Magento - Tips and Tricks: Cache

Wednesday, July 30, 2014

Magento : Difference between “Flush Magento Cache” and “Flush Cache Storage” in magento cache management

Flush Magento Cache

Removes all items in the default Magento cache (var/cache) and the var/full_page cache that have a Magento tag

Flush Cache Storage

Removes all items in the cache. This is the equivalent of deleting the entire contents of the cache folder on the server.If your system uses an alternate cache location, any cached files used by other applications will be removed.

Wednesday, December 4, 2013

Magento : Full Page Cache

Full Page Cache (FPC) is:
As in every thing that is generated from a script is written to HTML and served next time, improving performance (by reducing load and not having to generate the page for every visit).

In order to understand Magento Full Page Cache, we need to understand what the run function in Mage_Core_Model_App

public function run($params)
{
$options = isset($params['options']) ? $params['options'] : array();
$this->baseInit($options);
Mage::register('application_params', $params);

if ($this->_cache->processRequest()) {
$this->getResponse()->sendResponse();
} else {
$this->_initModules();
$this->loadAreaPart(Mage_Core_Model_App_Area::AREA_GLOBAL, Mage_Core_Model_App_Area::PART_EVENTS);

if ($this->_config->isLocalConfigLoaded()) {
$scopeCode = isset($params['scope_code']) ? $params['scope_code'] : '';
$scopeType = isset($params['scope_type']) ? $params['scope_type'] : 'store';
$this->_initCurrentStore($scopeCode, $scopeType);
$this->_initRequest();
Mage_Core_Model_Resource_Setup::applyAllDataUpdates();
}

$this->getFrontController()->dispatch();
}
return $this;
}

Here $this->_cache->processRequest()
line checks if you have defined a caching node like this under app/etc/test.xml

<config>
<global>
<cache>
<request_processors>
<lt>Bd_Fullpagecache_Model_Processor</lt>
</request_processors>
</cache>
</global>
</config>

The next thing that magento does is to find/initialize the class you have defined and it expects that you have an extractContent function defined in your model.

Friday, August 16, 2013

Magento : How to cache custom data into Magento

Use following code in configuration file as
<global>
    <cache>
        <types>
            <namespace_module module="namespace_module" translate="label description">
                <label>Your modules cache label</label>
                <description>Description of your modules cache</description>
                <tags>YOUR_MODULES_CACHE_TAGS</tags>
            </namespace_module>
        </types>
    </cache>
</global>
Then create a model class file witha variable and a method as
const CACHE_TAG_NAMESPACE_MODULE = 'YOUR_MODULES_CACHE_TAGS';
$cacheGroup = 'namespace_module';
$useCache = Mage::app()->useCache($cacheGroup);
if (true === $useCache) {
    // Cache is active
   $cacheId = "unique_name";
   if ($cacheContent = Mage::app()->loadCache($cacheId)) {
   $html = $cacheContent;
   return $html;
   }else{

   try {
       $cacheContent = $html;
       $tags = array(model::CACHE_TAG_NAMESPACE_MODULE);
       $lifetime = Mage::getStoreConfig('core/cache/lifetime');
       Mage::app()->saveCache($cacheContent, $cacheId, $tags, $lifetime);
        } catch (Exception $e) {
       // Exception = no caching
       Mage::logException($e);
   }
   return $html;
   }
} else {
    // Cache is not active
   return $html;
}

Also we can following code for clean the cache
Mage::app()->removeCache($cacheId);

By default Magento uses its file system to save cache (files located in the directory var/cache/).
Another option is the database, which is slower then the files option mostly because the database is a heavily used resource for Magento instances anyway. Then there are storage schemes that use RAM (which are much faster), e.g. APC (shared memory) or memcached (a networked caching server) or Redis.

The Magento cache is organized by tags, this means you have cache entries which belongs to a cache group.

APC is an opcode cache for PHP. It is a framework for caching and optimizing PHP code. APC also serves as a user cache. APC cache is stored in memory where performance gains over file system cache are huge.
There following step to configure APC in Magento
1. Install php5-apc package (like sudo apt-get install php5-apc)
2. Edit and configure setting in apc.ini
3. Add the following code between the global tags in app/etc/local.xml.
<global>
<cache>
<backend>apc</backend>
<prefix>mystore_</prefix>
</cache>
</global>

There following step to configure Memcache as a Fast Backend in Magento
1. Install Memcache as a PHP extension (apt-get install memcached )
2. And enable it in your php.ini
3. Add the following code between the global tags in app/etc/local.xml.
<cache>
<backend>memcached</backend>

<memcached>

<servers>

<server>
<host><![CDATA[127.0.0.1]]></host>
<port><![CDATA[11211]]></port>
<persistent><![CDATA[1]]></persistent>
</server>
</servers>
<compression><![CDATA[0]]></compression>
<cache_dir><![CDATA[]]></cache_dir>
<hashed_directory_level><![CDATA[]]></hashed_directory_level>
<hashed_directory_umask><![CDATA[]]></hashed_directory_umask>
<file_name_prefix><![CDATA[]]></file_name_prefix>
</memcached>
</cache>

There following step to configure Redis as a Fast Backend in Magento
1. Install redis (2.4+ required)
2. Install phpredis
3. Install the magento extension “Cm_Cache_Backend_Redis”
4. Add the following code between the global tags in app/etc/local.xml.
<cache>
<backend>Zend_Cache_Backend_Redis</backend> <slow_backend>database</slow_backend> <slow_backend_store_data>0</slow_backend_store_data> <auto_refresh_fast_cache>0</auto_refresh_fast_cache>
<backend_options>
<server><![CDATA[127.0.0.1]]></server>
<port><![CDATA[11211]]></port>
<database>database</database>
<use_redisent>0</use_redisent>  <automatic_cleaning_factor>0</automatic_cleaning_factor> 
</backend_options>
</cache>