function  load_libs($dir) {
        $dir_handle =  opendir ($dir);
         while (($file =  readdir ($dir_handle)) !==  false  ) {
             if ($file != "." && $file != ".." ) {
                $path = $dir . "/" . $file;                
                 include_once  $dir.'/'.$file;                 
                 if ( is_dir ($path)) {
                    load_libs($path);
                }                
            }
        }
         closedir ($dir_handle);
 

  function  load_libs($dir) {
        $dir_handle =  opendir ($dir);
         while (($file =  readdir ($dir_handle)) !==  false  ) {
             if ($file != "." && $file != ".." ) {
                $path = $dir . "/" . $file;                
                 include_once  $dir.'/'.$file;                 
                 if ( is_dir ($path)) {
                    load_libs($path);
                }                
            }
        }
         closedir ($dir_handle);

$it =  new  RecursiveDirectoryIterator($folder);
 foreach ( new  RecursiveIteratorIterator($it)  as  $file) {
 echo  $file . "\n";
}

	$start_time =  microtime ( true );
	
	
	$cashe =  file_get_contents ('db.txt');
	
	$c_files =  unserialize ($cashe);
	
	$folder = 'folder';
	 var_dump ($c_files);
	$it =  new  RecursiveDirectoryIterator($folder);
	 foreach ( new  RecursiveIteratorIterator($it)  as  $file) {
		 if (! in_array ($file->getPathName(),$c_files)) {
			$files[] = $file->getPathName();
		}
	}
	
	$res_files =  array_merge ($c_files,$files);
	
	 file_put_contents ('db.txt', serialize ($res_files));
	
	 var_dump ($files);		
	
	$end_time =  microtime ( true );	
	$res_time = $end_time - $start_time;	
	 printf ("Elapsed time %.3f seconds",$res_time);