WorkerPool.php
public function registerRead(LoopInterface $loop, callable $listener, $once = false)
    {
        if ($once) {
            $listener2 = function ($worker, $loop) use ($listener) {
                $this->unregisterRead($loop);
                call_user_func($listener, $worker, $loop);
            };
            foreach ($this->workers as $worker) {
                Selectable::registerRead($loop, $worker, $listener2);
            }
        } else {
            foreach ($this->workers as $worker) {
                Selectable::registerRead($loop, $worker, $listener);
            }
        }

        return $this;
    }
public function registerRead(LoopInterface $loop, callable $listener, $once = false)
    {
        if ($once) {
            $listener2 = function ($worker, $loop) use ($listener) {
                $this->unregisterRead($loop);
                call_user_func($listener, $worker, $loop);
            };
            foreach ($this->workers as $worker) {
                Selectable::registerRead($loop, $worker, $listener2);
            }
        } else {
            foreach ($this->workers as $worker) {
                Selectable::registerRead($loop, $worker, $listener);
            }
        }

        return $this;
    }
@param LoopInterface $loop
@param callable      $listener
@param bool          $once

@return $this