For per-request caching, #4065

memory.php

<?php defined('SYSPATH') or die('No direct script access.');

/**
 * Non-persistent, in-memory implementation of [Kohana Cache](api/Kohana_Cache).
 *
 * @package     Kohana/Cache
 * @category    Base
 * @author      Kohana Team
 * @copyright   (c) 2011 Kohana Team
 * @license     http://kohanaphp.com/license
 */
class Kohana_Cache_Memory extends Cache
{
	/**
	 * @var array
	 */
	protected $_data = array();

	public function delete($id)
	{
		unset($this->_data[$id];

		return TRUE;
	}

	public function delete_all()
	{
		$this->_data = array();

		return TRUE;
	}

	public function get($id, $default = NULL)
	{
		if ( ! isset($this->_data[$id]))
			return $default;

		list($expiry, $data) = $this->_data[$id];

		if ($expiry < now())
		{
			unset($this->_data[$id];

			return $default;
		}

		return $data;
	}

	public function set($id, $data, $lifetime = NULL)
	{
		if ($lifetime === NULL)
		{
			$lifetime = Arr::get($this->_config, 'default_expire', Cache::DEFAULT_EXPIRE);
		}

		$this->_data[$id] = array(now() + $lifetime, $data);

		return TRUE;
	}
}