PHP Multiple Concurrent Sessions Per User

Question

I\'m working on a web app using PHP on Apache. $_SESSION variables are used quite a bit for the information that must persist across pages.

We need each user to be a

Answer 1

Non-Atomic Concurrent Session Management access can be simulated with the following pseudo coded logic:

function main(){
  $locker = new SessionLocking();
  /** read elements the $_SESSION "cached" copy. **/
  $var1 = $_SESSION['var1'];
  $var2 = $_SESSION['var2'];
  /** Pseudo Atomic Read **/
  $locker->lock(); //session is locked against concurrent access.
  $var3 = $_SESSION['var3'];
  $locker->unlock(); //session is committed to disk (or other) and can be accessed by another script.
  /** Psuedo Atomic Write **/
  $locker->lock(); //session is locked against concurrent access.
  $_SESSION['var4'] = "Some new value";
  $locker->unlock(); //session is committed to disk (or other) and can be accessed by another script
}

CLASS SessionLocking {

private static $lockCounter=0;
private static $isLoaded=false;

function __constructor(){
  if (!self::$isLoaded) load();
}

private function load(){
 $this->lock();
 $this->unlock();
}

private function lock(){
  if ($lockCounter<1) try {session_start();} Catch(){}
  $lockCounter++; 
}

private function unlock(){
  if ($lockCount<1) return;
  $lockCounter--;
  if ($lockCounter<1) try {session_write_close();} Catch(){}
}
}