lib/osutil: Use x/sys/windows for SetLowPriority

lib/osutil/lowprio_windows.go

@@ -7,43 +7,19 @@
 package osutil
 
 import (
-	"syscall"
-
 	"github.com/pkg/errors"
-)
+	"golang.org/x/sys/windows"
-
-const (
-	// https://docs.microsoft.com/windows/win32/api/processthreadsapi/nf-processthreadsapi-setpriorityclass
-	aboveNormalPriorityClass   = 0x00008000
-	belowNormalPriorityClass   = 0x00004000
-	highPriorityClass          = 0x00000080
-	idlePriorityClass          = 0x00000040
-	normalPriorityClass        = 0x00000020
-	processModeBackgroundBegin = 0x00100000
-	processModeBackgroundEnd   = 0x00200000
-	realtimePriorityClass      = 0x00000100
 )
 
 // SetLowPriority lowers the process CPU scheduling priority, and possibly
 // I/O priority depending on the platform and OS.
 func SetLowPriority() error {
-	modkernel32 := syscall.NewLazyDLL("kernel32.dll")
+	handle, err := windows.GetCurrentProcess()
-	setPriorityClass := modkernel32.NewProc("SetPriorityClass")
-
-	if err := setPriorityClass.Find(); err != nil {
-		return errors.Wrap(err, "find proc")
-	}
-
-	handle, err := syscall.GetCurrentProcess()
 	if err != nil {
-		return errors.Wrap(err, "get process handler")
+		return errors.Wrap(err, "get process handle")
 	}
-	defer syscall.CloseHandle(handle)
+	defer windows.CloseHandle(handle)
 
-	res, _, err := setPriorityClass.Call(uintptr(handle), belowNormalPriorityClass)
+	err = windows.SetPriorityClass(handle, windows.BELOW_NORMAL_PRIORITY_CLASS)
-	if res != 0 {
-		// "If the function succeeds, the return value is nonzero."
-		return nil
-	}
 	return errors.Wrap(err, "set priority class") // wraps nil as nil
 }