Interop\Async\Loop::delay PHP 메소드

    public static function delay($time, callable $callback, $data = null)
    {
        $driver = self::$driver ?: self::get();
        return $driver->delay($time, $callback, $data);
    }

 protected function pollFilesystem()
 {
     if (empty($this->watchers)) {
         return;
     }
     $watchers = [];
     foreach ($this->watchers as $id => list($path, $events, $callback)) {
         $sync = $this->pool->invokeStaticMethod(static::class, 'collectStats', $path);
         $sync->when(function ($e, $v = null) use($id, $path, $events, $callback) {
             if (!$e) {
                 try {
                     if (isset($this->state[$id])) {
                         $this->triggerEvents($id, $this->state[$id], $v, $events, $callback);
                     }
                 } finally {
                     $this->state[$id] = $v;
                 }
             }
         });
         $watchers[] = $sync;
     }
     $await = new AwaitPending($watchers);
     $await->when(function () {
         $this->timer = Loop::delay($this->interval, function () {
             $this->pollFilesystem();
         });
     });
     return $await;
 }