Deliver on check to avoid background processing

deliver-on-check.php

<?php

/**
 * Wizard represents an object that generates mana over time
 */
class Wizard {
  
  private $mana = 0;
  
  private $last_checked = 0;
    
  private $max = 1000;
    
  private $rate = 100;

  /**
   * Constructor initializes the timer
   */
  public function __construct() 
  {
      $this->last_checked = time();
  }
    
  /**
   * Cash get function calculates since it was checked last time
   * As you can see, no background processing required.
   */
  public function getMana() 
  {
      $diff  = time() - $this->last_checked;
      if ($diff > 0) {
          $this->mana = min($this->max, $this->mana + ($diff * $this->rate));
          $this->last_checked = time();
      }
      
      return $this->mana;
  }
}

/*
 * Test code to show deliver on check on action
 */
$gandolf = new Wizard();

print("Startig mana: {$gandolf->getMana()}\n");

$sleep = mt_rand(0, 10);
print("Sleeping for {$sleep} seconds\n");
sleep($sleep);

print("New mana: {$gandolf->getMana()}\n");