lang: Use universal way to retrieve load

Sysinfo is not supported on macOS and results in a build error.

lang/funcs/facts/core/load_darwin.go

@@ -0,0 +1,38 @@
+// Mgmt
+// Copyright (C) 2013-2018+ James Shubin and the project contributors
+// Written by James Shubin <james@shubin.ca> and the project contributors
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+// +build darwin
+
+package core // TODO: should this be in its own individual package?
+
+/*
+#include <stdlib.h>
+*/
+import "C"
+
+// macOS/Darwin specific implementation to get load.
+func load() (one, five, fifteen float64, err error) {
+	avg := []C.double{0, 0, 0}
+
+	C.getloadavg(&avg[0], C.int(len(avg)))
+
+	one = float64(avg[0])
+	five = float64(avg[1])
+	fifteen = float64(avg[2])
+
+	return
+}

lang/funcs/facts/core/load_posix.go

@@ -0,0 +1,45 @@
+// Mgmt
+// Copyright (C) 2013-2018+ James Shubin and the project contributors
+// Written by James Shubin <james@shubin.ca> and the project contributors
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+// +build !darwin
+
+package core // TODO: should this be in its own individual package?
+
+import (
+	"syscall"
+)
+
+const (
+	// LoadScale factor scales the output from sysinfo to the correct float
+	// value.
+	LoadScale = 65536 // XXX: is this correct or should it be 65535?
+)
+
+// load returns the system load averages for the last minute, five minutes and
+// fifteen minutes. Calling this more often than once every five seconds seems
+// to be unnecessary, since the kernel only updates these values that often.
+// TODO: is the kernel update interval configurable?
+func load() (one, five, fifteen float64, err error) {
+	var sysinfo syscall.Sysinfo_t
+	if err = syscall.Sysinfo(&sysinfo); err != nil {
+		return
+	}
+	one = float64(sysinfo.Loads[0]) / LoadScale
+	five = float64(sysinfo.Loads[1]) / LoadScale
+	fifteen = float64(sysinfo.Loads[2]) / LoadScale
+	return
+}

lang/funcs/facts/core/loadfact.go

@@ -18,7 +18,6 @@
 package core // TODO: should this be in its own individual package?
 
 import (
-	"syscall"
 	"time"
 
 	"github.com/purpleidea/mgmt/lang/funcs/facts"
@@ -28,10 +27,6 @@ import (
 )
 
 const (
-	// LoadScale factor scales the output from sysinfo to the correct float
-	// value.
-	LoadScale = 65536 // XXX: is this correct or should it be 65535?
-
 	loadSignature = "struct{x1 float; x5 float; x15 float}"
 )
 
@@ -114,18 +109,3 @@ func (obj *LoadFact) Close() error {
 	close(obj.closeChan)
 	return nil
 }
-
-// load returns the system load averages for the last minute, five minutes and
-// fifteen minutes. Calling this more often than once every five seconds seems
-// to be unnecessary, since the kernel only updates these values that often.
-// TODO: is the kernel update interval configurable?
-func load() (one, five, fifteen float64, err error) {
-	var sysinfo syscall.Sysinfo_t
-	if err = syscall.Sysinfo(&sysinfo); err != nil {
-		return
-	}
-	one = float64(sysinfo.Loads[0]) / LoadScale
-	five = float64(sysinfo.Loads[1]) / LoadScale
-	fifteen = float64(sysinfo.Loads[2]) / LoadScale
-	return
-}

test/shell/load0.sh

@@ -0,0 +1,48 @@
+#!/bin/bash -e
+
+if env | grep -q -e '^TRAVIS=true$' && [[ $(uname) == "Darwin" ]]; then
+	# loadavg glibc calls don't seem to work properly on osx OS in travis
+	echo "Travis and Jenkins give wonky results here, skipping test!"
+	exit
+fi
+
+set -o errexit
+set -o pipefail
+
+# Expected load average values eg: load average: 1.64306640625, 1.8076171875, 1.82958984375
+# High precision results are preferred (more than the 2 digits in /proc/loadavg at least).
+# Precision varies (eg: 4, 9 or 11 digits). Hence no strict check for precision but
+# anything above 3 will do. It is assumed we will hardly ever get a precision lower than 3 digits
+# from the current implementations. Otherwise this test would need to be revised.
+regex="load average: [0-9]\,[0-9]{3,}, [0-9]\,[0-9]{3,}, [0-9]\,[0-9]{3,}"
+
+tmpdir="$($mktemp --tmpdir -d tmp.XXX)"
+
+# macOS workaround https://github.com/purpleidea/mgmt/issues/33
+touch "$tmpdir/loadavg"
+
+cat > "$tmpdir/load0.mcl" <<EOF
+\$theload = load()
+
+\$x1 = structlookup(\$theload, "x1")
+\$x5 = structlookup(\$theload, "x5")
+\$x15 = structlookup(\$theload, "x15")
+
+file "${tmpdir}/loadavg" {
+	content => printf("load average: %f, %f, %f", \$x1, \$x5, \$x15),
+	state => "exists",
+}
+EOF
+
+$timeout --kill-after=30s 15s ./mgmt run --tmp-prefix --converged-timeout=1 --lang "$tmpdir/load0.mcl"  &
+pid=$!
+wait $pid	# get exit status
+e=$?
+
+set +e
+egrep "$regex" "$tmpdir/loadavg" || fail_test "Could not match $tmpdir/loadavg to '$regex'."
+
+# cleanup if everything went well
+rm -r "$tmpdir"
+
+exit $e