10 Magento development tips | Episode 3 : Custom caching

Caching is one of the most powerful tools in a Magento 2 developer's arsenal for enhancing e-commerce site performance. Although Magento 2 provides several default cache types, there are times when application-specific data requires custom handling. Here's how you can effectively implement a custom cache in Magento 2 to store data optimally.

Why Use Custom Cache?

Before diving into implementation, understand why you might need a custom cache:

• Unique Data: If your modules deal with data that doesn't fit into Magento's existing cache types.
• Performance: For data that's frequently accessed but costly to generate.
• Control: To have fine-grained control over when and how data is cached or invalidated.

Step 1: Planning

Identify Data to Cache:

Begin by analyzing which data is most frequently used and consumes significant resources when generated.

Define Cache Lifetime:

Wisely choose the lifetime of cached data. Too short, and you won't reap performance benefits; too long, and you risk showing outdated information.

Step 2: Creating the Cache Type

Magento 2 allows you to create custom cache types through modules. Here's how:

Create a Module:

Set up a Magento 2 module if you don't have one already, located in app/code/YourNamespace/YourModule.

Define the Cache in cache.xml:

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Cache/etc/cache.xsd">
    <type name="your_unique_cache" translate="label,description" instance="YourNamespace\YourModule\Model\Cache\Type">
        <label>Your Custom Cache</label>
        <description>Description of your custom cache.</description>
    </type>
</config>

Implement the Cache Class:

<?php
namespace YourNamespace\YourModule\Model\Cache;

use Magento\Framework\App\Cache\Type\FrontendPool;

class Type extends \Magento\Framework\Cache\Frontend\Decorator\TagScope
{
    const TYPE_IDENTIFIER = 'your_unique_cache';
    const CACHE_TAG = 'YOUR_UNIQUE_CACHE';

    public function __construct(FrontendPool $cacheFrontendPool)
    {
        parent::__construct($cacheFrontendPool->get(self::TYPE_IDENTIFIER), self::CACHE_TAG);
    }
}

Step 3: Using the Cache

Dependency Injection:

In classes where you want to use the cache, inject Magento\Framework\App\CacheInterface through the constructor.

Saving and Loading Data:

<?php
use Magento\Framework\App\CacheInterface;

public function __construct(CacheInterface $cache)
{
    $this->cache = $cache;
}

public function getCustomData($identifier)
{
    $data = $this->cache->load($identifier);
    if ($data === false) {
        $data = $this->generateExpensiveData($identifier);
        $this->cache->save(serialize($data), $identifier, [Type::CACHE_TAG], 86400); // Cache for 24 hours
    }
    return unserialize($data);
}

private function generateExpensiveData($identifier)
{
    // Logic to generate expensive data
    return ['some' => 'data'];
}

Step 4: Cache Management

Cache Invalidation:

public function invalidateCache()
{
    $this->cache->clean([Type::CACHE_TAG]);
}

Define when cached data should be invalidated. This could be based on system events or user actions:

Cache Management UI:

Your custom cache will appear in the admin panel under Cache Management, allowing admins to clear it manually.

Step 5: Best Practices

• Use Cache Tags: Tags allow you to clean specific portions of the cache without clearing everything, which is crucial for dynamic data.
• Don't Overuse Caching: Ensure caching is used judiciously. Over-caching can increase memory usage without significant benefits.
• Testing and Monitoring: Test your caching implementation to ensure it works as intended and monitor performance before and after implementation.
• Documentation: Clearly document how your cache is used to help future developers understand and maintain the system.

Conclusion

Implementing a custom cache in Magento 2 can dramatically improve your site's performance, especially for application-specific data. By following these steps, you can ensure your cache is efficient, well-managed, and significantly contributes to the user experience. Remember, optimization is an ongoing process, so take time to evaluate and refine your caching approach over time.