Method ChangeState

tensorflow/lite/experimental/ruy/thread_pool.cc:60–100

Changes State; may be called from either the worker thread or the master thread; however, not all state transitions are legal, which is guarded by assertions. The Task argument is to be used only with new_state==HasWork. It specifies the Task being handed to this Thread.

  // The Task argument is to be used only with new_state==HasWork.
  // It specifies the Task being handed to this Thread.
  void ChangeState(State new_state, Task* task = nullptr) {
    state_mutex_.lock();
    State old_state = state_.load(std::memory_order_relaxed);
    RUY_DCHECK(old_state != new_state);
    switch (old_state) {
      case State::Startup:
        RUY_DCHECK(new_state == State::Ready);
        break;
      case State::Ready:
        RUY_DCHECK(new_state == State::HasWork ||
                   new_state == State::ExitAsSoonAsPossible);
        break;
      case State::HasWork:
        RUY_DCHECK(new_state == State::Ready ||
                   new_state == State::ExitAsSoonAsPossible);
        break;
      default:
        abort();
    }
    switch (new_state) {
      case State::Ready:
        if (task_) {
          // Doing work is part of reverting to 'ready' state.
          task_->Run();
          task_ = nullptr;
        }
        break;
      case State::HasWork:
        RUY_DCHECK(!task_);
        task_ = task;
        break;
      default:
        break;
    }
    state_.store(new_state, std::memory_order_relaxed);
    state_cond_.notify_all();
    state_mutex_.unlock();
    if (new_state == State::Ready) {
      counter_to_decrement_when_ready_->DecrementCount();
    }
  }

  static void ThreadFunc(Thread* arg) { arg->ThreadFuncImpl(); }