条件变量：应用

struct work {
  void (*run)(void *arg);
  void *arg;
}

void Tworker() {
  while (1) {
    struct work *work;
    wait_until(has_new_work() || all_done) {
      work = get_work();
    }
    if (!work) break;
    else {
      work->run(work->arg); // 允许生成新的 work (注意互斥)
      release(work);  // 注意回收 work 分配的资源
    }
  }
}