Add a command for querying number of CPU's

 * This is something of a stop-gap until we can come up w/ a unified interface
   for asking for this sort of information.  Something again to a 'build-host'
   command which we can query arch, os, version, endian, num-cpus, etc.

2 files changed, 25 insertions, 5 deletions

diff --git a/build b/build
index 45644f1..a990d33 100755
--- a/build
+++ b/build
@@ -315,11 +315,6 @@ export BUILDER_PATH PATH
 # include our default config
 test -f "${BUILDER_CFGDIR}/config" && include config
 
-# FIXME MAKE_OPTS should default to #CPUS + 1, until we can detect #CPUS, we
-# just set it to 2 for uni-processor systems.
-MAKE_OPTS="${MAKE_OPTS:--j2}"
-export MAKE_OPTS
-
 # Default build target
 # FIXME this should default to all/all
 TARGET="${TARGET:-all/all}"
@@ -339,6 +334,14 @@ export ARCH
 CHOST="${CHOST:-${CBUILD}}"
 export CHOST
 
+MAKE_OPTS=
+if test -z "${MAKE_OPTS}"; then
+	num_cpus="$(build-num-cpus)"
+	MAKE_OPTS="-j$((${num_cpus} + 1))"
+	unset num_cpus
+fi
+export MAKE_OPTS
+
 # if we aren't given an action then we do everything
 ACTION="install"
 if [ "$#" -gt "0" ]; then
diff --git a/libexec/build-num-cpus b/libexec/build-num-cpus
new file mode 100755
index 0000000..ab88f3f
--- /dev/null
+++ b/libexec/build-num-cpus
@@ -0,0 +1,17 @@
+#!/usr/bin/env build
+
+case "${CBUILD:-$(build-dumpmachine)}" in
+(*linux*)	eval 'build_num_cpus() { nproc; }';;
+(*)	die "unknown host '${CBUILD}'";;
+esac
+
+if test "${BUILDER_CALL_STACK}" = '__main__'; then
+	for arg; do
+		case "${arg}" in
+		(-h|-help|--help) echo 'usage: build num-cpus'; exit 0;;
+		esac
+	done
+	build_num_cpus "${@}"
+fi
+
+# vim: filetype=sh