/******************************************
 * class created by Exi (http://www.technobase.fm/member/1)
 * please find some information about on
 * http://blog.rarecore.eu/nfs-the-unperformed-file-system.html
 ******************************************/
 
class classDataBase {
 
    public static $connections;
    var $connection;
    var $Idx = 0;
    var $DBName;
 
    // error handling
    var $errNum; // error number
    var $errTxt; // error message
 
    // constructor - set default values
    function classDataBase() {
        if(!is_array(classDataBase::$connections)) {
            classDataBase::$connections = array();
            register_shutdown_function(array('classDataBase', 'DBCloseAll'));
        }
 
        $this->errNum = 0;
        $this->errTxt = "";
        $this->connectionID = false;
    }
 
    function Init($cDBName, $cDBHost, $cDBUser, $cDBPass) {
        $found = false;
        $retVal = false;
 
        if($this->connection) {
            $this->DBClose();
        }
 
        for($i=0; $iconnection = $a['connection'];
                        classDataBase::$connections[$i]['count']++;
                        $this->Idx = $i;
                        $found = true;
                        $retVal = true;
                        break;
                    }
            }
        }
 
        if(!$found) {
            $a = array();
 
            $retVal = $this->DBConnecting($cDBName, $cDBHost, $cDBUser, $cDBPass);
 
            if(!$retVal) {
                //Lost connection to MySQL server at 'reading authorization packet', system error: 0
                if($this->errNum != 2013) {
                    $mail  = "Error on connect to the Databasen";
                    $mail .= "Error Text: ".$this->errTxt."n";
                    $mail .= "Error Number: ".$this->errNum."n";
 
                    $this->ErrorMail($mail);
                }
 
                echo "<strong>Error on connect to the Database</strong>";
                exit();
            }    
 
            $a['dbname'] = $cDBName;
            $a['dbhost'] = $cDBHost;
            $a['dbuser'] = $cDBUser;
            $a['connection'] = $this-&gt;connection;
            $a['count'] = 1;
            array_push(classDataBase::$connections, $a);
        }
 
        $this-&gt;DBName = $cDBName;
 
        return $retVal;
    }
 
    function DBConnecting($cDBName, $cDBHost, $cDBUser, $cDBPass) {
        $retVal = true;
 
        // connect to database
        $this-&gt;connection = @mysql_connect($cDBHost, $cDBUser, $cDBPass);
 
        // throw error if connection failed ...
        if (!$this-&gt;connection) {
            $this-&gt;errNum = @mysql_errno();
            $this-&gt;errTxt = @mysql_error();
            $retVal = false;
        } else if(!@mysql_select_db($cDBName, $this-&gt;connection)) {
            $this-&gt;errNum = @mysql_errno();
            $this-&gt;errTxt = @mysql_error();
            $retVal = false;
        }
 
        return $retVal;
    }
 
    //function to execute statements
    function execSQL($SQLQuery, $mail = true) {
        $XSQL = false;
 
        if($this-&gt;connection) {
            $XSQL = mysql_query($SQLQuery, $this-&gt;connection);
 
            // Check for error
            if (!$XSQL) {
                $this-&gt;errNum = @mysql_errno($this-&gt;connection);
                $this-&gt;errTxt = @mysql_error($this-&gt;connection);   
 
                if($mail) {
                    $this-&gt;LogDBError($SQLQuery);
                }
            }
        }
 
        return $XSQL;
    }
 
    function query($SQLQuery) {
        return $this-&gt;execSQL($SQLQuery);
    }
 
    function queryCatch($SQLQuery) {
        return $this-&gt;execSQL($SQLQuery, false);
    }
 
    function insertId() {
        return mysql_insert_id($this-&gt;connection);
    }
 
    function affectedRows() {
        return mysql_affected_rows($this-&gt;connection);
    }
 
    //function to fetch the query
    function fetchArray($SQLQuery) {
        $XSQL = @mysql_fetch_array($SQLQuery);
 
        if(!$XSQL) {
            return false;
        } else {
            return $XSQL;
        }
    }
 
    function numRows($SQLQuery) {
        $XSQL = @mysql_num_rows($SQLQuery);
 
        if(!$XSQL) {
            return 0;
        } else {
            return $XSQL;
        }
    }
 
    //function to send a mail on error to the programer
    function ErrorMail($Content) {
        // send an email to the programmer?
        echo '<strong>change the ErrorMail function!!!</strong>'.$Content;
    }
 
    function LogDBError($Statement = "") {
        /*
        // log the database errors?!?
        $qry = 'INSERT INTO dberror
                        SET dberr_number = ''.$this-&gt;errNum.'',
                            dberr_text = ''.mysql_escape_string($this-&gt;errTxt).'',
                            dberr_statement = ''.mysql_escape_string($Statement).'',
                            dberr_site = ''.$_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI'].'',
                            dberr_ip = ''.$_SERVER['REMOTE_ADDR'].'',
                            dberr_time = ''.time().'',
                            dberr_sent = 0';
 
        @mysql_db_query($this-&gt;DBName, $qry, $this-&gt;connection);*/
 
        echo nl2br('
              dberr_number = ''.$this-&gt;errNum.'',
              dberr_text = ''.$this-&gt;errTxt.'''
             );
 
        echo '<strong>change the LogDBError function!!!'</strong>.$Statement;
    }
 
    function ListTables() {
        $result = @mysql_list_tables($this-&gt;DBName, $this-&gt;connection);
 
        $table_names = array();
 
        for($x=0; $x &lt; $this-&gt;numRows($result); $x++) {
            $table_names[$x] = @mysql_tablename($result,$x);
        }
 
        return $table_names;
    }
 
    function DBClose() {
        if($this-&gt;connection) {
            if(classDataBase::$connections[$this-&gt;Idx]['count'] == 1) {
                @mysql_close($this-&gt;connection);
            }          
 
            classDataBase::$connections[$this-&gt;Idx]['count']--;
            $this-&gt;connection = false;
        }
    }
 
    function DBCloseAll() {
        if(class_exists('mysql_session_handler')) {
            session_write_close();
        }
 
        for($i=0; $i
 
After creating our database class we want to write our own session handling. At first we've to create a simple MySQL Table. I called my table cache_session. I want to prefix my example tables with cache_.

/******************************************
 * class created by Exi (http://www.technobase.fm/member/1)
 * please find some information about on
 * http://blog.rarecore.eu/nfs-the-unperformed-network-file-system
 ******************************************/
include_once 'classDataBase.php';
if(!class_exists('mysql_session_handler')) {
    class mysql_session_handler {
        static $life_time;
        static $mysql;
 
        // construct
        function mysql_session_handler() {
            // read the maxlifetime setting from PHP
            mysql_session_handler::$life_time = get_cfg_var('session.gc_maxlifetime');    
 
            // register this object as the session handler
            session_set_save_handler(
                array(&$this, 'open'),
                array(&$this, 'close'),
                array(&$this, 'read'),
                array(&$this, 'write'),
                array(&$this, 'destroy'),
                array(&$this, 'gc')
            );  
 
            if(mysql_session_handler::$mysql == null) {
                // create a new database connection or use the already opened
                mysql_session_handler::$mysql = new classDataBase();
                mysql_session_handler::$mysql->Init('db', 'ip', 'user', 'password');
            }
        }
 
        // open session -> just to have. no action
        function open($save_path, $session_name) {
            global $sess_save_path;
            $sess_save_path = $save_path;
            return true;
        }
 
        // read session data
        function read($id) {
            $data = '';
 
            $qry = mysql_session_handler::$mysql->query("select session_data
                                                           from cache_sessions
                                                          where session_id = '".mysql_escape_string($id)."'
                                                            and session_expires >= ".time());
 
            while($fetch = mysql_session_handler::$mysql->fetchArray($qry)) {
                $data = $fetch[0];
            }
 
            return $data;
        }
 
        // insert / update session information
        function write($id, $data) {
            mysql_session_handler::$mysql->query("replace into cache_sessions
                                                              (session_id,
                                                               session_data,
                                                               session_expires)
                                                       values ('".mysql_escape_string($id)."',
                                                               '".mysql_escape_string($data)."',
                                                                ".(time() + mysql_session_handler::$life_time).")");
 
            return true;
        }
 
        // destroy a session
        function destroy($id) {
            mysql_session_handler::$mysql->query("delete from cache_sessions where session_id = '".mysql_escape_string($id)."'");
            return true;
        }
 
        // clean old session
        function gc() {
            // do not clean by an page call, use a cronjob to delete all expired entries every minute!
            /*mysql_session_handler::$mysql->query('delete from cache_sessions where session_expires < '.time());*/
 
            return true;
        }
 
        // close session
        function close() {
            return true;
        }
    }   
 
    $SessionHandler = new mysql_session_handler();
}

include 'mysql_session_handler.php';
session_start();
if(!isset($_SESSION['a'])) {
    $_SESSION['a'] = 1;
    echo 'session "a" not set!';
} elseif($_SESSION['a'] == 10) {
    session_destroy();
    echo 'session destroyed';
 
} else {
    $_SESSION['a']++;
    echo 'session "a" set!';
}

/******************************************
 * class created by Exi (http://www.technobase.fm/member/1)
 * please find some information about on
 * http://blog.rarecore.eu/nfs-the-unperformed-file-system.html
 ******************************************/
 
include_once 'Smarty.class.php';
include_once 'classDataBase.php';
include_once 'mysql_cache_handler.php';
 
class classSmarty extends Smarty {
    var $mysql;
 
    function classSmarty() {
        parent::Smarty(); 
 
        $this->template_dir  = '_smarty/templates';
        $this->compile_dir   = '_smarty/templates_c';
        $this->cache_dir     = '_smarty/cache';
        $this->config_dir    = '_smarty/config';
 
        $this->compile_check = true;
        $this->debugging     = false;
        $this->caching       = true;
 
        $this->mysql = new classDataBase();
        $this->mysql->Init('db', 'host', 'user', 'pass');
        $this->cache_handler_func = 'mysql_cache_handler';
    }
}

/******************************************
 * class created by Exi (http://www.technobase.fm/member/1)
 * please find some information about on
 * http://blog.rarecore.eu/nfs-the-unperformed-file-system.html
 ******************************************/
 
function mysql_cache_handler($action, &$smarty_obj, &$cache_content, $tpl_file = null, $cache_group = null, $compile_id = null, $exp_time = 0) {
    $db_table = 'cache_smarty';
 
    // create unique cache id
    $cache_id = md5($tpl_file.$cache_group.$compile_id); 
 
    switch ($action) {
        case 'read':
            // read cache from database
            $results = $smarty_obj->mysql->query("select smarty_content from $db_table where smarty_cacheId = '$cache_id' and smarty_expire > ".time()); 
 
            if(!$results) {
                $smarty_obj->_trigger_error_msg('cache_handler: query failed.');
            } 
 
            $row = $smarty_obj->mysql->fetchArray($results);
            $cache_content = $row[0]; 
 
            $return = $results;
            break; 
 
        case 'write':
            // save cache to database
            $results = $smarty_obj->mysql->query("replace into $db_table (
                                                           smarty_cacheId,
                                                           smarty_template,
                                                           smarty_group,
                                                           smarty_content,
                                                           smarty_expire
                                                         ) values (
                                                           '$cache_id',
                                                           '$tpl_file',
                                                           '$cache_group',
                                                           '".addslashes($cache_content)."',
                                                           '".($exp_time == 0 ? time() + 3600 : $exp_time)."' )"); // no expire => expire next hour
 
            if(!$results) {
                $smarty_obj->_trigger_error_msg('cache_handler: query failed.');
            } 
 
            $return = $results;
            break; 
 
        case 'clear':
            // clear cache info
            if(empty($cache_group) && empty($compile_id) && empty($tpl_file)) {
                $results = $smarty_obj->mysql->query("delete from $db_table"); 
 
            } else {
                /*
                if(!$smarty_obj->mysql->query("delete from $db_table where smarty_expire < ".time())) {
                    $smarty_obj->_trigger_error_msg('cache_handler: clear expired entries query failed.');
                }
                */
 
                if(strpos($cache_group, '|')) {
                   if(!empty($tpl_file)) {
                      $results = $smarty_obj->mysql->query("delete from $db_table where smarty_template = '$tpl_file' AND smarty_group LIKE '$cache_group%'"); 
 
                   } else {
                      $results = $smarty_obj->mysql->query("delete from $db_table where smarty_group LIKE '$cache_group%'"); 
 
                   }
                } else {
                   $results = $smarty_obj->mysql->query("delete from $db_table where smarty_cacheId = '$cache_id'"); 
 
                }
            } 
 
            if(!$results) {
                $smarty_obj->_trigger_error_msg('cache_handler: query failed.');
            } 
 
            $return = $results;
            break; 
 
        default:
            // error, unknown action
            $smarty_obj->_trigger_error_msg("cache_handler: unknown action "$action"");
            $return = false;
            break;
    } 
 
    return $return;
}

include_once 'classSmarty.php';
 
$smarty = new classSmarty();
$smarty->caching = true;
$smarty->cache_lifetime = 10;
 
$template = 'smarty.html';
$cache_id = 'smarty|1337';
 
if(!$smarty->is_cached($template, $cache_id)) {
    $smarty->assign('time', date('H:i:s', time()));
    $smarty->assign('a', rand(1, 9999));
    $smarty->assign('b', rand(1, 9999));
    $smarty->assign('c', rand(1, 9999));
}
 
$smarty->display($template, $cache_id);