Chris@0: <?php
Chris@0: namespace GuzzleHttp\Promise;
Chris@0: 
Chris@0: /**
Chris@0:  * A task queue that executes tasks in a FIFO order.
Chris@0:  *
Chris@0:  * This task queue class is used to settle promises asynchronously and
Chris@0:  * maintains a constant stack size. You can use the task queue asynchronously
Chris@0:  * by calling the `run()` function of the global task queue in an event loop.
Chris@0:  *
Chris@0:  *     GuzzleHttp\Promise\queue()->run();
Chris@0:  */
Chris@0: class TaskQueue implements TaskQueueInterface
Chris@0: {
Chris@0:     private $enableShutdown = true;
Chris@0:     private $queue = [];
Chris@0: 
Chris@0:     public function __construct($withShutdown = true)
Chris@0:     {
Chris@0:         if ($withShutdown) {
Chris@0:             register_shutdown_function(function () {
Chris@0:                 if ($this->enableShutdown) {
Chris@0:                     // Only run the tasks if an E_ERROR didn't occur.
Chris@0:                     $err = error_get_last();
Chris@0:                     if (!$err || ($err['type'] ^ E_ERROR)) {
Chris@0:                         $this->run();
Chris@0:                     }
Chris@0:                 }
Chris@0:             });
Chris@0:         }
Chris@0:     }
Chris@0: 
Chris@0:     public function isEmpty()
Chris@0:     {
Chris@0:         return !$this->queue;
Chris@0:     }
Chris@0: 
Chris@0:     public function add(callable $task)
Chris@0:     {
Chris@0:         $this->queue[] = $task;
Chris@0:     }
Chris@0: 
Chris@0:     public function run()
Chris@0:     {
Chris@0:         /** @var callable $task */
Chris@0:         while ($task = array_shift($this->queue)) {
Chris@0:             $task();
Chris@0:         }
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * The task queue will be run and exhausted by default when the process
Chris@0:      * exits IFF the exit is not the result of a PHP E_ERROR error.
Chris@0:      *
Chris@0:      * You can disable running the automatic shutdown of the queue by calling
Chris@0:      * this function. If you disable the task queue shutdown process, then you
Chris@0:      * MUST either run the task queue (as a result of running your event loop
Chris@0:      * or manually using the run() method) or wait on each outstanding promise.
Chris@0:      *
Chris@0:      * Note: This shutdown will occur before any destructors are triggered.
Chris@0:      */
Chris@0:     public function disableShutdown()
Chris@0:     {
Chris@0:         $this->enableShutdown = false;
Chris@0:     }
Chris@0: }