Modules

Kohana_Cache_Memcache
extends Cache
extends Kohana_Cache

Kohana Cache Memcache driver,

Supported cache engines

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) 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
© 2009-2010 Kohana Team
license
http://kohanaphp.com/license

Class declared in MODPATH/cache/classes/kohana/cache/memcache.php on line 83.

Constants

CACHE_CEILING

integer 2592000

DEFAULT_EXPIRE

integer 3600

Properties

public static string $default

default driver to use

string(4) "file"

public static Kohana_Cache $instances

instances

array(0) 

protected Kohana_Config $_config

protected array $_default_config

The default configuration for the memcached server

protected string $_flags

Flags to use when storing values

protected Memcache $_memcache

Memcache resource

Methods

public _failed_request( string $hostname , integer $port ) (defined in Kohana_Cache_Memcache)

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.

Parameters

  • string $hostname required - Hostname
  • integer $port required - Port

Tags

  • Since - 3.0.8

Return Values

  • void|boolean

Source Code

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'
			));
	}
}

public delete( string $id [, integer $timeout = integer 0 ] ) (defined in Kohana_Cache_Memcache)

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);

Parameters

  • string $id required - Id of entry to delete
  • integer $timeout = integer 0 - Timeout of entry, if zero item is deleted immediately, otherwise the item will delete after the specified value in seconds

Return Values

  • boolean

Source Code

public function delete($id, $timeout = 0)
{
	// Delete the id
	return $this->_memcache->delete($this->_sanitize_id($id), $timeout);
}

public delete_all( ) (defined in Kohana_Cache_Memcache)

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 Values

  • boolean

Source Code

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;
}

public get( string $id [, string $default = NULL ] ) (defined in Kohana_Cache_Memcache)

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');

Parameters

  • string $id required - Id of cache to entry
  • string $default = NULL - Default value to return if cache miss

Tags

Return Values

  • mixed

Source Code

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;
}

public set( string $id , mixed $data [, integer $lifetime = integer 3600 ] ) (defined in Kohana_Cache_Memcache)

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
}

Parameters

  • string $id required - Id of cache entry
  • mixed $data required - Data to set to cache
  • integer $lifetime = integer 3600 - Lifetime in seconds, maximum value 2592000

Return Values

  • boolean

Source Code

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);
}

public __clone( ) (defined in Kohana_Cache)

Overload the __clone() method to prevent cloning

Tags

Return Values

  • void

Source Code

public function __clone()
{
	throw new Kohana_Cache_Exception('Cloning of Kohana_Cache objects is forbidden');
}

public static instance( [ string $group = NULL ] ) (defined in Kohana_Cache)

Creates a singleton of a Kohana Cache group. If no group is supplied the default cache group is used.

// Create an instance of the default group
$default_group = Cache::instance();

// Create an instance of a group
$foo_group = Cache::instance('foo');

// Access an instantiated group directly
$foo_group = Cache::$instances['default'];

Parameters

  • string $group = NULL - The name of the cache group to use [Optional]

Tags

Return Values

  • Kohana_Cache

Source Code

public static function instance($group = NULL)
{
	// If there is no group supplied
	if ($group === NULL)
	{
		// Use the default setting
		$group = Cache::$default;
	}

	if (isset(Cache::$instances[$group]))
	{
		// Return the current group if initiated already
		return Cache::$instances[$group];
	}

	$config = Kohana::config('cache');

	if ( ! $config->offsetExists($group))
	{
		throw new Kohana_Cache_Exception('Failed to load Kohana Cache group: :group', array(':group' => $group));
	}

	$config = $config->get($group);

	// Create a new cache type instance
	$cache_class = 'Cache_'.ucfirst($config['driver']);
	Cache::$instances[$group] = new $cache_class($config);

	// Return the instance
	return Cache::$instances[$group];
}

protected __construct( array $config ) (defined in Kohana_Cache_Memcache)

Constructs the memcache Kohana_Cache object

Parameters

  • array $config required - Configuration

Tags

Source Code

protected function __construct(array $config)
{
	// Check for the memcache extention
	if ( ! extension_loaded('memcache'))
	{
		throw new Kohana_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 Kohana_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 Kohana_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;
}

protected _sanitize_id( string $id ) (defined in Kohana_Cache)

Replaces troublesome characters with underscores.

// Sanitize a cache id
$id = $this->_sanitize_id($id);

Parameters

  • string $id required - Id of cache to sanitize

Return Values

  • string

Source Code

protected function _sanitize_id($id)
{
	// Change slashes and spaces to underscores
	return str_replace(array('/', '\\', ' '), '_', $id);
}