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.
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.
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.
Below is an example of a memcache server configuration.
return [
// Name of group
'memcache' => [
// Using Memcache driver
'driver' => 'memcache',
// Available server definitions
'servers' => [
[
'host' => 'localhost',
'port' => 11211,
'persistent' => false
]
],
// Use compression?
'compression' => false,
],
]
In cases where only one cache group is required, set Cache::$default (in your bootstrap,
or by extending Kohana_Cache class) to the name of the group, and use:
$cache = Cache::instance(); // instead of Cache::instance('memcache')
It will return the cache instance of the group it has been set in Cache::$default.
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.
Class declared in MODPATH/cache/classes/Cache.php on line 3.
integer 3600
string $defaultdefault driver to use
string(4) "file"Kohana_Cache $instancesinstances
array(0) Config $_configarray(0) Overload the __clone() method to prevent cloning
voidfinal public function __clone()
{
throw new Cache_Exception('Cloning of Kohana_Cache objects is forbidden');
}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(['driver' => 'memcache', '...']);
// Set a new configuration setting
$cache->config('servers', ['foo' => 'bar', '...']);
// Get a configuration setting
$servers = $cache->config('servers);
mixed
$key
= NULL - Key to set to array, either array or config path mixed
$value
= NULL - Value to associate with key mixedpublic function config($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;
}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')
string
$id
required - Id to remove from cache booleanabstract public function delete($id);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();
booleanabstract public function delete_all();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');
string
$id
required - Id of cache to entry string
$default
= NULL - Default value to return if cache miss mixedabstract public function get($id, $default = null);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'];
string
$group
= NULL - The name of the cache group to use [Optional] Cachepublic static function instance($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', [':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];
}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
}
string
$id
required - Id of cache entry string
$data
required - Data to set to cache integer
$lifetime
= integer 3600 - Lifetime in seconds booleanabstract public function set($id, $data, $lifetime = 3600);Ensures singleton pattern is observed, loads the default expiry
array
$config
required - Configuration protected function __construct(array $config)
{
$this->config($config);
}Replaces troublesome characters with underscores.
// Sanitize a cache id
$id = $this->_sanitize_id($id);
string
$id
required - Id of cache to sanitize stringprotected function _sanitize_id($id)
{
// Change slashes and spaces to underscores
return str_replace(['/', '\\', ' '], '_', $id);
}