/phpcache.class.php

<?php

	

	/**

	 * This program is free software; you can redistribute it and/or modify

    * it under the terms of the GNU General Public License as published by

    * the Free Software Foundation; either version 2 of the License, or

    * (at your option) any later version.

    * 

    * This program is distributed in the hope that it will be useful,

    * but WITHOUT ANY WARRANTY; without even the implied warranty of

    * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

    * GNU General Public License for more details.

	 * 

    * You should have received a copy of the GNU General Public License

    * along with this program; if not, write to the Free Software

    * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

	 *

 	 * D O  N O T  R E M O V E  T H E S E  C O M M E N T S

	 *	 

	 * @Package PHPCache

	 * @Author  Hamid Alipour, http://blog.code-head.com/ http://www.hamidof.com/

	 */

	

	

	if( !defined('PHPCACHE_BASE_DIR') )   			define('PHPCACHE_BASE_DIR', 			dirname(__FILE__));

	if( !defined('PHPCACHE_DRIVER_DIR') ) 			define('PHPCACHE_DRIVER_DIR', 		PHPCACHE_BASE_DIR .DIRECTORY_SEPARATOR .'drivers');

	if( !defined('PHPCACHE_BD_LOGIN_ATTEMPT') ) 	define('PHPCACHE_BD_LOGIN_ATTEMPT', 100);

	

	define('PHPCACHE_TIME_NOW', 			time());

	define('PHPCACHE_1_SECOND', 			1);

	define('PHPCACHE_1_MINUTE', 			PHPCACHE_1_SECOND * 60);

	define('PHPCACHE_1_HOUR', 				PHPCACHE_1_MINUTE * 60);

	define('PHPCACHE_1_DAY', 				PHPCACHE_1_HOUR   * 24);

	define('PHPCACHE_1_WEEK', 				PHPCACHE_1_DAY 	* 4);

	define('PHPCACHE_1_MONTH', 			PHPCACHE_1_DAY		* 30);

	define('PHPCACHE_1_YEAR', 				PHPCACHE_1_MONTH	* 12);

	

	/**

	 *	PHPCACHE_GC_PROBABILITY = 10 &

	 * PHPCACHE_GC_DIVISOR = 100

	 * Means there is 10% chance that the garbage collection will be done on each

	 * PHPCache::configure($database) call

	 */

	if( !defined('PHPCACHE_GC_PROBABILITY') ) define('PHPCACHE_GC_PROBABILITY',	1);

	if( !defined('PHPCACHE_GC_DIVISOR') )   	define('PHPCACHE_GC_DIVISOR',			100);

	

	/**

	 * TO = Table optimizer

	 */

	if( !defined('PHPCACHE_TO_PROBABILITY') ) define('PHPCACHE_TO_PROBABILITY',	10);

	if( !defined('PHPCACHE_TO_DIVISOR') )   	define('PHPCACHE_TO_DIVISOR',			100);

	

	require_once PHPCACHE_BASE_DIR   .DIRECTORY_SEPARATOR .'phpcache.interface.php';

	require_once PHPCACHE_DRIVER_DIR .DIRECTORY_SEPARATOR .'phpcache.driver.interface.php';

	

	

	class PHPCache implements PHPCache_Interface {

		

		private $db_handle;

		private $db_table;

		static  private $instance;

		private $time_now;

		private $last_error;

		

		

		private function __construct($params) {

			if( !isset($params['type']) ) {

				$this->trigger_error('I couldn\'t find the database type in $params[\'type\'].');

			}

			$database_type = strtolower($params['type']);

			

			$driver_file   = PHPCACHE_DRIVER_DIR .DIRECTORY_SEPARATOR .'phpcache.driver.' .$database_type .'.class.php';

			if( !file_exists($driver_file) ) {

				$this->trigger_error('PHPCache doesn\'t support the database type in $params[\'type\'] yet.');

			}	

			require_once($driver_file);

			

			$driver_class		 = 'PHPCache_Driver_' .$database_type;

			$this->db_handle = new $driver_class($params);

			

			$this->db_table   = isset($params['table']) ? $params['table'] : 'PHPCache';

			$this->time_now   = PHPCACHE_TIME_NOW;

			$this->last_error = NULL;

			

			$this->clean_up();

		}

		

		public static function configure($params) {

			if( self::$instance == NULL ) {

				self::$instance = new PHPCache($params);

			}

		}

		

		public static function instance() {

			if( self::$instance == NULL ) {

				$this->trigger_error('You have to call PHPCache::configure first.');

			}

			return self::$instance;

		}

		

		public function create_table() {

			$this->db_handle->create_table($this->db_table);

		}

		

		public function store($key, $value, $expires) {

			$data = array(

				'PHPCache_key' 	 => $this->db_handle->escape(md5($key)),

				'PHPCache_value'	 => $this->db_handle->escape(serialize($value)),

				'PHPCache_expires' => $this->db_handle->escape($this->time_now + $expires)

			);

			

			$query = "

					REPLACE INTO 

						{$this->db_table}

					   (

							PHPCache_key,

							PHPCache_value,

							PHPCache_expires

						)

					VALUES

						(

							 {$data['PHPCache_key']},

							 {$data['PHPCache_value']},

							 {$data['PHPCache_expires']}

						)

			";

			

			if( $this->db_handle->query($query) ) {

				return true;

			} else {

				$this->last_error = $this->db_handle->error();

				return false;

			}

		}

		

		public function get($key) {

			$key 	= $this->db_handle->escape(md5($key));

			

			$query = "

				SELECT 

					PHPCache_value, PHPCache_expires

				FROM 	 

					{$this->db_table}

				WHERE

					PHPCache_key = $key

			";

			

			if( !($result = $this->db_handle->query($query)) ) {

				$this->trigger_error($this->db_handle->error());

				return false;

			}

			

			if( $result->num_rows < 1 ) {

				return false;

			}

			

			$data	  = $result->fetch_assoc();

			

			if( $data['PHPCache_expires'] < $this->time_now ) {

				return false;

			}

			

			if( $data['PHPCache_value'] && trim($data['PHPCache_value']) != '' ) {

				$_data = unserialize($data['PHPCache_value']);

				if( $_data === false ) {

					$this->trigger_error("Unserialize failed, you might need to increase the size of database column {$this->db_table}.PHPCache_value");

					return false;

				}

				return $_data;

			} else {

				return NULL;

			}

		}

		

		public function set_expire($key) {

			$key 	 		= $this->db_handle->escape(md5($key));

			$expires 	= $this->db_handle->escape($this->time_now - PHPCACHE_1_YEAR);

			

			$query = "

				REPLACE INTO 

					{$this->db_table}

					(

						PHPCache_key,

						PHPCache_expires

					)

				VALUES

					(

						 {$key},

						 {$expires}

					)

			";

			$this->db_handle->query($query);

		}

		

		public function remove($key) {

			$key 	 = $this->db_handle->escape(md5($key));

			$query = "

				DELETE

				FROM

					{$this->db_table}

				WHERE

					PHPCache_key = $key

			";

			$this->db_handle->query($query);

		}

		

		public function clean_up() {

			if( rand(1, PHPCACHE_GC_DIVISOR) <= PHPCACHE_GC_PROBABILITY ) {

				$this->gc();

			}

			if( rand(1, PHPCACHE_TO_DIVISOR) <= PHPCACHE_TO_PROBABILITY ) {

				$this->optimize_table();

			}

		}

		

		public function gc() {

			$query = "

				DELETE

				FROM 	 

					{$this->db_table}

				WHERE

					PHPCache_expires < {$this->time_now}

			";

			$this->db_handle->query($query);

		}

		

		public function optimize_table() {

			$this->db_handle->optimize_table($this->db_table);

		}

		

		private function trigger_error($msg) {

			$this->last_error = $msg;

			trigger_error("PHPCache Error: $msg", E_USER_ERROR);

			exit;

		}

		

		public function has_error() {

			return $this->last_error != NULL;

		}

		

		public function last_error() {

			return $this->last_error;

		}

		

	} // Class

	

?>