Merge pull request #497 from stevenh/freebsd-mem

Eliminate call to swapinfo on FreeBSD

mem/mem_freebsd.go

@@ -5,9 +5,7 @@ package mem
 import (
 	"context"
 	"errors"
-	"os/exec"
-	"strconv"
-	"strings"
+	"unsafe"
 
 	"golang.org/x/sys/unix"
 )
@@ -69,53 +67,66 @@ func VirtualMemoryWithContext(ctx context.Context) (*VirtualMemoryStat, error) {
 }
 
 // Return swapinfo
-// FreeBSD can have multiple swap devices. but use only first device
 func SwapMemory() (*SwapMemoryStat, error) {
 	return SwapMemoryWithContext(context.Background())
 }
 
+// Constants from vm/vm_param.h
+// nolint: golint
+const (
+	XSWDEV_VERSION = 1
+)
+
+// Types from vm/vm_param.h
+type xswdev struct {
+	Version uint32 // Version is the version
+	Dev     uint32 // Dev is the device identifier
+	Flags   int32  // Flags is the swap flags applied to the device
+	NBlks   int32  // NBlks is the total number of blocks
+	Used    int32  // Used is the number of blocks used
+}
+
 func SwapMemoryWithContext(ctx context.Context) (*SwapMemoryStat, error) {
-	swapinfo, err := exec.LookPath("swapinfo")
+	// FreeBSD can have multiple swap devices so we total them up
+	i, err := unix.SysctlUint32("vm.nswapdev")
 	if err != nil {
 		return nil, err
 	}
 
-	out, err := invoke.Command(swapinfo)
+	if i == 0 {
+		return nil, errors.New("no swap devices found")
+	}
+
+	c := int(i)
+
+	i, err = unix.SysctlUint32("vm.stats.vm.v_page_size")
 	if err != nil {
 		return nil, err
 	}
-	for _, line := range strings.Split(string(out), "\n") {
-		values := strings.Fields(line)
-		// skip title line
-		if len(values) == 0 || values[0] == "Device" {
-			continue
-		}
+	pageSize := uint64(i)
 
-		u := strings.Replace(values[4], "%", "", 1)
-		total_v, err := strconv.ParseUint(values[1], 10, 64)
-		if err != nil {
-			return nil, err
-		}
-		used_v, err := strconv.ParseUint(values[2], 10, 64)
-		if err != nil {
-			return nil, err
-		}
-		free_v, err := strconv.ParseUint(values[3], 10, 64)
+	var buf []byte
+	s := &SwapMemoryStat{}
+	for n := 0; n < c; n++ {
+		buf, err = unix.SysctlRaw("vm.swap_info", n)
 		if err != nil {
 			return nil, err
 		}
-		up_v, err := strconv.ParseFloat(u, 64)
-		if err != nil {
-			return nil, err
+
+		xsw := (*xswdev)(unsafe.Pointer(&buf[0]))
+		if xsw.Version != XSWDEV_VERSION {
+			return nil, errors.New("xswdev version mismatch")
 		}
+		s.Total += uint64(xsw.NBlks)
+		s.Used += uint64(xsw.Used)
+	}
 
-		return &SwapMemoryStat{
-			Total:       total_v,
-			Used:        used_v,
-			Free:        free_v,
-			UsedPercent: up_v,
-		}, nil
+	if s.Total != 0 {
+		s.UsedPercent = float64(s.Used) / float64(s.Total) * 100
 	}
+	s.Total *= pageSize
+	s.Used *= pageSize
+	s.Free = s.Total - s.Used
 
-	return nil, errors.New("no swap devices found")
+	return s, nil
 }