miscellany.hpp

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#ifndef CUDA_API_WRAPPERS_MISCELLANY_HPP_
#define CUDA_API_WRAPPERS_MISCELLANY_HPP_

#include "types.hpp"
#include "error.hpp"

#include <ostream>
#include <utility>

namespace cuda {

inline void initialize_driver()
{
    static constexpr const unsigned dummy_flags{0}; // this is the only allowed value for flags
    auto status = cuInit(dummy_flags);
    throw_if_error_lazy(status, "Failed initializing the CUDA driver");
}

inline void ensure_driver_is_initialized()
{
    thread_local bool driver_known_to_be_initialized{false};
    if (not driver_known_to_be_initialized) {
        initialize_driver();
        driver_known_to_be_initialized = true;
    }
}

namespace device {

inline device::id_t count()
{
    initialize_driver();
    // This function is often called before any device is obtained (which is where we
    // expect the driver to be initialized)
    int device_count = 0; // Initializing, just to be on the safe side
    status_t result = cuDeviceGetCount(&device_count);
    switch (result) {
    case (status_t) status::no_device:
        return 0;
    case (status_t) status::success:
        break;
    default:
        throw runtime_error(result, "Failed obtaining the number of CUDA devices on the system");
    }
    if (device_count < 0) {
        throw ::std::logic_error("cudaGetDeviceCount() reports an invalid number of CUDA devices");
    }
    return device_count;
}

} // namespace device


} // namespace cuda

#endif // CUDA_API_WRAPPERS_MISCELLANY_HPP_