R/multiCore.R

In lindbrook/packageRank: Computation and Visualization of Package Download Counts and Percentiles

#' Set or compute the number of cores for parallelized functions.
#'
#' @param x Logical or Numeric. \code{TRUE} returns the number of logical cores. \code{FALSE} uses one, single core. You can also specify the number of cores. For performance reasons, valid only for macOS and Unix. Windows defaults to one.
#' @noRd

multiCore <- function(x = TRUE) {
  if (.Platform$OS.type == "windows") {
    cores <- 1L
  } else {
    if (is.logical(x) | is.numeric(x)) {
      if (is.logical(x)) {
        if (x == TRUE) {
          # cores <- parallel::detectCores()
          cores <- max(1L, parallel::detectCores(), na.rm = TRUE)
        } else {
          cores <- 1L
        }
      } else if (is.numeric(x)) {
        # obs.cores <- parallel::detectCores()
        obs.cores <- max(1L, parallel::detectCores(), na.rm = TRUE)
        if (x > obs.cores) {
          msg <- 'For your system, the number of specified cores must be <= '
          stop(paste0(msg, obs.cores, "."))
        } else if (x <= 0) {
          stop("You must specify at least one core.")
        } else {
          cores <- as.integer(x)
        }
      } else stop("'x' must either be logical or numeric.")
    }
  }
  cores
}