Hashmap.h

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#include "open3d/core/Dtype.h"
#include "open3d/core/Tensor.h"
#include "open3d/core/hashmap/HashmapBuffer.h"

namespace open3d {
namespace core {

// Forward declaration of device-dependent classes
class DefaultHash;
class DefaultKeyEq;

template <typename Hash, typename KeyEq>
class DeviceHashmap;
typedef DeviceHashmap<DefaultHash, DefaultKeyEq> DefaultDeviceHashmap;

class Hashmap {
public:
    static constexpr int64_t kDefaultElemsPerBucket = 4;

    Hashmap(int64_t init_capacity,
            const Dtype& dtype_key,
            const Dtype& dtype_value,
            const SizeVector& element_shape_key,
            const SizeVector& element_shape_value,
            const Device& device);

    ~Hashmap(){};

    void Rehash(int64_t buckets);

    void Insert(const Tensor& input_keys,
                const Tensor& input_values,
                Tensor& output_addrs,
                Tensor& output_masks);

    void Activate(const Tensor& input_keys,
                  Tensor& output_addrs,
                  Tensor& output_masks);

    void Find(const Tensor& input_keys,
              Tensor& output_addrs,
              Tensor& output_masks);

    void Erase(const Tensor& input_keys, Tensor& output_masks);

    void GetActiveIndices(Tensor& output_indices);

    Hashmap Copy(const Device& device);
    Hashmap CPU();
    Hashmap CUDA(int device_id = 0);

    int64_t Size() const;

    int64_t GetCapacity() const;
    int64_t GetBucketCount() const;
    Device GetDevice() const;
    int64_t GetKeyBytesize() const;
    int64_t GetValueBytesize() const;

    Tensor& GetKeyBuffer();
    Tensor& GetValueBuffer();

    Tensor GetKeyTensor();
    Tensor GetValueTensor();

    std::vector<int64_t> BucketSizes() const;

    float LoadFactor() const;

protected:
    void AssertKeyDtype(const Dtype& dtype_key,
                        const SizeVector& elem_shape) const;
    void AssertValueDtype(const Dtype& dtype_val,
                          const SizeVector& elem_shape) const;

    Dtype GetKeyDtype() const { return dtype_key_; }
    Dtype GetValueDtype() const { return dtype_value_; }

private:
    std::shared_ptr<DefaultDeviceHashmap> device_hashmap_;

    Dtype dtype_key_ = Dtype::Undefined;
    Dtype dtype_value_ = Dtype::Undefined;

    SizeVector element_shape_key_;
    SizeVector element_shape_value_;
};

}  // namespace core
}  // namespace open3d