nbrOfWorkers() could still return a value with class attribute set to 'integer', e.g. plan(multicore)

Author: HenrikBengtsson

DESCRIPTION

@@ -1,5 +1,5 @@
 Package: future
-Version: 1.70.0-9010
+Version: 1.70.0-9011
 Title: Unified Parallel and Distributed Processing in R for Everyone
 Depends:
     R (>= 3.2.0)

R/backend_api-11.ClusterFutureBackend-class.R

@@ -38,9 +38,9 @@ ClusterFutureBackend <- local({
       if (is.numeric(workers)) {
         if (debug) mdebugf("workers: %g", workers)
         ## Preserve class attributes, especially "AsIs"
-        clazz <- class(workers)
+        clazz <- setdiff(class(workers), c("integer", "numeric"))
         workers <- as.integer(workers)
-        class(workers) <- clazz
+        if (length(clazz) > 0) class(workers) <- clazz
         stop_if_not(length(workers) == 1, is.finite(workers))
       } else {
         stop_if_not(length(workers) >= 1, !anyNA(workers))

R/backend_api-11.MulticoreFutureBackend-class.R

@@ -142,7 +142,7 @@ MulticoreFutureBackend <- function(workers = availableCores(constraints = "multi
   default_workers <- missing(workers)
   if (is.function(workers)) workers <- workers()
   stop_if_not(is.numeric(workers))
-  workers <- structure(as.integer(workers), class = setdiff(class(workers), mode(workers)))
+  workers <- structure(as.integer(workers), class = setdiff(class(workers), c("integer", "numeric")))
   stop_if_not(length(workers) == 1, is.finite(workers), workers >= 1)
 
   ## Fall back to sequential futures if only a single additional R process

R/backend_api-13.MultisessionFutureBackend-class.R

@@ -26,7 +26,7 @@ MultisessionFutureBackend <- function(workers = availableCores(constraints = "co
   default_workers <- missing(workers)
   if (is.function(workers)) workers <- workers()
   stop_if_not(is.numeric(workers))
-  workers <- structure(as.integer(workers), class = class(workers))
+  workers <- structure(as.integer(workers), class = setdiff(class(workers), c("integer", "numeric")))
   stop_if_not(length(workers) == 1, is.finite(workers), workers >= 1)
 
   ## Fall back to sequential futures if only a single additional R process

inst/testme/test-nbrOfWorkers.R

@@ -18,6 +18,7 @@ for (strategy in strategies) {
   n <- nbrOfWorkers()
   message(sprintf("nbrOfWorkers: %d", n))
   stopifnot(n == 1L)
+  stopifnot(is.null(attr(n, "class")))
 
   n <- nbrOfFreeWorkers()
   message(sprintf("nbrOfFreeWorkers: %d", n))
@@ -55,6 +56,7 @@ for (strategy in strategies) {
   n <- nbrOfWorkers()
   message(sprintf("nbrOfWorkers: %d", n))
   stopifnot(n == nworkers)
+  stopifnot(is.null(attr(n, "class")))
 
   n <- nbrOfFreeWorkers()
   message(sprintf("nbrOfFreeWorkers: %d", n))
@@ -120,4 +122,19 @@ message(sprintf("nbrOfWorkers: %g", n))
 stopifnot(n == length(workers))
 parallel::stopCluster(workers)
 
+message("Type of future: multicore/multisession with workers = I(1L)")
+for (strategy in c("multicore", "multisession")) {
+  if (strategy %in% supportedStrategies()) {
+    plan(strategy, workers = I(1L))
+    n <- nbrOfWorkers()
+    message(sprintf("nbrOfWorkers (%s): %g", strategy, n))
+    stopifnot(n == 1L)
+    if (strategy == "multicore") {
+      stopifnot(inherits(n, "AsIs"))
+    } else {
+      stopifnot(is.null(attr(n, "class")))
+    }
+  }
+}
+
 message("*** nbrOfWorkers() ... DONE")