time: isolate syscall reference in sys.go

R=dsymonds
CC=golang-dev
https://golang.org/cl/4291052

src/pkg/time/sleep.go

@@ -5,9 +5,8 @@
 package time
 
 import (
-	"syscall"
-	"sync"
 	"container/heap"
+	"sync"
 )
 
 // The Timer type represents a single event.
@@ -126,7 +125,7 @@ func sleeper(sleeperId int64) {
 				dt = maxSleepTime
 			}
 			timerMutex.Unlock()
-			syscall.Sleep(dt)
+			sysSleep(dt)
 			timerMutex.Lock()
 			if currentSleeper != sleeperId {
 				// Another sleeper has been started, making this one redundant.

src/pkg/time/sys.go

@@ -44,11 +44,19 @@ func sleep(t, ns int64) (int64, os.Error) {
 	// TODO(cw): use monotonic-time once it's available
 	end := t + ns
 	for t < end {
-		errno := syscall.Sleep(end - t)
-		if errno != 0 && errno != syscall.EINTR {
-			return 0, os.NewSyscallError("sleep", errno)
+		err := sysSleep(end - t)
+		if err != nil {
+			return 0, err
 		}
 		t = Nanoseconds()
 	}
 	return t, nil
 }
+
+func sysSleep(t int64) os.Error {
+	errno := syscall.Sleep(t)
+	if errno != 0 && errno != syscall.EINTR {
+		return os.NewSyscallError("sleep", errno)
+	}
+	return nil
+}