spanner: switch the session keepalive method from GetSession to SELECT 1

Change-Id: Idf8ed090f628a6c8d1ffe7b347b93b10471380cd
Reviewed-on: https://code-review.googlesource.com/c/gocloud/+/54090
Reviewed-by: Knut Olav Løite <koloite@gmail.com>
Reviewed-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Shanika Kuruppu <skuruppu@google.com>

spanner/internal/testutil/inmem_spanner_server.go

@@ -633,9 +633,6 @@ func (s *inMemSpannerServer) GetSession(ctx context.Context, req *spannerpb.GetS
 	if err := s.simulateExecutionTime(MethodGetSession, req); err != nil {
 		return nil, err
 	}
-	s.mu.Lock()
-	s.pings = append(s.pings, req.Name)
-	s.mu.Unlock()
 	if req.Name == "" {
 		return nil, gstatus.Error(codes.InvalidArgument, "Missing session name")
 	}
@@ -694,6 +691,11 @@ func (s *inMemSpannerServer) ExecuteSql(ctx context.Context, req *spannerpb.Exec
 	if err := s.simulateExecutionTime(MethodExecuteSql, req); err != nil {
 		return nil, err
 	}
+	if req.Sql == "SELECT 1" {
+		s.mu.Lock()
+		s.pings = append(s.pings, req.Session)
+		s.mu.Unlock()
+	}
 	if req.Session == "" {
 		return nil, gstatus.Error(codes.InvalidArgument, "Missing session name")
 	}

spanner/session.go

@@ -228,7 +228,10 @@ func (s *session) ping() error {
 	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
 	defer cancel()
 	// s.getID is safe even when s is invalid.
-	_, err := s.client.GetSession(contextWithOutgoingMetadata(ctx, s.md), &sppb.GetSessionRequest{Name: s.getID()})
+	_, err := s.client.ExecuteSql(contextWithOutgoingMetadata(ctx, s.md), &sppb.ExecuteSqlRequest{
+		Session: s.getID(),
+		Sql:     "SELECT 1",
+	})
 	return err
 }
 

spanner/session_test.go

@@ -371,7 +371,7 @@ func TestTakeFromIdleListChecked(t *testing.T) {
 	// Inject session error to server stub, and take the session from the
 	// session pool, the old session should be destroyed and the session pool
 	// will create a new session.
-	server.TestSpanner.PutExecutionTime(MethodGetSession,
+	server.TestSpanner.PutExecutionTime(MethodExecuteSql,
 		SimulatedExecutionTime{
 			Errors: []error{newSessionNotFoundError("projects/p/instances/i/databases/d/sessions/s")},
 		})
@@ -451,7 +451,7 @@ func TestTakeFromIdleWriteListChecked(t *testing.T) {
 	// Inject session error to mockclient, and take the session from the
 	// session pool, the old session should be destroyed and the session pool
 	// will create a new session.
-	server.TestSpanner.PutExecutionTime(MethodGetSession,
+	server.TestSpanner.PutExecutionTime(MethodExecuteSql,
 		SimulatedExecutionTime{
 			Errors: []error{newSessionNotFoundError("projects/p/instances/i/databases/d/sessions/s")},
 		})
@@ -1303,7 +1303,7 @@ func TestSessionHealthCheck(t *testing.T) {
 	}
 
 	server.TestSpanner.Freeze()
-	server.TestSpanner.PutExecutionTime(MethodGetSession,
+	server.TestSpanner.PutExecutionTime(MethodExecuteSql,
 		SimulatedExecutionTime{
 			Errors:    []error{newSessionNotFoundError("projects/p/instances/i/databases/d/sessions/s")},
 			KeepError: true,
@@ -1319,7 +1319,7 @@ func TestSessionHealthCheck(t *testing.T) {
 	})
 
 	server.TestSpanner.Freeze()
-	server.TestSpanner.PutExecutionTime(MethodGetSession, SimulatedExecutionTime{})
+	server.TestSpanner.PutExecutionTime(MethodExecuteSql, SimulatedExecutionTime{})
 	server.TestSpanner.Unfreeze()
 
 	// Test garbage collection.