Silverstripe partial caching methods

PageController.php

<?php

use SilverStripe\CMS\Controllers\ContentController;
use SilverStripe\Control\Director;
use SilverStripe\Core\Environment;

/**
 * Below are some methods that can be added to PageController for use in partial caching blocks.
 * Example: <% cached $EnvCacheKey, $ClassCacheKey('SilverStripe\CMS\Model\SiteTree') unless $DontCache %>
 */
class PageController extends ContentController
{
    /**
     * Generate a cache key for the current environment.
     *
     * @return string
     */
    public function EnvCacheKey()
    {
        return __FUNCTION__ . md5(serialize([
            // Dev mode can affect output
            Director::get_environment_type(),
            // Split cache by protocol to prevent accidental mixed-content issues
            Director::protocolAndHost(),
        ]));
    }

    public function TodayCacheKey()
    {
        // Reset cache every day to ensure date based content is accurate
        return __FUNCTION__ . date('Y-m-d');
    }

    /**
     * Get a cache key which represents the approximate state of a page
     *
     * @param string $class
     * @return string
     */
    public function PageCacheKey()
    {
        return __FUNCTION__ . md5(serialize([
            static::class,
            // Identify by ID, or URL as a fallback. Note that Security pages (and maybe others?)
            // generate a random ID so the fallback may be redundant
            $this->ID ? $this->ID : $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'],
            $this->request->params(),
            $this->LastEdited,
        ]));
    }

    /**
     * Get a cache key which get the approximate state of a class.
     * Will not capture things like sort order if changes bypass the ORM.
     *
     * @param string $class
     * @return string
     */
    public function ClassCacheKey($class)
    {
        return __FUNCTION__ . md5(serialize([
            $class,
            $class::get()->max('LastEdited'), // Catch created / edited
            $class::get()->count(), // Catch deleted
        ]));
    }

    /**
     * Use on a ManyManyList or potentially a DataList HasManyList.
     * 
     * Generate a cache key that covers:
     * - Which items are in this list
     * - The sort order of these items
     * - The most recent LastEdited value
     *
     * Note that for a DataList or HasManyList ClassCacheKey() should generally
     * be sufficient to invalidate when something changes.
     *
     * @param mixed $dataList
     * @return void
     */
    public function ListCacheKey($dataList)
    {
        return md5(serialize([
            // Namespace for this cacheblock
            $dataList->dataClass(),
            // This covers which objects are linked and their sort order
            $dataList->column('ID'),
            // This catches edits
            $dataList->max('LastEdited'),
        ]));
    }

    /**
     * Caching can be temporarily disabled by setting environmental
     * variable SS_DISABLE_PARTIAL_CACHING to true.
     * Add any other logical tests here that should prevent caching.
     */
    public function DontCache()
    {
        return Environment::getEnv('SS_DISABLE_PARTIAL_CACHING');
    }
}