1 <?php  2   3 /**  4  * 具体的需要缓存的对象， 因new的代价太高昂， 所以做一个缓存  5  */  6 class Worker  7 {  8     public function __construct()  9     { 10         //做一些代价高昂的事情，比如创建线程 11     } 12  13     public function run($class, $functionName) 14     { 15         //对$class做一些事情 16         //这个$class， 是想使用Worker的类 17  18         echo "<br/>我正在处理: {$class},  它的数据类型是：".gettype($class); //for test 19  20         call_user_func($functionName, $this); 21     } 22 } 23  24 class Pool 25 { 26     private $_pool = [];            //对象池 27     private $_maxNum;               //对象池中的最大对象数目 28     private $_waitingQueue = [];   //等待队列 29  30     function __construct($maxNum) 31     { 32         $this->_maxNum = $maxNum; 33  34         //初始化对象池 35         for ($i=0; $i<$this->_maxNum; $i++) { 36             $worker = new Worker(); 37             $this->_pool[] = $worker; 38         } 39     } 40  41     /** 42      * 从对象池中取出 43      * @param $class  Object  想使用Worker的对象 44      */ 45     public function get($class) 46     { 47         if (count($this->_pool)) { 48             $this->callWorker($class); 49         } else { 50             $this->pushToWaitingQueue($class); 51         } 52     } 53  54     /** 55      * 我已经使用好啦，还给你啦 56      * @param $worker 57      */ 58     public function done($worker) 59     { 60         echo "<br/>哈哈，我胡汉三又回来啦！";   //for test 61  62  63         $this->_pool[] = $worker; 64  65         if (count($this->_waitingQueue) > 0) { 66             $class = $this->popFromWaitingQueue(); 67             $this->callWorker($class); 68         } 69     } 70  71  72  73  74  75     private function callWorker($class) 76     { 77         $worker = array_pop($this->_pool); 78         $worker->run($class, [$this, ‘done‘]); 79     } 80  81     private function pushToWaitingQueue($class) 82     { 83         $this->_waitingQueue[] = $class; 84     } 85  86     private function popFromWaitingQueue() 87     { 88         return array_pop($this->_waitingQueue); 89     } 90 } 91  92  93  94 $pool = new Pool(3); 95  96 $c1 = 3; 97 $pool->get($c1); 98  99 $c2 = ‘sdfsdf‘;100 $pool->get($c2);