src/dawn/wire/client/Buffer.h

// Copyright 2019 The Dawn & Tint Authors
//
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//    this list of conditions and the following disclaimer in the documentation
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#ifndef SRC_DAWN_WIRE_CLIENT_BUFFER_H_
#define SRC_DAWN_WIRE_CLIENT_BUFFER_H_

#include <memory>
#include <optional>

#include "dawn/common/FutureUtils.h"
#include "dawn/common/Ref.h"
#include "dawn/common/RefCounted.h"
#include "dawn/webgpu.h"
#include "dawn/wire/WireClient.h"
#include "dawn/wire/client/ObjectBase.h"
#include "partition_alloc/pointers/raw_ptr.h"

namespace dawn::wire::client {

class Device;

class Buffer final : public ObjectWithEventsBase {
  public:
    static WGPUBuffer Create(Device* device, const WGPUBufferDescriptor* descriptor);

    Buffer(const ObjectBaseParams& params,
           const ObjectHandle& eventManagerHandle,
           const WGPUBufferDescriptor* descriptor);
    ~Buffer() override;

    ObjectType GetObjectType() const override;

    void MapAsync(WGPUMapModeFlags mode,
                  size_t offset,
                  size_t size,
                  WGPUBufferMapCallback callback,
                  void* userdata);
    WGPUFuture MapAsyncF(WGPUMapModeFlags mode,
                         size_t offset,
                         size_t size,
                         const WGPUBufferMapCallbackInfo& callbackInfo);
    void* GetMappedRange(size_t offset, size_t size);
    const void* GetConstMappedRange(size_t offset, size_t size);
    void Unmap();

    void Destroy();

    // Note that these values can be arbitrary since they aren't validated in the wire client.
    WGPUBufferUsage GetUsage() const;
    uint64_t GetSize() const;

    WGPUBufferMapState GetMapState() const;

  private:
    friend class Client;
    class MapAsyncEvent;

    // Prepares the callbacks to be called and potentially calls them
    void SetFutureStatus(WGPUBufferMapAsyncStatus status);

    bool IsMappedForReading() const;
    bool IsMappedForWriting() const;
    bool CheckGetMappedRangeOffsetSize(size_t offset, size_t size) const;

    void FreeMappedData();

    const uint64_t mSize = 0;
    const WGPUBufferUsage mUsage;
    const bool mDestructWriteHandleOnUnmap;

    std::weak_ptr<bool> mIsDeviceAlive;

    // Mapping members are mutable depending on the current map state.
    enum class MapRequestType { Read, Write };
    struct MapRequest {
        FutureID futureID = kNullFutureID;
        size_t offset = 0;
        size_t size = 0;
        // Because validation for request type is validated via the backend, we use an optional type
        // here. This is nullopt when an invalid request type is passed to the wire.
        std::optional<MapRequestType> type;
    };
    enum class MapState {
        Unmapped,
        MappedForRead,
        MappedForWrite,
        MappedAtCreation,
    };
    std::optional<MapRequest> mPendingMapRequest = std::nullopt;
    MapState mMappedState = MapState::Unmapped;
    // TODO(https://crbug.com/dawn/2345): Investigate `DanglingUntriaged` in dawn/wire.
    raw_ptr<void, DanglingUntriaged> mMappedData = nullptr;
    size_t mMappedOffset = 0;
    size_t mMappedSize = 0;

    // Only one mapped pointer can be active at a time
    // TODO(enga): Use a tagged pointer to save space.
    std::unique_ptr<MemoryTransferService::ReadHandle> mReadHandle = nullptr;
    std::unique_ptr<MemoryTransferService::WriteHandle> mWriteHandle = nullptr;
};

}  // namespace dawn::wire::client

#endif  // SRC_DAWN_WIRE_CLIENT_BUFFER_H_