clientv3: add Ctx() to return context of session

Signed-off-by: Wenkang Zhang <[email protected]>

client/v3/concurrency/session.go

@@ -32,6 +32,7 @@ type Session struct {
 	opts   *sessionOptions
 	id     v3.LeaseID
 
+	ctx    context.Context
 	cancel context.CancelFunc
 	donec  <-chan struct{}
 }
@@ -61,11 +62,14 @@ func NewSession(client *v3.Client, opts ...SessionOption) (*Session, error) {
 	}
 
 	donec := make(chan struct{})
-	s := &Session{client: client, opts: ops, id: id, cancel: cancel, donec: donec}
+	s := &Session{client: client, opts: ops, id: id, ctx: ctx, cancel: cancel, donec: donec}
 
 	// keep the lease alive until client error or cancelled context
 	go func() {
-		defer close(donec)
+		defer func() {
+			close(donec)
+			cancel()
+		}()
 		for range keepAlive {
 			// eat messages until keep alive channel closes
 		}
@@ -82,6 +86,12 @@ func (s *Session) Client() *v3.Client {
 // Lease is the lease ID for keys bound to the session.
 func (s *Session) Lease() v3.LeaseID { return s.id }
 
+// Ctx is the context attached to the session, it is canceled when the lease is orphaned, expires, or
+// is otherwise no longer being refreshed.
+func (s *Session) Ctx() context.Context {
+	return s.ctx
+}
+
 // Done returns a channel that closes when the lease is orphaned, expires, or
 // is otherwise no longer being refreshed.
 func (s *Session) Done() <-chan struct{} { return s.donec }

tests/integration/clientv3/concurrency/session_test.go

@@ -82,3 +82,32 @@ func TestSessionTTLOptions(t *testing.T) {
 	}
 
 }
+
+func TestSessionCtx(t *testing.T) {
+	cli, err := integration2.NewClient(t, clientv3.Config{Endpoints: exampleEndpoints()})
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer cli.Close()
+	lease, err := cli.Grant(context.Background(), 100)
+	if err != nil {
+		t.Fatal(err)
+	}
+	s, err := concurrency.NewSession(cli, concurrency.WithLease(lease.ID))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer s.Close()
+	assert.Equal(t, s.Lease(), lease.ID)
+
+	childCtx, cancel := context.WithCancel(s.Ctx())
+	defer cancel()
+
+	go s.Orphan()
+	select {
+	case <-childCtx.Done():
+	case <-time.After(time.Millisecond * 100):
+		t.Fatal("child context of session context is not canceled")
+	}
+	assert.Equal(t, childCtx.Err(), context.Canceled)
+}