How to cache a block in block_html cache type in Magento 2?

Question

I have a block file that does heavy data processing due to which my product page PHP rendering time increases above 2 seconds. I have disabled page_cache in my Magento 2 system so i cannot use cacheable="true" in my layout file that loads this block file with it's template. I am looking for a solution where i can cache this file code into block_html cache type. Can anyone please tell me the solution on how i can implement this functionality.

My SampleClass is below which is extending core Magento 2's \Magento\Catalog\Block\Product\View class:

class SampleClass extends \Magento\Catalog\Block\Product\View
{
 //rest of my code like __construct and other custom methods.
}

Answer 1

Finally got a solution for the above question. I have used two methods getCacheLifetime() and getCacheKeyInfo() of the core Magento 2 template block file and overridden those two methods of the class: Magento\Framework\View\Element\AbstractBlock.

The code looks like below:

//below code to set the life time of the cache
protected function getCacheLifetime()
{
    return parent::getCacheLifetime() ?: 3600;
}

//below method to keep cache key unique for each product page.
public function getCacheKeyInfo()
{
    $keyInfo     =  parent::getCacheKeyInfo();
    $keyInfo[]   =  $this->getProduct()->getId(); // adding the product id to the cache key so that each cache built remains unique as per the product page.
    return $keyInfo;
}

Answer 2

Or you can just add di.xml on your frontend area as below:

<type name="MyBlock">
    <arguments>
        <argument name="data" xsi:type="array">
            <item name="cache_lifetime" xsi:type="number">3600</item>
            <item name="cache_key" xsi:type="string">UNQKEY</item> // Not needed unless same block name and multiple outputs based on pid or something
        </argument>
    </arguments>
</type>