/**
* 程序执行时间
*
* @return int 单位ms
*/
function execute_time() {
$stime = explode ( ' ', SYS_START_TIME );
$etime = explode ( ' ', microtime () );
return number_format ( ($etime [1] + $etime [0] - $stime [1] - $stime [0]), 6 );
}