src/dawn/replay/Replay.h

// Copyright 2025 The Dawn & Tint Authors
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#ifndef SRC_DAWN_REPLAY_REPLAY_H_
#define SRC_DAWN_REPLAY_REPLAY_H_

#include <webgpu/webgpu_cpp.h>

#include <memory>
#include <ranges>
#include <string>
#include <variant>
#include <vector>

#include "absl/container/flat_hash_map.h"
#include "dawn/replay/Capture.h"
#include "dawn/replay/Deserialization.h"

namespace dawn::replay {

typedef std::variant<wgpu::Buffer, wgpu::Texture> Resource;
struct LabeledResource {
    std::string label;
    Resource resource;
};

// Replays a capture. For now we only support replaying the entire capture.
// In the future we'd like to be able to replay up to a certain point.
class Replay {
  public:
    static std::unique_ptr<Replay> Create(wgpu::Device device, const Capture* capture);

    MaybeError Play();

    // Gets the first object of type T with the given label, or nullptr if not
    // found. Note: We don't too much care this is slow as mostly used for
    // testing and debugging.
    template <typename T>
    T GetObjectByLabel(const char* label) const {
        auto isLabel = [label](const LabeledResource& res) { return res.label == label; };
        auto resourcesWithMachingLabel =
            mResources | std::views::values | std::views::filter(isLabel);
        for (const auto& res : resourcesWithMachingLabel) {
            const T* p = std::get_if<T>(&res.resource);
            if (p) {
                return *p;
            }
        }
        return nullptr;
    }

    template <typename T>
    T GetObjectById(schema::ObjectId id) const {
        auto iter = mResources.find(id);
        const T* p = std::get_if<T>(&iter->second.resource);
        return *p;
    }

  private:
    Replay(wgpu::Device device, const Capture* capture);

    MaybeError CreateResource(wgpu::Device device, ReadHead& readHead);

    wgpu::Device mDevice;
    const Capture* mCapture;

    using IdToResourceMap = absl::flat_hash_map<schema::ObjectId, LabeledResource>;
    IdToResourceMap mResources;
};

}  // namespace dawn::replay

#endif  // SRC_DAWN_REPLAY_REPLAY_H_