Merge pull request #1301 from Lomanic/issue1298

[process][windows] Use WaitForSingleObject with a 0 delay in PidExistsWithContext

Author: shirou

process/process_windows.go

@@ -285,8 +285,7 @@ func PidExistsWithContext(ctx context.Context, pid int32) (bool, error) {
 		}
 		return false, err
 	}
-	const STILL_ACTIVE = 259 // https://docs.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-getexitcodeprocess
-	h, err := windows.OpenProcess(processQueryInformation, false, uint32(pid))
+	h, err := windows.OpenProcess(windows.SYNCHRONIZE, false, uint32(pid))
 	if err == windows.ERROR_ACCESS_DENIED {
 		return true, nil
 	}
@@ -296,10 +295,9 @@ func PidExistsWithContext(ctx context.Context, pid int32) (bool, error) {
 	if err != nil {
 		return false, err
 	}
-	defer syscall.CloseHandle(syscall.Handle(h))
-	var exitCode uint32
-	err = windows.GetExitCodeProcess(h, &exitCode)
-	return exitCode == STILL_ACTIVE, err
+	defer windows.CloseHandle(h)
+	event, err := windows.WaitForSingleObject(h, 0)
+	return event == uint32(windows.WAIT_TIMEOUT), err
 }
 
 func (p *Process) PpidWithContext(ctx context.Context) (int32, error) {