Function lightgbm_sys::LGBM_BoosterUpdateOneIterCustom

pub unsafe extern "C" fn LGBM_BoosterUpdateOneIterCustom(
    handle: BoosterHandle, 
    grad: *const f32, 
    hess: *const f32, 
    is_finished: *mut c_int
) -> c_int

\brief Update the model by specifying gradient and Hessian directly (this can be used to support customized loss functions). \param handle Handle of booster \param grad The first order derivative (gradient) statistics \param hess The second order derivative (Hessian) statistics \param[out] is_finished 1 means the update was successfully finished (cannot split any more), 0 indicates failure \return 0 when succeed, -1 when failure happens