APC is legacy and does not exist anymore. But apcu works awesome so adjusted the config sample

application/config/config.sample.php

@@ -401,7 +401,7 @@ $config['error_views_path'] = '';
 |     - 'file'      : File-based caching (default, works everywhere)
 |     - 'redis'     : Redis in-memory cache (requires Redis server & extension)
 |     - 'memcached' : Memcached (requires Memcached server & extension)
-|     - 'apc'       : APC/APCu in-memory cache (requires APCu extension)
+|     - 'apcu'      : APCu in-memory cache (requires APCu extension)
 |     - 'wincache'  : Windows Cache (requires WinCache extension)
 |
 | 'cache_backup'

system/libraries/Cache/drivers/Cache_apc.php

@@ -1,218 +0,0 @@
-<?php
-/**
- * CodeIgniter
- *
- * An open source application development framework for PHP
- *
- * This content is released under the MIT License (MIT)
- *
- * Copyright (c) 2019 - 2022, CodeIgniter Foundation
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- *
- * @package	CodeIgniter
- * @author	EllisLab Dev Team
- * @copyright	Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
- * @copyright	Copyright (c) 2014 - 2019, British Columbia Institute of Technology (https://bcit.ca/)
- * @copyright	Copyright (c) 2019 - 2022, CodeIgniter Foundation (https://codeigniter.com/)
- * @license	https://opensource.org/licenses/MIT	MIT License
- * @link	https://codeigniter.com
- * @since	Version 2.0.0
- * @filesource
- */
-defined('BASEPATH') OR exit('No direct script access allowed');
-
-/**
- * CodeIgniter APC Caching Class
- *
- * @package		CodeIgniter
- * @subpackage	Libraries
- * @category	Core
- * @author		EllisLab Dev Team
- * @link
- */
-class CI_Cache_apc extends CI_Driver {
-
-	/**
-	 * Class constructor
-	 *
-	 * Only present so that an error message is logged
-	 * if APC is not available.
-	 *
-	 * @return	void
-	 */
-	public function __construct()
-	{
-		if ( ! $this->is_supported())
-		{
-			log_message('error', 'Cache: Failed to initialize APC; extension not loaded/enabled?');
-		}
-	}
-
-	// ------------------------------------------------------------------------
-
-	/**
-	 * Get
-	 *
-	 * Look for a value in the cache. If it exists, return the data
-	 * if not, return FALSE
-	 *
-	 * @param	string
-	 * @return	mixed	value that is stored/FALSE on failure
-	 */
-	public function get($id)
-	{
-		$success = FALSE;
-		$data = apc_fetch($id, $success);
-
-		return ($success === TRUE) ? $data : FALSE;
-	}
-
-	// ------------------------------------------------------------------------
-
-	/**
-	 * Cache Save
-	 *
-	 * @param	string	$id	Cache ID
-	 * @param	mixed	$data	Data to store
-	 * @param	int	$ttl	Length of time (in seconds) to cache the data
-	 * @param	bool	$raw	Whether to store the raw value (unused)
-	 * @return	bool	TRUE on success, FALSE on failure
-	 */
-	public function save($id, $data, $ttl = 60, $raw = FALSE)
-	{
-		return apc_store($id, $data, (int) $ttl);
-	}
-
-	// ------------------------------------------------------------------------
-
-	/**
-	 * Delete from Cache
-	 *
-	 * @param	mixed	unique identifier of the item in the cache
-	 * @return	bool	true on success/false on failure
-	 */
-	public function delete($id)
-	{
-		return apc_delete($id);
-	}
-
-	// ------------------------------------------------------------------------
-
-	/**
-	 * Increment a raw value
-	 *
-	 * @param	string	$id	Cache ID
-	 * @param	int	$offset	Step/value to add
-	 * @return	mixed	New value on success or FALSE on failure
-	 */
-	public function increment($id, $offset = 1)
-	{
-		return apc_inc($id, $offset);
-	}
-
-	// ------------------------------------------------------------------------
-
-	/**
-	 * Decrement a raw value
-	 *
-	 * @param	string	$id	Cache ID
-	 * @param	int	$offset	Step/value to reduce by
-	 * @return	mixed	New value on success or FALSE on failure
-	 */
-	public function decrement($id, $offset = 1)
-	{
-		return apc_dec($id, $offset);
-	}
-
-	// ------------------------------------------------------------------------
-
-	/**
-	 * Clean the cache
-	 *
-	 * @return	bool	false on failure/true on success
-	 */
-	public function clean()
-	{
-		return apc_clear_cache('user');
-	}
-
-	// ------------------------------------------------------------------------
-
-	/**
-	 * Cache Info
-	 *
-	 * @param	string	user/filehits
-	 * @return	mixed	array on success, false on failure
-	 */
-	public function cache_info($type = NULL)
-	{
-		return apc_cache_info($type);
-	}
-
-	// ------------------------------------------------------------------------
-
-	/**
-	 * Get Cache Metadata
-	 *
-	 * @param	mixed	key to get cache metadata on
-	 * @return	mixed	array on success/false on failure
-	 */
-	public function get_metadata($id)
-	{
-		$cache_info = apc_cache_info('user', FALSE);
-		if (empty($cache_info) OR empty($cache_info['cache_list']))
-		{
-			return FALSE;
-		}
-
-		foreach ($cache_info['cache_list'] as &$entry)
-		{
-			if ($entry['info'] !== $id)
-			{
-				continue;
-			}
-
-			$success  = FALSE;
-			$metadata = array(
-				'expire' => ($entry['ttl'] ? $entry['mtime'] + $entry['ttl'] : 0),
-				'mtime'  => $entry['ttl'],
-				'data'   => apc_fetch($id, $success)
-			);
-
-			return ($success === TRUE) ? $metadata : FALSE;
-		}
-
-		return FALSE;
-	}
-
-	// ------------------------------------------------------------------------
-
-	/**
-	 * is_supported()
-	 *
-	 * Check to see if APC is available on this system, bail if it isn't.
-	 *
-	 * @return	bool
-	 */
-	public function is_supported()
-	{
-		return (extension_loaded('apc') && ini_get('apc.enabled'));
-	}
-}