Find total logged in time of users in codeigniter - php

Question

I have to prepare a report in codeigniter of the login and logout time of users. I have overridden the session library and changed the function of set_userdata according to it.
My problem is when user doesn't select the logout button, or if he/she is logged in simultaneously from more then one system; in that case how can I keep a log of login and logout time?
I added the following code to the session_destroy function of the session library
$session_id=$this->userdata['session_id'];
$c_array=array('logout_time'=>date('Y-m-d H:i:s'));
$this->CI->db->where('session_id',$session_id);
$this->CI->db->update('login_activities',$c_array);
but the session_id changed after some time in the ci_session table

Answer 1

we cant always get the logout time, because if the user close the browser there won't be able to add a logout time, in the case of normal logout its ok..
here my suggession is:
instead of logout_time we need current_time and a usage field
if the user is logged an ajax is run on page for every second or (may be in 3 seconds or 5)
at every time the ajax runs: the current_time updated with the current time stamp, and the usage field must be updated with time in seconds that can be calculated by difference in login_time and current time
use the following function:
function getTimeInSec($t1, $t2)
{
$timeFirst = strtotime($t1);
$timeSecond = strtotime($t2);
$differenceInSeconds = $timeSecond - $timeFirst;
return $differenceInSeconds;
}
here $t1 is the current_time and $t2 is the login_time....
(both ar in format 'Y-m-d H:i:s')
script for ajax call:
<script>
jQuery(document).ready(function($){
getRefresh(1000);
});
function getHeader()
{
$.post("<?php echo site_url('mycontroller/refreshAjax');?>", {
},
function(response)
{
});
}
function getRefresh(tim)
{
getHeader();
setTimeout("getRefresh("+tim+")", tim);
}
</script>
in the controller function refreshAjax() there must be update query for the table to update...