) 2009-2012 Kohana Team
* @license http://kohanaphp.com/license
*/
class Kohana_Cache_Memcache extends Cache implements Cache_Arithmetic {
// Memcache has a maximum cache lifetime of 30 days
const CACHE_CEILING = 2592000;
/**
* Memcache resource
*
* @var Memcache
*/
protected $_memcache;
/**
* Flags to use when storing values
*
* @var string
*/
protected $_flags;
/**
* The default configuration for the memcached server
*
* @var array
*/
protected $_default_config = array();
/**
* Constructs the memcache Kohana_Cache object
*
* @param array $config configuration
* @throws Cache_Exception
*/
protected function __construct(array $config)
{
// Check for the memcache extention
if ( ! extension_loaded('memcache'))
{
throw new Cache_Exception('Memcache PHP extention not loaded');
}
parent::__construct($config);
// Setup Memcache
$this->_memcache = new Memcache;
// Load servers from configuration
$servers = Arr::get($this->_config, 'servers', NULL);
if ( ! $servers)
{
// Throw an exception if no server found
throw new Cache_Exception('No Memcache servers defined in configuration');
}
// Setup default server configuration
$this->_default_config = array(
'host' => 'localhost',
'port' => 11211,
'persistent' => FALSE,
'weight' => 1,
'timeout' => 1,
'retry_interval' => 15,
'status' => TRUE,
'instant_death' => TRUE,
'failure_callback' => array($this, '_failed_request'),
);
// Add the memcache servers to the pool
foreach ($servers as $server)
{
// Merge the defined config with defaults
$server += $this->_default_config;
if ( ! $this->_memcache->addServer($server['host'], $server['port'], $server['persistent'], $server['weight'], $server['timeout'], $server['retry_interval'], $server['status'], $server['failure_callback']))
{
throw new Cache_Exception('Memcache could not connect to host \':host\' using port \':port\'', array(':host' => $server['host'], ':port' => $server['port']));
}
}
// Setup the flags
$this->_flags = Arr::get($this->_config, 'compression', FALSE) ? MEMCACHE_COMPRESSED : FALSE;
}
/**
* Retrieve a cached value entry by id.
*
* // Retrieve cache entry from memcache group
* $data = Cache::instance('memcache')->get('foo');
*
* // Retrieve cache entry from memcache group and return 'bar' if miss
* $data = Cache::instance('memcache')->get('foo', 'bar');
*
* @param string $id id of cache to entry
* @param string $default default value to return if cache miss
* @return mixed
* @throws Cache_Exception
*/
public function get($id, $default = NULL)
{
// Get the value from Memcache
$value = $this->_memcache->get($this->_sanitize_id($id));
// If the value wasn't found, normalise it
if ($value === FALSE)
{
$value = (NULL === $default) ? NULL : $default;
}
// Return the value
return $value;
}
/**
* Set a value to cache with id and lifetime
*
* $data = 'bar';
*
* // Set 'bar' to 'foo' in memcache group for 10 minutes
* if (Cache::instance('memcache')->set('foo', $data, 600))
* {
* // Cache was set successfully
* return
* }
*
* @param string $id id of cache entry
* @param mixed $data data to set to cache
* @param integer $lifetime lifetime in seconds, maximum value 2592000
* @return boolean
*/
public function set($id, $data, $lifetime = 3600)
{
// If the lifetime is greater than the ceiling
if ($lifetime > Cache_Memcache::CACHE_CEILING)
{
// Set the lifetime to maximum cache time
$lifetime = Cache_Memcache::CACHE_CEILING + time();
}
// Else if the lifetime is greater than zero
elseif ($lifetime > 0)
{
$lifetime += time();
}
// Else
else
{
// Normalise the lifetime
$lifetime = 0;
}
// Set the data to memcache
return $this->_memcache->set($this->_sanitize_id($id), $data, $this->_flags, $lifetime);
}
/**
* Delete a cache entry based on id
*
* // Delete the 'foo' cache entry immediately
* Cache::instance('memcache')->delete('foo');
*
* // Delete the 'bar' cache entry after 30 seconds
* Cache::instance('memcache')->delete('bar', 30);
*
* @param string $id id of entry to delete
* @param integer $timeout timeout of entry, if zero item is deleted immediately, otherwise the item will delete after the specified value in seconds
* @return boolean
*/
public function delete($id, $timeout = 0)
{
// Delete the id
return $this->_memcache->delete($this->_sanitize_id($id), $timeout);
}
/**
* Delete all cache entries.
*
* Beware of using this method when
* using shared memory cache systems, as it will wipe every
* entry within the system for all clients.
*
* // Delete all cache entries in the default group
* Cache::instance('memcache')->delete_all();
*
* @return boolean
*/
public function delete_all()
{
$result = $this->_memcache->flush();
// We must sleep after flushing, or overwriting will not work!
// @see http://php.net/manual/en/function.memcache-flush.php#81420
sleep(1);
return $result;
}
/**
* Callback method for Memcache::failure_callback to use if any Memcache call
* on a particular server fails. This method switches off that instance of the
* server if the configuration setting `instant_death` is set to `TRUE`.
*
* @param string $hostname
* @param integer $port
* @return void|boolean
* @since 3.0.8
*/
public function _failed_request($hostname, $port)
{
if ( ! $this->_config['instant_death'])
return;
// Setup non-existent host
$host = FALSE;
// Get host settings from configuration
foreach ($this->_config['servers'] as $server)
{
// Merge the defaults, since they won't always be set
$server += $this->_default_config;
// We're looking at the failed server
if ($hostname == $server['host'] and $port == $server['port'])
{
// Server to disable, since it failed
$host = $server;
continue;
}
}
if ( ! $host)
return;
else
{
return $this->_memcache->setServerParams(
$host['host'],
$host['port'],
$host['timeout'],
$host['retry_interval'],
FALSE, // Server is offline
array($this, '_failed_request'
));
}
}
/**
* Increments a given value by the step value supplied.
* Useful for shared counters and other persistent integer based
* tracking.
*
* @param string id of cache entry to increment
* @param int step value to increment by
* @return integer
* @return boolean
*/
public function increment($id, $step = 1)
{
return $this->_memcache->increment($id, $step);
}
/**
* Decrements a given value by the step value supplied.
* Useful for shared counters and other persistent integer based
* tracking.
*
* @param string id of cache entry to decrement
* @param int step value to decrement by
* @return integer
* @return boolean
*/
public function decrement($id, $step = 1)
{
return $this->_memcache->decrement($id, $step);
}
}