[Summary view]

   1  <?php
   2  
   3  namespace GuzzleHttp\Promise;
   4  
   5  /**
   6   * A task queue that executes tasks in a FIFO order.
   7   *
   8   * This task queue class is used to settle promises asynchronously and
   9   * maintains a constant stack size. You can use the task queue asynchronously
  10   * by calling the `run()` function of the global task queue in an event loop.
  11   *
  12   *     GuzzleHttp\Promise\Utils::queue()->run();
  13   */
  14  class TaskQueue implements TaskQueueInterface
  15  {
  16      private $enableShutdown = true;
  17      private $queue = [];
  18  
  19      public function __construct($withShutdown = true)
  20      {
  21          if ($withShutdown) {
  22              register_shutdown_function(function () {
  23                  if ($this->enableShutdown) {
  24                      // Only run the tasks if an E_ERROR didn't occur.
  25                      $err = error_get_last();
  26                      if (!$err || ($err['type'] ^ E_ERROR)) {
  27                          $this->run();
  28                      }
  29                  }
  30              });
  31          }
  32      }
  33  
  34      public function isEmpty()
  35      {
  36          return !$this->queue;
  37      }
  38  
  39      public function add(callable $task)
  40      {
  41          $this->queue[] = $task;
  42      }
  43  
  44      public function run()
  45      {
  46          while ($task = array_shift($this->queue)) {
  47              /** @var callable $task */
  48              $task();
  49          }
  50      }
  51  
  52      /**
  53       * The task queue will be run and exhausted by default when the process
  54       * exits IFF the exit is not the result of a PHP E_ERROR error.
  55       *
  56       * You can disable running the automatic shutdown of the queue by calling
  57       * this function. If you disable the task queue shutdown process, then you
  58       * MUST either run the task queue (as a result of running your event loop
  59       * or manually using the run() method) or wait on each outstanding promise.
  60       *
  61       * Note: This shutdown will occur before any destructors are triggered.
  62       */
  63      public function disableShutdown()
  64      {
  65          $this->enableShutdown = false;
  66      }
  67  }