Buffer.hpp

/**
 * @file Buffer.hpp
 * @author ottojo
 * @date 5/25/21
 * Description here TODO
 */

#ifndef INFINIBAND_BUFFER_HPP
#define INFINIBAND_BUFFER_HPP

#include <memory>
#include <cassert>
#include <infiniband/verbs.h>
#include <fmt/format.h>
#include <gsl/gsl>

template<typename T>
class Buffer {
    public:
        explicit Buffer(std::size_t size, ibv_pd *protectionDomain) :
                _size(size),
                _data(new T[size]),
                memoryRegionMetadata(
                        ibv_reg_mr(protectionDomain, _data.get(), size * sizeof(T),
                                   IBV_ACCESS_LOCAL_WRITE | IBV_ACCESS_REMOTE_WRITE)) {
            if (memoryRegionMetadata == nullptr) {
                throw std::runtime_error{fmt::format("Registering send memory region failed: {}", strerror(errno))};
            }
        };

        ~Buffer() {
            if (memoryRegionMetadata != nullptr) {
                // This case occurs if this object was moved-from
                ibv_dereg_mr(memoryRegionMetadata);
            }
        }

        Buffer(const Buffer &) = delete;

        Buffer(Buffer &&rhs) noexcept {
            _size = rhs._size;
            _data = std::move(rhs._data);
            memoryRegionMetadata = rhs.memoryRegionMetadata;
            rhs.memoryRegionMetadata = nullptr;
        };

        Buffer &operator=(const Buffer &) = delete;

        Buffer &operator=(Buffer &&rhs) noexcept {
            if (this != &rhs) {
                _size = rhs._size;
                rhs._size = 0;
                _data = std::move(rhs._data);
                if (memoryRegionMetadata != nullptr) {
                    // This case occurs if this object was moved-from
                    ibv_dereg_mr(memoryRegionMetadata);
                }
                memoryRegionMetadata = rhs.memoryRegionMetadata;
                rhs.memoryRegionMetadata = nullptr;
            }
        };

        T &at(std::ptrdiff_t i) {
            assert(i < _size);
            return _data[i];
        }

        const T &at(std::ptrdiff_t i) const {
            assert(i < _size);
            return _data[i];
        }

        T *data() {
            return _data.get();
        }

        ibv_mr *getMR() {
            return memoryRegionMetadata;
        }

        [[nodiscard]] std::size_t size() const {
            return _size;
        }

    private:
        std::size_t _size;
        std::unique_ptr<T[]> _data;
        gsl::owner<ibv_mr *> memoryRegionMetadata;
};


#endif //INFINIBAND_BUFFER_HPP