R/get_cores_nb.R

In SticsRPacks/SticsOnR: Manage STICS Simulations Running the Executable or JavaStics,

#' Getting the available number of cores for parallel calculations
#'
#' @param parallel Logical for performing parallel loop (TRUE) or not (FALSE)
#' @param required_nb Wanted number of cores
#' @param ... To pass additional arguments (i.e. cores_nb, fake machine cores)
#'
#' @return Available cores number tu use
#'
#' @keywords internal
#'
#' @noRd
#'
#' @examples
#'
#' n_cores <- get_cores_nb()
#'
#' n_cores <- get_cores_nb(parallel = TRUE)
#'
#' n_cores <- get_cores_nb(parallel = TRUE, required_nb = 4)
#'
#'
get_cores_nb <- function(parallel = FALSE, required_nb = NA, ...) {

  # For sequential execution
  if (!parallel) {
    return(1)
  }

  # Getting true (from the machine) or fake cores number,
  # forcing it through cores_nb argument in
  # three dots arguments (for testing purpose)
  cores_nb <- get_cores(...)

  # Keeping one free core left
  if (cores_nb >= 2) {
    cores_nb <- cores_nb - 1
  }

  # Limiting the required cores, if any
  if (base::is.na(required_nb) ||
    required_nb > cores_nb) {
    return(cores_nb)
  }

  # Getting the right required cores number
  return(required_nb)
}


#' Detecting machine cores number
#'
#' @param ... To pass additional argument (for testing purpose)
#'
#' @return Total cores number
#'
#' @keywords internal
#'
#' @noRd
#'
#' @examples
#'
#' get_cores()
#'
#' get_cores(cores_nb = 4)
#'
#' @importFrom parallel detectCores
#'
get_cores <- function(...) {

  # Getting additional args list with cores_nb in it !
  dot_args <- list(...)

  # Getting real cores number
  if (!("cores_nb" %in% names(dot_args))) {
    return(detectCores())
  }

  # Returning a fake number of cores gave as an input
  return(dot_args$cores_nb)
}