为什么php页面刷新发布会话变量

Question

I am trying to release/unset a session variable after 2 minutes through unsetsession.php :

<?php

    session_start();

if (isset($_SESSION['LAST_ACTIVITY']) && (time() - $_SESSION['LAST_ACTIVITY'] > 120)) {
    // last request was more than 2 minutes ago
    unset($_SESSION['logged_in']);     // unset $_SESSION variable for the run-time
    unset($_SESSION['LAST_ACTIVITY']);
    session_unset();     // unset $_SESSION variable for the run-time 
    session_destroy();   // destroy session data in storage
}
$_SESSION['LAST_ACTIVITY'] = time(); // update last activity time stamp

?>

where the session variables are:

$_SESSION['logged_in'] = 1;
$_SESSION['LAST_ACTIVITY'] = time();

However, the session variables do not get unset but are unset when I refresh the page. The page is making a call to the file unsetsession.php. Why is the session not getting unset after 2 minutes?

EDIT : The page file.php has <?php include("includes/unsetsession.php") ?> on top of the page. When file.php is refreshed on the browser, the value of the session variable $_SESSION['logged_in'] = 1; gets changed to 0. It would not change after 2 mins. It only changes to 0 when the page is refreshed.

I am checking the value by running getsession.php on the browser which is:

<?php
  session_start();
  if(isset($_SESSION['logged_in']))
  echo "1";
  else
    echo "0";
?>

Answer 1

Well, you clearly have a problem on understanding how php works. Whenever you load your page, your php script will be executed once .

So you're going through your code the first time, your session variable is set. And now, it's over . Your php script has executed and it's just finished, it won't do anything anymore.

But if you refresh your page, the script will be called again. That time, the session variable is already set, and let's say it has been two minutes. So you enter the condition and destroy it. And your second call to the script is finished.

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So there's no really way on finding a solution to your problem right now, before you give us any more information on what you're trying to achieve.

Some solutions would be using javascript to regularly make an AJAX request to unsetsession.php for instance, or simply letting this as is: the session will not be unset until you load a page. That's not really a problem, most websites do it that way.