R/with-emissions-tracked.R

In CodeCarbonR: Track Energy Consumption and Carbon Emissions of R Code

#' Track emissions for a single block of code
#'
#' @param expr Code to run and measure.
#' @param country_iso_code 3-letter ISO code used to look up grid carbon
#'   intensity, e.g. `"USA"`. Call [list_carbon_tracker_countries()] for the
#'   supported codes.
#' @param ... Passed to [carbon_tracker()].
#' @return A `carbon_emissions_result`: `$result` holds the value of `expr`,
#'   `$emissions` holds the `carbon_emissions` object.
#' @examples
#' \donttest{
#' # Requires codecarbon to be installed (setup_carbon_tracker()); not run
#' # on CRAN's check machines, which don't have it.
#' if (carbon_tracker_ready()) {
#'   out <- with_emissions_tracked(
#'     Sys.sleep(1),
#'     country_iso_code = "USA",
#'     output_dir = tempdir()
#'   )
#'   print(out)
#' }
#' }
#' @export
with_emissions_tracked <- function(expr, country_iso_code = NULL, ...) {
  tracker <- carbon_tracker(country_iso_code = country_iso_code, ...)
  tracker$start()
  on.exit(tracker$stop())
  result <- expr
  on.exit()
  new_carbon_emissions_result(result, tracker$stop())
}

new_carbon_emissions_result <- function(result, emissions) {
  structure(list(result = result, emissions = emissions), class = "carbon_emissions_result")
}

#' @export
print.carbon_emissions_result <- function(x, ...) {
  print(x$emissions)
  invisible(x)
}