Modules

abstract Kohana_Cache

This class is a transparent base class for Cache and should not be accessed directly.

Kohana Cache provides a common interface to a variety of caching engines. Tags are supported where available natively to the cache system. Kohana Cache supports multiple instances of cache engines through a grouped singleton pattern.

Supported cache engines

Introduction to caching

Caching should be implemented with consideration. Generally, caching the result of resources is faster than reprocessing them. Choosing what, how and when to cache is vital. PHP APC is presently one of the fastest caching systems available, closely followed by Memcache. SQLite and File caching are two of the slowest cache methods, however usually faster than reprocessing a complex set of instructions.

Caching engines that use memory are considerably faster than the file based alternatives. But memory is limited whereas disk space is plentiful. If caching large datasets it is best to use file caching.

Configuration settings

Kohana Cache uses configuration groups to create cache instances. A configuration group can use any supported driver, with successive groups using the same driver type if required.

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
                    array(
                         'host'       => 'localhost',
                         'port'       => 11211,
                         'persistent' => FALSE
                    )
             ),
             '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

Details of the settings specific to each driver are available within the drivers documentation.

System requirements

  • Kohana 3.0.x
  • PHP 5.2.4 or greater
package
Kohana/Cache
category
Base
version
2.0
author
Kohana Team
copyright
© 2009-2012 Kohana Team
license
http://kohanaphp.com/license

Class declared in MODPATH/cache/classes/Kohana/Cache.php on line 77.

Constants

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 Config $_config

Default value:
array(0) 

Methods

final public __clone( ) (defined in Kohana_Cache)

Overload the __clone() method to prevent cloning

Tags

Return Values

  • void

Source Code

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

public config( [ mixed $key = NULL , mixed $value = NULL ] ) (defined in Kohana_Cache)

Getter and setter for the configuration. If no argument provided, the current configuration is returned. Otherwise the configuration is set to this class.

// Overwrite all configuration
$cache->config(array('driver' => 'memcache', '...'));

// Set a new configuration setting
$cache->config('servers', array(
     'foo' => 'bar',
     '...'
     ));

// Get a configuration setting
$servers = $cache->config('servers);

Parameters

  • mixed $key = NULL - Key to set to array, either array or config path
  • mixed $value = NULL - Value to associate with key

Return Values

  • mixed

Source Code

public function config($key = NULL, $value = NULL)
{
	if ($key === NULL)
		return $this->_config;

	if (is_array($key))
	{
		$this->_config = $key;
	}
	else
	{
		if ($value === NULL)
			return Arr::get($this->_config, $key);

		$this->_config[$key] = $value;
	}

	return $this;
}

abstract public delete( string $id ) (defined in Kohana_Cache)

Delete a cache entry based on id

// Delete 'foo' entry from the default group
Cache::instance()->delete('foo');

// Delete 'foo' entry from the memcache group
Cache::instance('memcache')->delete('foo')

Parameters

  • string $id required - Id to remove from cache

Return Values

  • boolean

Source Code

abstract public function delete($id);

abstract public delete_all( ) (defined in Kohana_Cache)

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()->delete_all();

// Delete all cache entries in the memcache group
Cache::instance('memcache')->delete_all();

Return Values

  • boolean

Source Code

abstract public function delete_all();

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

Retrieve a cached value entry by id.

// Retrieve cache entry from default group
$data = Cache::instance()->get('foo');

// Retrieve cache entry from default group and return 'bar' if miss
$data = Cache::instance()->get('foo', 'bar');

// Retrieve cache entry from memcache group
$data = Cache::instance('memcache')->get('foo');

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

abstract public function get($id, $default = NULL);

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

  • 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->load('cache');

	if ( ! $config->offsetExists($group))
	{
		throw new 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];
}

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

Set a value to cache with id and lifetime

$data = 'bar';

// Set 'bar' to 'foo' in default group, using default expiry
Cache::instance()->set('foo', $data);

// Set 'bar' to 'foo' in default group for 30 seconds
Cache::instance()->set('foo', $data, 30);

// 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
  • string $data required - Data to set to cache
  • integer $lifetime = integer 3600 - Lifetime in seconds

Return Values

  • boolean

Source Code

abstract public function set($id, $data, $lifetime = 3600);

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

Ensures singleton pattern is observed, loads the default expiry

Parameters

  • array $config required - Configuration

Source Code

protected function __construct(array $config)
{
	$this->config($config);
}

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);
}