Loading the Optimal WordPress Object Cache Implementation (modified)

object-cache.php

<?php

/**
 * Based on an idea and code by webdev studios: https://webdevstudios.com/2015/11/03/loading-the-optimal-wordpress-object-cache-implementation-in-your-production-staging-and-local-development-environments/
 */


$plugin_dir = ( defined( 'WP_PLUGIN_DIR' ) ? WP_PLUGIN_DIR : WP_CONTENT_DIR . '/plugins' );

// If Redis exists and redis server is configured,
if ( class_exists( 'Redis' ) && isset( $GLOBALS['redis_server'] ) ) {

	// Then load our object cache plugin (if available).
	if ( file_exists( $plugin_dir . '/wp-redis/object-cache.php' ) ) {
		require_once $plugin_dir . '/wp-redis/object-cache.php';
	}
	
}

// Fallback to check for memcached if redis server isn’t available
elseif ( class_exists( 'Memcache' ) && isset( $GLOBALS['memcached_servers'] ) ) {

	// Then load our object cache plugin (if available).
	if ( file_exists( $plugin_dir . '/memcached/object-cache.php' ) ) {
		require_once $plugin_dir . '/memcached/object-cache.php';
	}

}


/**
 * If we can't use the object-cache, we need some trickery
 * for WP to believe we aren't actually using an object-cache
 * (which it assumes since we have this file)
 */
else {

	// Helper/callback.
	function set_wp_using_ext_object_cache_to_false() {
		wp_using_ext_object_cache( false );
	}

	// Set to false now.
	// (After this file loads, WP resets to true.)
	set_wp_using_ext_object_cache_to_false();

	// Include the built-in WP object-caching.
	require_once( ABSPATH . WPINC . '/cache.php' );

	// Hook in to reset to false,
	add_action(
		'muplugins_loaded', // To the earliest hook,
		'set_wp_using_ext_object_cache_to_false',
		-9999 // At a super early priority.
	);
}