Merge pull request #1012 from Astone-Chou/lint

improve code quality

server/grpc/grpc.go

@@ -222,7 +222,9 @@ func (g *grpcServer) handler(srv interface{}, stream grpc.ServerStream) error {
 	// set the timeout if we have it
 	if len(to) > 0 {
 		if n, err := strconv.ParseUint(to, 10, 64); err == nil {
-			ctx, _ = context.WithTimeout(ctx, time.Duration(n))
+			var cancel context.CancelFunc
+			ctx, cancel = context.WithTimeout(ctx, time.Duration(n))
+			defer cancel()
 		}
 	}