Method wait

tpool/task.cc:59–65

      m_cv.notify_all();
  }
  void waitable_task::wait(std::unique_lock<std::mutex>& lk)
  {
    m_waiter_count++;
    while (m_ref_count)
      m_cv.wait(lk);
    m_waiter_count--;
  }
  void waitable_task::wait()
  {
    std::unique_lock<std::mutex> lk(m_mtx);