Simple page caching by technoslab.blogspot.com

<?php

/*
------------------------------------------------------
SIMPLE PAGE CACHING ENGINE
Author: Manish Raj
Website: http://technoslab.blogspot.com
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Table structure for cache.pages
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CREATE TABLE `pages` (
`pagehash` varchar(32) DEFAULT NULL,
`page` blob,
`cachetime` bigint(21) DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1
------------------------------------------------------
Usage:
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<?php
require('./class.cache.php');
$cache = new cache('localhost','root','','cache',3306,20);
?>
------------------------------------------------------
*/

class cache
{
    private $dbhost, $dbuser, $dbpass, $dbname, $dbport ;
    private $lifespan = 60 ;
    private $dbhandle = null ;
    private $pagehash = '' ;
    private $page = '' ;
    private $save = false ;

    // Constructor
    function __construct( $dbhost, $dbuser, $dbpass, $dbname, $dbport = 3306, $lifespan = 60 )
    {
        $this->dbhost = $dbhost ;
        $this->dbuser = $dbuser ;
        $this->dbpass = $dbpass ;
        $this->dbname = $dbname ;
        $this->dbport = $dbport ;
        $this->lifespan = $lifespan ;
        $this->connect() ;
        $this->render() ;
    }

    // Connect to database
    function connect()
    {
        $this->dbhandle = @new mysqli( $this->dbhost, $this->dbuser, $this->dbpass, $this->dbname, $this->dbport ) ;
        if ( ! empty( $this->dbhandle->connect_error ) )
        {
            exit( 'MySQL connection error.' ) ;
        }
    }

    // Retrive current page's md5 hash
    function current()
    {
        return md5( implode( '', $_GET ) . implode( '', $_POST ) . $_SERVER['REQUEST_URI'] ) ;
    }

    function render()
    {
        $current = $this->current() ;
        $lifespan = $_SERVER['REQUEST_TIME'] - $this->lifespan ;
        $check = $this->dbhandle->query( 'SELECT page FROM `pages` WHERE pagehash = "' . $current . '" AND cachetime > ' . $lifespan ) ;
        if ( $check->num_rows == 1 )
        {
            $contents = $check->fetch_object() ;
            echo $contents->page ;
            $this->delete() ;
            exit ;
        }
        else
        {
            ob_start() ;
            $this->save = true ;
            $this->pagehash = $current ;
        }
    }

    // Save to database
    function save( $pagehash, $page )
    {
        $this->dbhandle->query( 'INSERT INTO `pages` (pagehash,page,cachetime) VALUES ("' . $pagehash . '","' . $this->dbhandle->escape_string( $page ) . '",' . $_SERVER['REQUEST_TIME'] . ')' ) ;
    }

    // Delete old cached pages
    function delete()
    {
        $lifespan = $_SERVER['REQUEST_TIME'] - $this->lifespan ;
        $this->dbhandle->query( 'DELETE FROM `pages` WHERE cachetime < ' . $lifespan ) ;
    }

    // Destructor
    function __destruct()
    {
        if ( $this->save == true )
        {
            $this->page = ob_get_contents() ;
            ob_end_clean() ;
            $this->save( $this->pagehash, $this->page ) ;
            echo $this->page ;

        }
        if ( $this->dbhandle != null )
        {
            $this->dbhandle->close() ;
        }
    }
}

?>