think\Process::readPipes PHP Method

    private function readPipes($blocking, $close)
    {
        $result = $this->processPipes->readAndWrite($blocking, $close);
        $callback = $this->callback;
        foreach ($result as $type => $data) {
            if (3 == $type) {
                $this->fallbackExitcode = (int) $data;
            } else {
                $callback($type === self::STDOUT ? self::OUT : self::ERR, $data);
            }
        }
    }