[#1270] neofs-node: Add timeout for grpc GracefulStop()

GracefulStop() may be blocked until all server-side streams
are finished. There is no control over such streams yet, so
application may be frozen in shutdown stage.

Naive solution is to add timeout for GracefulStop(). At this
point healthy connection will be finished and unhealthy
connections will be terminated by Stop().

Signed-off-by: Alex Vanin <alexey@nspcc.ru>

cmd/neofs-node/grpc.go

@@ -4,6 +4,7 @@ import (
 	"crypto/tls"
 	"fmt"
 	"net"
+	"time"
 
 	grpcconfig "github.com/nspcc-dev/neofs-node/cmd/neofs-node/config/grpc"
 	"github.com/nspcc-dev/neofs-node/pkg/util/logger"
@@ -95,7 +96,19 @@ func stopGRPC(name string, s *grpc.Server, l *logger.Logger) {
 
 	l.Info("stopping gRPC server...")
 
+	// GracefulStop() may freeze forever, see #1270
+	done := make(chan struct{})
+	go func() {
 		s.GracefulStop()
+		close(done)
+	}()
+
+	select {
+	case <-done:
+	case <-time.After(1 * time.Minute):
+		l.Info("gRPC cannot shutdown gracefully, forcing stop")
+		s.Stop()
+	}
 
 	l.Info("gRPC server stopped successfully")
 }