Addressed review comments

Signed-off-by: Oleg Solodkov <oleg.solodkov@xored.com>

pkg/networkservice/common/mechanisms/recvfd/server_test.go

@@ -34,7 +34,6 @@ import (
 	"github.com/networkservicemesh/api/pkg/api/networkservice/mechanisms/cls"
 	"github.com/networkservicemesh/api/pkg/api/networkservice/mechanisms/common"
 	"github.com/networkservicemesh/api/pkg/api/networkservice/mechanisms/kernel"
-	"github.com/networkservicemesh/sdk/pkg/tools/grpcfdutils"
 	"github.com/stretchr/testify/require"
 	"go.uber.org/goleak"
 	"google.golang.org/grpc"
@@ -46,14 +45,14 @@ import (
 	"github.com/networkservicemesh/sdk/pkg/networkservice/common/mechanisms/sendfd"
 	"github.com/networkservicemesh/sdk/pkg/networkservice/core/chain"
 	"github.com/networkservicemesh/sdk/pkg/networkservice/core/next"
+	"github.com/networkservicemesh/sdk/pkg/tools/grpcfdutils"
 	"github.com/networkservicemesh/sdk/pkg/tools/grpcutils"
 	"github.com/networkservicemesh/sdk/pkg/tools/sandbox"
 )
 
 type checkRecvfdServer struct {
-	onRecvFile map[string]func()
-
-	t *testing.T
+	t                     *testing.T
+	onFileClosedCallbacks map[string]func()
 }
 
 func (n *checkRecvfdServer) Close(ctx context.Context, conn *networkservice.Connection) (*empty.Empty, error) {
@@ -76,6 +75,16 @@ func (n *checkRecvfdServer) Request(ctx context.Context, request *networkservice
 	return next.Server(ctx).Request(ctx, request)
 }
 
+func (n *checkRecvfdServer) onRecvFile(fileName string, file *os.File) {
+	// checking a file is closed by recvfd by setting a finalizer
+	runtime.SetFinalizer(file, func(file *os.File) {
+		onFileClosedCallback, ok := n.onFileClosedCallbacks[fileName]
+		if ok {
+			onFileClosedCallback()
+		}
+	})
+}
+
 func createFile(fileName string, t *testing.T) (inodeURLStr string, fileClosedContext context.Context, cancelFunc func()) {
 	f, err := os.Create(fileName)
 	require.NoError(t, err, "Failed to create and open a file: %v", err)
@@ -134,7 +143,7 @@ func TestRecvfdClosesSingleFile(t *testing.T) {
 	var testChain = chain.NewNetworkServiceServer(
 		&checkRecvfdServer{
 			t: t,
-			onRecvFile: map[string]func(){
+			onFileClosedCallbacks: map[string]func(){
 				inodeURLStr: cancelFunc,
 			},
 		},
@@ -208,8 +217,8 @@ func TestRecvfdClosesMultipleFiles(t *testing.T) {
 
 	var testChain = chain.NewNetworkServiceServer(
 		&checkRecvfdServer{
-			t:          t,
-			onRecvFile: onFileClosedFuncs,
+			t:                     t,
+			onFileClosedCallbacks: onFileClosedFuncs,
 		},
 		recvfd.NewServer())
 

pkg/registry/common/recvfd/server_test.go

@@ -21,6 +21,7 @@ package recvfd_test
 import (
 	"context"
 	"net/url"
+	"os"
 	"path"
 	"runtime"
 	"testing"
@@ -50,9 +51,8 @@ import (
 )
 
 type checkNseRecvfdServer struct {
-	onRecvFile map[string]func()
-
-	t *testing.T
+	t                     *testing.T
+	onFileClosedCallbacks map[string]func()
 }
 
 func (n *checkNseRecvfdServer) Unregister(ctx context.Context, endpoint *registry.NetworkServiceEndpoint) (*empty.Empty, error) {
@@ -79,6 +79,15 @@ func (n *checkNseRecvfdServer) Find(query *registry.NetworkServiceEndpointQuery,
 	return next.NetworkServiceEndpointRegistryServer(server.Context()).Find(query, server)
 }
 
+func (n *checkNseRecvfdServer) onRecvFile(fileName string, file *os.File) {
+	runtime.SetFinalizer(file, func(file *os.File) {
+		onFileClosedCallback, ok := n.onFileClosedCallbacks[fileName]
+		if ok {
+			onFileClosedCallback()
+		}
+	})
+}
+
 func getFileInfo(fileName string, t *testing.T) (inodeURLStr string, fileClosedContext context.Context, cancelFunc func()) {
 	fileClosedContext, cancelFunc = context.WithCancel(context.Background())
 
@@ -109,8 +118,8 @@ func TestNseRecvfdServerClosesFile(t *testing.T) {
 	)
 
 	var checkRecvfdServer = &checkNseRecvfdServer{
-		t:          t,
-		onRecvFile: make(map[string]func()),
+		t:                     t,
+		onFileClosedCallbacks: make(map[string]func()),
 	}
 
 	var nseRegistry = registrychain.NewNetworkServiceEndpointRegistryServer(
@@ -151,7 +160,7 @@ func TestNseRecvfdServerClosesFile(t *testing.T) {
 	// setting onRecvFile after starting the server as we're re-creating a socket in grpcutils.ListenAndServe
 	// in registry case we're passing a socket
 	inodeURLStr, fileClosedContext, cancelFunc := getFileInfo(testFileName, t)
-	checkRecvfdServer.onRecvFile[inodeURLStr] = cancelFunc
+	checkRecvfdServer.onFileClosedCallbacks[inodeURLStr] = cancelFunc
 
 	var testEndpoint = &registry.NetworkServiceEndpoint{
 		Name:                "test-endpoint",

pkg/tools/grpcfdutils/transceiver.go

@@ -14,23 +14,28 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// +build linux
+
+// Package grpcfdutils provides utilities for grpcfd library
 package grpcfdutils
 
 import (
 	"net"
 	"os"
-	"runtime"
 
 	"github.com/edwarnicke/grpcfd"
 )
 
+// NotifiableFDTransceiver - grpcfd.Transceiver wrapper checking that received FDs are closed
+//     OnRecvFile - callback receiving inodeURL string and a file received by grpcfd
 type NotifiableFDTransceiver struct {
 	grpcfd.FDTransceiver
 	net.Addr
 
-	OnRecvFile map[string]func()
+	OnRecvFile func(string, *os.File)
 }
 
+// RecvFileByURL - wrapper of grpcfd.FDRecver method invoking callback when a file is received by grpcfd
 func (w *NotifiableFDTransceiver) RecvFileByURL(urlStr string) (<-chan *os.File, error) {
 	recv, err := w.FDTransceiver.RecvFileByURL(urlStr)
 	if err != nil {
@@ -40,12 +45,7 @@ func (w *NotifiableFDTransceiver) RecvFileByURL(urlStr string) (<-chan *os.File,
 	var fileCh = make(chan *os.File)
 	go func() {
 		for f := range recv {
-			runtime.SetFinalizer(f, func(file *os.File) {
-				onFileClosedFunc, ok := w.OnRecvFile[urlStr]
-				if ok {
-					onFileClosedFunc()
-				}
-			})
+			w.OnRecvFile(urlStr, f)
 			fileCh <- f
 		}
 	}()