############## Caching Driver ############## CodeIgniter features wrappers around some of the most popular forms of fast and dynamic caching. All but file-based caching require specific server requirements, and a Fatal Exception will be thrown if server requirements are not met. .. contents:: Table of Contents ************* Example Usage ************* The following example will load the cache driver, specify `APC <#apc>`_ as the driver to use, and fall back to file-based caching if APC is not available in the hosting environment. :: $this->load->driver('cache', array('adapter' => 'apc', 'backup' => 'file')); if ( ! $foo = $this->cache->get('foo')) { echo 'Saving to the cache!<br />'; $foo = 'foobarbaz!'; // Save into the cache for 5 minutes $this->cache->save('foo', $foo, 300); } echo $foo; ****************** Function Reference ****************** .. php:class:: CI_Cache is_supported() =============== .. php:method:: is_supported ( $driver ) This function is automatically called when accessing drivers via $this->cache->get(). However, if the individual drivers are used, make sure to call this function to ensure the driver is supported in the hosting environment. :param string $driver: the name of the caching driver :returns: TRUE if supported, FALSE if not :rtype: Boolean :: if ($this->cache->apc->is_supported() { if ($data = $this->cache->apc->get('my_cache')) { // do things. } } get() ===== .. php:method:: get ( $id ) This function will attempt to fetch an item from the cache store. If the item does not exist, the function will return FALSE. :param string $id: name of cached item :returns: The item if it exists, FALSE if it does not :rtype: Mixed :: $foo = $this->cache->get('my_cached_item'); save() ====== .. php:method:: save ( $id , $data [, $ttl]) This function will save an item to the cache store. If saving fails, the function will return FALSE. :param string $id: name of the cached item :param mixed $data: the data to save :param int $ttl: Time To Live, in seconds (default 60) :returns: TRUE on success, FALSE on failure :rtype: Boolean :: $this->cache->save('cache_item_id', 'data_to_cache'); delete() ======== .. php:method:: delete ( $id ) This function will delete a specific item from the cache store. If item deletion fails, the function will return FALSE. :param string $id: name of cached item :returns: TRUE if deleted, FALSE if the deletion fails :rtype: Boolean :: $this->cache->delete('cache_item_id'); clean() ======= .. php:method:: clean ( ) This function will 'clean' the entire cache. If the deletion of the cache files fails, the function will return FALSE. :returns: TRUE if deleted, FALSE if the deletion fails :rtype: Boolean :: $this->cache->clean(); cache_info() ============= .. php:method:: cache_info ( ) This function will return information on the entire cache. :returns: information on the entire cache :rtype: Mixed :: var_dump($this->cache->cache_info()); .. note:: The information returned and the structure of the data is dependent on which adapter is being used. get_metadata() =============== .. php:method:: get_metadata ( $id ) This function will return detailed information on a specific item in the cache. :param string $id: name of cached item :returns: metadadta for the cached item :rtype: Mixed :: var_dump($this->cache->get_metadata('my_cached_item')); .. note:: The information returned and the structure of the data is dependent on which adapter is being used. ******* Drivers ******* Alternative PHP Cache (APC) Caching =================================== All of the functions listed above can be accessed without passing a specific adapter to the driver loader as follows:: $this->load->driver('cache'); $this->cache->apc->save('foo', 'bar', 10); For more information on APC, please see `http://php.net/apc <http://php.net/apc>`_ File-based Caching ================== Unlike caching from the Output Class, the driver file-based caching allows for pieces of view files to be cached. Use this with care, and make sure to benchmark your application, as a point can come where disk I/O will negate positive gains by caching. All of the functions listed above can be accessed without passing a specific adapter to the driver loader as follows:: $this->load->driver('cache'); $this->cache->file->save('foo', 'bar', 10); Memcached Caching ================= Multiple Memcached servers can be specified in the memcached.php configuration file, located in the application/config/ directory. All of the functions listed above can be accessed without passing a specific adapter to the driver loader as follows:: $this->load->driver('cache'); $this->cache->memcached->save('foo', 'bar', 10); For more information on Memcached, please see `http://php.net/memcached <http://php.net/memcached>`_ Dummy Cache =========== This is a caching backend that will always 'miss.' It stores no data, but lets you keep your caching code in place in environments that don't support your chosen cache.