Method wait

src/system/task_tracker.h:17–20

wait until task k has been finished

  // wait until task k has been finished
  void wait(int k) {
    ULock l(mu_);
    cond_.wait(l, [this, k]{ return (task_.count(k) && task_[k] == true); });
  }

  // non-blocking wait
  bool tryWait(int k) {