Merge pull request #379 from magiconair/fix-host-boottime-race

Fix data race in host.BootTime

host/host.go

@@ -6,10 +6,7 @@ import (
 	"github.com/shirou/gopsutil/internal/common"
 )
 
-var (
-	invoke         common.Invoker
-	cachedBootTime = uint64(0)
-)
+var invoke common.Invoker
 
 func init() {
 	invoke = common.Invoke{}

host/host_darwin.go

@@ -11,6 +11,7 @@ import (
 	"runtime"
 	"strconv"
 	"strings"
+	"sync/atomic"
 	"time"
 	"unsafe"
 
@@ -72,9 +73,13 @@ func Info() (*InfoStat, error) {
 	return ret, nil
 }
 
+// cachedBootTime must be accessed via atomic.Load/StoreUint64
+var cachedBootTime uint64
+
 func BootTime() (uint64, error) {
-	if cachedBootTime != 0 {
-		return cachedBootTime, nil
+	t := atomic.LoadUint64(&cachedBootTime)
+	if t != 0 {
+		return t, nil
 	}
 	values, err := common.DoSysctrl("kern.boottime")
 	if err != nil {
@@ -86,9 +91,10 @@ func BootTime() (uint64, error) {
 	if err != nil {
 		return 0, err
 	}
-	cachedBootTime = uint64(boottime)
+	t = uint64(boottime)
+	atomic.StoreUint64(&cachedBootTime, t)
 
-	return cachedBootTime, nil
+	return t, nil
 }
 
 func uptime(boot uint64) uint64 {

host/host_freebsd.go

@@ -11,6 +11,7 @@ import (
 	"runtime"
 	"strconv"
 	"strings"
+	"sync/atomic"
 	"time"
 	"unsafe"
 
@@ -68,9 +69,13 @@ func Info() (*InfoStat, error) {
 	return ret, nil
 }
 
+// cachedBootTime must be accessed via atomic.Load/StoreUint64
+var cachedBootTime uint64
+
 func BootTime() (uint64, error) {
-	if cachedBootTime != 0 {
-		return cachedBootTime, nil
+	t := atomic.LoadUint64(&cachedBootTime)
+	if t != 0 {
+		return t, nil
 	}
 	values, err := common.DoSysctrl("kern.boottime")
 	if err != nil {
@@ -83,9 +88,10 @@ func BootTime() (uint64, error) {
 	if err != nil {
 		return 0, err
 	}
-	cachedBootTime = boottime
+	t = uint64(boottime)
+	atomic.StoreUint64(&cachedBootTime, t)
 
-	return boottime, nil
+	return t, nil
 }
 
 func uptime(boot uint64) uint64 {

host/host_linux.go

@@ -14,6 +14,7 @@ import (
 	"runtime"
 	"strconv"
 	"strings"
+	"sync/atomic"
 	"time"
 
 	"github.com/shirou/gopsutil/internal/common"
@@ -85,10 +86,14 @@ func Info() (*InfoStat, error) {
 	return ret, nil
 }
 
+// cachedBootTime must be accessed via atomic.Load/StoreUint64
+var cachedBootTime uint64
+
 // BootTime returns the system boot time expressed in seconds since the epoch.
 func BootTime() (uint64, error) {
-	if cachedBootTime != 0 {
-		return cachedBootTime, nil
+	t := atomic.LoadUint64(&cachedBootTime)
+	if t != 0 {
+		return t, nil
 	}
 	filename := common.HostProc("stat")
 	lines, err := common.ReadLines(filename)
@@ -105,8 +110,9 @@ func BootTime() (uint64, error) {
 			if err != nil {
 				return 0, err
 			}
-			cachedBootTime = uint64(b)
-			return cachedBootTime, nil
+			t = uint64(b)
+			atomic.StoreUint64(&cachedBootTime, t)
+			return t, nil
 		}
 	}
 

host/host_windows.go

@@ -7,6 +7,7 @@ import (
 	"os"
 	"runtime"
 	"strings"
+	"sync/atomic"
 	"syscall"
 	"time"
 	"unsafe"
@@ -135,16 +136,21 @@ func bootTime(up uint64) uint64 {
 	return uint64(time.Now().Unix()) - up
 }
 
+// cachedBootTime must be accessed via atomic.Load/StoreUint64
+var cachedBootTime uint64
+
 func BootTime() (uint64, error) {
-	if cachedBootTime != 0 {
-		return cachedBootTime, nil
+	t := atomic.LoadUint64(&cachedBootTime)
+	if t != 0 {
+		return t, nil
 	}
 	up, err := Uptime()
 	if err != nil {
 		return 0, err
 	}
-	cachedBootTime = bootTime(up)
-	return cachedBootTime, nil
+	t = bootTime(up)
+	atomic.StoreUint64(&cachedBootTime, t)
+	return t, nil
 }
 
 func PlatformInformation() (platform string, family string, version string, err error) {