src/dawn/native/CallbackTaskManager.h

// Copyright 2021 The Dawn & Tint Authors
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#ifndef SRC_DAWN_NATIVE_CALLBACKTASKMANAGER_H_
#define SRC_DAWN_NATIVE_CALLBACKTASKMANAGER_H_

#include <functional>
#include <memory>
#include <mutex>
#include <vector>

#include "dawn/common/MutexProtected.h"
#include "dawn/common/RefCounted.h"
#include "dawn/common/TypeTraits.h"

namespace dawn::native {

enum class CallbackState {
    Normal,
    ShutDown,
    DeviceLoss,
};

struct CallbackTask {
  public:
    virtual ~CallbackTask() = default;

    void Execute();
    void OnShutDown();
    void OnDeviceLoss();

  protected:
    virtual void FinishImpl() = 0;
    virtual void HandleShutDownImpl() = 0;
    virtual void HandleDeviceLossImpl() = 0;

  private:
    CallbackState mState = CallbackState::Normal;
};

class CallbackTaskManager : public RefCounted {
  public:
    CallbackTaskManager();
    ~CallbackTaskManager() override;

    void AddCallbackTask(std::unique_ptr<CallbackTask> callbackTask);
    void AddCallbackTask(std::function<void()> callback);
    template <typename... Args>
    void AddCallbackTask(void (*callback)(Args... args), Args... args) {
        static_assert((!IsCString<Args>::value && ...), "passing C string argument is not allowed");

        AddCallbackTask([=] { callback(args...); });
    }
    bool IsEmpty();
    void HandleDeviceLoss();
    void HandleShutDown();
    void Flush();

  private:
    struct StateAndQueue {
        CallbackState mState = CallbackState::Normal;
        std::vector<std::unique_ptr<CallbackTask>> mTaskQueue;
    };
    MutexProtected<StateAndQueue> mStateAndQueue;
};

}  // namespace dawn::native

#endif  // SRC_DAWN_NATIVE_CALLBACKTASKMANAGER_H_