fix(agent): retire replaced tunnel sessions (#541)

go-gost/x/registry/chain.go

@@ -28,7 +28,13 @@ func (r *chainRegistry) Register(name string, v chain.Chainer) error {
 }
 
 func (r *chainRegistry) replace(name string, v chain.Chainer) {
-	r.m.Store(name, v)
+	old, loaded := r.m.Swap(name, v)
+	if !loaded {
+		return
+	}
+	if retirer, ok := old.(interface{ Retire() }); ok {
+		retirer.Retire()
+	}
 }
 
 func (r *chainRegistry) Get(name string) chain.Chainer {

go-gost/x/registry/chain_test.go

@@ -16,6 +16,15 @@ func (c testChainer) Route(context.Context, string, string, ...chain.RouteOption
 	return c.route
 }
 
+type retiringTestChainer struct {
+	testChainer
+	retired bool
+}
+
+func (c *retiringTestChainer) Retire() {
+	c.retired = true
+}
+
 type testRoute struct {
 	nodes []*chain.Node
 }
@@ -49,3 +58,20 @@ func TestReplaceChainOverwritesExistingRegistration(t *testing.T) {
 		t.Fatalf("expected replacement chain route, got %#v", route)
 	}
 }
+
+func TestReplaceChainRetiresPreviousRegistration(t *testing.T) {
+	name := "replace_chain_retire_tdd"
+	ChainRegistry().Unregister(name)
+	defer ChainRegistry().Unregister(name)
+
+	old := &retiringTestChainer{}
+	if err := ChainRegistry().Register(name, old); err != nil {
+		t.Fatalf("register old chain: %v", err)
+	}
+	if err := ReplaceChain(name, testChainer{}); err != nil {
+		t.Fatalf("replace chain: %v", err)
+	}
+	if !old.retired {
+		t.Fatal("previous chain was not retired")
+	}
+}