PHP 对象池模式

1. 原文：https://designpatternsphp.readthedocs.io/zh_CN/latest/Creational/Pool/README.html

2. <?php
   
   namespace DesignPatternsCreationalPool;
   
   use Countable;
   
   
   class WorkerPool implements Countable
   {
       /**
        * @var StringReverseWorker[]
        */
       private $occupiedWorkers = [];
   
       /**
        * @var StringReverseWorker[]
        */
       private $freeWorkers = [];
   
       public function get(): StringReverseWorker
       {
           if (count($this->freeWorkers) == 0) {
               $worker = new StringReverseWorker();
           } else {
               $worker = array_pop($this->freeWorkers);
           }
   
           $this->occupiedWorkers[spl_object_hash($worker)] = $worker;
   
           return $worker;
       }
   
       public function dispose(StringReverseWorker $worker)
       {
           $key = spl_object_hash($worker);
   
           if (isset($this->occupiedWorkers[$key])) {
               unset($this->occupiedWorkers[$key]);
               $this->freeWorkers[$key] = $worker;
           }
       }
   
       public function count(): int
       {
           return count($this->occupiedWorkers) + count($this->freeWorkers);
       }
   }
   
   class StringReverseWorker
   {
       private $noncestr;
   
       public function __construct()
       {
           $this->noncestr = time().mt_rand(100,999);
       }
   
       public function run(string $text)
       {
           return strrev($text);
       }
   }
   
   $pool = new WorkerPool();
   $w1 = $pool->get();
   $w2 = $pool->get();
   
   var_dump($w1);
   echo "<hr/>";
   var_dump($w2);
   echo "<hr/>";
   
   $pool->dispose($w1);
   $w3 = $pool->get();
   var_dump($w3);