Factor out setting of B2_JOBS

Allows reuse in other scripts

ci/enforce.sh

@@ -46,11 +46,7 @@ if [ -z "$B2_CXXSTD" ]; then
     export B2_CXXSTD=11
 fi
 
-# default parallel build jobs: number of CPUs available + 1
-if [ -z "${B2_JOBS}" ]; then
-    cpus=$(grep -c 'processor' /proc/cpuinfo || python -c 'import multiprocessing as mp; print(mp.cpu_count())' || echo "2")
-    export B2_JOBS=$((cpus + 1))
-fi
+. "$(dirname "${BASH_SOURCE[0]}")"/set_num_jobs.sh
 
 # Build cmdline arguments for B2 as an array to preserve quotes
 if [ -z "$B2_CI_VERSION" ]; then

ci/set_num_jobs.sh

@@ -0,0 +1,17 @@
+#
+# Copyright 2017 - 2019 James E. King III
+# Copyright 2022 Alexander Grund
+#
+# Distributed under the Boost Software License, Version 1.0.
+# (See accompanying file LICENSE_1_0.txt or copy at
+#      http://www.boost.org/LICENSE_1_0.txt)
+#
+# Determine a good number of (build) jobs to use and stores it in B2_JOBS
+#
+
+if [ -z "${B2_JOBS:-}" ]; then
+    # default parallel build jobs: number of CPUs available + 1.
+    # In case of failure 2 CPUs are assumed
+    cpus=$(grep -c 'processor' /proc/cpuinfo || python -c 'import multiprocessing as mp; print(mp.cpu_count())' || echo "2")
+    export B2_JOBS=$((cpus + 1))
+fi